June 26
Crop, Soil, & Pest Management Field School, UK Spindletop Farm, Lexington, KY.
4 General hours: Categories 1 (Ag Applicator), 10 (Demo and Research), 12 (Retail Pesticide Sales Agent).
Contact: Dr. J. D. Green (859) 257-4898.
A BLUE MOLD WATCH EXPANDED WEST ACROSS
Southern Kentucky with an ADVISORY REMAINING
statewide: To our knowledge, blue mold has not been
confirmed in Kentucky, Indiana, Ohio, Missouri, or West
Virginia as of June 17, even with nearly 60 days of
continuously conducive weather for blue mold. We have been
missing only the pathogen, but it has probably arrived recently
in low numbers, but could expand rapidly under current
weather.
The closest confirmed activity is from Green and Claiborne counties in eastern Tennessee and Robertson County in west Tennessee. These outbreaks reportedly involve only small areas, but nearby activity is also likely considering the highly conducive weather they have been experiencing. Sporulation was reported as strong from both the eastern and western Tennessee sites, and multiple generations of lesions were present. So assume there has been movement! The level of blue mold development has increased significantly in southern Georgia and South Carolina during the past couple of weeks where they have also been experiencing ideal weather for blue mold, but with inoculum present and building fast. Very strong centers of inoculum production are present in some of these areas resulting in increased spore loads moving north. Our region has been fortunate that storm systems have generally been such that most of that inoculum has been either moving away from Kentucky or been washed out prior to reaching us. But some may be getting through, thus expect more of the type activity being reported from Robertson County, Tennessee. Moreover, the activity in west Tennessee is particularly threatening considering the storm systems recently experienced and the fact this now places inoculum directly into the prevailing winds to several of Kentucky’s key tobacco production areas. We may have low levels of blue mold under development over a wide front, which could expand rapidly, considering the weather events of the past week.
The potential for blue mold development in the Ohio River Valley continues to increase rapidly as the cool, wet weather persists and the disease builds in Tennessee and in the southeastern USA. We have posted a Blue Mold Watch for southeastern Kentucky and for southern Kentucky to as far west as Christian County. The highest potential is in those counties in close proximity to the activity in Tennessee, plus the general increased risk throughout the southern Appalachian Mountains. But, much wider development is possible if earlier outbreaks have gone unreported! All should appreciate that cloudy weather is keeping the young tobacco plants highly susceptible and environmental conditions are highly favorable for infection to occur, if viable spores arrive. Winds from the sources mentioned above may have carried spores across a wide front into Kentucky, so growers are advised to maintain aggressive fungicide programs in all transplant production and holding situations, and to scout field plants at least twice weekly for blue mold. Should blue mold be found within a county, weekly fungicide spray programs with Acrobat MZ should be immediately put in place, followed by activation of the plant with Actigard 50W once the plants are 18 inches tall and able to tolerate the treatment. This preventive program should already be in place for areas under a watch or warning. Additional sprays of Acrobat MZ may also be needed later in the season after the second application of Actigard if strong blue mold pressure is present, especially for late maturing varieties. Growers still moving transplants need to seriously consider the potential of moving blue mold with the transplants across a wide front in Kentucky, but especially with plants from counties under the watch in southeastern and southern Kentucky.
Should blue mold be found, immediately get sample material to one of our two Plant Disease Diagnostic Labs for confirmation and testing. This is required for the first outbreak in each county of Kentucky. We have already had several suspected cases submitted, in which the submitter was confident they were dealing with blue mold. But in each of these cases, diseases or disorders other than blue mold were involved. Let’s take steps to insure we are not dealing with rumors of blue mold, but also get all communities with confirmed activity on the map!
Application guidelines for the fungicides labeled for blue mold control in transplant production systems and in the field in Kentucky have been presented in recent issues of Kentucky Pest News:
Transplant fungicides in the March 24, 2003 issue number 978 at web address- http://www.uky.edu/Agriculture/kpn/kpn_03/pi030324.htm
Field fungicides in the April 28, 2003 issue number 983 at
web address -
http://www.uky.edu/Agriculture/kpn/kpn_03/pi030428.htm
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
See this article under the VEGETABLE section.
A supplemental 24(c) label that allows the use of POAST
(sethoxydim) herbicide in Kentucky on tobacco fields has
been renewed. POAST is marketed by MicroFlo company for
selective postemergence control of annual and perennial
grasses. The granting of a supplemental 24(c) label by the
EPA will allow the use of POAST on tobacco for at least three
more years. This special local need label expires December
2005.
POAST 1E is the only formulation of sethoxydim labeled for use on tobacco fields. POAST is registered as a Restricted Use Pesticide. A copy of the supplemental label should be in the hands of the applicator at time of application. General guidelines for use of POAST on tobacco are highlighted below:
CROP STAGE: POAST can be applied any time after transplanting. The only restriction is to avoid applications within 42 days of harvest.
WEED SIZE: POAST is a selective herbicide for control of grasses. In general, apply when annual grasses are small (6 to 8 inches) and actively growing. The exception would be shattercane and johnsongrass, which should be approximately 18 to 25 inches at time of first application.
RATE: Apply POAST (1.5 pt/A) plus an Oil Concentrate (2 pt/A). Dash HC (1 pt/A) may be used instead of oil concentrate as a spray solution additive. Spray volume can range from 5 to 20 GPA (gallons per acre) with an optimum at 10 GPA. Good spray coverage is needed for adequate control. More than one application may be needed for rhizome johnsongrass. Make the first application of POAST (1.5 pt/A) when johnsongrass plants are 20 to 25 inches; followed by a second application of POAST (1 pt/A) when regrowth is 12 inches. A maximum of 4 pt/A of POAST can be applied per season to tobacco.
SPOT TREATMENT: In some situations a spot treatment with a back-pack sprayer or other high volume sprayer may be the desired method of application. To apply, prepare a 1% to 1.5% solution of POAST plus a 1% solution of Oil Concentrate. This is equivalent to POAST 1% (1.3 oz/gal) or 1.5% (2 oz/gal) plus Oil Concentrate 1% (1.3 oz/gal). Apply spray solution to the grass foliage on a spray-to-wet basis.
CULTIVATION: The label states "do not cultivate within 5
days before or 7 days after applying POAST".
See "Insect Management Recommendations" for more insecticide recommendations on tobacco and other crops and livestock.
There is a general misconception that soybean cyst nematode
(SCN) is not a problem (or is not as damaging) in doublecrop
soybean as it is in full-season soybean. This is not true and
the yields of both full-season and doublecrop soybean can be
seriously impacted by SCN. The bottom line is this: if SCN
populations are above threshold and an SCN-susceptible
soybean is planted, yield damage will result. And the higher
the population is above threshold, the greater the yield loss
up to a point.
If you are planning on planting a SCN-susceptible soybean variety this year following wheat harvest, it is in your best interest to send us a representative soil sample before planting and have us run a SCN analysis. The cost is $8.50 per sample. Instructions for SCN sample collection and submission are available from your local county Extension office.
For more information about soybean pests, visit "Insect Management Recommendations".
This is the second of several articles aimed at keeping you
informed about the developing soybean rust situation and
our response to this potential challenge.
Soybean rust has yet to be reported in the continental United States. However, based upon how rapidly the disease has spread in South America during 2002-2003, and previously in Africa, all indications are that eventual infestation by one or both soybean rust organisms, Phakopsora pachyrhizi and P. meibomiae, is a certainty. Of course, the big unknown is when infestations will occur. Presently, there are no Phakopsora spp. reported on any legume hosts in the continental U.S. Nonetheless, it is prudent to assume the worst and to get prepared now in case either Phakopsora spp. arrives in 2003.
By far, the most destructive of the two pathogens is P. pachyrhizi. Yield loss resulting from infection by P. meibomiae, by comparison, is very limited. Nonetheless it is critical that we initiate surveillance activities for detection of both pathogens. Economically, there is a great deal riding on which pathogen is detected first. For example, millions of acres of soybean will likely be sprayed with fungicides when P. pachyrhizi is detected. However, most farmers will probably adopt a "wait and see" management approach if P. meibomiae is detected. The economic consequences would be devastating if the pathogens were misidentified. Because of the airborne nature of Phakopsora spp., there are no plans to implement quarantine measures once one or both pathogens are detected in the continental U.S.
The purpose of this article is to outline national and local plans for surveillance of Phakopsora spp. in legumes (especially soybean) this summer, and the appropriate response from the various agricultural sectors. I will start at the highest level of the "surveillance pyramid" and work backwards in the surveillance process.
Identification of soybean rust.
It has been predetermined by all involved agencies that the
Animal and Plant Health Inspection Service (APHIS) of the
United States Department of Agriculture (USDA) will make
the initial announcement when soybean rust is found in the
continental U.S. This decision was made in consideration of
the great economic impact soybean rust is likely to have in
this country. The announcement will be made only after a
Phakopsora spp. has been identified and confirmed by
highly specific and reliable diagnostic tests, conducted by
scientists at the Plant Protection and Quarantine (PPQ),
APHIS, USDA Laboratory in Beltsville, Maryland. All
samples suspected to be soybean rust, from anywhere in
the continental U.S., will be sent to this facility for further
diagnostic testing.
The USDA/APHIS/PPQ Laboratory in Beltsville will only receive samples related to soybean rust (i.e., soybean and other legumes) from diagnostic laboratories affiliated with universities or state departments of agriculture. In the case of Kentucky, all samples submitted to Beltsville will originate from the University of Kentucky Plant Disease Diagnostic Laboratories (PDDL's) in Lexington or Princeton. The PDDL's will accept soybean rust samples from any source, but we strongly encourage all clientele groups to submit samples though their local county extension office. The main reason for this is to preserve a trail of information that would allow us to go back to the exact site of sampling, if necessary. This type of information is often lost or not collected when clientele submit samples directly to the PDDL's. It is critical that we have the capability to return to the exact spot from which a specific plant sample is submitted.
Surveillance during the summer of 2003.
For 2003, the PDDL's are seeking samples of any rust on
soybean, any species of clover, all edible and ornamental
beans, and kudzu since these are all known hosts of
Phakopsora spp. Please note that alfalfa is not a host plant for
either soybean rust pathogen. Also, be aware that other rusts
commonly occur on legumes in Kentucky aside from those
that may be caused by Phakopsora spp. The point here is to not
get overly concerned just because you see a legume rust.
There is an excellent chance that neither Phakopsora sp. will be
involved. The converse is true for soybean and kudzu which
are not subject to any rust pathogens native to Kentucky.
I am aware that nobody is likely to scout kudzu, specifically, but we are asking everyone to keep an eye out for anything resembling rust lesions/pustules anytime you are around that weed. All involved scientists agree that kudzu is likely to play a major role in the epidemiology of soybean rust once the disease becomes established.
We are requesting samples from both commercial operations and home gardens. However, all samples must be submitted through the local county extension office. The agents, in turn, will forward all suspected legume rust samples to the appropriate PPDL in either Lexington or Princeton. Once received, all samples will be observed by trained and experienced PDDL diagnosticians and plant pathology specialists. We will immediately forward any suspected Phakopsora spp. samples to the USDA/APHIS/PPQ Laboratory in Beltsville for further study. Please be advised that there may be a delay in receiving a diagnostic response if our analysis indicates a need to submit a sample to Beltsville.
Sampling protocol.
Regardless of who has collected or submitted a suspect
soybean/legume rust sample, there is a specific sampling
protocol to follow:
The potato leafhopper has been active in the state for several
weeks now so "hopperburn" symptoms will be evident in
many fields. "Hopperburn" is a distinctive wedge-shaped
yellowing of tips of alfalfa leaves that results from sap
feeding by these tiny green insects. This damage is due to a
toxic effect of the insect's saliva. Diseases and nutritional
deficiencies also cause yellowing of alfalfa but these
symptoms are not confined to the tips. Intense leafhopper
feeding may reduce plant height, protein and vitamin A
content of the hay. Once symptoms are apparent on plants
much of the damage has been done. See Ent 16 for insecticide
recommendations and action thresholds for this insect.
See Insect Recommendations for more alfalfa pest recommendations.
If it ever dries up, the combines will begin harvesting wheat
at a frantic pace. Some people look at this as the end of the
wheat season but in some respects it is only the middle. Yes,
the crop is made but much of it has not gone to market or
even more importantly it is contracted but YOU are still
holding the grain. Proper storage may be one of the most
difficult, yet important steps in your overall wheat business
plan.
Without question, of our major field crops (corn, soybean and wheat), wheat is the most difficult to store. This is largely because unlike corn and soybean we do not have fall and winter to help us in the short run. We begin wheat storage in the warmest and most moist (humid) time of the year Just right for insect activity! However, we do know that good results can be obtained if good management is used. Dr. McNeill and I were able to see in our work during the 2002 storage season, that high quality, dry, untreated wheat, stored in clean, dry, treated bins went to delivery in the fall without an insect dock! It can be done, and in some cases the advantage of having wheat without an insecticide residue (even a legal one) adds value to the commodity.
Listed below is a checklist that we have put together to provide a framework for good storage. Certainly your experience may prompt you to alter the list. You may also use the list as a form of record keeping or documentation of what you have done to the crop. Just by identifying the bins, ticking the boxes, and adding some dates you can show a buyer your management plan.
You may also be interested in a more comprehensive publication on grain storage principals. This publication; Entfact-145, may be found on the Entomology web pages at: http://www.uky.edu/Agriculture/Entomology/entfacts.htm Look in the "Field Crops" section.
Wheat insecticide recommendations can be found in ENT- 47, Insecticide Recommendations for Small Grains. In our grain pesticide publications, storage insecticides are always the final page in the publication for each crop. Remember, stored grain insecticides are changing rapidly. Be sure to check often at: http://www.uky.edu/Agriculture/PAT/recs/crop/croprec.htm
You should note that we do NOT recommend the use of malathion on stored grain because:
--Most formulations of this product are no longer labeled
for stored wheat,
--Many storage insects are no longer controlled by
malathion,
--Grain is being rejected due to excessive residue, which
results from the over application made in and effort to
get control.
If you use a "protectant" Reldan (if available) and Storcide are the currently registered products.
Before Harvest
During Harvest / Binning
Insecticides and Fumigants Recommended for Wheat
We recommend that you do not use malathion for any treatments. Most forms of malathion are no longer labeled for use. More importantly the product no longer provides adequate insect control. See: ENT-47 Insecticide Recommendations for Small Grains.
Empty bins - applied to walls and floor: Tempo DO NOT APPLY TO GRAIN!
Under Floor Fumigants Chloro-pic , (Can not currently be shipped you will only find it if your local dealer has some on hand or in large e.g 200 lb. bottles) Methyl-Bromide, Phostoxin,/Fumtoxin. THESE PRODUCTS ARE EXTREMELY DANGEROUS
Protectant - applied directly to the bulk grain: Storcide and Reldan are registered.
"Cap out" treatments applied to the top 4" of grain - (Do not make this application if a protectant has been applied to the bulk grain: Reldan for beetles or Reldan or products containing Bacillus thuringiensis e.g. Dipel , Javelin , Sok- B.t. etc. for Indian meal moth.
Bulk Grain Fumigants Phostoxin / Fumtoxin .
See "Insect Management Recommendations" for more wheat pest information.
The prolonged wet weather Kentucky has experienced for the past two months has been taking a significant toll on vegetable and tobacco crops. Grower's abilities to transplant and conduct other normal field operations have been seriously hampered. On those crops that have been planted, additional problems are mounting. Infectious disease activity has been increasing rapidly, but we have addressed this issue and the importance of aggressive spray programs in recent articles. Another area of major concern, but often overlooked, is the damage to the plant associated with the saturated root zone.
When soils are water-saturated, plants roots can be in an oxygen-deficient condition and thus respiration and metabolic activities can be markedly impacted due to low oxygen and high levels of carbon dioxide and other chemicals. Therefore, most of the functions normally performed by the root system are in potential jeopardy of performing poorly or in altered manners. The temperature at the time of the saturation and the duration of the events greatly impact the severity and symptom pattern.
Saturated soils result in loss or reduction in normal root functions. Nutrient and water adsorption and their translocation are often impacted; consequently, wilting, yellowing, stunting, and nutrient deficiencies are the most common symptoms associated with flooded soils with most vegetables and tobacco. During periods of high evaporation or high temperatures, the above- ground symptoms of saturated soils usually involve wilting and severe stunting, but the cool temperatures have limited such development this year. As temperatures start to increase, expect to see much more of the sudden wilting and yellowing of plants.
Hormonal imbalances often occur when roots are in saturated soils, especially at cool temperatures, as production declines in the root-made hormones while stress/aging hormone production increases in other parts of the plant. These shifts create serious imbalances in the levels, ratios, and timing of hormones which results in abnormal plant development. Some plants are showing strong leaf epinasty (bending and twisting of the leaf petioles) resulting from increase ethylene production, while adventitious roots proliferate from the stem due to auxin imbalance. Timing of flower production and development can also be greatly impacted, which can significantly impact timing of fruit for critical market windows.
In some plants, the cortex of flood-damaged roots will be slightly darker in color and with time, discoloration may be noticed in the lower vascular system of the plants. Such plants are prime targets for infection by a wide range of soilborne fungi and bacteria, too.
Where plants are taking up herbicides, normal degradation
may not be occurring, resulting in herbicide damage from
materials normally tolerated by the crop.
Foliar rust diseases on cool-season grasses in Kentucky are favored by factors that slow the growth of the grass, such as low nitrogen or low soil moisture status. Normally, in actively growing turf, rust infections are mowed off before they cause much damage to the leaf. Since rust fungi are obligate parasites (meaning they can only grow on live host tissue), they cease growing in lawn clippings. Thus, maintaining active turf growth through cultural practices combined with regular mowing is usually sufficient to manage the disease under Kentucky conditions.
Unfortunately, this is not a good time of the year to fertilize cool-season grasses. The addition of moderate to high rates of nitrogen will enhance summer diseases like summer patch and may also weaken the grass's resistance to temporary drought stress. (I know it's hard to imagine such a thing as temporary drought, given the kind of spring we've had, but summer is just beginning.) For these outbreaks of rust, I do recommend maintaining adequate soil moisture through the summer. This will help maintain slow growth, giving the grass some chance against the disease; also, plants affected by rust need more water than unaffected plants just to avoid wilting. "Spoon-feeding" nitrogen by applying 1/8 to 1/10 lb N/1000 sq ft every 10- 14 days will also help the sward survive until the end of August, when high rates of soluble nitrogen will promote recovery.
For high-maintenance swards where managers wish to treat with fungicides, Heritage and the DMI fungicides propiconazole (Banner MAXX and related products) and triadimefon (Bayleton and related products) are the most effective, safe choices. Recognize that a fungicide spray can only protect new growth from infection; it cannot cause disease leaves to become healthy again.
Cool wet weather, cloudy skies and high humidity during the past month or so have favored several diseases of perennial ornamental plants in the garden. The following are some of the diseases that have been observed recently in the plant disease diagnostic laboratory or in the field, or that might be observed in Kentucky during this time.
Downy Mildew. Downy mildew diseases are caused by obligate parasite oomycete fungi that form mycelium in plants and sporulate in great numbers through stomata. The sporangia make white, gray, or violet patches usually on the undersides of leaves. Downy mildew diseases occur on many different kinds of plants. For the most part, each disease is caused by its own species of downy mildew fungus. Downy mildews are favored by cool, overcast, and moist weather - conditions which were in abundance this spring. In addition, this disease is favored by availability of soft, succulent host tissues. Favorable weather conditions also promoted succulent growth this spring. Downy mildew of foxglove and coreopsis, caused by species of Plasmopara and of Potentilla, caused by species of Peronospora have been observed. Some other downy mildew hosts include:
Botrytis Blight. Caused by the fungus Botrytis cinerea, botrytis blight is also called gray mold. The fungus generally is weakly parasitic, growing on senescent parts of many different host plants. In wet and humid weather, the fungus decays affected plant parts and produces powdery gray to tan sporulation on rotted tissues. This spring, Botrytis gray mold has been observed on begonia, rose, peony, periwinkle and other hosts. This fungus has a very wide host range including such ornamentals as anemone, aster, begonia, calendula, carnation, chrysanthemum, dahlia, geranium, lily, marigold, peony, primrose, rhododendron, rose, snapdragon, sunflower, zinnia and many others.
Fungal Leaf Spots. Black spot is well-developed on susceptible roses. Cercospora and Septoria leaf spots have also been observed. The fungus Cercospora is an imperfect fungus and it generally causes somewhat circular spots with tan centers. Different species of Cercospora cause leaf spots that affect calla lily, calendula, columbine, geranium, hollyhock, and rose. Septoria species cause, spots, blotches, and blights. In the diseased tissue, the Septoria fungus produces pycnidia, tiny black fruiting structures, which can be seen with a hand lens. Septoria affects carnation, chrysanthemum, daisy, marigold, peony, phlox and other hosts.
Bacterial Blights. Wet weather has favored dissemination of several of the bacterial diseases, particularly those which do well in cool weather. Species such as Pseudomonas often cause shoot blights in cool, wet weather and some Xanthomonas species cause leaf spots. Although there has not been much fire blight this year, species of Erwinia may be causing soft rot diseases in some instances. Bacterial blights of rose-of-Sharon (Pseudomonas) and of canna (Xanthomonas) have been observed. Carnation, chrysanthemum, delphinium, gladiolus, nasturtium, sunflower, and many other ornamentals can also be hosts to Pseudomonas. Xanthomonas (causing leaf spots and blights) and Erwinia (causing soft rots) have very wide host ranges among ornamentals.
Powdery mildew. Powdery mildew is a threat all season long when there is high humidity. Almost all perennial and annual ornamentals, too numerous to list here, are susceptible to one or another powdery mildew. Along with wet weather this spring, long periods of high humidity favored powdery mildew of many garden plants.
Because of disease-favorable weather, Kentucky gardeners
and County Extension Agents may be seeing a more than
usual accumulation of spots, blights, and mildews this
spring. In many cases, there is little that can be done to
save already affected plants and in most cases, these
diseases will slow down as weather becomes warmer and
drier.
Adult Japanese beetles have begun to emerge. As is usually
the case, it's difficult to predict how serious a problem the
adult beetles and their offspring (turf-feeding grubs) will be
this year. Detailed information on this pest can be found in
ENT-5, Japanese Beetles in the Urban Landscape. Options for
protecting landscape plants from foliage feeding adults are
summarized below; grub control will be discussed in a
subsequent newsletter.
Plant Selection- The best way to avoid perennial battles with adult Japanese beetles is to select plant material that is less preferred. Publication ENT-5 lists species and cultivars of trees and shrubs that are less likely to be attacked. Japanese beetles have become less of a problem in recent years throughout much of Kentucky. For this reason, choosing a plant solely upon its susceptibility to Japanese beetles may be less crucial than in years past.
Hand Picking and Exclusion- Removing beetles by hand may suffice for smaller plants and when beetle numbers are relatively low. Volatile odors released from beetle-damaged leaves attract more beetles. Thus, by not allowing Japanese beetles to accumulate, plants will be less attractive to other beetles. One of the easiest ways to remove beetles from small plants is to shake them off early in the morning when the insects are sluggish. The beetles may be killed by shaking them into a bucket of soapy water. Highly valued plants such as roses can be protected by covering them with cheesecloth or other fine netting during peak beetle activity (usually late June to mid-July).
Insecticides- Various insecticides including Sevin, Tempo (= Bayer Advanced Lawn& Garden Multi-Insect Killer), Scimitar (= Spectracide Triazicide) , Talstar, malathion, and Orthene are labeled for control of adult Japanese beetles. Sevin is very effective and is the product of choice for many homeowners. Foliage and flowers should be thoroughly treated. The application may need to be repeated at 7-10 day intervals to prevent reinfestation during the adult flight period, or after heavy rains. Follow label directions and avoid spraying under windy conditions. Insecticidal soaps may kill beetles that are hit by the spray, but they provide no residual protection. Botanical insecticides such as neem or pyrethrum are not very effective.
Bagworm eggs have 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 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 non-infested 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. Since the window of opportunity for this approach has passed, insecticides are now the only effective means of control. For homeowners, Sevin, Bayer Advanced Lawn& Garden Multi-Insect Killer, Spectracide Triazicide, or Bacillus thuringiensis (BT) work well. For nursery and landscape professionals, other effective products include Astro, Mavrik, Scimitar, Suspend, Talstar and Tempo.
For further information, see Entfact 440: Bagworms on Landscape Plants.
Use of a mosquito larvicide may be beneficial when it is impractical to eliminate a breeding site. Larvicides are insecticides which are used to control immature mosquitoes before they have a chance to develop into biting adults. An article on mosquito larvicides, found in KPN # 986 (May 19, 2003), discussed Mosquito Dunks and other products based upon a toxin produced by the soil bacterium Bacillus thuringiensis israelensis (Bti). Now, homeowners can purchase the methoprene-based larvicide, PreStrike. PreStrike is formulated as a granule and comes in a shaker bottle. Less than a dozen granules are needed to prevent mosquitoes from developing in a flower pot bottom or bird bath. Less than a teaspoon of PreStrike granules are needed to treat 100 feet of rain gutter. In ornamental ponds and similar long- standing bodies of water, mosquito development will be prevented for up to a month; longer protection is afforded in methoprene-treated sites that periodically dry out.
Mosquito breeding sites are not always obvious or accessible so some nearby sources will remain undetected or impractical to treat. Also, mosquitoes can fly in from some distance away. Therefore, it may be necessary to take additional measures against adults. Mosquitoes prefer to rest in protected sites during the day. Yards with lots of trees, shrubs, and dense vegetation or properties adjoining such areas, can have nightmarish problems. Consequently, removal of tall weeds and overgrowth is part of an integrated mosquito management program.
To further reduce intolerable levels of biting mosquitoes, insecticides can be applied to the lower limbs of shade trees, shrubs, and other shaded areas, such as under decks and along foundations. Pyrethroid insecticides are effective but will need to be reapplied periodically. A hose-end sprayer is usually most effective and convenient for such applications. Always read and follow label directions before using any pesticide. Some homeowners may wish to hire a professional for this service.
Some registered insecticides for adult mosquito control on lawns and vegetation.
| Insecticide Common Name | Brand Name |
|---|---|
| cyfluthrin | Bayer Advanced PowerForce Mosquito Killer |
| lambda-cyhalothrin | Spectracide Triazicide |
| permethrin | Ortho Mosquito B Gone Spectracide Mosquito Stop |
Many consumer products claim to attract, repel, capture or kill mosquitoes. Most of these devices do not appreciably reduce mosquito abundance or incidence of bites, or else their claims are unproven. Electrocuting devices or "bug zappers" using ultraviolet light as an attractant are generally ineffective in reducing outdoor populations of mosquitoes and their biting activity. Studies indicate that mosquitoes make up only a tiny percentage of the insects captured in such traps. The majority are moths, beetles and other harmless night flying insects.
Other types of mosquito traps utilize carbon dioxide, warmth, light, and various chemicals (e.g., octenol) as attractants and claim to capture tremendous numbers of adult mosquitoes. Such devices often cost hundreds of dollars and some sell for more than $1000. Performance claims to the contrary, such traps seldom have been shown to actually reduce populations of biting mosquitoes on one's property, or the frequency of bites. In some situations, they could even attract more mosquitoes into the area they were meant to protect.
Advertisements for portable electronic devices using high- frequency, ultrasonic sound routinely appear in magazines, claiming to keep mosquitoes and other pests at bay. Some supposedly repel mosquitoes by mimicking the wing beat frequency of a hungry dragon fly! Scientific studies have repeatedly shown these devices to be of negligible benefit in deterring mosquitoes and reducing bites. Companies that market such devices with unsubstantiated claims have been told to cease and desist by consumer protection agencies, but others continue to appear hoping that consumers will buy them. Save your money, as these devices seldom if ever provide any appreciable measure of protection.
Citronella oil does has mosquito-repelling properties, and the scented candles can provide some protection. For maximum effect, use multiple candles placed close (within a few feet) of where people are sitting. A single candle located at the center or edge of a picnic blanket probably won't provide much benefit other than atmosphere. Mosquito-repellent plants, garlic, and other oft-advertised botanical products generally are ineffective.
Bats and certain types of birds (e.g., purple martins) are often cited as effective natural agents for managing outdoor mosquitoes. Conservation groups and nature magazines often suggest building bat and bird houses on one's property to promote nesting and to protect against mosquitoes. Although insectivorous bats and birds do eat mosquitoes, they make up only a very small portion of their natural diet. Much like the mechanical "bug zappers," bats and birds capture all manner of other flying insects also. Efforts to colonize and conserve these animals should not be done with the primary intent of diminishing biting mosquitoes. When it comes to managing mosquitoes, a pretty good rule of thumb is if the approach or device sounds too good to be true it probably is.
Samples during the past week included Fusarium and Pythium root rots in corn; Botrytis blight/stem cankers, Rhizoctonia damping-off, Pythium root rot, Phytophthora root rot (black shank), target spot, alfalfa mosaic virus, water-damaged roots/stems, nutritional problems, and hormonal imbalance in tobacco.
In fruits and vegetables, we diagnosed black rot, crown gall, and anthracnose on grape; double blossom on raspberry; cedar-apple rust, leaf hopper and hail injury on apple; brown rot on peach; Botrytis blight on rosemary; blackleg of potato; manganese toxicity in squash; physiological leaf roll, magnesium deficiency, and flood-damaged roots on tomato; and Pythium root rot on watermelon.
In ornamentals and turf, we saw Alternaria leaf spot on impatiens; Phytophthora aerial blight on vinca; Botrytis blight and rust on geranium; bacterial spot on ivy; brown patch on fescue; bacterial blight on holly; and anthracnose and jumping oak gall on oak.
UKREC-Princeton, KY, June 6 - 13| Black cutworm
| 0
| True armyworm
| 14
| European corn borer
| 0
| Southwestern corn borer
| 6
| Corn earworm
| 5
| | |
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
