Controlled Pollination Is a Horticultural Practice That Has Been a Part of the Tree Fruit Industry for Close to Eighty Years

Controlled Pollination is a horticultural practice that has been a part of the tree fruit industry for close to eighty years. The ability to effectively supplement natural pollination in orchards had long been the dream of orchardists. Around 1930, during the beginning years of the Great Depression, farm advisors in Washington State, recognizing the need to improve upon the economic efficiency of apple orchards, advised growers to remove less profitable varieties of apples from their orchards. The farm advisors recommended lower yielding and lower value apples with blocks containing Red Delicious and Winesaps. After the trees were in their fourth to fifth leaf, it was discovered that while Red Delicious did a good job of pollinizing the Winesaps, the Winesaps were not pollinizing the Red Delicious. The reason for this was that the Winesap apple was a triploid, and could not be used to pollinize any other variety of apple.

Inadvertently, the farm advisors, by recommending that Winesap be planted with Red Delicious created a large scale cross-pollination crisis, which resulted in inadequate fruit set and devastating financial problems for many growers in central Washington. The need to find a solution to the problem of inadequate cross-pollination in these orchards, was the force that brought Mina and Vernon Firman and Leo Antles, independently to find a solution of the pollination dilemma. Working with research information that was previously undertaken by Cornell University, it took many years of trial and error and hard work by these industry pioneers to develop the ability to produce the high quality pollens and application methods that orchardists have available today.

BEGINNINGS OF CONTROLLED POLLINATION When the practice of Controlled Pollination was in its infancy, housewives in the Wenatchee Washington area were employed in the spring to gather apple flowers in orchards from which pollen could be extracted. There are a number of archived photographs of these housewives working off of orchard ladders with coffee cans strapped to their hips with screens over the top. In these photographs, the housewives can be seen picking individual flowers from apple trees, and then rubbing the flowers over the screen to remove the yellow anthers. The anthers were then cured until the pollen dehisced from the anther.

Using an artist‘s brush, the pollen was then brushed by hand onto the individual king blooms in the blossom clusters. The results that were achieved from the hand application of apple pollen was an unqualified success! The experiment which occurred in north central Washington, while being very labor intensive, proved the value of Controlled Pollination as a means of overcoming pollination problems.

From this rather humble beginning, the horticultural practice of Controlled Pollination has developed over the years and is now commonly employed by tree fruit growers throughout the world as a means of remedying a variety of pollination related problems. Controlled Pollination has proven beneficial in improving the overall fruit set in orchards, improving fruit size and quality, and the profitability of orchards that were considered only marginally profitable. The cultural practice of Controlled Pollination is used to improve the production of Apples, Cherries, Apricots, Plums, Pears, Prunes, Almonds, Kiwi’s, Pistachios, Olives, Pecans and other specialty fruit and nut varieties.

PHOTO OF ORCHARD WITH BLOSSOM THINNERS

THE PROCESS OF PRODUCING POLLEN The process of producing horticultural pollen begins with growers who have orchards that annually produce more blossoms on their trees than is required to set good commercial crops of fruit. The process of thinning these blossoms from the trees, allows the energy that would be expended for a tree to produce the many small fruits that are normally set without blossom thinning, to be redirected into producing larger fruits of higher quality. In comparison to trees in which the practice of blossom thinning has not been incorporated, blossom thinned trees consistently produce fruits of larger size and higher quality. Blossom thinning also produces many resting spurs which produce a stronger, more consistent bloom for the following season.

When blossom development is at the proper stage of maturity, crews of agricultural workers are brought into the orchard to thin some of the blossoms that are in the balloon stage of development. Timing is very critical at this stage of producing pollen, if the pollen produced is to be of high viability.

1. At the end of the day, the blossoms must be quickly taken to the processing site, where the flowers go through a machine where they are shredded and the anthers separated from the flower parts. The anthers are then cleaned by hand to remove any remaining flower parts. 2. Once the anthers are cleaned, they are then spread over paper covered trays and then placed on drying racks in climatically controlled drying rooms. Here is a critical juncture in the process of producing high viability horticultural pollen. The anthers, which are the male part of the flower on which the pollen is retained, must be dried at relatively low temperatures until the pollen grains begin to dehisce (come free) from the anther. This process can take anywhere from 16 to 48 hours, depending upon the variety of pollen, and the environmental conditions present. 3. Information for each batch of pollen produced is recorded, indicating the orchard from which it was gathered, the variety, date and time it was placed on the drying racks. 4. Once the anthers and freed pollen are at the proper stage of dryness, the pollen is then taken up and placed into sealed mason jars, which are then placed into commercial freezers where the pollen is kept frozen in order to maintain its viability. 5. When the pollen collection season has ended, samples of pollen from each collecting site and from each day is tested for viability. The pollen is again tested in the spring, before the growing season begins, to ensure that the pollen has remained viable throughout its storage. Scientists have found that horticultural pollen, when properly produced and cared for, can remain frozen for two to five or more years without any significant loss of viability.

Natural Cross Pollination With natural cross pollination, honey bees, which are the primary pollinators for tree fruits, must work their way down orchard rows before they come to a pollinizer variety, where they will hopefully work the tree and pick up viable pollen on their bodies to transport to receptive blossoms on the main crop variety further down the row.

Nature’s Way Nature‘s way of pollinating flowers can be a slow and sometimes ineffective process when weather conditions are not conducive to bee activity, pollen viability, and flower receptivity. Studies have demonstrated that there is very little bee activity below 50° F. Bee flight generally does not take place in sufficient quantity for orchard pollinization until 60° F is reached.

Multiseeded Varieties of Tree Fruits Studies have shown that multi-seeded varieties of tree fruits can require up to 50 visits per flower from honey bees, in order to be successfully and completely pollinized. Consider the number of individual visits necessary for honey bees to pollinate just 10% of the flowers of a mature apple tree which may contain 10 to 12,000 flowers.

With Controlled Pollination With Controlled Pollination, pollen that is consistently higher in viability than that which is found naturally in orchards (due to the varying maturity level of blossoms in orchards), is carried by the 15 to 30,000 worker bees in each hive directly from the hive into the orchard, each time the bees leave the hive, passing through the pollen dispenser placed on the front of the hive. Worker bees each leave the hive and return 10 to 20 times per day, and each time they leave they pick up viable pollen from the pollen dispenser, and in turn take pollen to the most receptive flowers in the orchard, flowers that have most recently opened, to which they are instinctively attracted. That can add up to 400,000 visits or more from each hive of bees —- bees that are carrying highly viable pollen directly to the most receptive flowers.

Additionally, if air application methods are used, honey bees and other insects will help to redistribute pollen that the grower has applied to the orchard. Studies have shown that pollen that has been applied via an air application, tends to stimulate additional bee activity. Pollen dispensers and other means of pollen application will be discussed in more detail later in this publication.

STUDIES HAVE PROVEN THE EFFECTIVENESS OF CONTROLLED POLLINATION Over the years, numerous studies have been conducted by respected university research facilities throughout the United States and the world , and by independent scientists, to assess the effectiveness and the results that can be achieved through the use of Controlled Pollination. The results of these studies have almost universally established the effectiveness of Controlled Pollination in correcting the following problems.

PROBLEM CAUSE Poor Fruit Set Inadequate Cross Pollination

Excessive Fruit Drop Inadequate Cross Pollination Small and Lopsided Fruit Inadequate Cross Pollination

Poor Quality Fruit Inadequate Cross Pollination

 In a study conducted by Dr. Daniel Mayer, of the Department of Entomology at Washington State University at Prosser, Washington, Dr. Mayer performed controlled tests with pollen dispensers for Bing Cherry pollination. Dr. Mayer states in his findings, “That in all tests, honey bees effectively moved pollen from inserts to flowers accomplishing pollination.”

Mayer, Dr. Daniel F. . "Pollination of Cherries." Washington Sate Horticultural Association. Department of Entomology, WSU, IAREC. Yakima Convention Center, Yakima, WA. 8 Dec. 1993. Speech.

The results of a large scale test conducted by Dr. Mayer over a three year period with Cherries is provided on the following page in Table 3.

Table 3 Date Treatment Tons Per Acre 1983 Bouquets 6 1984 No Supplemental Pollen 3 1985 Pollen Inserts 15

Note: Yield of Cherries as a result of various pollen supply sources. Mayer, Dr. Daniel F. . "Pollination of Cherries." Washington Sate Horticultural Association. Department of Entomology, WSU, IAREC. Yakima Convention Center, Yakima, WA. 8 Dec. 1993. Speech. In a publication by the Cooperative Extension Service, College of Agriculture, University of Illinois at Urbana– Champaign, entitled Pollen Inserts for Apple Pollination, it states:

Using pollen inserts on colonies of honey bees is the most effective way to temporarily increase fruit set in an improperly planted orchard. These inserts are also of value in properly planted orchards during those years of when the major pollinating variety has a light bloom ……or there is a lack of a coordinated bloom. This method of increasing pollination had been used by Illinois fruit growers for many years and has produced good crops in orchards that were previously unprofitable. See page 18 for the entire study.

The Relative Effectiveness of Pear Pollen Sources, is the title of a paper written by Herman G. Thoennissen, of AgriNorthwest, Kennewick Washington. In the paper, Mr. Thoennissen states:

Research and observations in commercial orchards have shown that cross pollination Improves fruits and increases seed content. High seed content has been linked to:

 Fruit spears being less prone to June drop  Higher fruit mineral levels, especially CA  Larger and more evenly shaped fruit  Increased fruit firmness

In his summary, Mr. Thoennissen states:

Beehive pollen dispensers are an economical and successful source of pollen and are used to pollinate crops as part of the regular management practices.

For the entire study by Hermann Thoennissen on pear pollinaton, see page 21.

Kieran Lavelle, Top Fruit Advisor, in the Netherlands, in a paper written in the spring of 2000 states:

To improve pollination in an orchard……..work with Controlled Pollination.1 This method was originally introduced in the USA and for the last 6 years has been used in Holland. With this method, (pollen which is imported from the USA) is brought into an orchard by applying it to a Bee Booster ® (pollen dispenser), which is placed before a beehive. When the bees are foraging, they transfer the pollen to apple flowers. In many tests, this pollen proved to be as viable as fresh pollen. For orchards with a shortage of pollination, this might be a way to improve this situation.

Pollen Dispensers Increase Fruit Set in Almonds

From Dag A. Weinbaum , S.A. Thorp and R.W. Eisikowitch, a study published in the Journal of Apicultural Research in 2000, Vol. 39, they write, Pollen dispensers increase fruit set and yield in Almonds under some commercial conditions. Pollen dispensers increased the fruit set percentage and yield in the (orchards where there was a 2 to 1 ratio. One pollinizer row to two of the main crop Nonpareil variety). The impact of pollen dispensers was significant at 50 meters (150 feet), but was diminished at 150 meters(450 feet).2

1 Lavelle, Kieran. ―Improving Fruit Set of Triploid Varieties.‖ Agriculture and Rural Development Spring (2000): 5. http://www.dardni.gov.uk. Web. 10 Nov. 2010 2 Dag, A, SA Weinbaum, RW Thorp, and D Eisilowitch. ―Pollen Disepensors (inserts) increase fruit set and yield in almonds under some commercial conditions.‖ Journal of Apicultural Research 39 (2000): pp.117-123. http://www.ibra.org.uk/. Web. 11 Nov. 2010 5

EFFECTIVE POLLINATION PERIOD

When The Weather Becomes Favorable, first the buds begin to swell and then the flowers emerge. The development of pollen grains and the embryo sac proceed. As the petals unfold, the stigma becomes receptive to pollination and the anthers dehisce, releasing pollen grains. Pollen grains on the receptive stigma germinates and starts growing down the style. In Apple and Pear, under ideal conditions, the pollen tubes may traverse the style in 48 hours.

Pollination and Fertilization are both critical to fruit set and final yield. Pollination is the arrival of pollen (the male part of the reproductive cycle) on the stigma of the pistil (the female part of the flower). Under optimal conditions, the pollen germinates producing a pollen tube which grows through the tissues of the stigma, style and ovary to the ovule, which contains the egg. The fusion of sperm and egg is fertilization. The product of fertilization is the embryo which develops into the young seedling within the ovule. After fertilization, the ovule develops into the seed within the ovary, which develops into the fruit. The successful completion of these two processes is essential for fruit set.

The Blooming Period of the pollinizer variety of tree in the orchard should slightly precede that of the main variety for optimum pollination. However the sequence of bloom coordination between the pollinizer variety and the main variety can vary substantially from year to year. Pollen should start dehiscing from the pollinizer variety before the anther dehiscence of the main variety, rather than after it in order to provide the viable pollen necessary for pollination. Flowers are most receptive to pollination in the butter cup stage of development, just as they are opening. This is also the period in which flowers are the most attractive to honey bees, as their fragrance is stronger. The receptivity of flowers begins to decline once the flowers are fully open.

Pollen Viability Some tree fruit varieties produce pollen that is infertile and which germinates poorly if at all. Triploid varieties of apples are examples of a variety whose pollen has poor viability. Under field conditions at moderate temperatures, high humidity and high light intensity, pollen has a short life and is viable for only a few hours. Cool temperatures , low humidity and less intense light conditions will prolong a flower‘s receptivity to pollination for several days. However, this extended receptiveness to pollination is dependent upon the temperature and general weather conditions, as well as the nutritional condition of the tree.

Inadequate Chilling Hours is one of the major reasons why it is difficult to set good crops of deciduous fruit in areas where there are insufficient chilling hours to bring trees out of dormancy effectively. Inadequate chilling hours produces many serious consequences to the ability of trees to produce fruit. The coordination of the main crop variety and that of the pollinizer variety can be seriously out of coordination. The blossoms can have defects such as multiple stigmas, deformed filaments and anthers that contain very little pollen. In adequate chill hours are a very real problem in the Central Valley of California. Low chill hours do not enhance production of plant hormones. Gibberellin is needed to prevent abscission of fruit— fruit fall. Chemically it can be applied after fruit set (petal fall), at a concentration of 1ml of hormone spray to 10 liters of water.

Controlled Pollination is a well recognized and established cultural practice that is regularly incorporated into many orchard management programs, as a means of correcting seasonal pollination problems. When weather is a problem or there is insufficient coordinated bloom for adequate pollination,

Fertilization: Union of sperm nucleus with egg cell nucleus inside ovule which forms zygote and embryo through cell division.

Second sperm nuclei unites with polar nuclei to form nutritive endosperm.

or if the bloom has been damaged by frost, Controlled Pollination can be used to improve the pollination and fruit set of orchards. Timing the application of pollen is very critical. The best results are usually achieved by scheduling the pollen application over the entire blooming period. If a grower is waiting to see if bloom overlap may more closely coordinate before making the decision to apply pollen, then the grower may be losing the one opportunity they have to set a good crop for that year. If flower receptivity and pollen viability are lost, or if there is insufficient time for the pollen tube to grow down the style and fertilize the ovule, then the application of pollen will not produce the needed results. It is important to plan ahead for the application of pollen, whenever possible. The results that are achieved will be greatly improved.

Effective Pollination Period The Effective Pollination Period (EPP) is simply described as the longevity of the ovule minus the length of time required for the pollen tube to reach the ovule to deliver sperm to the egg so that fertilization can take place. See Chart Number 5.

Chart Number 5

Low Nitrogen Flowers Receptive Period of Stigmas Effective Pollination Period

Pollen Tube Growth Period

Longevity Of Ovule

High Nitrogen Flowers Receptive Period of Stigmas Effective Pollination Period

Pollen Tube Growth Period

Longevity Of Ovule

1 2 3 4 5 6 7 8 9 10 11 12 13 Days After Anthesis (flower is fully open and functional)

Chart Number 6 Factors Affecting The Effective Pollination Period Factor Stigma Receptivity Ovule Longevity Pollen Tube Growth Nitrogen Deficiency Unknown Decrease Unknown High Temperatures Decrease Decrease Decrease Low Temperatures Unknown Increase Decrease Wind Decrease N/A N/A Temperature & Pollen Tube Growth in Apple 60

Tube Growth 10 Relative Pollen 0 41 42.8 44.6 46.4 48.2 50 51.8 53.6 55.4 57.2 59

Mean Temperature (F°) over 24 hrs 7

Apple Pollen Germination Cox Orange Pipin / Idared

) 100

20 (After 6 Hours (After 0

of Germination Percent 8 to 10° C 14 to 16° C 19 to 21° C 24 to 26° C 28 to 30° C 57.2 to 60.8 F 66.2 to 69.8°F 75.2 to 78.8 °F 82.4 to 86°F 46.4 to 50°F

Cultural Practices that Affect Pollination and Fruit Set

Nutrition The nutrition of an orchard has a large impact on pollination and fruit set.

Nitrogen Application = Ovule Longevity: Nitrogen is particularly important for the number of days that an ovule stays viable. Viability has been improved in deciduous trees by a summer application of nitrogen, despite the fact the trees were not nitrogen-deficient (Williams 1965). The use of nitrogen should be considered to enhance ovule viability, fruit set and yield. Nitrogen that is applied in the spring, can not improve the viability of the ovule, or extend the Effective Pollination Period. Creating a good nitrogen reserved in the flower buds is the main thing that must be achieved. Urea sprays applied post harvest can accomplish this. By creating a good nitrogen reserve, a longer Effective Pollination Period is achieved. Ovule longevity is very important in determining fruit set. After a specific period of time, if fertilization has not taken place, the embryo sac then becomes nonviable and fertilization can not occur, even if pollination and pollen tube growth have occurred.

Boron Application = Pollen Tube Growth. It has long been known that boron is essential for pollen germination, for the successful growth of a pollen tube through the stigma, style and ovary to the ovule, and for mitotic divisions necessary to produce sperm, (see Lovatt and Drugger, 1984). Pollen from trees with a good Boron level stays viable for a longer period. Growth of the pollen tube through the style is strongly temperature related. For example, with an average daily temperature of 7°C (44.6°F), it takes 10 days before the pollen tube reaches the ovule. With an average temperature of 12° C (53.6°F), it takes 5 days to reach the ovule. At 15°C (59°F) it only takes two days for the pollen tube to reach the ovule. For this reason it is very important for the more northern fruit growing areas to keep the boron levels high. Boron applied as a fall or spring application to trees that were not boron deficient increased fruit set in a number of different deciduous tree fruits (Batjer and Rogers, 1953; Chaplin 1977; Thompson and Batjer 1950). This was especially apparent when cooler temperatures affected the region during bloom, (Hanson and Breen, 1985).

Multiple Pollen Source Effect: This is an effect observed by PollenPro and many growers with whom we have worked. The effect was first noted by apple growers in California. They noticed that when a mixture of Red Delicious and Golden Delicious apple pollen was applied to a blocks of Fuji‘s, the resulting rate of pollination and fruit set appeared to be higher than that which occurred in a similar block of Fuji‘s to which only a single pollen source was applied.

We at PollenPro had no explanation for this effect when it was reported to us. However, the enthusiasm of the growers convinced us that this was something worthy of further investigation. The growers that had reported this effect reordered a blended pollen of red and golden delicious for the following season. Bob Firman asked another of his grower friends in California to try this blend of pollen on one of his blocks of Fuji. All of the reports that we received from the growers who used the blended Red and Golden Delicious pollen were an enthusiastic confirmation of what had initially been reported — that the blocks of apples upon which the blended pollen was used produced a superior rate of fruit set, when compared to a single variety of pollen applied to similar blocks of apples.

PollenPro Has Been An Advocate Of Using Multiple Pollen Varieties ( blended pollens) now for many years, because of the successful results achieved by these Apple growers. The varieties we recommend the use of blended pollens for include: Apples, Pears, Cherries, Apricots and Plums. We have received reports of equitant success from growers when using blended pollens in these varieties of tree fruits.

A number of years ago, PollenPro was provided with a study conducted by Dr. Gregory Lang, a researcher at the University of Washington Research Station at Prosser, Washington.

In the study, Dr. Lang observed a relationship between the longevity of the stigma with single and multiple sources of pollen on Blueberries. While this study does not directly correlate to tree fruits, Dr. Lang thinks that PollenPro‘s observation of using multiple pollen sources results in higher pollination and fruit set rate has merit, in tree fruits requiring cross pollination. He thinks that longer receptivity to pollination in tree fruit varieties requiring cross-pollination, may be due to competition sensed by the stigma from differing varieties of pollen. To summarize, it appears that multiple pollen sources on the stigmatic surface of a flower may induce the flower to remain receptive to pollination, pollen tube growth and fertilization for a longer period of time. Which permits a longer Effective Pollination Period.

Methods of Application

Pollen Dispensers Fararri Insert Pollen dispensers are devices that were developed in The Fararri Insert is a very simple but effective device in the 1930‘s as a means of dispensing pollen to hives of vented by Thomas Fararri. In it‘s simplest form, the honey bees as they leave the hive. Pollen dispensers Fararri insert is a wooden stick approximately 1‖ x 1‖ have been the subject of many studies conducted by and 16‖ in length with a 45 degree grove routed out in respected researchers and have been found to be an the center. Pollen is placed in the routed out center of efficient and effective means of transporting pollen out the insert and bees must exit and enter the hive through to the orchard. In strong bee colonies (and strong bee this center opening. Once again, the Fararri insert colonies are becoming harder to find) 25,000 to 30,000 performs the job of getting the pollen onto the bees as pollen and nectar collecting bees, each make up to they leave the hive. The problem of swarming around twenty trips per day between the hive and the orchard. the entrance to the hive through the insert is still Theses bees are seeking the newly opened flowers, present, although to a lesser degree than with the which are the most receptive to pollination. The reason Harwood-Antles pollen dispenser that bees are attracted to freshly opened flowers, is because freshly opened flowers give off a stronger Bee Booster ® Pollen Dispenser fragrance, than flowers that have been opened for several hours or several days.

Do the math yourself. If you take a colony of 30,000 bees each making up to twenty trips per day between the hive and the orchard, that equals 600,000 trips per day —- trips where bees are carrying highly viable pollen from the pollen dispenser in front of the hive, out to the most receptive flowers in the orchard.

As with any new technology, many different designs of The Bee Booster ® pollen dispenser is the dispensers were tried and discarded before any one latest advancement in pollen dispensers. The Bee preformed satisfactorily. Booster ® was developed by Bob Firman, the founder of PollenPro, formerly FirmYield Pollen. Bob, Harwood–Antles Pollen Dispenser having been a part of agriculture and the pollen industry For many years the Harwood-Antles pollen dispenser for much of his life was well aware of the limitations was the industry standard. Basically, it was a small associated with the existing designs of pollen wooden box like device that was placed in the front of dispensers. the bee hive with two wooden legs that extended into the hive to keep it in place. The pollen was placed in the Existing pollen dispensers were effective in their own top of the dispenser and falls to the bottom where the right, but as previously mentioned there were still bees walk through it upon exiting the hive. The problems associated with each, which limited their Harwood-Antles pollen dispenser worked effectively as ultimate effectiveness. After years of studying the the bees transported the pollen to the receptive flowers problems associated with existing pollen dispensers, in the orchard. and after talking with many growers and getting their However, there were several problems associated with ideas on how to improve pollen dispensers, Bob came it‘s design. One problem was that due to the restrictive up with the concept for the Bee Booster ® pollen traffic flow that the dispenser created through the hive, dispenser. bees would swarm around the entrance unable to get in, while bees on the inside would have to force their What makes the Bee Booster ® pollen dispenser way out through the bees attempting to enter the hive, unique and superior to other pollen dispensers, is the or would seek out alternative exits. Another problem one way design in which it is constructed. Because of was that since both bees exiting the hive as well as it‘s design with a Plexiglas plate in the front of the bees returning to the hive are using the same entrance, dispenser, where the pollen is placed, as the bees exit pollen that was intended to be taken out to the orchard the hive they are naturally drawn to the light passing was drug back into the hive by the returning bees. through the Plexiglas plate and exit through this area,

picking up pollen on their bodies as they leave the hive.

Today, the problem of pollen loss with bees dragging it back into the hive is still a major drawback with this design.

The Bee Booster® pollen dispenser dispenser on the hive, make sure that the clear, plastic (continued). plate is facing outward, and that you are able to read The reason that bees are drawn to the light coming the words Bee Booster® , which is molded into the through the Plexiglas plate, is because outside light is top. what they naturally see when leaving the hive with no dispenser present. When bees return to the hive, due to Pollen Application Using a Bee Booster® the positioning of the Plexiglas plate, they find it very The application of pollen should take place over the difficult to pass into the hive over the Plexiglas plate. course of as many days as the bloom is receptive to The Bee Booster ® is constructed of black, ABS pollination. Better results are usually achieved when plastic. The black ends of the Bee Booster ® pollen is applied over most of the bloom period. The simulate the dark band of the hive entrance bees earlier bloom; the first flowers to open, are usually the normally see when returning to the hive. The bees are stronger flowers and in many cases will set a fruit that thus drawn to the dark ends of the Bee Booster ® , will grow larger and be of higher quality, than latter and do not do not return through the center section opening blooms. where the pollen is located, and do not drag pollen back into the hive. Pollen should be applied to the Bee Booster® pollen dispenser only when bee flight is occurring. The By utilizing a bee‘s natural direction of being attracted to stronger the bee flight, the more viable pollen will be the natural light visible from outside of the hive when taken out to the orchard. This also means that during exiting, and also by utilizing a bee‘s attraction to the heavy bee flight, pollen will have to be reapplied to the dark band of the hive entrance, which they normally see Bee Booster® more frequently, up to once per hour upon returning to the hive, several important advances during heavy bee flight. are accomplished.

1. The elimination of bees swarming around the outside of the hive unable to enter, while other bees are unable to leave because of the traffic congestion. 2. Most importantly, pollen wastage has been greatly reduced by bees dragging pollen back into the hive upon returning, since bees do not return through the pollen upon reentering the hive.

The last thing a grower wants, is to place expensive pollen into a dispenser only to be wasted by bees returning from their foraging activities and reentering the hive through the same entryway they took upon leaving, thus dragging pollen back into the hive with them.

PollenPro recommends that two Bee Booster ® pollen dispensers be used per acre. The Bee Booster ® should be placed on the most active hives. The Bee Booster ® should initially be placed on the hives during the early morning hours or late evening when there is little bee flight, at least 24 hours in advance of when the beginning application of pollen is anticipated. When placing the Bee Booster® pollen

Methods of Application

Dispenser Management method of hive placement, up to an hour may be As soon as hives are placed in the orchard, pollen gained in bee flight each day. dispensers should be placed in front of the beehives. 2. The second advantage of placing inverted orchard Bees need to learn how to fly out and return through boxes is that you get to choose the location and pollen dispensers and this early training assists with the spacing of the placement of the hives, which is a effectiveness of the pollen application when pollen very important consideration when you are dispensers are used. Over the bloom period, 30 to 60 attempting to cover an entire orchard with well grams of undiluted pollen should be dispensed per placed hives. Bee keepers attempt to move bees acre. When weather conditions are conducive for into an orchard as quickly as possible, sometimes pollination, bee activity indicates how frequently that the without much consideration for hive placement. By pollen should be renewed in the dispenser; that can be having your bees placed on inverted orchard boxes, up to once per hour. When bee activity is not as great, you are more clearly identifying where you want the then the pollen should be renewed 2 to 3 times per day, hives placed. or when the amount of pollen is low in the dispenser. Aircraft Application One to two teaspoons of pollen should be placed in the Aircraft application is the fastest of all application dispenser with each renewal. If quantities of pollen are methods for pollen. With aircraft application, a fixed seen on the ground in front of the dispenser, this wing aircraft or helicopter is used to carry the pollen to indicates that too much pollen is being used at one the orchard. A mechanical, battery operated dispenser time, and the bees are being forced to ‘burrow‘ through is used to meter the pollen mixture out of the bottom of the pollen in order to leave the hive. If this is the case, the aircraft. The pollen used in this application is diluted then the amount of pollen placed in the dispenser at to 1/4 strength (1/4 pollen to 3/4 carrier mix) and should each renewal should be reduced. be applied at the rate of 300 to 500 grams of 1/4

strength pollen per acre. The pollen should be divided Pollinator Management into two applications to be most effective. Honey bee management is extremely important when using pollen dispensers. Strong colonies of bees are Studies have shown that pollination occurs at the time absolutely essential in order to deliver pollen quickly of application and continues as bee‘s redistribute the and effectively. In addition to providing transportation of pollen throughout the orchard. Observations in the field pollen from the hive dispensers to the orchard, bee indicate that pollen applied in this manner serves to activity is also important to further distribute pollen stimulate and attract bees. within the orchard.

Bees should not be introduced to an orchard until there is sufficient open bloom to hold the bees on site. 10% of the bloom should be open before bees are brought in. Groups of four or more hives should be placed at 300 foot intervals, so that the furthest tree to be pollinated is no more than 150 feet from the group of hives. Two strong hives of bees are recommended for most tree fruit crops. All cracks in the hive and hive openings must be covered; a strong duct tape is recommended. All competing weeds and flowering plants from any other source should be cut down before the hives are placed in the orchard. Completely avoid the use of any insecticides, and do not use any fungicides (which may damage the pollen) after the bees are placed in the orchard.

Inverted orchard boxes are a good platform on which pallets of hives should be placed. By placing inverted orchard boxes in the orchard for beehive placement you achieve two thing; 1. By placing the pallets of bees on the orchard boxes, they are elevated off of the cooler orchard floor. This warms the bees faster in the morning and thus they start working (flying) sooner. By using this

Pollen Application with PollenPro’s ATV Pollen Applicator.

Orchardists have been applying pollen using blowers mounted on ATV‘s for nearly 20 years. The practice started in the Central Valley of California with growers applying pollen to Almond orchards, and because of its success, the practice expanded to other nut and tree fruit varieties.

The application of pollen with ATV mounted blowers has dramatically increased over the last several years. The application of pollen using ATV mounted blowers has several advantages over the more traditionally used means of pollen application, of utilizing bee hive pollen dispensers. With the colony strength of bee hives lessening over the last decade due to disease and parasite infestations, the ATV application of pollen has become a more popular alternative for application horticultural pollen to orchards.

One of the advantages of utilizing ATVs equipped with pollen blower systems, is that orchardists are no longer at the mercy of bee flight as the sole means they have for achieving pollination in their orchards. Bee flight is very minimal at temperatures below 55° F. Not only does temperature dramatically affect bee flight, but so does wind, rain, hive placement and overcast conditions.

The second, and most obvious advantage of utilizing ATVs equipped with pollen blower systems, versus bee hive pollen dispensers, is that the application of pollen is done totally at the grower‘s discretion. When the temperature and weather conditions are right, the grower is in a position of being able to apply pollen to his orchard solely at his discretion, as well as deciding how much pollen he wants to apply and whether to apply pollen to the entire block, or only to certain sections of his blocks.

An additional advantage with the ATV application of pollen, is that applications can be accomplished very quickly and easily, during the most optimal time of day, when weather conditions are at their best.

For Growers that raise pears and plums, the use of an ATV pollen applicator is a good alternative to using pollen dispensers. Since bees are not attracted to working pears and certain varieties of plums, if pollen in used in beehive pollen dispensers, bees may work another variety of fruit if there is a block in close proximity or other blooming other plants on the orchard floor, before working pears and plums. An ATV pollen applicator is a good alternative when bees do not co-operate in pollinizing these varieties.

Successful Pollen Application with ATV Mounted Blower Systems

Using Controlled Pollination, in whatever form is quite often not a clearly defined science. Using horticultural pollen to improve the pollination and subsequent fruit set in your orchards is a practice that is not easily quantifiable, unless you are willing to stand the expense to have the seeds of the fruit genetically tested by a certified laboratory. Uncertainty remains as to whether your crop was set due to natural pollination, or by the use of Controlled Pollination.

Growers who have consistently utilized Controlled Pollen applications to improve the fruit set of their orchards firmly believe that using high quality, horticultural pollen is an important cultural practice required to obtain the desired fruit set in their orchards. If Controlled pollination is done properly, then the results speak for themselves—it works!

When and How to Apply Pollen with PollenPro’s ATV Pollen Blower System

Several things should be done in advance before the application of pollen with an ATV mounted blower system.

The Orchard 1. Make sure that prunings have been removed from the drive rows between the trees. During pollination season, having to stop to have a tire repaired is the last thing that a grower needs. 2. Make sure that the placement of beehives in the orchard is done in such a manner so that the ATV will have sufficient room to maneuver through the drive rows. 3. To gain the optimum performance from your bees, have your beekeeper place your hives on inverted bin boxes, and make sure the boxes are placed in locations where there will be good overall coverage for the entire block for the foraging bees. The location where the bee hives are placed should also be in a sunny location. By placing bee hives on bin boxes above the cooler orchard floor, bees will start to fly and work the orchard up to an hour earlier in the morning, than if the hives were set on the ground. 4. Eliminate competing bloom. This is particularly important if you are growing varieties of trees, such as pears and some varieties of plums, which are not attractive to foraging bees. 5. Apply a pre-bloom spray of boron and calcium a week to ten days before pollen application. Boron and Calcium are essential components for good pollination and fruit set. Studies have found that pollen tubes grow faster and straighter when higher quantities of boron and calcium are present in plant tissue.

The Equipment 1. Both the ATV that will be used for the pollen application, and the pollen blower need to be in good working order, equipment tested and oil changed where needed. 2. Mount the pollen blower on the ATV and make sure that the controls are working properly. 3. Each season, before pollen is applied to your orchard, the pollen blower system should be calibrated, so that the proper application setting in relationship to the ground speed is achieved. This can be done by utilizing powdered or granular sugar to simulate the pollen mixture in the appropriate amount for a one acre application (in most 200 grams or approximately 7 ounces). A mark should be placed on the rheostat dial once the proper application rate is achieved for future reference. 4. Once the blocks of trees have been identified on which pollen will be applied the next decision that needs to be made is the number of applications for each block, whether 2, 3, or 4 applications will be made.

The Personnel 1. Training is essential for the people who will applying pollen to your orchards. Not only is pollen an expensive product, but the results of successful pollen application can either make your orchard profitable or not profitable for the season. In the field, pollen should be maintained frozen in a cooler box. Bagged pollen should be in the bottom of the cooler with frozen (Cold Ice®) on top of it. Remove only as much pollen as will be required for each application. Thoroughly mix the pollen with the carrier mix in the bag. Pollen will quickly unthaw when mixed with the carrier mix. 2. Thoroughly explain to the person doing the application how it should be done; the direction, the anticipated number of applications, so that they completely understand the process. 3. Ground speed is a very important factor when applying pollen with an ATV Blower System. Ten miles an hour should be the maximum ground speed in order to achieve good coverage. Adjust the outlet ports of the blower system to direct the pollen into the tree canopy.

Pollen Application The application of pollen can be separated into two distinct areas. The first area is the issue of timing. At what stage of blossom development should Bee Booster Pollen Dispenser pollen be applied to the orchard? The second issue is the manner in which pollen is to be applied; beehive pollen dispensers; ATV or Helicopter applications.

Pollen is the male sexual component of a flower. In order to set a good crop of fruit, viable pollen in sufficient quantities must be transferred to the receptive stigmas of the flowers throughout the entire orchard. In general, tree fruit flowers remain receptive to pollination for 12 to 72 hours after the flower has opened, depending upon the tree fruit variety, the nutritional status of the tree as well as enviormental conditions. Flowers remain receptive to pollination for a shorter period of time when weather conditions are hot and dry. During cool, moist conditions, flowers remain receptive to pollination for a longer period of time, but this longer receptivity is quite often offset by the slower growth of the pollen tube which occurs during cool weather. The EPP (Effective Pollination Period) is most directly dependent upon the nutritional condition of the orchard and the temperature.

Examining The Bloom In the Orchard It is important to closely examine the bloom of your orchard. 1. To assess the stage of development 2. To assess the coordination of the bloom between the pollinizer variety and the main crop variety. 3. A sampling of flowers should be made to assess any frost damage that may have occurred.

It is fairly easy to determine the stage of development your bloom is in, as well as the flowers receptivity to pollination. Pick a newly opened flower from the block you want to pollinize. Examine the anthers; the little yellow sacks or in the case of Pears, the pink to red sacks which surround the stigmas, the center of the flower. These are the flowers anthers, the sponge like sacks which hold the pollen. To the naked eye, the anthers have a smooth, deeply colored appearance before they have begun to dehisce their pollen. Under the microscope, the anthers have an appearance similar to that of a sponge, with a pock marked surface which retain the pollen grains. When the anthers have dehisced their pollen, they begin to shrivel and turn brownish in color. From the time the flower first opens, to the time that the anthers dehisce their pollen, this is the period in when the flower is the most receptive to pollination.

One problem that can exist even during ‗normal years‘, is that there may be little coordination between the bloom of the main crop and that of the pollinizer variety. This may be true in specific areas of the orchard or across the entire block.

To combat this problem, we recommend that pollen be applied with two or more applications over the course of the bloom period. The reason for this recommendation, is that even during seasons when flowers of a particular section of trees or for the entire orchard are blooming fairly evenly, there is still a timing difference between the opening, receptivity and pollen availability between flowers. By planning for two or more applications of pollen to be applied to the orchard, most of the bloom can be effectively covered. In cooler climates, the opening of flowers may be more extended, requiring a longer pollen application period. In warm climates, be prepared to quickly apply as much pollen as possible, for the bloom my not remain receptive to pollination for a long period of time.

HOW TO GET STARTED 1. On the day of the application, remove a sufficient quantity of pollen only for that day‘s application. Place the pollen in a portable cooler box with super-ice packs covering it. Keep the pollen frozen for as long as possible—it will quickly warm up once it has been removed from the cooler. 2. Take one rounded teaspoon of pollen and evenly apply it over the plastic plate of the Bee Booster ® pollen dispenser per application. During strong bee flight, the pollen might have to be replenished every hour. Continue applying pollen through out the day, as long as bee flight is sufficient to warrant the application.

CHECK OFF LIST

If you are planning to apply pollen to your orchards in the spring, there are a number of things that need to be addressed before the pollination season begins.

1. Secure a source of pollen. This may sound like a very basic consideration, but in some years pollen of certain tree fruit varieties can be in short supply. Make certain that you either purchase the pollen you will require or reserve the pollen in advance.

2. Make the decision on how you will apply the pollen. The decision must be made as to whether you will be using pollen dispensers for the application or whether you will be using ATV application, puffer guns or Helicopter application.☼ PollenPro would be happy to assist in determining the best method for applying pollen in your orchard. Just give us a call.

3. Personnel How many people will be required to adequately apply pollen to your orchard? The old saying that ‘timing is everything’, is most appropriate when it comes to pollination and pollen application. Having sufficient personnel available to apply pollen in a timely and effective manner is an absolute requirement when it comes to successful pollen application. Quite often when growers have reported that they have not been satisfied with the results they achieved with the application of pollen, it can be attributed to not having sufficient numbers of trained personnel to accomplish the application effectively. Schedule sufficient people in order to get the pollen application done in a timely and effective manner. Explain to your people the proper way to care for and apply pollen. Pollen needs to be kept frozen in a cooler box when in the field. PollenPro will provide you with a cooler box and ‗Super Ice‘ for this purpose if desired. If the pollen is properly cared for and applied correctly, the results you achieve should speak for themselves.

4. Timing the Application Someone needs to be responsible for checking on the bloom development in the orchard, and the availability of equipment for the pollen application in your blocks. If your blocks of trees are like most other blocks, there is usually not complete uniformity in bloom development. One section of your block will usually come into bloom a little before the other sections. Obviously, if this occurs you will want to start the application of pollen in the early section of your block before you begin the application in the later section.

5. Care Of Pollen In The Field Make sure that you remove only the amount of pollen that you will be using during that day‘s application from the freezer where it is kept. Place the pollen that will be used during that day in a cooler box with frozen ‗Super Ice‘ packets on top of it. Keep the cooler box in a cool location, out of the sun. Remove the pollen for each application from the cooler box and allow it to warm up for a short time before beginning the application. Make sure that the remaining pollen is kept frozen in the cooler box.

Most commercially grown varieties of apples are diploid varieties; those containing 34 chromosomes, and are self-sterile, that is they require the pollen of another variety of apple in order to be fertilized. Most diploid varieties of apples are cross fertile and can be used as pollinizers, providing the bloom period coordinate.

Some varieties of apples, known as triploids; varieties Photo of Apples containing 51 chromosomes, such as Gravenstein, Bookoop, King, Mutsu, Rhode Island Greening, Jonagold, Stayman and Winesape, cannot be used as pollinizers because their pollen is not viable.

A few apple varieties, such as Rome Beauty, Jonathan, York, Newtown Pipin are partly self-fertile, but set much better crops when cross-pollinized.

Golden Delicious is listed in many books and nursery catalogs as being self-fertile, but is actually self-sterile and set only about 1% of bloom when self pollinized and protected from open pollination.

ALL COMMERCIALLY GROWN VARIETIES OF APPLES BENEFIT FROM CROSS- POLLINATION

The application of pollen will improve the production of your apple blocks more than any other horticultural practice, by ensuring that there is adequate cross pollination. The application of pollen can help correct a variety of pollination related problems.

The Importance of Setting the King Bloom In general terms, the king bloom is usually the strongest flower in the cluster of apple flowers. The king bloom usually is the first flower to open in a cluster, which is nature‘s way of ensuring that the strongest flower is pollinized. Side blooms are a tree‘s way of ensuring that some of its flowers are pollinized if something should happen to the king bloom. In general, apples produced from the king bloom will be larger than apples set from the side bloom from the same spur. Having adequate sources of available pollen is extremely important when trying to set the king bloom.

Poorly Coordinated Bloom The ways that your trees respond to each new season is based upon a wide variety of cultural and environmental factors. Some of these factors you can control, and others you cannot. There is not much that can be done to encourage your main crop trees to more closely coordinate bloom time with your pollinizer varieties. In some seasons, the application of pollen to your orchard may be the only solution that you have to set a good crop of fruit when the bloom overlap is poorly coordinated.

Light Pollinizer Bloom When there are insufficient numbers of pollinizer trees blooming in your orchards, and the main crop variety is blooming and receptive to pollination, this results in a shortage of available pollen. The shortage of available, viable pollen is a factor that will greatly reduce your orchard‘s pollination and fruit set. And this condition will obviously result in a shortage of apples at harvest time, which will greatly reduce your returns.

The application of pollen can provide the high quality pollen source for your orchard, which will help to compensate for light pollinizer bloom and set your apples, which in turn will produce higher profits for you.

Cooperative Extension Service, Collage of Agriculture University of Illinois at Urbana– Champaign POLLEN INSERTS FOR APPLE POLLINATION Producing a commercial crop of apples in Illinois requires not only good management but also adequate cross-pollination by insects— primarily by bees. Honey bees are desirable because they are good pollinators and because their number and location can be controlled. Although many wild bees are better pollinators, they fluctuate in numbers from year to year and are easily affected by heavy rains, drought, and other elements of the weather. However, honey bees and other insects are good orchard pollinators only if there is enough compatible pollen available to be transferred between varieties. Increasing the number of bees in an orchard will not compensate for a lack of available pollen.

Some orchards in Illinois and elsewhere are improperly planted and are not producing commercial crops because they lack sufficient supplies of compatible pollen. Orchards with combinations of Jonathan and Red Delicious types, Jonathan and Stayman or Turley types and solid blocks of Jonathans are those most commonly deficient. Orchards where pollinizers are early or late in relation to the other varieties suffer from lack of coordinated bloom. For example Lodi may bloom too early and Rome Beauty may bloom too late for the best pollination of Red Delicious, Golden Delicious and Jonathan. Some low producing orchards make fair crops in good years, while others remain productive until near by sources of pollen are removed, such as old blocks of Golden Delicious. Still other orchards have compatibility varieties, but set fruit poorly because there are too many rows of each variety, particularly of Red Delicious.

Using pollen inserts on colonies of honey bees is the most effective way to temporarily increase fruit set in an improperly planted orchard. These inserts are also of value in properly planted orchards during those years when the major pollinizing variety (usually Golden Delicious) has a light bloom. The insert is a device that is placed in the entrance of the hive so that outgoing bees walk through a pan containing live compatible pollen. The pollen is picked up by the bees hairs and carried to the blossoms. This method of increasing pollination has been used by Illinois fruit growers for many years and has produced good crops in orchards that were previously unprofitable.

Pollen inserts can be operated by the grower on rented hives. Tell the beekeeper when you arrange for the colonies that you intend to use inserts and that his hives must have bottom boards with entrances 7/8‖ deep. The bottom must also be free of comb, cleats, and any other objects that would interfere with the placement of inserts. You will need a bee hat, veil and gloves in order to service the hives.

One insert per acre should be used at king bloom, immediately after the bees are moved into the Orchard. Place the inserts into the hive the afternoon before you intend to apply the pollen to allow the colonies to adapt to the inserts in advance.

If time is short, put the inserts in place during the early morning of the day the pollen is to be applied. In either case, be sure that the pans (the bottom of the hives) are completely dry before putting the pollen into them. When you place the insert in place, make sure there are no other openings in the hive. Do not allow the bees to fly from any opening except the one where the pollen insert is located.

Put pollen into the insert about once an hour when bee flight is heaviest —- usually from 10 am. to 3 pm. During one or two good days of pollination weather. Aim for 6 to 8 hours of application during one

or two days. Apply 20 grams per acre per insert per acre for young trees and 30 grams or more per acre for full bearing trees. Put 1 level teaspoon (approximately 2 grams) of pollen into each insert every hour during the period of heavy flight. Scatter the pollen along the length of the insert. Keep the pollen frozen at 0° F until the day that it is used. Keep it cool and dry when applying it in the orchard. Pollen that is kept frozen can be reused the next season.

All Pear varieties are self-sterile and thus require a pollinizer variety to set a crop. The lack of adequate numbers of pollinizers and poor bloom coordination between the pollinizer variety and the main crop variety are often the most limiting factor in Pear production. Also, because pear flowers produce little nectar they are unattractive to honey bees, so pollination is done largely by pollen gathering homey bees. All varieties are cross– fertile except for Seckle which will not pollinate Bartlett.

ALL COMMERCIALLY GROWN VARIETIES OF PEARS BENEFIT FROM CROSS-POLLINATION

The application of pollen will improve the production of your Pear blocks more than any other horticultural practice, by ensuring that there is adequate cross pollination. The application of pollen can help correct a variety of pollination related problems.

Light Pollinizer Bloom When there are insufficient numbers of pollinizer trees blooming in your orchards, and the main crop variety is blooming and receptive to pollination, this results in a shortage of available pollen. The shortage of available, viable pollen is a factor that will greatly reduce your orchards pollination and fruit set. And this condition will obviously result in a shortage of Pears at harvest time, which will greatly reduce your returns.

The application of pollen your orchard with the high quality of pollen it requires to set a good crop. The application of pollen will help to compensate for light pollinizer bloom and set your Pears, which in turn will produce higher profits for you.

Working with Honey Bees

Because of the fact that Pear flowers produce little nectar, honey bees are not attracted to pear flowers and seek other forage if available. Due to this reason, more care must be taken when placing honey bee hives in the orchard. There should be at lest 10 to 20 percent of bloom open in pear orchards before bringing in bee hives. The placement of bee hives in Pear orchards is very critical in order to obtain good pollination. In Pears, bees should not be expected to forage more than 150 feet in any direction from their hive. Additionally, it is very important when pollinizing pears with bees, that all competing flowers from weeds and other sources be eliminated if possible. Many growers have been successful utilizing pheromone based bee attractants to keep bees in Pear orchards by making the flowers more attractive to the bees. Some growers have also found it effective to apply sugar water to their pear trees to make the flowers more appealing to bees. If pollen dispensers are to be used, the pollen should be placed in the insert soon after the inserts are in place in order to stimulate the bees interest in Pear flowers. The air application of pollen has proven very successful in setting Pear blocks, and is not limited by the foraging preferences of honey bees.

Poor Weather Conditions Poor weather conditions during the pollination season have always been a problem for tree fruit growers. Cool, rainy weather inhibits bee activity which in turn directly reduces the transfer of pollen, pollination and the crops that are set. In the spring, time is always of the essence when it comes to pollination. When there are breaks in the weather, it is essential that growers are prepared to apply pollen to their orchards. There could only be a few hours of good pollination weather, when the bees are active, and the temperature warm enough for good pollen tube growth. If that window of opportunity is missed, then the ability to set a crop of fruit is lost for the entire year. By applying pollen when that window of opportunity is open, the grower has taken that first step toward setting a good crop. The application of pollen can make all the difference between profitability and economic loss.

What can be done in this situation? 1. Turn your bee hives into pollinizer trees. Using pollen dispensers during breaks in the weather which allows for bee flight, increases the chance that bees will be taking viable pollen with them directly from the hive to the flowers that are receptive to pollination in the orchard. 2. The air application of pollen will disperse pollen throughout the orchard, setting fruit as well as allowing bees to pick up some of the pollen and transfer it to other blossoms.

Timing the Application is Essential Pollen that is applied before the flower is receptive to pollination or after the flower has lost its viability will not produce the desired results of pollination and fruit set. Fruit tree flowers are the most receptive to pollination in the ‗popcorn‘ stage of development, just as they are beginning to open. To determine a flower‘s receptivity to pollination, pick a flower just as it is beginning to open. You will see grouped in the center of the flower red or pink anthers. The anthers remain smooth and red or pink in color as long as they have not dehisced their pollen. With Pears, there is no mistaking the difference between anthers that have dehisced their pollen and anthers that have not. As pear flowers dehisce their pollen, the anthers begin to shrivel and turn greenish-grey.

In warm and dry conditions, Pear flowers are the most receptive to pollination as soon as they have opened. In cooler, moist conditions, Pear flowers may not become receptive to pollination until 24 hours after opening.

Once the anthers of a flower have dehisced their pollen and begun to shrivel and turn greenish-grey, the stigma of the flower should still be receptive to pollination for a limited time. The continued receptivity of pear flowers is dependent on a variety of environmental conditions; the weather, temperature, pollen availability, bee flight and nutritional health of the tree.

The best results for pollination are achieved when the weather is cool enough for an extended bloom period and yet warm enough for rapid germination and pollen tube growth. The minimum temperature for good pollen germination is 60° Fahrenheit. 65 to 75 degrees Fahrenheit is considered the ideal temperature for germination and pollen tube growth

The Relative Effectiveness of Pear Pollen Sources Hermann G. Thoennissen AgriNorthwest, Kennewick, WA

The source for all pear pollen are the pollen sacs contained in the anther. The anther sits at the end of the filament. The filament is attached to the ovary. This paper will discuss the effectiveness of different pollen sources for pollination in commercial pear orchards. The sequence of pollination, fertilization and fruit set have been researched extensively worldwide and several papers have been published on these topics. Besides the pollen source, pollination is influenced by the following factors:

1. Climatic Factors: Temperature, humidity, wind, precipitation, light intensity. 2. Bee—Related Factors: Colony strength, bee activity, foraging behavior, hive placement, sequence of introduction of hives into orchard, relationship of grower to beekeeper. 3. Cultural Practice Factors: Spray program before and during bloom, cover crop management, canopy density, nutritional status of trees, especially N + B, pollination management, method of frost protection. 4. Genetic Factors: Pollen viability, stigma receptivity, germination rate of pollen, pollen fertility, compatibility between varieties, effective pollination period.

These factors are only mentioned here as each of them is vital and integral in setting a good pear crop; they will not be part of the following discussion.

In order to set high quality Pear crops annually, 3 to 5 percent of the flowers must develop into fruit. The first step toward fruit set is pollination. Pollination is the transfer of the pollen of the pollinizer, the source flower, to the receptive stigma by the agent of transfer, the pollinator. Most commercial Pear varieties will not produce seeded fruit and are therefore self-sterile. Some varieties are partly self-fruitful and therefore will develop seeded fruit when pollinated. This process is called parthenocarpy.

Research and observation in commercial orchards have shown that cross-pollination improves fruits and increases seed content. High seed content has been linked to;

1. Spears being less prone to June drop. 2. Higher fruit mineral levels, especially CA. 3. Larger and more evenly shaped fruit. 4. Increased fruit firmness. Flower fertility is the capacity of a flower to develop into a fruit, if cross pollinated. Flower fertility is expressed as the number of set fruit per 100 flower clusters.

Varieties Fruit Set (1) (1) Number of fruit per 100 flower clusters D’Anjou 30 to 40 Bosc 50 to 80 Comice 20 to 30 35 to 40 after thinning Seckel 100 to 120 39 to 40 after thinning Bartlett 50 to 60

The lower the fertility of a variety, the more a grower has to optimize cross pollination. D‘Anjou and Comice are varieties which are very difficult to set. Only when pollination is optimized can these varieties set a crop annually. In order to optimize pollination all factors influencing pollination have to be strong. If any one factor in the pollination equation is zero the results will be zero.

Pollen Sources in Pear Orchards 1. Pollinizer trees and grafts 2. Beehive Pollen Dispensers 3. Bouquets 4. Dusters 5. Aerial Application (Airplane, Helicopter and ATV Mounted Blowers) 6. Manual Application (Hand Application)

Pollinizer Trees and Grafts All decisions regarding pollinizers revolve around the selection of the pollinizer variety, the density of pollinizers per acre, and the placement, patterns and management of the pollinizer variety.

Selection When selecting a pollinizer, pollen variety, pollen longevity, pollen fertility, pollen germination rate, overlap of anther dehiscence with stigma receptivity and compatibility of the varieties have to be evaluated. It is highly unlikely that all of these criteria will be at close to optimum annually at the time of pollination. I firmly believe in the use of multiple pollinizers. This also reduces the risk of non-performance of one pollinizer due to factors such as break of dormancy, and therefore, poor or no bloom overlap, the effects due to diseases such as fire blight or simply poor return bloom.

Density When observing and analyzing pear orchards in different parts of the world, it becomes obvious to me that in most cases, there is a direct correlation between the amount of pollinizers and the yield, the fruit shape, the fruit size and the seed count. This particularly holds true for blocks of 15 or more acres. Of orchards which are planted in patterns where the ratio of one variety to the other is 1 to 1 or 2 to 1 have good crops even in years with cold, wet springs, or in years like 1985 (spring frost in the Yakima Valley). As a result of these observations and from experiences of pear orchardists I have worked with, I recommend to plant pear orchards with a high density of pollinizers.

Placement Pollinizers should be placed so that even under unfavorable conditions, sufficient pollination is assured. With an orchard of two varieties, solid row patterns of 1 to 1 or 2 to 2 are sufficient. Patterns exceeding three rows of one variety and 1 to 3 rows of another variety will have more fruit with lower seed count. As bee movement is mainly parallel to the tree row direction (78%), the trees in the center of 4, 5 or 6 row patterns have a much smaller chance of cross pollination than trees across the row from a pollinizer. Denser trees further discourage bees from working across rows, thus further impacting cross pollination negatively. If for management purposes, 4 or 6 row patterns are chosen, pollinizers should be planted in every row, not further than 60 to 70 feet apart on a staggered pattern. To further enhance cross pollination, at least two cultivars should be used.

Beehive Pollen Dispensers Three types of pollen dispensers are commonly used in the Northwest. The Harwood-Antles, the Ferrari and the Bee Booster dispenser. All three work under the principle that the bee leaving the hive emerges through the dispenser containing pollen. This pollen will stick to its body and thus be carried to the flower. The use of dispensers should be discussed with beekeepers as not all hives can be equipped with one.

Pollen needs to be ordered ahead of time and should meet all criteria listed earlier under genetic factors. The pollen should be kept refrigerated until it is put into the dispenser. Pollen should be undiluted in order not to irritate bees. Dispensers should be filled prior to the bees leaving the hives in the morning. If bee activity is good, a refill later in the day might be needed. The author prefers to fill the dispenser prior to the first flight and then decide later in the day as to refill or wait for the next day. This decision depends on the percentage of bloom which is open, the weather forecast and bee flight. This decision is always somewhat of a gamble.

.Bouquets, Dusters, Aerial Applications, Hand Brushes All of these techniques I consider supplemental. They can be used in years where regular pollination and Beehive pollen dispensers will not set a crop. The use of bouquets needs to be planned for well in advance. Bouquets are labor intensive, particularly when bouquets have to be transported. Trees from which bouquets are taken should have been pruned to facilitate the use of part of the tree for bouquets according to Mayer. Six points should be considered when handling bouquets.

1. Cut the branches when the first bloom opens 2. Keep bouquets fresh and renew as they wilt 3. Make bouquets large, use buckets 4. Keep buckets filled with water 5. Hang bouquets half way up the trees near the blossoms to be pollinated 6. Protect bouquets from wind

Hand dusters or puffer guns are mounted on long poles four to six feet long. There are also motor driven blowers being used. They all require some practice to use as one can pull 30 grams of pollen onto just a few trees instead of one acre.

Aerial applications through aircraft, power dusters or air blast sprayers have been shown in experiments not to be very effective. The author…..who has not personally used aerial applications of pollen…..is aware of the use of helicopters to apply pollen. This practice has been recommended by respected horticultural advisors in Washington State.

Manual application of pollen with a hand brush (artist‘s brush) to individual flowers works. Application with brushes requires a large labor force for a short period of time.

Most commercially grown Sweet Cherry varieties are self-sterile and some varieties are intra- sterile; Bing, Lambert and Napoleon will not pollinize each other, and thus require a different pollinizer. Stella is one exception in being self-fertile and a universal pollinizer. Lapins also appear to be self-fertile. The lack of adequate bloom coordination between pollinizer variety and the main crop variety, as well as insufficient numbers of pollinizer trees are often the most limiting factors in Cherry production.

So why has everyone suddenly planted Cherries? The answer is obvious! With what other tree fruit crop can a grower receive as high of returns as they can with Cherries—- in good years.

Achieving good pollination is even more important when growing Cherries than it is with any other tree fruit crop because of the shear number of flowers which must be set in order to have a good crop.

Most Commercially Grown Cherry Varieties Benefit from Cross Pollination

Controlled Pollination Produces Remarkable Results Correcting These Pollination Problems

Poorly Coordinated Bloom Poorly coordinated bloom between the main crop variety and the pollinizer variety can result in a pronounced reduction in the amount of pollen available to set the main crop variety. Cherry flowers are usually receptive to pollination from 12 to 48 hours, depending upon environmental and weather conditions. By waiting too long to see if the bloom of the pollinizer variety will coordinate more closely with the main crop variety, growers may be losing that one window of opportunity to use supplemental pollen in order to set a crop that year. Flower receptivity and pollen viability could be lost, and thus there could be insufficient time for the pollen tube to germinate on the stigma, grow down the style and fertilize the ovule; the Effective Pollination Period. By applying pollen when a lack of coordinated bloom is apparent, growers are ensuring that the pollen needed to set a good crop is available.

Poor Weather Condition Unfavorable weather conditions during the pollination season has always been a problem that tree fruit growers have had to contend with. But what can be done about the weather? Unfortunately, nothing can be done to control the weather, and cool, rainy weather in the during pollination season is the last thing that an orchardist wants. Cool, rainy weather inhibits bee activity and reduces pollen tube growth (Effective Pollination Period) which in turn reduces pollination and fruit set in the orchard. While cool weather may increase the longevity of the ovule, if pollen tube growth is reduced by too great of a factor, then the ovule of the flower will loose it‘s ability to set fruit.

Timing the Application Flowers are most receptive to pollination in the ‗Popcorn‘ state of development, just as they are opening. To determine a flower‘s receptivity to pollination, pick a cherry flower just after it has opened. Grouped in the center of the flower are the yellow anthers. Cherry anthers are very small and may require magnification to see clearly. Under magnification the anthers look like a sponge, and the pollen grains are contained upon the surface of this spongy material. When Cherry anthers are fresh and the pollen viable they have a bright yellow appearance. After they have dehisced their pollen the anthers look shriveled and brown. In warm and dry conditions, cherry flowers are the most receptive to pollination as soon as they have opened. Under cool, moist conditions, Cherry flowers may not be the most receptive until 24 hours after opening.

Once the anthers have dehisced their pollen and begun to shrivel and turn brown, the stigma of the flower may still be receptive to pollination. To determine if the stigma is still receptive, examine the stigma; the surface of the stigma should appear shiny and have the style, the tube that extends down to the base of the flower, should appear bright green. If the stigma and style are still ‗healthy‘, viable, then pollen can still be successfully applied and a good crop set.

With pollination, the best overall results are achieved when the weather is cool enough for an extended bloom, and yet warm enough for rapid germination and pollen tube growth. The minimum temperature for good pollen germination is 60° Fahrenheit. 65 ° to 70° Fahrenheit is considered ideal pollen germination temperatures.

POLLENPRO BULLETIN NUMBER 3 CHERRY POLLINATION STUDY

Pollination of Cherry Dr D.F. Mayer Department of Entomology, WSU, IAREC Prosser, Washington Taken from the proceedings of the 89th annual meeting of the Washington State Horticultural Association Cherries grown in the Pacific Northwest include sweet Cherries (prunes Avium L.). Sweet Cherries have white, faintly fragrant flowers in clusters. The 5 petals of the flower are oval and white and the flower is about an inch across. Both pollen and nectar produced by these flowers are attractive to bees. All Cherries including sweet cherries, are basically incapable of automatic pollination. In the Pacific Northwest, our major sweet Cherry variety, Bing, is self-sterile or self-unfruitful: requiring another variety of pollen to produce fruit. Wind does not accomplish pollination and bee pollinators are necessary for Cherry Pollination.

Osmia Bee Pollinators During the past several years we have attempted to use Osmia Bees for pollination of tree fruits. Bees were established in Cherry or Pear orchards in their nesting tubes and bee activity was monitored. During some seasons we did obtain good renesting of the bees, however, only a few were ever observed working Cherry.

Bumble Bee Pollinators During the past 3 years we have attempted to use managed colonies of bumble bees for pollination of tree fruits. Colonies were established In Cherry or Pear orchards and bee activity was monitored. The bumble bees foraged from the colonies. However, only a very few were seen working Cherry or Pear flowers. The colonies used in these tests contained from 25 to 125 workers. Larger colonies may be better pollinators, but it is difficult

POLLINATION OF CHERRY, BY D.F. MAYER (CONTINUED) To obtain large bumble bee colonies at Cherry blossom time.

Honey Bee Pollinators Cherry flowers are highly attractive to bees. Cherry nectar sugar concentration is fairly high (Table 1). However the amount of nectar per flower is quite low, usually less than one micro liter. Most foragers, (70% to 80%) collect pollen from Cherry rather than nectar. Pollen collectors take an average of 61 seconds to visit 5 flowers. Nectar collectors work faster though with an average of 35 seconds to visit 5 flowers. Honey bee forages visit only 2 or 3 trees in one trip in a standard planting which means that every tree of the main variety should have a pollinizer tree adjacent. Honey bee behavior was investigated in high density cherry planting. Only 15 % of the bees moved to an adjacent row ( across the isle space). Most bees (82%) observed switching trees moved to a second or third tree in the same row. This data points out the importance of planting pollinizer trees in every row of the main variety since honey bees tend to work down the rows. Honey bees forage at low temperatures, however, maximum foraging doesn‘t occur until temperatures reach 65 degrees (Table 2)

Table 1 Table 2 Sugar concentration in nectar of various Cherry varieties Relative honey bee foraging at various temperatures Variety Percent Sugar Temperatures Percent Foraging Bing 43 65 degrees F 100 Rainier 32 63 degrees F 62 Lambert 36 54 degrees F 21 Chinook 41 51 degrees F 6 Van 44

Montmorency 37 Honey Bee Management Honey bee colonies should be placed in Cherry orchards just as the bloom opens. Research by Dr. Ed Proebsting suggests the first flowers to open produce superior fruit so it is imperative to set those first flowers. We suggest that Cherry growers use 2 strong colonies of bees per acre. We compared the number of bees per tree using one colony per acre and two colonies per acre and found twice as many bees foraging the trees in orchards with 2 colonies. One colony per acre does not saturate the orchard with pollinators.

We suggest that colonies be placed about 100 yards apart. We compared the number of bees per tree per minute at different distances from the colonies and found that temperature below 65 degrees F about a third more bees worked within 20 yards of the colonies compared 100 yards away. Conversely, with temperatures above 65 degrees F there were about the same number of bees 30 yards from the colonies compared to 120 yards away.

Honey bee colonies should be placed where they receive early morning sun. We found that colonies placed in the sun have 50% more flight activity during the early morning than colonies placed in the shade in an orchard. Also, colonies should be placed on bins to get them off of the cold ground. Colonies should be placed on a knoll and not down in a draw where cold air flows. Colonies should be set in groups of four to twelve. This increases competition at the flowers and helps ensure the bees visit both the main variety and the pollinizer.

Continued on the next page

POLLINATION OF CHERRY, BY D.F. MAYER (CONTINUED)

Pollen Inserts We conducted several tests with bee pollen dispensers for Bing Cherry pollination. In all tests, honey bees effectively moved pollen from inserts to flowers accomplishing pollination. The results from a large scale test over 3 years are given in Table 3. In hand pollination studies Early Burlat, Moreau, Black Republican, Black Tartarian, Van and Vista were good pollen sources for Bing.

Table 3 Yield of Cherries as a result of various pollen supply sources. Date Treatment Tons per Acre

1983 Bouquets 6

1984 No supplemental Pollen 3 1985 Pollen Inserts 15 Pollinizers Six varieties of ornamental Cherries (Serrulata, Kwanzen, Subhirtella, Mt Fuji, Accolade, Armanagawa) were tested for pollination of Bing. Pollen was collected from the ornamental and germinated and hand pollination studies conducted. Germination was poor for all 6 varieties and no Bing fruit was set by hand pollination.

Aerial Application of Pollen Pollen was applied to a number of different Cherry orchards by helicopter and fruit set was recorded in treated and untreated parts of the orchard. Applying pollen by helicopter to Cherries did not increase fruit set as compared to the untreated checked in any of the tests.

Genetic Incompatibilities in Sweet Cherry Varieties. Bloom, Pollination, and Fruit Set. WSU, n.d. Web. 10 Nov. 2011.

Genetic Incompatibility in Sweet Cherry Varieties

1. The pollination of Sweet Cherry’s is genetically controlled by a single gene with alternative forms (multiple alleles), designated S1, S2, S3 S4……….

2. Pollen tubes bearing an S allele in common with either S alleles of the pistols cells fail to fertilize the ovule because its growth is inhibited in the style.

3. Types of incompatibility: A. Self-incompatibility : Where pollen from the same cultivar is rejected. B. Cross-incompatibility: When pollen from another cultivar is rejected because of sharing the same S allele.

Sweet Cherry Pollen Incompatibility Groups 13 Groups Identified as incompatible with members of the same group. Group I (S1, S2) : Black Tartarian (A & B) Group II (S1, S3) : Van Group III (S3, S4) : Bing, Lambert, Napoleon (Royal Ann) Group VII (S4, S5) : Black Republican, Burlat Group VIII (S2, S5) : Schmidt Group IX (S1, S4) Chinook, Rainier Group XIII (S2, S4) : Ulster

Most commercially grown Japanese Plum varieties are self

-sterile, and thus require cross pollination in order to produce commercial crops. Some varieties such as Santa Rosa, Late Santa Rosa, Beauty and Nubian are partly self-fruitful, but will bare heavier crops with cross pollination. Varieties that produce large amounts of viable pollen and are good pollinizers for other varieties are Santa Rosa, Late Santa Rosa, Wickson, Latoda, and Casselman. The lack of adequate pollination due to poor bloom coordination between the pollinizer variety and the main crop variety, as well as insufficient numbers of pollinizers, is often the most limiting factor in Japanese Plum production.

Poorly Coordinated Bloom Poorly coordinated bloom between the main crop variety and the pollinizer variety can result in a pronounced reduction in the amount of pollen available to set the main crop variety. Plum flowers are usually receptive to pollination from 12 to 48 hours, depending upon environmental and weather conditions. By waiting too long to see if the bloom of the pollinizer variety will coordinate more closely with the main crop variety, growers may be losing that one window of opportunity to use supplemental pollen in order to set a crop that year. Flower receptivity and pollen viability could be lost, and thus there could be insufficient time for the pollen tube to germinate on the stigma, grow down the style and fertilize the ovule; the Effective Pollination Period. By applying pollen when a lack of coordinated bloom is apparent, growers are ensuring that the pollen needed to set a good crop is available.

During cool spring conditions, when there are breaks in the weather, the grower must be prepared to apply pollen. During some pollination seasons, there may be only a few good hours of pollination weather, when the bees are active and the temperature is warm enough for pollen germination. Timing the Application Flowers are most receptive to pollination in the ‗Popcorn‘ state of development, just as they are opening. To determine a flowers receptivity to pollination, pick a cherry flower just after it has opened. Grouped in the center of the flower are the yellow anthers. Plum anthers are very small and may require magnification to see clearly. Under magnification the anthers look like a sponge, and the pollen grains are contained upon the surface of this spongy material. When Plum anthers are fresh and the pollen viable they have a bright yellow .

appearance. After they have dehisced their pollen the anthers look shriveled and brown. In warm and dry conditions, Plum flowers are the most receptive to pollination as soon as they have opened. Under cool, moist conditions, Plum flowers may not be the most receptive until 24 hours after opening.

Bees Are Not Attracted To Certain Types Of Plum Flowers The fact that honey bees are not attracted to certain varieties of plum flowers creates a major problem for Plum growers in knowing how to approach pollinizing their plum blocks. Bees prefer to forage in many other varieties of blooming plants before turning to forage in Plums. Bees will work plums, but care must be taken when placing honey bee colonies in your blocks of Plums. If possible, any competing flowering plants should be eliminated so that bees will concentrate on working Plum flowers. Make sure that at least 10% of the Plum blossom is open before bees are moved into the orchard, in order to establish the bees working in the Plums and are not lured away by more attractive blossoms elsewhere.

Apricots are usually the first tree fruit variety to bloom in the spring. And as the harbinger of spring, Apricots can also be the variety most susceptible to damaging frosts. Apricot varieties such as Goldbar, Goldstrike, Goldrich require cross pollination. Rival and other varieties also greatly benefit from cross pollination. Many Commercially Grown Apricot Varieties Require Cross Pollination To Set Commercial Crops.

Controlled Pollination can Produce Remarkable Results in Correcting These Pollination Problems.

Light Pollinizer Bloom A light pollinizer bloom will result in the shortage of available pollen to set the main crop trees in the orchard. Pollen can be applied through several means in order to supplement a lack of available pollen in the orchard. Poorly Coordinated Bloom Poorly coordinated bloom between the main crop variety and the pollinizer variety can result in a pronounced reduction in the amount of pollen available to set the main crop variety. Apricot flowers are usually receptive to pollination from 12 to 48 hours, depending upon environmental and weather conditions. By waiting too long to see if the bloom of the pollinizer variety will coordinate more closely with the main crop variety, growers may be losing that one window of opportunity to use supplemental pollen in order to set a crop for that year. Flower receptivity and pollen viability could be lost, and thus there could be insufficient time for the pollen tube to germinate on the stigma, grow down the style and fertilize the ovule; the Effective Pollination Period. By applying pollen when a lack of coordinated bloom is apparent, growers are ensuring that the pollen needed to set a good crop is available.

Poor Weather Condition

What can be done about the weather? Unfavorable weather conditions during the pollination season has always been a problem that tree fruit growers have had to contend with. But what can be done about the weather? Unfortunately, nothing can be done to control the weather, and cool, rainy weather in the during pollination season is the last thing that an orchardist wants. Cool, rainy weather inhibits bee activity and reduces pollen tube growth (Effective Pollination Period) which in turn reduces pollination and fruit set in the orchard. While cool weather may increase the longevity of the ovule, if pollen tube growth is reduced by too great of a factor, then the ovule of the flower will loose it‘s ability to set fruit.

What can be done in this situation? 1. Turn your bee hives into pollinizer trees. Using pollen dispensers during breaks in the weather which allows for bee flight, increases the chance that bees will be taking viable pollen with them directly from the hive to the flowers that are receptive to pollination. 2. The air application of pollen will disperse pollen throughout the orchard, setting fruit as well as allowing bees to pick up some of the pollen and transfer it to other blossoms.

Timing the Application Flowers are most receptive to pollination in the ‗Popcorn‘ stage of development, just as they are opening. To determine a flowers receptivity to pollination, pick an apricot flower just after it has opened. Grouped in the center of the flower are the yellow anthers. Apricot anthers are small and may require magnification to see clearly. Under magnification the anthers look like a sponge, and the pollen grains are contained upon the surface of this spongy material. When Apricot anthers are fresh and the pollen viable, they have a bright yellow appearance. After they have dehisced their pollen the anthers look shriveled and brown. In warm and dry conditions, Apricot flowers are the most receptive to pollination as soon as they have opened. Under cool, moist conditions, Apricot flowers may not be the most receptive until 24 hours after opening.

Apricot Orchard, Moxee, WA

Conclusion Controlled or Supplemental Pollination is a horticultural practice that for almost eighty years, has been demonstrated as an effective means of correcting a wide range of pollination related problems. The application of pollen should be considered as vital and necessary to successfully growing tree fruits as the application of fertilizer is to producing high quality marketable fruit. Without adequate supplies of pollen in the orchard, regardless of the source, pollination and fruit set will be negatively affected! Controlled Pollination is without question the most cost effective means a grower has for ensuring the adequate fruit set of his orchards.

Controlled Pollination as a horticultural practice is far from perfect. Just as tree fruit growers are at the mercy of Mother Nature, so are the pollen companies from which you obtain your pollen. One thing of which you can be assured, is that PollenPro is dedicated to providing tree fruit growers with the highest quality pollen available, and the most advanced means of applying pollen to your orchards. We are committed to your success.