December 2004 Berry/Vegetable Times Berry/Vegetable Times December 2004 In this issue... From Your Extension that produce early fruit, freezes in Strawberry Freeze Protection Page 2 February and March are of great Agent… concern. Fruit and open flowers will Blueberry Cold Protection Early Season Arthropod Pests in Page 2 freeze at higher temperatures than the Strawberry Crop: Cyclamen flowers that have not opened, and Mites Now that a couple of cold dormant buds are even more cold fronts have come through and we see Early Season Arthropod Pests in Page 3 hardy. the Strawberry Crop: the cold weather the rest of the Factors to pay attention to Lepidopterous Larvae, Aphids country is having, we are starting to are temperature, wind speed, and dew think about cold protection. An Pesticide Registrations and Page 5 point. The predicted low temperature Actions excellent publication entitled plays a part in deciding whether to “Protecting Blueberries from Freezes cold protect and the method of Pesticide Potpourri Page 5 in Florida” by Drs. Paul Lyrene and protection. Wind speed can GCREC Center Update Page 6 Jeff Williamson came out this year influence the effectiveness of the on EDIS. I will give a brief overview sprinkler irrigation method of freeze SPECIAL GCREC FACT Page 7 here, but be sure to read the paper to protection. And dew point (an SHEET learn all the helpful information that Powdery Mildew of Strawberries indicator of the amount of water it contains. The paper can be found vapor in the air) affects how quickly at http://edis.ifas.ufl.edu/HS216, or air temperature drops. Moist air get in touch with me for a copy. retains more heat than dry air. Also, Blueberries enter a dormant when the dew point is low, the rate of condition in the winter where there is evaporative cooling is high, which is no growth and this aids in surviving of concern when sprinkler irrigation cold weather. If the blueberry plant is used for freeze protection. is fully dormant it is very cold hardy, Site selection can influence and in Florida air temperatures temperatures in the field. For usually do not get low enough to example, hillsides can be warmer Calendar of Events cause plant damage. Also, blueberry than bottomland when nights are still. plants need a certain amount of Also, making sure soil is moist, Dec. 14 Pesticide License Testing. Hills. chilling to break dormancy and grow compacted, and free of weeds prior to Co. Extension Office. (813) 744-5519. and flower well the next spring. a freeze can help maximize moisture Each variety has its own in the air, and thereby maximize air Jan. 11/05 Pesticide License Testing, Hills. characteristic chilling requirement, Co. Extension Office. (813) 744-5519 temperature. and this is the main reason why some If you use overhead varieties do better in central Florida irrigation for freeze protection you than others. Plants in our area of the must be able to pump large volumes A monthly newsletter of the University of Florida IFAS, Gulf Coast Research and Education Center, state frequently do not lose all their of water to get good protection. and Florida Cooperative Extension Service. leaves and this can affect the amount Remember that when the air is dry it Hillsborough County Cooperative Ext. Service of chill time they accumulate. Plants 5339 CR 579, Seffner, FL 33584 will take even higher volumes of (813) 744-5519 SC 541-5772 that retain at least some of their water to give protection to the plants. Alicia Whidden, Editor Mary Chernesky, leaves will not have their chill On calm nights, the sprinkler system Director requirement satisfied as quickly as can be turned on when the Gulf Coast Research and Education Center plants that loose all their leaves. temperature in the coldest part of the 13138 Lewis Gallagher Road, Dover, FL 33527 Since the industry in west (813) 744-6630 SC 512-1160 Christine Cooley, Layout and Design central Florida is based on varieties (Continued on page 2) Jack Rechcigl, Director IFAS is an Equal Employment Opportunity —Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards1 of the County Commissioners Cooperating. December 2004 Berry/Vegetable Times field is 32°. If there is a low dew soaking and cracking), spread strawberry farmer, and sometimes point (i.e., the air is very dry), the disease inoculum, and result in the many farmers, discover cyclamen system should be turned on when the loss of bed integrity. mites in their crops. The problem temperature is 34°. Turn the system Most of the freeze events in needs to be recognized early and off when icicles are falling from the Hillsborough and Manatee County treated immediately to avoid plants, or the wet bulb temperature (where the main strawberry detrimental effects on yield. This has risen above 32°. If wind speeds production area is located) are mite can be a very serious pest in the are high, it may be difficult to radiation freezes (little or no wind), area. Infested plants are stunted and achieve uniform coverage, and with air temperature typically produce a late and reduced crop. The watering may cause more damage bottoming out in the low 30s or high cyclamen mite is found frequently on than it prevents. Fortunately, windy 20s. In this type of freeze, growers ornamental crops in Florida, freezes are not common in west will generally wait to turn on their particularly those crops produced in central Florida. sprinkler irrigation system until the greenhouses. However, widespread In most situations, watering air temperature just above the plastic infestations in Florida strawberry the field the afternoon before a mulch, in an area open to the sky, is fields occur only occasionally. In the freeze can reduce damage. For pot 31 °F. Standard practice for a northeastern United States, culture, water the pots and the system where sprinklers are spaced California and the Pacific Northwest ground around the pots – if possible. 50 ft. x 50 ft. is to use 9/64-inch cyclamen mites in strawberry crops Just remember: there are nozzles in the sprinkler heads and are common. The following more factors to consider in a freeze run the system so that there is 75 summarizes points concerning this event than just the expected pounds of water pressure to the pest that are important to Florida minimum temperature. Watering for heads. Such a system should apply strawberry growers. cold protection is not always the best water uniformly and in sufficient choice. If you do use the sprinkler quantity (about 0.15 inch per hour). irrigation method, make sure the It is important that sprinklers make system 1) applies water uniformly at least one revolution per minute for over your planting, and 2) puts out adequate freeze protection. the volume of water needed for When an advective (windy) adequate freeze protection. freeze is expected, and temperatures A happy and joyous holiday are predicted to drop into the low to season to everyone! mid 20s, it is common practice to use Alicia Whidden 11/64-inch nozzles (to provide the (813) 744-5519 Ext. 134 additional water needed for Cyclamen mites. protection) and turn the sprinkler [email protected] Symptoms of Attack on system on when the air temperature reaches 34 °F. However, if wind Strawberries from Hillsborough speeds are 10 mph or greater, at least County: When local strawberry fields are infested we find that some flower and fruit damage is likely to occur. strawberry leaves are small, Strawberry Freeze Once the sprinkler system chlorotic, highly wrinkled, Protection has been turned on, it should remain thickened, and possess short petioles. Craig Chandler on until the wet bulb temperature has Runners oftentimes have numerous risen above 32 °F. small "thorns" rather than a smooth texture. Additional symptoms While strawberry crown tissue isn’t usually injured until it include dark brown, dry flowers, reaches a temperature of about 20 ° russeted berries and poorly F, damage to flowers and fruit can developed root systems. start to occur when tissue Early Season Arthropod Examination of plants under a temperature reaches 30 °F. Sprinkler Pests in the Strawberry stereomicroscope reveal cyclamen irrigation is the standard method for mites in the crevices of leaf wrinkles, protecting strawberry flowers and Crop: Cyclamen Mites on unopened and opened flowers, on fruit from freeze damage. This James F. Price and Silvia I Rondon newly formed fruit and in the plant method of protection is convenient bud. Some plants contain as many as and can be highly effective, although Almost every year from a few hundred of these mites. it can also damage fruit (water Thanksgiving into early January (Continued on page 3) some Hillsborough County 2 December 2004 Berry/Vegetable Times Development of the Mite Infestation: Control of an Kelthane? . All pesticide label Problem on Strawberries: outbreak of cyclamen mites is restrictions must be observed. Problems with the cyclamen mite on difficult to achieve, so strategies Special predatory mites are sold to strawberries in Florida develop from should be directed toward preventing control cyclamen mites, however the setting infested plants imported from an outbreak through the use of plants predators cannot control an the north. In more northern climates, certified to be free of the pest. To infestation sufficiently under our where strawberries are grown for late control cyclamen mites established conditions to avoid excessive losses. spring fruiting, cyclamen mites in a fruiting crop in Florida, it is Summary of Precautions overwinter as adult females in the extremely important to detect the Against Cyclamen Mites: crowns of infested strawberry plants.