The Kentucky Blue Mold Warning System is now on the web. Its URL
address is:
http:
//www.uky.edu/Agriculture/kpn/kyblue/kyblue.htm
or get to it from the link on the bottom of the page.
This web site contains the Current Blue Mold Status Report for Kentucky along with information on the biology and control of blue mold. To assist in remaining current with this rapidly changing disease, this site is linked directly to Kentucky's Agricultural Weather Web Site and the North American Blue Mold Forecast System Web Site at North Carolina State University. It is also linked to the Kentucky Pest News and the Department of Plant Pathology which jointly operate the site.
The site is still under construction, so some details are still being modified. However, we feel its value currently justifies becoming operational now. Your understanding and cooperation will be appreciated during the start-up phase.
Corn producers in the western and southern portions of the state should begin scouting for European corn borer larvae. Because of the warm spring we have experienced, corn borer activity is early this year. However, many areas have experienced severe weather during moth emergence, mating and egg-laying, this may reduce levels of first generation larvae in some fields.
In particular, producers should pay close attention to early planted fields that are ahead of other fields in the area. These fields typically attract more intense egg laying. Most corn hybrids grown today resist European corn borer when they are less than 18 inches tall. However, as they continue to grow, their resistance diminishes.
Producers using Bt-corn hybrids should not have any problems with the first generation of this insect. However, some Bt-corn technologies do not have full season control and may allow for some damage by the second generation. Keep in mind that some European corn borer damage may still occur even in fields planted with Bt-corn seed, but the damage should be rare. Approximately 2 to 5 percent of the seed may produce plants that do not express Bt. In addition, plants producing Bt may have a small number of very small pin holes in the leaves, as the larvae must ingest a small amount of leaf material to be controlled.
STATEWIDE SITUATION: The level of blue mold activity is increasing rapidly in western Kentucky, and spores generated there and in western Tennessee have been spreading eastward across the Commonwealth. Based on evaluations conducted in the field on May 26, it appears that blue mold has been spread already across the state from west to east (confirmed as far east as Estill County) via a spore shower about two weeks ago. Weather conditions for the past several days have been nearly ideal for blue mold to develop where viable spores have landed on unprotected tobacco and the volume of spores is probably now sufficient to pose a significant risk to fields (statewide) as well as beds.
The North American Blue Mold Forecast System at North Carolina State University has issued a high risk advisory for spore movement over most of Kentucky. Therefore, a BLUE MOLD WATCH exists statewide for all field and transplant production, with WARNINGS for several areas.
Control programs should be in place and maintained (for transplants as well as field plantings) until the a major weather change develops.
The majority (75%) of Kentucky's tobacco crop remains massed in transplant production systems, ideal sites for blue mold to cause great damage quickly. So the industry needs to concentrate on keeping transplants protected. But, the situation is changing sufficiently that newly planted fields need fungicide protection as well, especially in counties with or neighboring those with active blue mold. Do not wait until you see blue mold in your field to start field sprays, but based on current levels of inoculum consideration should to where you are located relative to the source when making field spray decisions. Also keep in mind that the cost of making field applications at the current stage of field-growth is not high and adequate coverage is possible on small plants even with less than ideal spray equipment.
Growers need to be very careful in movement of transplants about the state. Also, growers need to understand that we cannot control the current strains of blue mold in transplant operations by waiting until the disease appears to start sprays! Timing (preventive) and coverage (complete surfaces) are critical to control.
WESTERN KENTUCKY: BLUE MOLD WARNING for the following State Extension Areas: Purchase, Pennyrile, Green River and Mammoth Cave! Blue mold activity is increasing rapidly in western Kentucky and could develop rapidly following the blue mold-favorable weather events of the past week. Control programs should be in place and maintained for transplant and field production in this region.
Blue mold has been confirmed in burley and dark tobacco transplant production systems in the following western Kentucky counties: Caldwell, Calloway, Christian, Daviess, Hancock, Logan, Todd, Simpson, Warren and Webster. However, it probably is active by now in all tobacco producing counties in western Kentucky. An additional threat to this region of Kentucky is the activity in western and middle Tennessee, as far west as Henry Co. and east to Macon Co. It is also active north of the Ohio River in Spencer County, Indiana. Even though Florida plants apparently served as the source of initial inoculum for this region, the outbreak is no longer confined to Florida sources. Secondary spread has occurred widely. Evidence suggest several spore shower probably occurred within the past 10-14 days. I suspect blue mold is much more widespread in the region than has been reported to us.
CENTRAL KENTUCKY: BLUE MOLD WATCH! (WARNING FOR WASHINGTON COUNTY and ESTILL COUNTIES). Blue mold has been confirmed in a direct-seeded greenhouse in Washington Co. and outdoor beds in Estill Co. The source of spores is not known, but probably airborne within the past two weeks from southwest (Kentucky or Tennessee). Recall that low-level risk of airborne movement of blue mold from western sources to central Kentucky has developed several times during the past two weeks and during the past 5 days the risk has been much higher. Blue mold could be develop rapidly in transplant production systems in this region from a single point-source of inoculation in beds. Fungicide spray programs should be maintained in all transplant production systems in this region. Field sprays should be started in all counties with active blue mold or neighboring counties. I suspect more counties in this region will be added to the list with active disease almost daily.
SOUTH-EASTERN, EASTERN AND NORTHERN KY: BLUE MOLD WATCH! Blue mold has not been confirmed in these regions, but it may be active at low levels. Growers in these regions are urged to keep fungicide sprays in place in all transplant systems and become ready to start field sprays on a short notice. Remain alert to all sources of active blue mold. In addition to the above activity, blue mold could threaten this region from the active in eastern Tennessee, which is now active as far north as Hancock County, Tn.
TRANSPLANT ADVISORY: Growers should assume that transplants moving from the following areas may have been exposed or infected with blue mold: western Kentucky, western Tennessee, central Kentucky, east Tennessee, Florida and Georgia. Kentucky's tobacco industry should remain very alert to the movement of blue mold on transplants, both from in-state and out-of-state sources. It is recommended that growers obtaining transplants from off their farm, use locally produced transplants in order to reduce spread of blue mold from region to region. Also, remain alert to the changing blue mold situation, because a source of transplant that was blue mold-free previously could have become contaminated in the last few days.
WEB-SITE: Our Blue Mold website is a good place to keep up with blue mold happenings impacting Kentucky. Especially important is the link to the North American Blue Mold Forecast System at North Carolina State University, which gives a future look at where blue mold is forecast to move via airborne routes.
The URL address is: http://www.uky.edu/Agriculture/kpn/kyblue/kyblue.htm
Plants may wilt for a variety of reasons soon after they are set in the field. Check them for signs of leaf-feeding and carefully scoop soil from around the base of the plant to expose the below-ground portion of the stem and root system. Insect damage is typically seen as gouges or tunnels in healthy, white tissue. Cutworms are most frequently the source of insect injury but occasionally wireworms are found.
With the relatively moist soil conditions in many areas, cutworms will do a significant amount of leaf feeding chewing large, irregular holes, especially in leaves lying on the soil surface. If the bud is not damaged and the stem is not cut, the plant can recover. Hot sun and dry soil forces the cutworms to feed below ground where they sever the stem, killing the plant.
Rescue treatments for cutworms, which include Orthene and Proxol as foliar sprays, are most effective as stomach poisons. Prospects for control are best when cutworms are feeding aboveground on the leaves and are poorest when feeding is below the soil surface.
Wireworms tunnel into stems, entering the plant below the soil surface. These dark brown, hard- bodied beetle larvae usually can be found by splitting the stalk lengthwise. There are no effective rescue treatments for this pest. However, if the plant is not girdled by the attack, it will probably survive but remain noticeably stunted during the remainder of the season. Usually neighboring plants will be larger because of reduced competition and there will be no appreciable yield loss. The wireworm is usually removed when a damaged plant is pulled and replaced.
Several insects can attack tobacco transplants soon after they are set in the field. Small (1/16" diameter), round holes are chewed by tobacco flea beetles. Usually there are several holes on each leaf and the small beetles can be seen on the foliage. Expect moderate to heavy feeding injury from these small insects over the next 3 to 4 weeks. These beetles will lay their eggs at the base of tobacco plants and eventually die. A new group of adults will emerge from the soil in about 30 days. The larval stage of tobacco flea beetles feeds on the roots of the plant and probably causes little injury to the plant.
Palestriped flea beetles have been a serious problem in years following mild winters. They are larger than the tobacco flea beetle and have a distinct pale stripe on each wing cover. Damage by this insect can be much more severe than the tobacco flea beetle but Orthene or Admire transplant water applications should provide good control. A foliar spray can be applied if not transplant water insecticide was used.
Spotted cucumber beetles (southern corn rootworms) will feed some on tobacco but do not occur in large numbers. Their round feeding holes are larger (1/4") than the flea beetle but occur only on scattered plants. These insects feed on a wide variety of crops and weeds so their effect usually is not focused on a particular species. They rarely cause enough damage to be of concern.
The Food Quality Protection Act requires that the EPA assess the risks from all uses of pesticides. Among those in Group One are organophosphate, carbamate, and B1 and B2 carcinogenic pesticides. The following active ingredients (brand names) are livestock insecticides recommended primarily for grub and lice control: coumaphos (Co-Ral), famphur (Warbex), fenthion (Tiguvon), phosmet (Prolex), trichlorfon (Neguvon), methoxycholr, permethrin (Atroban, Ectiban, De-Lice) and amitraz (Taktic). Group One products are subject to tolerance reassessment within the next two years. Replacement products (non-FQPA pesticides) include doramectin (Dectomex), eprinomectin (Eprinex), ivomectin (Ivomec), cyfluthrin (Cylence), and lambda-cyhalothrin (Sabre). (Agrichemical Insider)
Symptoms of frogeye leaf spot are plainly evident on leaves of apple and crabapple throughout Kentucky this week. In many plantings in eastern Kentucky, frogeye leaf spot will be more prevalent than other diseases such as scab or rust which are also visible now.
The symptoms appearing now on leaves are small (1/8 - 1/4 inch) distinct circular, brown spots. The center portion of the spot may become tan colored, while the outer edge remains dark brown, giving it a frogeye appearance. By contrast, apple scab develops as dark brown to black diffuse spots without sharp margins, and rust spots will have a distinct yellow-orange color. Signs of disease in the form of tiny black pycnidia (fungal fruiting bodies) of the causal fungus may develop in the center of the spot. Pycnidia can be examined with the aid of a hand lens and will appear as tiny black "pimples" when viewed through the magnifier. These pycnidia contain thousands of spores that are the source of continued infections. As leaf spots become more numerous and coalesce, leaves yellow and fall.
The cause of frogeye leaf spot and also black rot of the fruit and a canker disease of apple twigs and branches is a fungus called Botryosphaeria obtusa. This fungus is capable of attacking over 100 different kinds of trees and shrubs in Kentucky, so inoculum is quite widespread. The infections now being seen on the leaves most likely originated from cankers on dead twigs and branches in the tree. The black rot fungus frequently invades last year's infections of fire blight, still another disease, causing a canker of the branch or twig. Such cankers may weaken the limb to the extent that the branch breaks under a heavy fruit load, or is killed outright. Often a cone-shaped area of affected leaves will appear just beneath such a canker.
In trees with many cankers and spotted leaves, fruit infections have probably already occurred, but fruit decay will not appear until fruits mature. Infections usually begin in the blossom end of the developing fruit. As the fruits enlarge, a brown decayed area appears. The decay is often characterized by a series of concentric rings alternating from black to brown on the fruit surface. Pycnidia are scattered over the surface of the decayed fruit. Eventually, the rotted fruits dry out and mummify, sometimes hanging on the tree until the next season.
Control suggestions include:
* Prune out and destroy all dead twigs and
branches. When pruning, promote rapid wound
closing by not leaving stubs or making flush cuts.
* Thin out branches to promote good air
movement.
* Remove mummified fruit (infected the previous
year).
* Protect the fruits from injury caused by insects or
harsh spray materials.
* Promote optimum robust growth.
* Protectant fungicides used to control scab are
generally effective against frogeye leaf spot.
Four serious pests of landscape trees dogwood borer, bronze birch borer, flatheaded apple tree borer, and honey locust borer have emerged. The dogwood borer is the most serious pest of ornamental dogwoods, especially stressed trees in full sun. The bronze birch borer is a severe pest of white or paper birch, especially cultivated trees under stress. Flatheaded apple tree borers are major pests of red maples, hawthorns, flowering crabapple, and several other hardwoods, especially those which are newly transplanted or under stress. Honey locust borers are serious pests of transplanted and established urban trees with limited root zones. Mated females of all four species fly to host trees and lay eggs on the bark.
Management Borers rarely injure healthy trees or shrubs growing in their natural environments. When transplanted into landscape settings, every effort should be made to minimize plant stresses such as drought, soil compaction, sun scald, soil compaction, lawn mower/weed trimmer injuries, etc. Because newly planted are under considerable stress, preventive sprays are advisable during the first couple of growing seasons after planting. Timing is crucial in order to have a lethal residue of insecticide on the bark to intercept newly-hatched larvae before they burrow into the tree. Now is the appropriate time to apply protectant sprays for all four species. Lindane or Dursban are effective, and should be sprayed to runoff on the trunk and main scaffold limbs. A second application, three weeks after the first one, provides extended protection.
Bagworm eggs have now hatched and the young larvae are at their most vulnerable stage for treatment. This caterpillar is a serious defoliator of many different kinds of landscape and nursery plants. They are especially damaging to evergreens such as juniper, arborvitae, spruce, pine and cedar.
Bagworms overwinter as eggs within spindle- shaped bags made of silk and bits of plant material. Young larvae emerge and immediately begin feeding on the upper side of leaves, camouflaged within a tiny bag pointed upward. The bag is gradually enlarged as the larva grows. Older larvae strip evergreens of their needles and consume whole leaves of susceptible hardwood species, leaving only the larger veins.
Control- The best time to control bagworms is during the next few weeks, while the larvae are small. Carefully inspect susceptible landscape plants, especially evergreens, for last year's bags. Preventive treatment is often justified on plants that were heavily infested with bagworms the previous year. Small bagworms may also disperse to previously uninfested plant material after becoming wind-borne on silken strands.
Overwintering eggs can be destroyed by hand-picking old bags during the winter or early spring. However, this window of opportunity has passed, and insecticides are now the only effective means of control. For homeowners, Sevin, Dursban, Malathion, or the microbial insecticide Bacillus thuringiensis (BT) work well. For nursery and landscape professionals, other effective products include Astro, Decathlon, Mavrik, Orthene, Pounce, Scimitar, Talstar and Tempo.
(For more on this pest, see the new Entfact-440, Bagworms on Landscape Plants .)
Small, dark flies (about 1/3 the size of a house fly) have begun to show up in large numbers in some areas and can be seen resting on just about any surface from plants to vehicles. These are probably adults of seed maggot and root maggot flies that have just completed a generation. The larval or maggot stages occur in soils with high organic matter and do well in cool, wet soils. The adults are harmless. These flies are often killed by a fungus disease and are seen stuck to plant foliage. Often whitish fungal structures can be seen growing out of the dead flies. You may get some questions about these insects.
Several species of gall mites produce striking symptoms on maples but they rarely affect tree health. Maple bladder galls are green or red "warts" that can be found on the upper surface of red or silver maple leaves. Long, thin maple spindle galls arise from sugar maple leaves. Green or red felt-like patches on the underside of silver and red maples are erineum galls.
These galls are produced by tiny mites that feed on the new leaf growth in the spring. Galls, produced by leaf tissue, develop around the mites providing food and shelter. Colonies containing hundreds of mites can flourish in the gall. Adults will disperse form the gall and move to newly developing leaves. Gall production slows and stalls as new leaf growth ceases in late spring. Leaves produced during late spring and summer usually do not have galls. See Entfact 404 for more information on maple galls .
If you haven't been receiving calls about large, black bees hovering around the eaves, decks, and wood siding of your clients' homes, you will shortly. These are probably carpenter bees searching for mates and nesting sites. Carpenter bees cause cosmetic and structural damage to wood. They can be quite intimidating to homeowners and have the potential to inflict painful stings.
The Problem- Carpenter bees are similar in appearance to bumble bees, but have nesting habits which are different. Bumblebees nest in the ground, whereas carpenter bees tunnel into wood to lay their eggs. Bare, unpainted, or weathered softwoods are preferred, especially redwood, cedar, cypress and pine. Painted or pressure-treated wood is much less susceptible to attack. Common nesting sites include eaves, fascia boards, siding, wooden shake roofs, decks and outdoor furniture.
Carpenter bees overwinter as adults in old nest tunnels. After mating, the fertilized females excavate tunnels in wood, laying their eggs within a series of small cells. The cells are provisioned with a ball of pollen on which the larvae feed, emerging as adults in late summer. The entrance hole and tunnels are perfectly round and about the diameter of your finger. Coarse sawdust, the color of fresh cut wood, is often seen beneath the entry hole, and burrowing sounds may be heard within the wood. Female carpenter bees may excavate new tunnels or enlarge and reuse old ones. Serious damage can result when the same piece of wood is utilized for nesting year after year.
Males are often aggressive, hovering in front of people who are around the nests. The males are harmless, however, since they lack stingers. Female carpenter bees can inflict a painful sting, but seldom will unless handled or molested.
The Solution- The best time to control carpenter bees is before the tunnels are fully constructed. Liquid sprays of Sevin, Dursban, Ficam, or a synthetic pyrethroid (permethrin, cypermethrin, cyfluthrin, etc.) can be applied to wood surfaces attracting large numbers of bees. Wettable powder, flowable and microencapsulated formulations perform better than emulsifiable concentrates since treated surfaces tend to be porous. Residual effectiveness of most spray formulations sold to homeowners is only about 7-10 days, so the treatment may need to be repeated. Carpenter bee tunnels that already have been excavated are best treated by puffing an insecticide dust (e.g., Sevin, Ficam, Drione) into the nest opening. Aerosol sprays sold for wasp or bee control also are effective and often more convenient than dusts for the homeowner. Although carpenter bees are less aggressive than wasps, female bees provisioning their nests will sting. Treatment is best performed at night or while wearing protective clothing.
Leave the hole open for a few days after treatment to allow the bees to contact and distribute the insecticide throughout the nest galleries. Then plug the entrance hole with a piece of wooden dowel coated with carpenter's glue, wood putty, or other suitable sealant. This will protect against future use of the old nesting tunnels, as well as moisture intrusion and wood decay.
Carpenter bees normally will not tunnel into painted wood. Therefore, a more permanent solution is to paint unfinished wood surfaces, especially those with a history of being attacked. Wood stains and preservatives are less reliable than painting, but will provide some degree of repellency versus bare wood. To further discourage nesting, garages and outbuildings should be kept closed when carpenter bees are actively searching for nesting sites.
We are continuing to see many tobacco diseases--Pythium root rot, Rhizoctonia diseases, blackleg, blue mold. Pythium has been especially prevalent in the last week, with root infectious and blackening and constriction of stems from Pythium stem infections. Heat injury and fertility problems (both low and high) are also common. Head scab of wheat was seen last week in Western KY.
In the landscape, we are seeing a variety of infectious problems, including: Phomopsis twig blight on juniper and false cypress, Discula anthracnose and spot anthracnose on dogwood, as well as anthracnose on maples, Cladosporium leaf spot on peony, bacterial spot on English ivy, powdery mildew on euonymus and ageratum, and rose rosette virus on rose.
Fruit and vegetable diseases include peach leaf curl (still prevalent) on peach and nectarine, and the similar disease of plum, plum pockets; orange rust on blackberry; apple scab; and bacterial speck and Sclerotinia collar rot on tomato.
| Princeton | |
| Black cutworm | 8 |
| True armyworm | 48 |
| European corn borer | 12 |
Lee Townsend
Extension Entomologist