Northeast Region Horticulture News

Volume 1, Issue 2 Summer, 2018 Leaves of Three...or Five...or Seven! Poison Ivy NE Region Master Gardener has Several Imposters. By Kerry Heafner Groups:  NORTHEAST LOUISIANA MASTER All three species cause an allergic reac- GARDENERS, OUACHITA PARISH. tion on the skin of most people who touch them with bare skin. The rash is  RIVER RIDGE MASTER GARDEN- caused by the oil urushiol, and some ERS, WEST CARROLL AND EAST people have reactions that are severe CARROLL PARISHES.

enough to warrant emergency medical  DELTA MASTER GARDENERS, attention. CONCORDIA, CATAHOULA, AND TENSAS PARISHES. So, how do you distinguish poison ivy, D’ARBONNE MASTER GARDEN- poison oak, and poison sumac? There  ERS, UNION PARISH. are several characters to consider.

Poison ivy (Toxicodendron radicans) climbing on a tree trunk. Habitat Photo by Carol Pinnell-Alison. Poison ivy (Toxicodendron radicans) is not as habitat-specific as its two conge- ners. It has a very broad ecological am- plitude, and this is why poison ivy is the poison plant most commonly encoun- tered in Louisiana gardens and land- scapes. It will grow in wet areas, dry areas, sunny areas, or shady areas. It isn’t choosey. On the other hand, poi- son oak (Toxicodendron pubsecens) is restricted to dry, upland areas. It will not be encountered in wet habitats unlike poison sumac (Toxicodendron vernix), which is a wetland plant, often found in sloughs or on creek sides. Un- Poison oak (Toxicodendron pubescens) photographed by, and less property sits directly adjacent to a used with permission of, Selena Dawn McMillan in Kisatchie wetland, the likelihood of encountering Northeast Region National Forest. poison sumac in a home landscape is Horticulture Agents:

virtually nil. KERRY HEAFNER: Summer means outdoor activities. And outdoor MOREHOUSE, OUACHITA, AND UNION activities usually include the inevitable encounter Habit PARISHES with rash-causing plants. A bad reaction from Habit refers to the form in which plants DONNA LEE: EAST CARROLL, WEST either one can mean a season of misery for a lot grow. All three species are woody, de- CARROLL, AND MADISON PARISHES. of gardeners. ciduous plants. Poison ivy is a vine. An Knowing how to accurately identify poison ivy, KYLIE MILLER: CATAHOULA AND especially robust, upright-growing spec- CONCORDIA PARISHES poison oak, and poison sumac, and distinguish imen may have a shrub-like appear- them from non-poison imposters can be a useful ance, but it is still a climbing vine. Poi- CAROL PINNELL-ALISON: FRANKLIN AND RICHLAND PARISHES skill for those of us who spend a lot of time out- son oak and poison sumac are both doors. shrubs. Poison sumac may Northeast Region Horticulture News

Poison Ivy…(continued from Page 1) even grow into a small tree with Poison ivy (T. radicans) and poison large specimens reaching as tall oak (T. pubescens) have leaves as 30 feet. However, specimens that are divided into three leaflets each whereas poison sumac (T. this size are encountered only vernix) has leaves that are pin- rarely. Whatever its size, poi- nately compound with up to 13 son sumac is never a vine. leaflets per leaf. In fact, it may more closely resemble an ash Leaves than a non-poison sumac (Rhus Leaves are the primary way sp.) typically seen on roadside banks. The leaflets of poison oak these three poison species are resemble small white oak leaves identified and distinguished. and are fuzzy. Leaflets of poison The leaves of all three species ivy may be variously lobed de- Poison sumac (Toxicodendron vernix) has pinnately compound pending on habitat and sunlight, are always alternately arranged leaves and is always a shrub or small tree. Photograph by Selena on the stems and are always but will be smooth. Leaflets of Dawn McMillan. poison sumac are typically not compound. That is, each leaf is lobed. But simply having three leaflets doesn’t mean a divided into leaflets. plant is poison ivy, or poison oak, and certainly “Leaves of three, let it be!” should be revamped to “Leaflets not poison sumac. A lot of plants not even closely of three, let it be!” related to these three species are misidentified as poison something! Poison Ivy Imposters

Virginia creeper, Parthenocissus quinquefolia, is misidenti- Peppervine, Ampelopsis arborea, is often misidentified as fied as both poison ivy and poison oak. Palmately com- poison ivy but has bipinnately compound leaves unlike poison pound leaves (five leaflets) distinguish it from poison ivy, ivy. Photograph by Kerry Heafner. oak, and sumac. Photograph by Kerry Heafner. Peppervine (Ampelopsis arborea) is a member of Virginia creeper (Parthenocissus quinquefolia) is the grape family (Vitaceae) and is possibly the most also a member of the grape family. Young commonly-occurring vine in the southeastern Unit- leaves of Virginia creeper are often trifoliate like ed States. Not poisonous at all, it often gets mistak- those of poison ivy. But, the mature leaves are en for poison ivy (or oak, or sumac). It is an aggres- immediately recognizable. Its vining habit distin- sive grower and can overtake an area in a land- guishes it from both poison oak and sumac. scape in short order. Page 2 Volume 1, Issue 2

Poison Ivy Imposters…(continued from Page 2)

Box elder (Acer negundo) is a tree alternately-arranged leaves. Poison often encountered in riparian sumac and ivy are more likely to be habitats. A species of maple, it found with box elder than poison has pinnately compound leaves oak, which is a species of drier, up- that rarely exhibit more than land sites. three leaflets. Young specimens Other vines may be mistaken for are easily mistaken for poison ivy. poison ivy or erroneously called However, box elder is easily dis- poison oak or sumac. Learning to tinguished from poison ivy by its distinguish harmless plants from

having oppositely-arranged leaves either will make for more pleasant as opposed to poison ivy’s always and safe outdoor experiences this summer. Box elder (Acer negundo) will always have oppositely-arranged leaves as opposed to alternately-arranged leaves of poison ivy, oak, and sumac.

Summer Lawn Care. By Donna R. Lee

July, August, and September are often our driest The reason behind this is if lawns are fertilized in months of the year with temperatures exceeding 95 late fall and an early frost occurs then the new degrees F and little to no rain. Not only do we suffer growth produced by the later fertilizer application but so do our lawns. What do we do? can cause damage to the lawn. If you feel the need To answer that question we need to go back to our to winterize try an application of potash, 0-0-60. lawn care guidelines. LSU AgCenter Turf Specialist, Dr. Be careful of pre-packaged winterize bags. Many Ron Strahan, recommends fertilizing lawns in April, of these include nitrogen in the mix. June and August with no nitrogen applications after August.

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Summer Lawn Care (continued)

Recommendations for mowing heights are specific to the type The most important thing to do during drought peri- grass you have. St. Augustine prefers a mowing height of 3 ods is water, water and water some more. Instead of inches, Cenitpede likes 1-1.75 inches, Zoysiagrass prefers 1-2 watering for a short period of time every two to three inches and Bermudagrass really likes 0.5-2 inches, but don’t days, it is recommended to water deeply one day per week. The water deeply method works for ornamen- scalp. tals, vegetables and trees also. What does all of this have to do with drought and lawns? Bottom line, great lawns require a bit of work but are Following these two recommendations will give you a healthi- well worth it. Fertilize properly, use the correct mow- er lawn which can sustain longer periods of drought than an er height and water as needed. This will go a long way unhealthy lawn will be able to sustain. toward a healthy lawn.

Summer Tomato Questions. By Carol Pinnell-Alison Tomatoes are a favorite vegetable in the home the plant roots not being able to take up enough garden. It is very common to get visits or calls calcium. Calcium is not a highly mobile element in from distressed gardeners with tomato plants or the soil. Factors limiting root growth like cold wet fruit that have something wrong with them. The soils or a fluctuation in water supply can cause the first calls are about having a large, healthy plant condition. Other factors are rapidly growing plants but no fruit. This is usually due to over fertilizing due to over fertilization with ammonium nitrate, the plant, especially with nitrogen. Over fertiliza- insufficient calcium in the soil, and high relative hu- tion keeps the plant in its growth stage and de- midity. Taking a soil sample for analysis is an inex- lays it from converting to its reproductive stage of pensive way to check on the fertility needs of your flowering and setting fruit. Once the plant begins garden site. The LSU AgCenter has a soil testing lab to fruit, the first cluster of fruit may have blossom on main campus in Baton Rouge. The cost to analyze end rot. This is a physiological disorder caused by a soil sample is $10.

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Summer Tomato Questions (continued)

As the weather gets hotter, our spring planted tomato As the plant grows, there are many diseases and insects that plants begin to produce less fruit. High nighttime tem- can damage it and the fruit. It is important to select tomato peratures reduce the viability of the pollen. It is best varieties that have resistance to diseases for planting. Fun- to plant a second crop of heat tolerant tomato plants gicides can be applied to control fungal diseases but there if you want to continue harvesting fruit through the are no pesticides that will control viral diseases like tomato summer and fall. Some heat tolerant varieties are spotted wilt virus. Common insect pests are stink bugs, leaf Bella Rosa, Tribeca, Tribute, Floralina, Florida 91, footed bugs, and tomato hornworms, which defoliate a Heatwave II, Solar Fire, Solar set, Sunmaster, and plant overnight. Insecticides can be used to control insects. Phoenix. Make sure to identify the disease or insect correctly and Another frequent question concerning a tomato plant apply the correct pesticide for their control. Read and fol- disorder is related to weed control. Tomato plants are low the pesticide label for all mixing, application timings and very sensitive to glyphosate-based herbicides. Many fruit harvest intervals after an application. home gardeners unintentionally spray glyphosate too close to their vegetable gardens resulting in a yellow or white discoloration on the leaves. The LSU AgCenter has several publications available for gardeners. Some of these are free and can be picked up at your local Cooperative Extension office. We have several publications for purchase which may be ordered from our web site through our online store.

Blossom end rot in tomatoes. Photograph by Carol Pinnell-Alison. Top Photograph: a leaf-footed bug on a tomato plant. Bottom Photo- graph: glyphosate damage on a tomato plant. Photographs by Carol Pinnell-Alison.

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Summer Tomato Questions (continued)

‘Omar’s Lebanese’ is an heirloom, beefsteak tomato. Heirloom varieties tend to be less re- sistant diseases than varieties bred specifically for disease resistance. Seeds from heirloom and open-pollinated varieties can be saved year after year because they breed true unlike seeds of hybrid varieties. Photograph by Kerry Heafner.

Tomato hornworm, the bane of many home garden- ers who covet summer tomatoes. Photograph by Carol Pinnell-Alison.

Two Louisiana Super Plants for Hot Weather!

The dog days of summer take their toll on much of the seasonal color in our landscapes. But, Angelonia can be counted on for summer color no matter how high daytime temperatures and relative humidities soar. The ‘Serena’ series of Angelonia is available in a variety of colors, all of which last through the worst part of summer’s heat and into fall. Plants get as tall as 20 inches. ‘Serenita Raspberry’ is a shorter variety, getting to 14 inches tall, with aptly-named flowers. Both ’Serena’ and ’Serenita Raspberry’ tolerate full sun all day and will even perform when dry periods come along in late sum- mer. ’Serena’ Angelonia was named as a Louisiana Super Plant in 2011. ’Serenita Raspberry’ was named in 2016. ‘Archangel’ is another variety seen in garden centers this summer. Angelonia thrives in heat and prefers a well-draining soil amended with generous amounts of compost. Fertilizing at the beginning of the season should see it through to fall.

‘Serenita Raspberry’ Angelonia is a Louisiana Super Plant “built” for hot, dry weather. Photograph by LSU AgCenter. Page 6 Volume 1, Issue 2

Plant Pumpkins Now for Fall Fun! By Kylie Miller and Carol Pinnell-Alison.

Our summer gardens are winding down in the hot humid weather of July and August. Gardeners may be getting a bit weary with weeding and watering. Don’t give up quite yet if you want to enjoy some fruits of your labor on the fun side of gardening later this fall. Consider planting pumpkins. Children and adults love pumpkins for decorating for Halloween or the center piece for the Thanksgiving table. Pumpkin pie is a bonus! Pumpkins are available in several sizes, shapes, and colors. Smaller sized varieties, no larger than 40 pounds, perform better under Louisiana growing conditions. Time to plant is in July for Halloween.

Pumpkins need a lot of space so plan accordingly. They can be planted by either direct-seeded into the ground or transplanted. They need to be planted in a sunny, well- drained location. Before planting the rows, apply 1 -1.5 A pumpkin on the vine. Photograph by Kylie Miller. pounds of complete fertilizer like 13-13-13 per 20 feet of row. This is best to be done a couple weeks before planting. Plant each hill (2-5 seeds per hole) 3-6 feet apart from one another and skip every other row. Plant seed in a hole about an inch deep. Make sure to water often since this is a dry time of the year.

When choosing which varieties to grow, think about how you would like to use them. Pumpkins used as decorations look great when mixing different sizes, textures, and col- ors. Suggested small varieties include ‘Sunlight,’ ‘Early Abundance,’ ‘Baby Bear,’ and ‘Darling.’ Recommended larger pumpkin varieties are ‘Connecticut Field,’ ‘Cinderella,’ and ‘Charisma.’

Photograph by LSU AgCenter.

Insects to scout for are Squash vine borer and cucumber beetles. Diseases include Bacterial wilt, brought in by the cucumber beetle, downy mildew, and powdery mildew. For control methods visit the LSU AgCenter website. Pumpkins are harvested when they become fully mature and the color is fully developed. The skin should be hard to puncture with your thumbnail. When cutting the pumpkins from the vine leave 2-4 inches of stem attached to the pumpkin to increase the storage life. Photograph by LSU AgCenter.

Page 7 LSU AGCENTER

Agents’ Question: Why do my tomatoes stop producing when hot weather hits? Q & A for Answer: Daytime temperatures above 90 degrees inhibit the ability of tomato pollen to leave

Summer the anthers of the stamens. To help your tomato flowers pollinate, gently flick the flowers with

a finger a couple times during the day, and you may notice better fruit set.

Question: How can I prolong the life of my basil plants? They’ve flowered and now they look

like they’re on their way out.

Answer: Simply deadhead the flowers back to the first pair of leaves and your basil plants

should put out new lateral shoots. Water after deadheading, and you should be able to make

pesto until temperatures moderate this fall. Also, as the number of daylight hours gradually

decreases, basil will start to give up its ghost.

Go to the Ag Journal page at www.myarklamiss.com to submit your lawn or garden question. Tune in to Louisiana Living with Ashley Doughty on Tuesdays at 4:30 p.m., and LSU AgCenter Horticulturist Kerry Heafner will answer your questions! Mark Your Calendar!