MAPLE PETIOLE BORER damage evident; CANKERWORMS AND LOOPERS in trees; EASTERN TENT CATERPILLAR
tents on wild cherry trees (#424); CARPENTER BEES tunneling in wood (#611); CARPENTER ANTS
around homes (#613).
The recent spate of rain and overcast days is a reminder that spring has sprung. For those producing tobacco transplants, the arrival of spring should also be a reminder to keep a close watch for the development of disease in transplant systems and to maintain good production practices so as to minimize the risk of losses to disease. Over the next few weeks, we will take a look at some diseases commonly seen on tobacco transplants and recommended control practices.
Sclerotinia Collar Rot
Caused by the fungus Sclerotinia sclerotiorum, collar rot was rarely seen in the pre-float-system era; however, outbreaks are now common in Kentucky. The first symptom of collar rot is a small, dark green, water-soaked lesion at the base of a transplant's stem. Clusters of infected transplants, often located in areas of poor air movement, will be apparent and will have a yellow, wilted, unthrifty appearance. The size of the cluster, or "focus", is usually 4-16" in diameter. Fungal growth, in the form of white, cottony mycelium (fungal mass), may be present if humidity is high, along with irregularly-shaped, black sclerotia. Sclerotia may resemble seeds or rodent droppings, and can be a source of inoculum for outbreaks in subsequent years if not properly disposed of.
Collar rot is favored by cool, wet weather (overcast days) and is most likely to develop on rapidly growing plants (5-7 weeks after germination). Often, the disease is first reported after the canopy closes in float beds, approximately 10 days after the first clipping. High humidity and long periods (>16 hours) of leaf wetness are important contributing factors to development of disease and are associated with poor air circulation in transplant facilities. Sclerotiorum is an efficient colonizer of dead plant matter and weakened plants, and can utilize these types of tissues as a bridge to infect healthy plants.
How does S. sclerotiorum get started in a float system? Typically, sclerotia on old plant debris germinate in spring and produce cup- shaped fruiting bodies called apothecia, which in turn produce spores (ascospores) that are wind-dispersed. Although the ascospores may travel as far as 1.5 miles, most will be deposited within 100 yards of the point of origin. Ascospores may land on susceptible tissue and germinate in water films on leaf surfaces. Germinated ascospores produce hyphae (fungal "threads") that penetrate tissue and begin the disease process.
There are no fungicides labeled for control of Sclerotinia collar rot on tobacco transplants. Once established, collar rot can be devastating; therefore, prevention is the key to success in managing this disease. Increasing air movement within the float system with properly installed heating equipment and fans will shorten drying times on foliage and minimize favorable conditions for Sclerotinia. Proper heating and cooling will also minimize injury to seedlings (injured or unhealthy plants are more prone to collar rot and other diseases). Reducing plant populations in the system will also improve air movement through the plant canopy, as will the maintenance of proper water levels so that the trays ride high in the beds (tops above the side-boards). Fertility should be kept at recommended levels; excessive fertilization (particularly nitrogen) can lead to a lush, dense canopy that will take longer to dry and will be more susceptible to collar rot. Plant debris should not be allowed to remain in contact with transplants. Clip seedlings with a high- vacuum mower to ensure complete removal of leaf pieces. More frequent clippings will reduce the amount of tissue that must be removed by the mower at clipping time and will result in less leaf material left on the transplants. Leaf clippings and diseased plants, by far the most common source of inoculum, should be discarded a minimum of 100 yards from the transplant facility, or buried (the best choice). It has been reported that over 300 species of plants, including many weeds, are hosts to S. sclerotiorum. Home gardens should not be planted near transplant facilities, and every effort should be made to remove weeds from the area.
Blue Mold Status
No active blue mold has been reported in the U.S. as of 8 April 2005. A blue mold advisory will be issued when the disease is reported in the U.S.
Recommended Fungicides for Control of Blue Mold - Addendum
FIELD: In last week's article, I wrote that Dithane DF and Acrobat 50WP were the only labeled materials for use on blue mold in transplanted tobacco. Two compounds were left off the list of options: Actigard 50WG and streptomycin. Actigard has been shown to be an effective product when used in conjunction with other materials, but may not perform well under extremely high disease pressure. Streptomycin has demonstrated limited efficacy against blue mold in past UK trials.
A comprehensive guide for foliar disease control will be issued in the coming weeks.
For the latest blue mold status and other tobacco disease information, check the KY Blue Mold Warning System online.
http://www.uky.edu/Agriculture/kpn/kyblue/kyblue.htm
For more information about tobacco pests, visit "Insect Management Recommendations".
The following are several label updates that will be of interest to turfgrass managers.
Insignia 20WG fungicide (active ingredient pyraclostrobin) was initially labeled for use on golf course turfs. The label was recently expanded to include the following turf sites: residential and commercial lawns, recreational areas (including athletic fields), and sod farms.
Based on the data I have seen, Insignia is good to excellent for control of anthracnose, brown patch, gray leaf spot, pink snow mold/Microdochium patch, red thread, leaf rusts, and take all. Several of these are not significant disease problems outside of golf courses. However, there are several that can cause moderate to severe damage in certain circumstances on these newly added turf sites. In particular, this is the case for brown patch on new seedings of tall fescue, gray leaf spot on perennial ryegrass, rusts on Kentucky bluegrass and perennial ryegrass, and red thread. Thus, Insignia will serve as a new option for those disposed to using fungicides to combat these diseases.
Keep in mind that pyraclostrobin is a strobilurin fungicide (=Group 11 fungicide) just like Heritage (azoxystrobin) and Compass (trifloxystrobin). Therefore, users are advised not to use any of these fungicides in succession, in order to reduce the risk of fungicide resistance to this fungicide family.
A 2(ee) recommendation for the use of Endorse WP fungicide (active ingredient polyoxin D zinc salt) against Fairy Ring (including Marasmius spp., Lepiota spp., and Agaricus spp.) was issued by Cleary Chemical Corporation. A 2(ee) recommendation allows for the use of a pesticide against a pest not specifically indicated on the label, as long as the use is otherwise consistent with the label (with respect to use rates, timing, restrictions, and so on). Details of this recommendation are given in a bulletin. The bulletin describing this recommendation must be in the possession if the user at the time of pesticide use. A copy of the bulletin may be available from your pesticide supplier or directly from Cleary at 1-800-524-1662 or www.clearychemical.com.
In a search for efficacy data, I could find none that specifically support this use. Therefore I cannot make a comment on its overall efficacy.
Clover mites are accidental invaders that can be a temporary nuisance in the early spring. These tiny, reddish brown creatures appear only as moving dark spots to the naked eye. Sheer numbers, plus the resulting red-brown stain left behind if they are crushed, make them unwelcome visitors on patios, outdoor furniture, and as accidental home invaders. Clover mites are not blood feeders and will not harm people or pets, nor will they infest household products. Once inside a home or building they will soon die.
Clover mites feed on clover and grasses. They can be especially abundant in the heavy, succulent growth of well-fertilized lawns. They usually enter a home around windows or doors so they are usually seen crawling along sills or thresholds. A soapy rag or wet sponge can be used to clean mites off of surfaces. Wipe carefully to avoid crushing the mites and causing stains. The crevice tool of a vacuum cleaner may also be used to pick up mites. Rely on non-chemical control indoors. Do not apply insecticides to kitchen counters or other interior surfaces.
There is an increased potential for invading structures when grass extends up to the foundation. A plant bed or open area will provide a barrier that will stop many mites and provide a long term solution to persistent problems. Avoid over-fertilizing lawns. This creates situations that are ideal for mites to increase to tremendous numbers.
Several bee species nest in the ground. They can sting if handled or stepped on but are not aggressive defenders of their nests. Control may be warranted on children's play areas or if excessive tunneling is creating bare spots. Carbaryl or Sevin, applied to burrowed areas according to label directions for turf pests, can reduce ground bee activity. However, this approach is a temporary solution. The bees are nesting there because the site is attractive - well-drained or sandy soil with relatively a sparse grass stand. Site alteration is needed to provide a long-term solution. Over-seeding bare areas, adequate fertilization, and watering should improve turf stand make areas less attractive to these bees. Raising the mowing height may help, also.
Most ground bees are 3/8 to ˝" long and vary in color from solid black to brightly metallic and have "hairy bodies". These "wild" bees are important pollinators and should be left alone if they are not causing a problem.
Kentucky flowering crabapples, in bloom now, are enjoyed for their profuse flowers and for their attractive foliage and fruit.. Experienced growers and homeowners are well aware that springtime is also the time of year that many of the important diseases of flowering crabapple are most active.
Many flowering crabapples are made unsightly or are severely injured by one or more of four common diseases-apple scab, fire blight, cedar- apple rust, and powdery mildew. Unless resistant crabapples are selected and grown, fungicide sprays used as disease preventatives must be included in the maintenance program, especially for susceptible crabapples growing in the nursery.
Managing apple scab caused by the fungus Venturia inaequalis.
The entomology department receives many calls from clients wanting to know what can be done to protect their home from termites. Oftentimes they also wonder if a certain practice or condition is likely to cause termite problems. Homeowners can reduce the risk of infestation by following these suggestions.
1. Eliminate wood contact with the ground. Many termite infestations result from structural wood being in direct contact with the soil. Earth-to-wood contact provides termites with easy access to food, moisture, and shelter, as well as direct, hidden entry into the building. Wood siding, porch steps, door and window frames and similar wood items should be at least six inches above ground level. Eliminating wood-to-ground contact may require re-grading or pulling soil or mulch back from the foundation, cutting the bottom of siding, or supporting steps or posts on a concrete base. Contrary to popular belief, wood that has been pressure treated is not immune to termite attack. Termites will enter pressure-treated wood through cut ends and cracks and also build tunnels over the surface.
2. Don't let moisture accumulate near the foundation. Termites are attracted to moisture and are more likely to "zero in" on a structure if the soil next to the foundation is consistently moist. Water should be diverted away from the foundation with properly functioning gutters, down spouts and splash blocks. Leaking faucets, water pipes and air conditioning units should be repaired, and the ground next to the foundation should be graded (sloped) so that surface water drains away from the building. Homes with poor drainage may need to have tiles or drains installed. Lawn sprinklers and irrigation systems should be adjusted to minimize puddling near the foundation.
3. Reduce humidity in crawl spaces. Most building codes call for 1 square foot of vent opening per 150 square feet of crawlspace area. For crawlspaces equipped with a polyethylene vapor barrier (see below), the total vent area often can be reduced to 1 square foot per 300 to 500 square feet of crawl space area. One vent should be within 3 feet of each exterior corner of the building. Vents should be kept free of leaves, dirt and debris, and should not be obstructed by vegetation. Moisture and humidity in crawl spaces can be further reduced by installing 4-6 ml polyethylene sheeting over about 75 percent of the soil surface. The soil cover will act as a vapor barrier to reduce evaporation from the soil and condensation of moisture on joists and subflooring. Vents and vapor barriers are installed by pest control companies.
4. Do not store wood or paper against the foundation or inside the crawl space. Firewood, lumber, cardboard boxes, newspapers, and other cellulose materials attract termites and provide a convenient source of food. When stacked against the foundation they offer a hidden path of entry into the structure and allow termites to bypass any termiticide soil barrier that is present. Vines, ivy, and other dense plant material touching the house should also be avoided. Where practical, dead stumps and tree roots around and beneath the building should be removed, along with old form boards and grade stakes left in place after the building was constructed.
5. Use mulch sparingly, especially if you already have termites or other conducive conditions. Many people use landscape mulch for its aesthetic and plant health benefits. Excessive or improper usage, however, can contribute to termite problems. Termites are attracted to mulch primarily because of its moisture-retaining properties, and the insulation it affords against temperature extremes. The mulch itself is of poor nutritional value to termites and a non-preferred source of food. Since the moisture retaining properties of mulch are more of an attractant than the wood itself, it males little difference what type of mulch is used (cypress, pine bark, eucalyptus, etc.). Contrary to popular belief, crushed stone or pea gravel are comparable to wood mulch in terms of attraction, since they also retain moisture in the underlying soil. Where mulch is used, it should be applied sparingly (2-3 inches is usually adequate), and should never be allowed to contact wood siding or framing of doors or windows.
6. Consider treatment by a professional pest control firm. Buildings have many natural openings through which termites can enter, most of which are hidden. While the above measures will help make a house less attractive to termites, the best way to prevent infestation is to treat the adjoining soil with a termiticide. There are two general categories of termite treatment, liquids and baits. The purpose of a liquid treatment is to make the ground around the foundation repellent and/or toxic to termites so that they will not infest the structure. While most of the liquid termiticide products are repellent, three newer materials, Termidor® (fipronil), Premise® (imidacloprid), and Phantom® (chlorfenapyr) are non-repellent to termites foraging in the soil. Consequently, termites tunneling into the treated zone are killed. In Kentucky, these products are proving very reliable in their ability to control termites in the initial attempt. Baits can also be installed to eliminate termites foraging around structures (see newly revised Entfacts 604: Termite Control: Answers for Homeowners, and 639: Termite Baits: A Guide for Homeowners).
Preventively treating a home for termites is a reasonable investment, especially if the structure has no prior history of treatment. If the building was previously treated by a pest control firm, it's a good idea to maintain the warranty by paying the annual renewal fee. Should termites re-infest the building, (which can happen even if the initial treatment was performed correctly), the company will return and retreat the affected area at no additional charge.
Whether or not a person chooses to have their home treated, they should know the signs of termite infestation:
Eliminating or treating a pest's breeding site often is right at the top of the list of pest management options. It's best if the breeding site is very specific - like freshly deposited cow manure - the egg- laying site of choice for female horn flies and face flies. This allows the option of feed-thru larvicides (insecticides that control fly larvae or maggots) that pass through the digestive tract and are present at toxic levels in manure.
Active ingredients used as oral larvicides include the insect growth regulator methoprene (Altosid) and the organophosphate insecticide tetrachlorvinophos (Rabon). Insect growth regulators affect the development of larvae and prevent them from emerging as adults. In contrast, organophosphate insecticides kill by disrupting normal function of the nervous system. In either case, they must be present at or above levels in the manure that are toxic to the larvae. Either active ingredient can be formulated in several different ways and is available under several different brand names.
Methoprene - Altosid 0.5% Premix Dose or Altosid 0.1% IGR Block to prevent the breeding of horn flies in the manure of treated cattle. Dose rate 0.8 to 1.5 milligrams per 100 lbs body wt/ cow/ per day.
Tetrachlorvinophos - Rabon 7.76 Oral Larvicide Premix - to prevent development of horn flies and face flies in manure of treated beef and lactating dairy cattle. Dose rate 70 milligrams per 100 lbs body wt/ cow/ day.
General recommendations for oral larvicides
It's risky to predict insect problems. Nevertheless… More than the usual number of samples of face flies, collected from masses around houses and barns, have arrived for identification during the past two weeks. These flies have left the shelter of over-wintering sites and will be moving to pastured cattle for the summer. Keep an eye out for large, early populations in your herds.
Large numbers of face flies on pastured cattle can mean an increased incidence of pinkeye. The abrasive mouthpart of this fly mechanically injury injures the conjunctiva and can spread the organisms associated with pinkeye as they feed on eye secretions. While pinkeye can be spread several ways, a sound face fly control program is an important part of reducing eye irritation and limiting spread of the disease.
Adult face flies, fresh from a winter of hiding in a shelter, move back to pastures for the summer. Females feed on tears and other cattle secretions for proteins. They move to freshly deposited manure pats to lay clusters of eggs. Larval development takes about 10 days, followed by a pupal stage of about the same duration. The flies spend much of their time resting on trees and fences, returning often to cattle to feed again. The limited time spent on animals makes control challenging.
For more information livestock pests, visit "Insect Management Recommendations".
UKREC-Princeton, KY, April 1 - 8, 2005| Black Cutworm
| 3
| True Armyworm
| 6
| | |
View trap counts for the entire 2005 season at - http://www.uky.edu/Ag/IPMPrinceton/Counts/2005trapsfp.htm
For information on trap counts in southern Illinois visit the Hines Report at - http://www.ipm.uiuc.edu/pubs/hines_report/index.html. The Hines Report is posted weekly by Ron Hines, Senior Research Specialist, at the University of Illinois Dixon Springs Agricultural Center
NOTE: Trade names are used to simplify the information presented in this newsletter. No endorsement by the Cooperative Extension Service is intended, nor is criticism implied of similar products that are not named.
Lee Townsend
Extension Entomologist