A continuing education program will be held in Princeton, KY on July 25, 1997 at the Research and Education Center. This meeting is in cooperation with the Fumigation Service and Supply, Inc. of Indianapolis, IN and the Kentucky Feed and Grain Association (KFGA). The meeting will run from 9 am to 5 pm Central time.
Topics and Speakers
A registration fee of $100 per person ($75 for KFGA members) is required. Attendance is limited to 75 people. To register call Barb Bass at 317-846-3399 or request a form at InsectsLtd@aol.com
There is good news and bad news
GOOD NEWS: First, only small amounts of blue mold have been detected in Kentucky. This is especially good news considering Kentucky experienced a very long period of very favorable weather while being bombarded with spore showers from the south. Second, the potential for blue mold spread via airborne spores has declined sharply with the several days of hotter and drier weather. Such weather is not conducive to spread of blue mold, plus it is allowing growers to get their crops out of the crowded beds and into the field. Third, we have found no evidence to indicate that blue mold has been introduced this year on southern transplants.
BAD NEWS: Blue mold is already here, including metalaxyl- resistant strains. Blue mold will continue to develop where infections have already occurred. Furthermore, we do not have reliable information on the level of infections that have occurred. Because the plants were growing poorly during the infection periods, typical lesions did not develop, but that does not mean that infections did not occur. Blue mold can infect poorly growing plants, but lesion development is greatly delayed in such plants. Until the plants begin to grow normally, dormant-type infections will not become obvious. Spread within transplant systems and through transplant movement is currently the main risks for Kentucky. Some growers have become desperate for transplants and commercial transplants are being offered from communities where active blue mold exists.
STATEWIDE BLUE MOLD WATCH: I have considered canceling the blue mold watch for Kentucky, but have elected to keep it in place until most of the crop has been transplanted and begins to grow normally. Until then, estimates on the level of blue mold activity are unreliable. As soon as reliable information can be obtained, we will adjust the advisory status, appropriate with the situation.
Selected counties have been upgraded to a BLUE MOLD WARNING due to confirmed blue mold within the county or near the county border. Even those counties under warnings can be adjusted downward if the outbreaks are brought under control.
BLUE MOLD WARNINGS ARE IN PLACE FOR THE FOLLOWING COUNTIES:
The level of blue mold in all these counties is still very low. The only strong outbreaks identified in Kentucky, thus far, are near Fairview near the Christian/Todd line, southern Shelby County, and in central Menifee County. All other confirmed outbreaks involve isolated lesions found by plant pathologists or county agents while scouting for the disease. Let's not forget about the strong blue mold activity occurring in the south and east, especially that in east Tennessee and western Virginia.
Kentucky's weather is expected to be much less favorable for blue mold development during the next several days. The bright sunlight should kill airborne spores, supporting only local spread of the fungus. The higher temperatures should rapidly improve growth rates, favoring development of lesions where infections have already occurred, but new sporulation could be markedly suppressed where daytime temperatures reach the 90's and/or night temperatures remain in the high 70's. Conditions will remain very favorable to support movement of blue mold within dense plant beds, float beds, and greenhouses. But, with drier conditions, the fungicides should stay put.
RECOMMENDED ACTIONS: TRANSPLANTS: Growers can reduce their vulnerability to blue mold by getting fungicides sprays made and transplanting where possible. Blue mold infected plants should not be set. Under no circumstances should infected transplants be moved out-of-state, or from one region to another within Kentucky. If infected plants must be used, they should be utilized within the local community where the outbreak has occurred.
TRANSPLANT MOVEMENT ADVISORY: Transplants from most tobacco producing regions of the US may have been exposed to blue mold during the past month, including most regions of Kentucky. Blue mold is activity in portions of Florida, Georgia, South Carolina, North Carolina, Virginia, Maryland, Pennsylvania, Tennessee, and Kentucky. Long distance movement of transplants, from more than a few counties away, should be considered only after carefully considering the risks. Consider carefully the blue mold status of the community producing the transplants and the production regimes involved. Plants under the most rigorous fungicide programs (complete coverage, 5-day spray interval, with Ferbam, Dithane DF or Acrobat MZ) and disease management systems have the greatest probability of being free of blue mold. Plants from communities where blue mold warnings are in effect have the greatest risk of harboring blue mold. Plants from transplant production systems with active blue mold should not be used, rather the plants should be promptly destroyed.
DESTROY ABANDONED PLANT BEDS IMMEDIATELY: Any large over- grown plant beds should be destroyed immediately to keep them from serving as "BLUE MOLD INCUBATORS". County Extension Agents need to strongly stress this point locally.
ADVISORY FOR OUT-OF-STATE TRANSPLANTS: Moving plants from any state where active blue mold is occurring is risky. As the blue mold threat increases in the south, the risk of introducing blue mold on transplants increases rapidly!
FUNGICIDE RESISTANCE: Laboratory tests demonstrate that both strains of blue mold are operating in Kentucky. Metalaxyl-resistant strains have been confirmed from two of the three most active cases: Christian and Shelby counties. Metalaxyl-sensitive strains were recovered from central Kentucky and some of the material from Christian County. Assays are not yet complete on the material from Menifee County.
SPRAY PROGRAMS: The greatest success with spray programs will occur when:
DITHANE DF RELABELED
Dithane DF fungicide registration has been renewed under a
24-C status in Kentucky. The renewed label is effective
through June 16, 1998. The rates and uses are exactly the
same as in 1997.
Recent wet weather has been favorable for a common disease of spring-seeded alfalfa called Rhizoctonia stem canker. In one case, the disease was quite severe and associated with areas of flooding during the heavy rains in March, prior to seeding. Precisely why deposition of soil on a field during a flood favored the disease is unclear. Perhaps the soil contain high inoculum levels of Rhizoctonia fungus; perhaps the ecological disturbance of flooding caused native populations of Rhizoctonia to flourish. In any event, this unfortunate pattern may be repeated elsewhere.
SYMPTOMS: Individual shoots turn yellow, sometimes with a bit of reddening along major veins. Leaves on these shoots curl from wilting, and the tips of the shoots often droop downward to form a "shepherd's crook". Down near the soil line, a lesion (or "canker") is present on the stem, and usually girdles it. The canker may be dark brown or a light brown with a dark brown border. In the field, the disease looks very much like anthracnose, although stem canker generally has been more common in Kentucky during the 1990's.
OCCURRENCE: This alfalfa disease most commonly occurs in new seedings, although it can occur at any time in the life of a stand. Fields where a sod has been incorporated into the soil often have the highest disease severity, although once again, flooding pre-seeding appears to have favored the disease in some locations this year. Fresh organic matter probably serves as a food base for the fungus that causes the stem cankers (Rhizoctonia solani AG-4). This very same fungus is also active now in causing rotted areas of roots, which can be seen as black, somewhat superficial lesions on tap roots. R. solani AG-4 is very common in our soils, and very aggressive under the right conditions. The fungus is unfortunately one of the risk factors that producers face when growing alfalfa.
PROGNOSIS: Plants showing Rhizoctonia stem canker in a new seeding generally will not recover. Unfortunately, there is no management action that a producer can use as a rescue practice, nor is there really any preplant practice we can recommend to prevent this disease. However, the damage that is visible now is probably all that will occur for the rest of the season. Keep in mind that alfalfa sometimes has a remarkable ability to compensate for missing plants. If the stand is not excessively thin, long-term yields will probably not be affected greatly. Extension Agriculture Agents can provide information on stand densities suitable for hay production and grazing.
Economic infestations of European corn borer have been found in several central and western Kentucky counties. Problems appear to be most common in early plantings. Producers need to be scouting their corn fields for first generation corn borers at this time. Producers in western Kentucky should also keep an eye out for Southwestern corn borer in corn planted after May 1. Damage by southwestern corn borer, while not as widespread, has been increasing and severe in some fields. The most effective time to control southwestern corn borer is during its first generation.
The following table from ENT-49, European Corn Borers in Corn, should help growers determine whether a treatment for European corn borer would be profitable for them. If fields are found to be close to threshold, but not over, then the fields should be rescouted in 3 to 5 days.
Potential preventable yield loss to European corn borer in field corn.
| Growth stage | Percentage of Infested Plants | ||||
| 40% | 50% | 60% | 70% | 80% | |
| Early whorl | 4.9 | 6.5 | 8.3 | 10.3 | 12.6 |
| Late whorl | 3.9 | 5.2 | 6.6 | 8.3 | 10.1 |
| Pretassel | 5.9 | 5.2 | 10.0 | 12.4 | 15.0 |
| Pollen shed | 3.9 | 5.2 | 6.6 | 8.3 | 10.1 |
| Kernels initiated | 2.7 | 3.6 | 4.5 | 5.6 | 6.9 |
To use this table you will need to estimate (1) the percentage of infested plants in the field, (2) anticipated yield (bu/a), (3) expected crop value ($/bu), and (4) control cost ($/a for insecticide + application cost).
As an example, suppose you have a field that you expect will yield 150 bu, you hope to get $2.50/bu, there is an 60% infestation in the pretassel stage, and the cost of control is $8/a ($6 for the insecticide and $2/a application cost). The table indicates that there is a 10% preventable yield loss if no treatment is made. This translates into a 15 bu/a yield loss (150 bu/a x 0.10) or a $37.50 loss per acre (15 bu/a x $2.50 /bu). Subtract the control cost and the example shows a $29.50 advantage for a properly timed insecticide treatment.
If using and insecticide for control, TIMING and PLACEMENT are the keys to success. Larvae must be controlled before they bore into the stalk! We can also use the plant to our advantage. Most of the larvae are located in the whorl, so an application over the whorl will direct the insecticide to larvae inside the whorl like a funnel. In general, granular formulations do have a slight advantage over liquids for control, but high levels of control can be obtained with liquids or granules.
Corn producers west of Elizabethtown need to realize that there are two species of corn borers that will attack corn, the well known European corn borer and the more destructive southwestern corn borer. The southwestern corn borer is typically more of a problem in late planted corn (after May 1) and has a lower threshold for control than the European corn borer. Late in the season, southwestern corn borer larvae girdle stalks just above the soil line. This can cause serious harvest losses if infestations are severe. These Southwestern and European corn borer larvae are similar in appearance but the following table can be used to distinguish them.
Comparison of SWCB and ECB
| Characteristic | SWCB | ECB |
| Symptoms | Window pane feeding to whorl; dead heart | Window Pane feeding to whorl |
| Symptoms (2nd-gen) | Feeding in Leaf axils; stalk boring concentrated in the bottom 2/3 of plant; girdlig at base of stalk | Feeding in leaf axils; stalk boring concentrated in the middle 1/3 of plant; broken tassels |
| Eggs | Singly or groups of 2 to 5 eggs; three transverse red bars | In groups of 10 to 30 eggs; without markings |
| Larvae | Creamy-white with numerous black spots. Crochets (small hooks) on the bottom of the prolegs in a complete circle. | Creamy-white with numerous black spots; faint gray stripes running lengths of body. Crochets (small hooks) on the bottom of the prolegs in an almost complete circle |
| Occurrence | Early June through harvest | Early June through harvest |
When monitoring fields for corn borers, it is VERY IMPORTANT to pull the whorls of a few damaged plants to determine:
Ants are one of the most frequent and persistent pests encountered around the home. At least a dozen species may be found indoors, including pavement ants, carpenter ants, odorous house ant, acrobat ant, and pharaoh ant. Besides being a nuisance, they contaminate food, build unsightly mounds on our property, and cause structural damage by hollowing out wood for nesting.
Ant control can be very frustrating. Repeated attempts often are required to maintain ants at tolerable levels. This column provides tips on how to eliminate ants with more success and less effort. Recommendations pertain to all of the common ant species found in Kentucky except carpenter ants, which were discussed in an earlier (5/12/97) newsletter.
THE SOLUTION
The mistake most people make when attempting to control
ants is only spraying the ones they see. This approach
usually fails because the ants seen foraging over exposed
surfaces are only a small portion of the colony.
Typically, there will be thousands of additional ants,
including one or more egg-laying queens hidden somewhere in
a nest. The importance of eliminating queens and other
colony members within nests cannot be overstated and is the
key to effective ant control.
Ants build their nests in many different locations, both inside and outside of buildings. Control of indoor-nesting ants requires a somewhat different approach than for ants nesting outdoors, because indoor nests usually are hidden or inaccessible.
Ants Nesting Indoors- Buildings contain many favorable nesting sites for ants. Preferred sites include spaces behind walls, cabinets, light switches and receptacles, behind window and door frames, and beneath floors. Most of these areas are hidden, making it extremely difficult to determine the precise location of the ant colony. When the location of the nest cannot be determined, or the nest is inaccessible, insecticidal baits are the preferred solution for homeowners. The advantage in using baits is that foraging ants take the insecticide back to the nest and feed it to the queen(s) and other members of the colony. Within a short period of time (usually within a week), the colony is destroyed.
Ant baits are convenient to use. Most consumer formulations come pre-packaged with the insecticide and food attractant confined within a plastic, child-resistant container. Two of the more effective containerized bait products which can be purchased in most grocery and discount stores are Combat (R) SuperBait for ants and Raid Ant Bait ( Mettastop(R)). Place the baits next to wherever ants are seen, preferably beside ant "trails" -- invisible odor trails that worker ants follow between food and the nest. Do not spray other insecticides or cleaning agents around the bait stations as this will keep ants from feeding on the bait. Initially, you should see an increase in the number of ants around the bait station. Do not spray them. This indicates that the ants are feeding on the bait and transporting the insecticide back to the nest. Ant activity around the bait station should subside in a few days as the number of ants in the colony declines. Continue to place other baits wherever ants are seen.
Another commercially-prepared ant bait that often works is Terro II(R), sold in some hardware stores. Place dabs of the bait on small pieces of waxed paper, or on the back (nonsticky side) of masking tape along ant trails, but away from children and pets. Replace with fresh dabs of bait daily until ant activity ceases.
IMPORTANT NOTE: Insecticidal baits will not normally control carpenter ants. Elimination of carpenter ants is discussed in ENT-57, Ant Control In and Around Structures.
Ants Nesting Outdoors- Ants noticed inside the home may actually be nesting outdoors in the yard. Trace the ants back to the point where they are entering from outside, such as over a window sill or beneath an exterior door. Nests will often be located in the ground, where they may be marked by a mound or anthill. Other times, the nest will be concealed under stones, landscaping timbers, pavement, or beneath tall grass adjacent to the foundation wall. Some kinds of ants prefer to nest underneath siding or behind wood trim that has been moisture damaged. While it takes patience to locate a nest outdoors, results will be more rapid and permanent than if you spray only where ants are seen. One way to entice ants to reveal the location of their outdoor or indoor nest(s) is to place small dabs of honey, maple, or corn syrup next to where ants are seen. After the ants have fed, they soon will head back to the nest.
Once a below-ground nest is discovered, the colony can be eliminated by thoroughly spraying or drenching the nest location with carbaryl (Sevin), diazinon, or chlorpyrifos (Dursban). Large colonies will require greater amounts of liquid to move the insecticide throughout the network of underground galleries within the nest. Using a bucket to apply the diluted insecticide is an effective method. Follow label directions for treating ant mounds, paying attention to precautions for mixing and application. Another approach would be to use the new effective and convenient bait product, Combat(R) Ant Killing Granules. Available through some retail stores, the bait is intended to be sprinkled in small quantities on outdoor ant mounds, along pavement cracks, and other areas where outdoor ants are nesting or foraging.
Ant entry into homes can be reduced by caulking around doors (especially along bottom outside edge of thresholds), windows, and openings where pipes and wires enter the building. Chronic ant problems can further be reduced by applying one of the above-mentioned liquid insecticide formulations around the outside perimeter of the building. Pay particular attention to structural points of entry, such as around doors and where utility pipes and wires enter from the outside. Also consider applying a 3-to 6-foot swath along the ground adjacent to the foundation, and a 2-to 3-foot band up the foundation wall. Longer residual (1-3 months versus 1-2 weeks) can be obtained by using a microencapsulated (slow-release) insecticide formulation. A few such liquid formulations of Dursban are now being stocked by lawn/garden shops and hardware stores.
Broadcast spraying or applying conventional insecticide granules to the yard (e.g., diazinon or Dursban) seldom, if ever, solves an indoor ant problem. In Kentucky, such applications are a waste of money, effort, and a potential polluter of streams, lakes, and waste water. They also eliminate beneficial ants which may be important allies in suppressing other pests on your property.
Where trade names are used, no endorsement is intended, nor criticism implied of similar products not named.
Japanese beetles were caught in monitoring traps last weekend, indicating that the adult flight period has begun. Infestations in Kentucky have been less severe in recent years, presumably due to the increased influence of natural control agents. Nonetheless, it is still hard to predict how serious a problem the beetles will be this year.
Life Cycle and Habits
Most people are familiar with the metallic green and bronze
appearance of adult Japanese beetles. The beetles begin to
emerge from the ground in June, and are abundant throughout
most of the summer. They feed on nearly 300 species of
plants, devouring leaves, flowers, and overripe or wounded
fruit. Adults are particularly fond of roses, grapes,
purple-leaved Norway and Japanese maples, linden, purple
leaf plum, and most varieties of flowering crabapple.
Plants in full sun are preferred, and beetles usually feed
in groups on the upper foliage. The adults are extremely
mobile and can infest new areas from very long distances.
From a management standpoint, it's important to recognize that both adults and larvae cause damage. Moreover, because the adults are capable of flying long distances, controlling one life stage will not preclude potential problems with the other. Adults and larvae must be dealt with individually, and in a different manner. Outlined below are options for protecting trees, shrubs and flowers from adult Japanese beetles. Grub control will be covered in a later newsletter as we approach the optimum time for soil treatment in August.
What Works
What Doesn't Work
Japanese beetle traps continue to be sold in many garden centers. These traps catch large numbers of beetles, but do not reduce damage to plantings. Research conducted at UK showed that traps attract many more beetles than are actually caught. Consequently, susceptible plants along the flight path of the beetles and in the vicinity of traps are likely to suffer more severe damage than if no traps were used at all. If clients wish to experiment with traps, they should be placed far away from gardens and landscape plants.
We are seeing many nutritional problems lately, such as deficiencies of zinc, magnesium and nitrogen on corn, and temporary phosphorus deficiency and manganese toxicity on tobacco. Infectious diseases continue to affect tobacco, with outbreaks of blue mold occurring in several areas of the state, as well as black root rot, target spot, black shank, blackleg and anthracnose. Brown spot(Septoria) was diagnosed on soybean.
On fruit trees, fireblight was seen on pear and frogeye leaf spot and cedar-apple rust were seen on apple. On vegetables, Botrytis stem canker, Sclerotinia stem canker, anthracnose, early blight and powdery mildew were diagnosed on tomato. Powdery mildew (Erisyphe) was also seen on cucumber.
On ornamentals, powdery mildew continues to be a problem on herbaceous plants, as well as woody plants, especially dogwood. Slime molds are being seen on turf, but drier weather should alleviate this common concern of homeowners
| Princeton | |
| Black Cutworm | 1 |
| True Armyworm | 5 |
| European Corn Borer | 0 |
| Corn Earworm | 0 |
| Southwestern Corn Borer | 0 |
| Allen Co. | |
| European Corn Borer | 2 |