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About this time of year we begin to see many examples of herbicide 'drift' or weed control materials that carry distances from their point of application. The most serious offenders are auxin-like, growth-regulating herbicides such as 2,4-D and other herbicides of this type (called phenoxy herbicides) used for controlling broadleaf weeds and vegetation in lawns, crops, and pasture areas. There are several formulations of these materials that vaporize into a gas that can blow up to several miles where the gas is absorbed by sensitive garden plants. The herbicide moves within the plant to the growing point where resultant leaves formed in the next several days are deformed, twisted, and curled. Plants are usually not killed but fruit and flower production is delayed for several days up to several weeks as the plants recover from this injury. Other forms of herbicide drift may include contact herbicides that drift as particles (small droplets) onto susceptible vegetation. A wide range of materials may be involved and a range of symptoms from yellowing tips of foliage, spots or dead areas on leaves, or stunting/deformed growth patterns on susceptible vegetation. This type of spray injury usually will carry a shorter distance (one to two hundred yards under 'worst case' conditions).
Remember that the individuals who are responsible for the spraying are liable for any damage done to surrounding plants. Use formulations that are not volatile (don't vaporize as easily), spray only on calm days or when wind is blowing in a favorable direction. Avoid using high pressure, a fine mist, or upwardly directed sprays so as to minimize drift.
All broadleaf plants may be susceptible to injury. However, the ones that are especially sensitive include tomatoes, peppers, redbud, grape, and melon plants. There is nothing that can be done to counteract or un-do damage that may be done by applications of these herbicides. (CWM)
I have not seen any watermelon anthracnose, but the wet weather has been favorable for development. Growers should be on the lookout for this disease now. Look for small black spots on the leaves or stems of young plants. The lesions are often associated with the leaf veins. Anthracnose may also affect cucumbers and muskmelons but not squash or pumpkin.
Unfortunately, none of the current watermelon cultivars have good resistance against anthracnose, but there are resistant cucumber varieties available. Periodic fungicide applications may be necessary during wet weather in mid-summer. Apply chlorothalonil (Bravo, Terranil, others), mancozeb (Dithane, Manzate, others) or azoxystrobin (Quadris). (NT)
Grapes: Wet June weather has triggered outbreaks of black rot and downy mildew on grapes. Black rot affects both leaves and fruit, although the most dramatic damage occurs on the berries. Look for developing berries that begin to turn dark purple or black. The infected berries eventually will shrivel but will tend to cling to the cluster. If you look carefully you will see the tiny black fruiting structures (pycnidia) dotting the surface of the shriveled berry. Black rot is difficult to control once the fruit rot phase has developed. Try to manage the vines (tie up drooping vines, remove leaves next to fruit clusters) such that there is good air movement. Routine fungicide applications are necessary to inhibit further infection. During wet weather, don't stretch out the application interval to more than 10 days or so. There are many fungicides labeled for black rot. Some of the more effective products include Nova (sold as Immunox for homeowners), Bayleton, Elite, Ferbam, Procure, Rubigan, Abound, Sovran, and Flint. Mancozeb is also effective but the waiting interval (66 days to harvest) precludes further use of this product on most varieties.
Another disease that may be causing problems is downy mildew. Look for a white cottony growth on the surface of the berries. This fungus will also cause light yellow spots on the upper surface of the leaves. A white, wispy growth appears on the lower leaf surface. Many of the products listed for the control of black rot are weak or have no effect against downy mildew. Products with some activity against mildew include Captan, Abound, fixed coppers, Ridomil Gold MZ or Ridomil Gold Copper, and Sovran.
Cherries: Sour cherry harvest is just about over. To keep foliage free of cherry leaf spot and powdery mildew, make a fungicide application after harvest. Products that will control both leaf spot and powdery mildew include Nova, Rubigan, Indar or Elite.
Apples: Fireblight has been reported in several areas of the state. Applications of streptomycin now will not have much effect. If you are attempting to remove blighted twigs or limbs now, be sure to prune 10-12 inches below the blighted area. Never prune out fireblight during wet weather. Try to minimize further spread to expanding shoots by controlling insects.
Peaches: It is very important to control brown rot of fruit during the
3-4 week period before harvest. Several fungicides are available for control. See the tree
fruit spray guide for details. (NT)
Heavy fruit loads this season may cause limbs to break if they are not given extra support. As fruits increase in size, the additional weight on individual branches may be substantial. One-inch thick boards can be used to prop up limbs.
Here's how. Cut a "V" in the on the top edge of the board on which the limb will rest so that it doesn't slip off. Long limbs that are heavily loaded with fruit may need a prop in the center and another to support the outer part of the limb. A plastic belt-like material that is about 2 inches wide may also be used. This can be tied to a heavily loaded limb, then to a large diameter limb above for support. Where a large limb is used for support, it is good to have it supporting limbs on opposite sides so the weight is balanced. Another solution is to wrap a tape or belt material around the tree in a spiral to prevent limbs from bending until they break. Heavy twine may be used, but it should be removed when the fruit is picked or soon after so it does not cut into the bark on the limb. Check trees regularly, up to two times a week during the last month the fruit are maturing. You will find additional limbs that need support. Tending to the heavily loaded tree limbs will reduce the number of broken limbs and help keep a balance of the fruiting wood in your tree. (WU)
The diagnostic lab has received numerous samples of dead buffalograss from western Kansas this spring. In fact, this pattern of poor winter survival of buffalograss has been noted for several years in the northwest part of the state. The exact cause of the problem still remains a mystery although there may be several factors contributing to the decline. Symptoms are variable, but many homeowners report the appearance of large, irregular patches of turf that never green up. Both the roots and stolons are dead and, in some cases, severely rotted. Apparently, many of these lawns looked to be in good shape before entering winter dormancy.
I have been unable to consistently find a fungus associated with decline. We do know that the spring dead spot pathogen of bermudagrass can also damage buffalograss. However, this fungus has not been isolated from any damaged turfgrass. I have not completely ruled out a fungal etiology, and it is possible that other soil borne pathogens are associated with the decline.
Other factors may also be contributing to damage. Certainly, many buffalograss lawns
were severely damaged last summer as a result of chinch bug infestations. These tiny
insects can cause a substantial amount of injury and were widespread last season. Evidence
of chinch bug damage should be apparent in July and August, but many people may have
confused the damage with dormancy resulting from the drought. This chinch bug damage would
have predisposed the turf to continued winter damage. By the way, chinch bug activity for
this season will start soon (if it hasn't already) so be on the lookout. I also think that
a few of the highly maintained, irrigated buffalograss lawns may have been damaged by
grubs. Terry Mannell (Ellis County) and I found one such lawn in Hays. Fall grub damage is
probably not the major cause of the decline. Another factor that may play a role in
buffalograss decline is injury associated with spring-applied pre-emergence herbicides.
Some of these herbicides, if applied at excessive rates, could cause injury. (NT)
Several golf courses are experiencing problems with anthracnose on the putting greens. This disease will show up as blotchy areas in the turf that turn lime green and begin to thin. Both creeping bentgrass and annual bluegrass may be damaged. Interestingly, all the samples of anthracnose I have seen this season have been on creeping bentgrass. We normally associate anthracnose with hot weather, but this isn't always the case. It seems that excessive rains with high humidity and moderate temperatures will also trigger anthracnose development. Certainly, high daytime temperatures can make things much, much worse.
Control of anthracnose can be very difficult. The main objective is to eliminate as many potential stresses to the bentgrass as possible. Raising the mowing height, even by a small increment will help. Do not core the greens or topdress with sand. The physical movement of the sand on top of the putting surface will injure the grass blades and predispose them to further damage. If compaction is a problem, consider fracturing the profile with a hydroject machine. Light watering (syringing) at mid-day will cool the turfgrass. If anthracnose develops in areas with poor air movement, consider installation of fans. A light fertilization (1/8 - 1/10 lb nitrogen) may also stimulate new growth.
Fungicide applications for curative anthracnose control can be tricky. Everyone seems to have their favorite product. Many superintendents swear by high rates of thiophanate methyl (Cleary's 3336, Fungo and others) although research data to support this claim is somewhat thin. Others believe that azoxystrobin can provide some control. Still others use chlorothalonil (Daconil and others) or a combination of chlorothalonil with a sterol inhibiting fungicide such as Banner MAXX. While the fungicides may help suppress the fungus, the key to controlling anthracnose is to prevent stresses that predispose the turfgrass to injury. (NT)
The spittlebug derives its name from the white, frothy" spittle" the nymphs produce. Adults are large, black leafhoppers about 1/3-inch long with two red stripes that go crosswise across the back. The eyes and abdomen are bright red. Though the nymphs resemble the adults, they are smaller and wingless. Color varies from yellow to white to orange but the eyes are always red.
Spittlebug nymphs suck plant juices like aphids, but they remove so much water and carbohydrates that excess fluid is produced. They cover themselves with this fluid and then produce the spittle by bubbling air from the tip of the abdomen into the liquid. The spittle mass helps protect the nymphs from drying and predators.
Spittlebugs normally do not achieve high enough populations to cause damage. If they do, forcefully hosing the plants several times may achieve the level of control needed. If not, carbaryl (Sevin) will kill them. (WU)
Of all garden denizens, squash bugs are (perhaps) the most frequently mentioned pest across the state of Kansas. All varieties of summer and winter squash as well as most pumpkin varieties serve as host plants for squash bugs.
Often times, squash bugs are first noted when plants seem to wilt almost overnight. Upon close inspection of affected plants, squash bug nymphs and adults are seen scurrying about, most often after they have fallen off of plants which were lifted off of the ground. Population control efforts at that point in time are akin to closing the barn door after the horses have been let out.
However, currently, events in squash bug population buildups are still in the early stages, and therefore, implementation of monitoring activities and the application of an appropriate insecticide should help to minimize (if not eliminate) squash bug damage in squash and pumpkin plantings.
Squash bug control efforts are a continual ongoing activity because adult squash bugs are present throughout the season. Some of the adults are those which overwintered, while others are those which developed (during the current season) from eggs deposited by the overwintered females. And many overwintered females persist into the growing season and may still be depositing eggs along side of their daughters. Thus the necessity of a continual effort on the part of gardeners to keep ahead of squash bugs if the want to ensure maximum production of squashes and pumpkins.
Squash bugs prefer to deposit their eggs in masses (generally) between vein angles on lower leaf surfaces. Eggs are easily identified by their bronzish/brownish coloration. The period of egg hatch can be determined by designating several egg masses to be inspected every couple of days. The emergence of nymphs from these eggs (and from other undetected/unmonitored masses) marks the initiation point for applying an appropriate registered insecticide. Re-treatments, perhaps on a weekly basis, may be necessary to keep ahead of squash bugs.
As important as the timing of insecticide applications is the coverage achieved with each application. Squash bugs tend to remain hidden/out-of-sight given their preference for feeding on lower leaf surfaces. They are additionally shielded/hidden in thick foliar canopies. Therefore a mist-like spray application does little to reduce squash bug numbers. Rather, insecticides should be delivered under high pressure to ensure penetration to all parts of the foliage. Also, use adequate amounts of water carrier to ensure total plant coverage with the insecticide.
A new Extension Bulletin on squash bugs and squash vine borers can be obtained in local County Extension Offices. (BB)
Trees naturally shed bark as they grow. The amount of bark shed varies significantly from one year to the next and usually is not noticeable. However, some trees, such as sycamore, London Planetree and silver maple, shed bark in large patches or strips. During a year with heavy shedding homeowners may become concerned that the tree is sick or dying. Such is usually not the case. Sycamore and London planetree normally show a bright green coloration on the branches when the bark first falls off but soon return to a normal color. Maple reveals an orange coloration after shedding but it, too, soon returns to a normal color. There is nothing wrong with the tree as long as the shedding bark simply reveals underlying bark rather than bare wood. (WU)
Contributors:
Ward Upham, Extension Associate; Ned Tisserat, Plant Pathologist; Bob Bauernfeind, Entomologist, Chuck Marr, Vegetables
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