Category: Poison Ivy

Miscellaneous: Poison Ivy Identification and Control

5/2/2017

Learning to identify poison ivy is vital if you wish to avoid the rash that accompanies exposure. Unfortunately, poison ivy can make identification difficult because it occurs in three forms: an erect woody shrub, a groundcover that creeps along the ground, and a woody vine that will climb trees.

When poison ivy climbs, it forms numerous aerial roots that give the vine the appearance of a fuzzy rope. The leaves of poison ivy also vary. Though the compound leaf always has three leaflets, the leaf margins may be toothed, incised, lobed or smooth. The size of the leaves also can vary, although usually the middle leaflet is larger than the other two. Also, the middle leaflet is the only one with a long stalk; the other two are closely attached to the petiole (leaf stem). The number of leaves gives rise to the saying: "Leaves of three, let it be!" Poison ivy is often confused with Virginia creeper or Woodbine. Each of these vines, however, has five leaflets rather than three.

There are three methods commonly used to eradicate poison ivy. These include pulling or grubbing out the plants by hand, cutting off the vine, and then treating the cut stump or the regrowth, and spraying the plants directly. The method used depends somewhat on the plant's growth form.

If the plant is growing as a groundcover, direct spray or grubbing the plant out is often used. If grubbing, wear gloves and a long-sleeved shirt. The soil must be moist for grubbing to work well. Wash the clothes and yourself immediately after you finish. It might also be a good idea to rinse the washing machine.

If the plant is in the shrub form, direct spray is the most common control method. If the plant is a woody vine that has climbed a tree, the preferred method is to cut the plant off at the base and treat the sprouts after they emerge. Some triclopyr herbicides also have instructions on treating a freshly cut stump directly. Triclopyr (Brush-B-Gon Poison Ivy Killer, Brush Killer Stump Killer) is most often used for poison ivy control. Other Herbicides that can be used include glyphosate (Roundup, Killzall Weed and Grass Killer, Nutgrass, Poison Ivy and VineKiller) or dicamba. Poison ivy is tough. Repeat applications may be necessary. (Ward Upham)

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Horticulture Newsletter 2016, No. 17

4/26/2016

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Video of the Week:
Supertunias Grow Big

Vegetables:
Sweet Corn Primer

It used to be simple to decide which sweet corn to plant. You simply chose a cultivar and planted when the soil temperature reached 55 degrees. Now it has become more complicated due to genetic advances in sweet corn. Breeders have found certain genes that improve “standard” sweet corn. Below is an overview of the types commonly available to homeowners.

Standard (su): This is our “normal” sweet corn and contains a “sugary gene” (su). Standard sweet corn should be isolated from field corn, popcorn, supersweets and ornamental corn. To isolate one type of corn from another, do not plant one type within 200 to 250 feet or be sure to have a difference of 12 to14 days in time to maturity. Plant when the soil temperature reaches at least 55 degrees. Recommended varieties include Honey and Cream, Silver Queen, Sterling Silver, Jubilee, or Merit.

Supersweet (sh2): Though supersweets have up to three times the sweetness of standard sweet corns and hold their sweetness longer after harvest due to the sh2 gene, they do have some drawbacks such as tougher kernels and a lack of some of that good “corn” flavor. They also need to be isolated from other sweet corn types and are very sensitive to cooler soils. Wait until the soil temperature reaches 65 degrees before planting. Try Candy Store, Florida Staysweet, Sugar Loaf, Sweet Time, or Sweetie.

Sugar Enhanced (se): These are probably the most popular type of sweet corn grown due to their tender kernels, good flavor and less sensitivity to cool soils (60 degree soil temperature for planting). They hold their post-harvest sweetness longer than standard types but will not hold sweetness as long as the supersweets. The sweetness from the sugar-enhanced types is due to the “se gene.” If both parents were se types, the variety is known as an se+ or se se. If only one parent was an se type and the other an su type, then the variety will be listed as se. They do not need to be isolated other than from the supersweets. Suggested varieties include Bodacious, Ambrosia, Sweet Temptation, Delectable and Miracle.

Triplesweet (synergistic): The newest types of sweet corns blend the su, se and supersweet types with the goal of combining the best characteristics of each. We don’t have firm recommendations yet but you may want to try Serendipity, Polka, Avalon or Frisky. (Ward Upham)

Turf:
Powdery Mildew on Lawn

We have had a number of instances of powdery mildew on lawns in eastern and southern Kansas. Though the disease looks serious, it rarely causes lasting damage to the turf.

Individual blades look like they have been dusted with flour. Closer inspection reveals a white, powdery growth primarily on the upper surface of the leaves. As the disease progresses, turfgrass blades wither and die. Kentucky bluegrass grown in the shade is the most likely to be affected though other species can be susceptible. High relative humidity, poor air movement, and air temperatures around 65°F favor disease development. Try to improve light and air penetration.

The development of mildew often indicates areas of the lawn that are unsuitable for turfgrass. Consider other types of ground covers for these areas.

Several fungicides, including triadimefon (Bayleton), propiconazole (Banner MAXX, Fertilome Liquid Systemic Fungicide), and myclobutanil (Eagle, Immunox) are effective in reducing the incidence of powdery mildew. (Ward Upham)

Pests:
Carpenter Bees

Although carpenter bees look much like bumblebees, they are easy to identify if you know what to look for. Bumblebees have hairy abdomens that are usually yellow and black. Carpenter bees’ abdomens are shiny blue-black. Carpenter bees are solitary (do not form colonies) and are nonaggressive unless provoked. Only the female possesses a stinger. The male may act aggressive but is harmless. Carpenter bees get their name from the ability of the female to bore into wood. Holes are about a half-inch in diameter and may be 6 inches deep. The female then builds six to eight cells off the main tunnel and lays an egg in each.

Developing larvae feed off of "bee bread" (pollen and nectar) regurgitated by the female bee. Larvae become adults by late August and September, but do not emerge until the following spring. Individual holes may not cause much damage, but cumulative effects of numbers of bees can weaken structures. Painting wood surfaces can make them less attractive to bees. Stains seem to have little effect. Insecticides, such as Sevin, can be used to treat openings. Sprays and dusts are both effective but sprays may only last for 1 to 2 weeks and require retreatment. Dusts are most easily applied with a puffer duster. It is best to treat near sundown when the bees have returned to their tunnel. (Ward Upham)

Termites or Ants

Both termites and ants are able to swarm and may have wings during part of their lives. Since these insects are close to the same size, people often misidentify flying ants as termites. Since flying ants do not attack wooden structures like termites, it is helpful to be able to tell the difference.

Fortunately, there are several differences that can easily distinguish the two. For example, ants have a thin waist; the waist of a termite is thick. Also, ants' antennae are elbowed, while termites' are not. Thirdly, termites have two pairs of wings that are of equal length. Ants also have two pairs of wings, but theirs are of unequal length. Homeowners who find signs of termite activity should shop for a reputable pest control firm. (Ward Upham)

Miscellaneous:
Storm Damage and the Garden

Various parts of the state have had high winds, excessive rainfall and hail. This column deals with what can be done to help our gardens recover.

Heavy rain: The force of rainfall pounding on the soil can result in a thick crust that prevents seed emergence and partially blocks oxygen from reaching roots. A light scraping after the soil surface has dried is all that is needed to correct these problems. Be careful of deep tilling as it may damage young, tender roots.

Standing water: Standing water cuts off oxygen to the roots, which can result in plant damage if it doesn’t drain quickly enough. Most plants can withstand 24 hours of standing water without harm. Hot, sunny weather can make a bad situation worse by the water becoming hot enough to “cook” the plants. There isn’t much that can be done about this unless a channel can be cut to allow the water to drain.

Hail damage: Plants should recover quickly as long as the leaves only were damaged by the hail as leaves regenerate quickly. The situation becomes much more serious if the stems and fruit were damaged. The plant can recover from a few bruises but if it looks like the plants were mowed down by a weed whip, replanting is in order.

Leaning plants: Either wind or water can cause plants to lean. They should start to straighten after a few days. Don’t try to bend them back as they often break easily. (Ward Upham)

Field Bindweed Control

Field bindweed is difficult to control, especially for homeowners, but there are options.

Home Vegetable Gardens: Weed control requires taking the treated portion of the garden out of production for a time.

Glyphosate - Glyphosate is sold under a wide variety of names, the most common being Roundup. Take the garden out of production when treating.

1. Glyphosate is a non-selective herbicide that will kill whatever it hits but is inactivated when it contacts the soil.

2. Glyphosate is most effective when applied to bindweed that is at or beyond full bloom. You can treat earlier but don't skip the late summer to fall application.

3. Do not apply to bindweed that is under moisture stress or not growing well.

Turf: Selective herbicides are available. A herbicide with the trade name of Drive (quinclorac) is now packaged in homeowner combination herbicides such as Fertilome Weed-Out with Q, Ortho Weed-B-Gon Max + Crabgrass Control, Monterey Crab-E-Rad Plus and Bayer All-in-One Lawn Weed and Crabgrass Killer.

Commercial applicators can also use Drive (quinclorac) as well as Q4 (contains quinclorac). Products with Drive work better than glyphosate and are selective. Note that lawns treated with Drive should not use clippings in compost or as mulch as Drive is very stable on grass clippings. We recommend clippings be returned to the lawn anyway but if they are bagged, they should be discarded. Do not apply products with Drive over exposed roots of trees and ornamentals. It would be best to avoid spraying beneath the canopy of any trees to avoid possible damage. If there are plans to convert a section of lawn to a vegetable garden, do not use Drive on that area. Eggplants can be damaged if planted within 12 months of areas treated with Drive, and tomatoes can be damaged if planted within 24 months. Shrub Beds: Use a spray of glyphosate between plants. Use a shield if spraying near plants to keep spray from contacting green plant material. Remember, glyphosate will hurt your shrubs if it contacts green tissue.

It is possible to control field bindweed by pulling, but you must be extremely persistent. I remember reading a study from the 1940s that found that bindweed produces enough energy to start strengthening the roots when it reached the six-leaf stage. So, if pulling, never allow plants to produce more than six leaves. (Ward Upham)

Poison Ivy Identification and Control

Learning to identify poison ivy is vital if you wish to avoid the rash that accompanies exposure. Unfortunately, poison ivy can make identification difficult because it occurs in three forms: an erect woody shrub, a groundcover that creeps along the ground, and a woody vine that will climb trees.

When poison ivy climbs, it forms numerous aerial roots that give the vine the appearance of a fuzzy rope. The leaves of poison ivy also vary. Though the compound leaf always has three leaflets, the leaf margins may be toothed, incised, lobed or smooth. The size of the leaves also can vary, although usually the middle leaflet is larger than the other two. Also, the middle leaflet is the only one with a long stalk; the other two are closely attached to the petiole (leaf stem). The number of leaves gives rise to the saying: "Leaves of three, let it be!" Poison ivy is often confused with Virginia creeper or Woodbine. Each of these vines, however, has five leaflets rather than three.

There are three methods commonly used to eradicate poison ivy. These include pulling or grubbing out the plants by hand, cutting off the vine, and then treating the regrowth, and spraying the plants directly. The method used depends somewhat on the plant's growth form. If the plant is growing as a groundcover, direct spray or grubbing the plant out is often used. If grubbing, wear gloves and a long-sleeved shirt. The soil must be moist for grubbing to work well. Wash the clothes and yourself immediately after you finish. It might also be a good idea to rinse the washing machine. If the plant is in the shrub form, direct spray is the most common control method. If the plant is a woody vine that has climbed a tree, the preferred method is to cut the plant off at the base and treat the sprouts after they emerge. Some triclopyr herbicides also have instructions on treating a freshly cut stump directly. Triclopyr (Brush-B-Gon Poison Ivy Killer, Brush Killer Stump Killer) is most often used for poison ivy control. Other Herbicides that can be used include glyphosate (Roundup, Killzall Weed and Grass Killer, Nutgrass, Poison Ivy and VineKiller) or dicamba. Poison ivy is tough. Repeat applications may be necessary. (Ward Upham)

Contributors: Ward Upham, Extension Associate

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Horticulture Newsletter 2014 No.22

6/3/2014

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Video of the Week:
Poison Ivy

Turfgrass:
Little Barley in Lawns

Many people mistake little barley (Hordeum pusillum) for a little foxtail because the foxtail and little barley seedheads are similar. However, little barley is a winter annual that thrives in the cooler spring temperatures but dies out in the summer. Foxtail, on the other hand, is a summer annual that does well in hot weather. Also, foxtail will not produce seedheads until mid- to late-summer.

At this point there is no control for little barley other than a glyphosate product such as Roundup. However, Roundup will kill whatever it hits and cannot be used in a lawn situation. The only preemergence herbicide that I know is labeled for lawn situations is Surflan. Monterey Lawn and Garden also sell it under the name of Weed Impede. Surflan can only be used on warm-season grasses (bermudagrass, buffalograss, zoysiagrass) and tall fescue grown in warm-season areas. Because little barley is a winter annual, apply the preemergence herbicide in September. (Ward Upham)

Flowers:
Sidedressing Annual Flowers

Modern annual flowers have been bred to flower early and over a long period of time. They are not as easily thrown off flowering by high nitrogen levels as vegetables are. As a matter of fact, providing nitrogen through the growing season (sidedressing) can help maintain an effective flower display for warm-season flowers.

Apply a high nitrogen sidedressing four to six weeks after flowers have been set out. Additional fertilizations every three to four weeks can be helpful during a rainy summer, or if flower beds are irrigated. Common sources of nitrogen-only fertilizers include nitrate of soda, urea, and ammonium sulfate. Blood meal is an organic fertilizer that contains primarily, but not exclusively, nitrogen. Use only one of the listed fertilizers and apply at the rate given below.

Nitrate of soda (16-0-0): Apply 1/3 pound (.75 cup) fertilizer per 100 square feet.
Blood Meal (12-1.5-.6): Apply 7 ounces (7/8 cup) fertilizer per 100 square feet.
Urea (46-0-0): Apply 2 ounces (1/4 cup) fertilizer per 100 square feet.
Ammonium Sulfate (21-0-0): Apply 4 ounces (½ cup) fertilizer per 100 square feet.

If you cannot find the above materials, you can use a lawn fertilizer that is about 30 percent nitrogen (nitrogen is the first number in the set of three) and apply it at the rate of 3 ounces (3/8cup) per 100 square feet. Do not use a fertilizer that contains a weed killer or weed preventer. (Ward Upham)

Iris Leaf Scorch

The symptoms of iris leaf scorch are distinctive in that the leaves burn back from the tips and turn a tannish to brownish color. The center leaves of the fan are affected first. Leaf scorch differs from iris leaf spot in that the color is uniform rather than being concentrated in spots that eventually may coalesce. However, both conditions may be present at the same time.

Another distinctive symptom is the loss of roots on affected plants. Surprisingly, rhizomes are not affected. Though iris leaf scorch may occur at any time during the growing season, it is most common in early summer, and we are seeing a significant amount of it now. Fortunately, the disease does not seem to spread easily. Completely healthy plants are often right next to scorched ones.

So, what do we do about it? There was a study done a number of years ago that identified the causal organism as a mycoplasma and showed that subjecting rhizomes from scorched plants to 104 degrees F for 3 to 4 days cured the problem. However, I can’t locate a copy of the study, so I am hesitant to recommend it without reservation. Another recommendation I have seen is to give the rhizomes the “hot asphalt treatment.” This consists of digging the rhizomes and placing them on asphalt in the sun to let them cure for a week. Really, I’m not making this up. A third option suggested by a University of Nebraska publication is to lift affected plants and store them in a dry, cool place until replanting in early August. This is one of those situations where you must choose which option is the most appealing, and run with it. (Ward Upham)

Ornamentals:
How Healthy is My Tree?

One of the most important clues in determining the health of your trees is the amount of new growth that tree produces. A healthy tree should have a minimum of 4 to 6 inches of new growth each year. Check branches with the tips in the open and not shaded by the tree itself. Anything less than 4 inches on the majority of branches suggests the tree is under a great deal of stress.

So, how do you tell where the new growth stops? Look for a color change in the stem. New growth is often greener than that from the previous year. There is also often an area of what looks like compressed growth where growth transitions from one year to the next. Lastly, look at leaf attachment. Leaves are only produced on current seasons’ growth. Therefore, new growth stops where leaves are no longer attached directly to the twig but to side branches. However, pay attention as leaves may be appear to be attached directly to last year’s growth but are actually borne on short spurs. If you look closely, you can tell the difference.

All this clue tells you is whether a tree is under stress or not. It does not tell you what is causing poor growth. This year, the most common cause by far is environmental stress caused by the warm, dry winter of 2011-2012 and the drought and hot summer temperatures in 2011 and 2012. Also, this last winter was cold and very windy causing a great deal of winter damage.

Stress is cumulative. In other words, trees may not have completely recovered from stressful conditions that occurred several years ago. The accumulating stress may have damaged root systems. In some cases, root systems were damaged enough that those trees may struggle as we enter summer. Though the roots were able to keep up with moisture demands during the cooler spring weather, they may not be able to as temperatures rise. Such trees may suddenly collapse and die or slough off branches they can no longer support. If possible, water to a depth of 12 inches every couple of weeks we do not receive rain in order to avoid further stress. (Ward Upham)

Pests:
Carpenter Bees

Although carpenter bees look much like bumblebees, they are easy to identify if you know what to look for. Bumblebees have hairy abdomens that are usually yellow and black. Carpenter bees’ abdomens are shiny blue-black. Carpenter bees are solitary (do not form colonies) and are nonaggressive unless provoked. Only the female possesses a stinger. The male may act aggressive but is harmless.

Carpenter bees get their name from the ability of the female to bore into wood. Holes are about a half-inch in diameter and may be 6 inches deep. The female then builds six to eight cells off the main tunnel and lays an egg in each. Developing larvae feed off of "bee bread" (pollen and nectar) regurgitated by the female bee. Larvae become adults by late August and September, but do not emerge until the following spring.

Individual holes may not cause much damage, but cumulative effects of numbers of bees can weaken structures. Painting wood surfaces can make them less attractive to bees. Stains seem to have little effect. Insecticides, such as Sevin, can be used to treat openings. Sprays and dusts are both effective but sprays may only last for 1 to 2 weeks and require retreatment. Dusts are most easily applied with a puffer duster. It is best to treat near sundown when the bees have returned to their tunnel. (Ward Upham)

Bristly Rose Slug

This insect has been skeletonizing rose leaves in the Kansas City area. This is not a caterpillar but is the larva of a sawfly. Close examination of this small (½ inch) larva will reveal very fine, hair-like spines in clusters.

Young larvae will remove the green layer of a leaf leaving behind a clear material. As the larvae mature, they make holes in the leaf and eventually may consume all of the leaf but the major veins.

Since these insects are not caterpillars (larvae of moths or butterflies), BT, found in Dipel and Thuricide will not be an effective treatment. However, a strong jet of water will dislodge the slugs and make it difficult for them to return to the plant. Other effective treatments include insecticidal soap, horticultural oils, spinosad (Fertilome Borer Bagworm, Leafminer and TentCaterpillar Spray or Captain Jack’s Deadbug Brew) and permethrin (various trade names). (Ward Upham)

Oak Vein Galls

We are seeing a high number of oak galls this year, especially vein pocket gall on pin oak leaves.Vein pocket gall causes abnormal swelling of the leaf near the veins. Actually, there are hundreds of different types of galls, each of which is caused by a specific insect. Insects that can cause different galls on oaks include tiny, non-stinging wasps and flies which cause abnormal growths to develop on the leaves, twigs or branches of oak trees. There are even some mites that can cause galls. These galls can include growths that are round, spiny, flattened, elongated or star-shaped. Galls form in response to a chemical that the insect or mite injects into the plant tissue. Eggs laid by a mature female hatch into legless grubs around which the gall forms. The larvae feed, develop, and pupate inside these galls. The adults may emerge either the same season or may overwinter inside the gall depending on the life history of that specific insect.

Generally, these gall insects do not cause significant damage to their hosts, though some of the leaf galls can cause enough deformity to make a tree unsightly. Also, severe infestations of twig galls can cause twig dieback or, rarely, tree death. However, just because a twig is covered with galls does not mean it is dead. I have seen twigs that looked like a solid mass of galls leaf out in the spring.

Insecticide sprays applied when galls are noticed are ineffective because damage has already occurred. Also, larvae are unaffected because of the protection afforded by the gall. Insecticide sprays can kill emerging adult wasps and flies, but long emergence periods and short residuals of most contact insecticides make this impractical. Stem and twig galls can be pruned if this is deemed to be practical and necessary. Fortunately, natural predators and parasites usually bring these insects under control given a year or two. Therefore, the best option is usually to do nothing. (Ward Upham)

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Miscellaneous: Poison Ivy Identification and Control

Horticulture Newsletter 2016, No. 17

Video of the Week:
Supertunias Grow Big

Vegetables:
Sweet Corn Primer

Turf:
Powdery Mildew on Lawn

Pests:
Carpenter Bees

Termites or Ants

Miscellaneous:
Storm Damage and the Garden

Field Bindweed Control

Poison Ivy Identification and Control

Horticulture Newsletter 2014 No.22

Video of the Week:
Poison Ivy

Turfgrass:
Little Barley in Lawns

Flowers:
Sidedressing Annual Flowers

Iris Leaf Scorch

Ornamentals:
How Healthy is My Tree?

Pests:
Carpenter Bees

Bristly Rose Slug

Oak Vein Galls

Authors

Subscribe to the newsletter by entering your e-mail and clicking the link below

Archives

Categories

Miscellaneous: Poison Ivy Identification and Control

Horticulture Newsletter 2016, No. 17

Video of the Week:Supertunias Grow Big

Vegetables:Sweet Corn Primer

Turf:Powdery Mildew on Lawn

Pests:Carpenter Bees

Termites or Ants

Miscellaneous:Storm Damage and the Garden

Field Bindweed Control

Poison Ivy Identification and Control

Horticulture Newsletter 2014 No.22

Video of the Week: Poison Ivy

Turfgrass: Little Barley in Lawns

Flowers: Sidedressing Annual Flowers

Iris Leaf Scorch

Ornamentals:How Healthy is My Tree?

Pests:Carpenter Bees

Bristly Rose Slug

Oak Vein Galls

Authors

Subscribe to the newsletter by entering your e-mail and clicking the link below

Archives

Categories

Video of the Week:
Supertunias Grow Big

Vegetables:
Sweet Corn Primer

Turf:
Powdery Mildew on Lawn

Pests:
Carpenter Bees

Miscellaneous:
Storm Damage and the Garden

Video of the Week:
Poison Ivy

Turfgrass:
Little Barley in Lawns

Flowers:
Sidedressing Annual Flowers

Ornamentals:
How Healthy is My Tree?

Pests:
Carpenter Bees