by William Nesmith
A field day focusing on blue mold research will be held on Thursday, August 28 at 1:30 PM at the University of Kentucky, Robinson Experiment Station, located three miles south of Jackson, Ky on highway 15. I apologize for the short notice, but circumstances have only recently come together to warrant having this event. These plots were shown during the stations field day on July 24, but inadequate disease pressure existed at that time to separate treatment effects. Thanks to a strong outbreak of blue mold there during the past three weeks, large differences were present last week and hopefully will hold through August 28. This should be an excellent opportunity to see and photograph the level of blue mold control provided by different experimental treatments, varieties, and properly applied Acrobat MZ applications
Category 2b (8:20 AM - Noon, Testing at 1:00 PM)
November 5, 1997
1997 Wood Preservative Workshop
Hardin Co. Cooperative Extension Office
Elizabethtown, KY
Categories 1, 2a, 3, 4, 10 & 12 (Cat. 2a: 8:30 AM - 12:20 PM, Testing at 1:00 PM; Cat. 3, 10. 12: 8:30 AM - Noon, Testing at 1:00 PM; Cat. 1, 4, 10, 12: 9:45 AM - 2:00 PM, Testing at 2:00 PM)
November 11, 1997
McCracken Co. Extension Office
Paducah, KY
November 18, 1997
Fayette Co. Extension Office
Lexington, KY
December 22, 1997
419 Reed Hall
Morehead State University
by William Nesmith
A blue mold advisory is in effect statewide. BLUE MOLD WARNINGS remain in effect for EASTERN and NORTHERN KENTUCKY, including the Bluegrass and Lake Cumberland regions. Blue Mold Watch/Warning (county dependant) also remains in effect for western Kentucky (west of Interstate 65).
At this time of year, the best information about the blue mold status and risks involved, should come from the local county extension offices, because crop conditions are highly variable from community to community within counties. Blue mold could threaten late crops anywhere in Kentucky, where rapid new growth develops, because inoculum is present from both western and eastern Kentucky and night-time conditions are favorable. Furthermore, blue mold is active as small fleck-like lesions in many stunted and poorly growing crops in central Kentucky and can strike quickly at damaging levels in the top growth with cool wet weather. If there is sufficient moisture to support new growth, expect blue mold, especially in fog pockets.
In the watch and warning areas, localized strong pockets of blue mold are still occurring. Management decisions should include considerations for blue mold control. Properly applied fungicide sprays will provide the best protection against blue mold in crops not yet topped. The benefits from high pressure become more obvious as canopy closes, because of improved cover on the portions of the leaf nearest the stem. Recall the 30 day waiting interval between last application and harvest. If blue mold is a threat to crops at topping, including MH-type chemicals in the sucker control program will aid in reducing losses to blue mold. Be sure to prevent sucker-regrowth in crops already harvested.
Tobacco aphids are increasing steadily on late-set tobacco. It is important to continue to manage aphids to protect expanding leaves at the top of the plant. Large numbers of aphids on these leaves will keep the leaves from expanding to their full size and subsequently to their potential weight. Foliar sprays of either Golden Leaf (endosulfan) or Orthene (acephate), applied when about 20% of the plants are infested with aphid colonies, will protect against yield losses to this important insect.
Both long-horned (antennae as long as or longer than the body) or short-horned (antennae noticeably shorter than the body) are active and may be responsible for some of the holes in tobacco leaves. Grasshoppers generally occur in grassy field margins or pastures but can be driven into tobacco by mowing or clipping hay fields. They can eat a lot of leaf tissue in a short period of time so it is best to check grassy areas next to tobacco fields regularly. If grasshopper activity is significant (10+ per square yard) then treat that area to kill the insects before they move into the crop. They are too destructive to allow them to move into the field before attempting to do anything. Sevin can be used for grasshopper control on pastures and hayfields. See the label for directions.
| FUNGICIDE | PRODUCT/ag/ACRE | METHOD/NOTES |
| Untreated Control | --- | --- |
| Acrobat MZ 69 WP | 2.5% | Gallons adjusted to crop stage, max of 5 applications |
| Acrobat MZ 69 WDG | 2.5% | Compared directly with WP |
| Aliette 80 WDG | 4 lbs/A | Max of 5 applications |
| Acrobat 50 WP Aliette WDG | 0.23 lbs/A plus2 lbs | Max of 5 applications |
| Acrobat 50 WP Aliette WDG | 0.23 lbs/A plus2 lbs/A | Max of 5 applications |
| Actigard 50 WG(CGA-245704) | 14.2 g/A | foliar for 2 applications, followed by 28.4 g/A for 3 weekly sprays |
| Actigard 50 WG | 28.4 g/A | foliar as curative as needed, weekly |
| Actigard 50 WG | 14.2g in20 gal water/A | using broadcast boom with flat fans |
| Actigard 50 WG | 14.2g in100 gal water/A | using hollow-cone with drops |
| Actigard 50 WG | 14.2 g/A | two applications followed by Acrobat MA @ 2.5% solution as needed up to 4 applications |
| Acrobat MZ | 2.5% | foliar sprays until layby then 2 applications of Actigard 50 WG @ 14.2 g/A |
| ICIA5504 | 0.24 pts/A | foliar spray |
| ICIA5504 | 0.48 pts/A | foliar spray |
Border Rows:
Ridomil Gold 1 pt/A, banded at early cultivation and layby.
Experimental Design:
Study is located in 4, 8-row sections of NCBH129, which was
planted on Jun 24. The sections are about 72 ft. long.
Each section will be divided into 4-rows (dividing the sections in half) and individual treatment plots are 10 ft. long (about 6 plants) and 3 rows wide or (35 sq ft area). The border row is the outside row (extreme left or right adjacent to sod-strip)
Mike Smith, CES for Agriculture in Henderson County, reported some extremely high southwestern corn borer pheromone trap catches in the Henderson area. The trap catch totals for the ten day period beginning August 1 were 128, 425, and 978. Last year during this same period, the maximum trap catch count was 113. What does this mean for corn producers in that area? Southwestern corn borer appears to be a very serious threat this year, particularly for late planted corn in this area. With the flooding early this past spring, the is a high percentage of river bottom fields that were planted late and are potentially at risk this pest.
While both generations of the Southwestern corn borer can cause yield loss to corn producers, it is the second generation that is the most damaging. These larvae begin feeding in the mid and lower zones of tassel-stage corn in mid to late July. Typically they feed between the layers of husk on the primary ears. After about two weeks, the larvae begin tunneling in the stalk. Characteristically they make a straight line through the middle of the stalk. The second generation will overwinter as larvae. These larvae move to the base of the plant and girdle the plant before tunneling downward. This is the most serious damage caused by this insect. Larvae girdle the stalk by chewing internal groove around the stalk about an inch above the soil line. This leaves only a thin outer layer of the stalk for support.
Now is a good time to monitor fields that have had a history of Southwestern corn borer, or fields in the western portion of the state that are late planted. Producers should try to distinguish between European and Southwestern corn borers. The European has a dark head, a pinkish white body, and faint gray stripes running the length of the body. The southwestern corn borer has a dark head and a creamy-white body with numerous black spots. Producers should identify fields with high southwestern corn borer levels. Because the larvae attack the base of the plant, insecticidal control is difficult. These fields will need to be harvested as early as possible to minimize harvest losses due to lodging.
Gray leaf spot caused by Pyricularia grisea is generally regarded as an emerging disease of high-maintenance perennial ryegrass and tall fescue in the southern portions of the ranges of adaptation of these cool-season grasses. In recent years, we have seen very significant--even catastrophic--outbreaks of this disease on perennial ryegrass fairways in Kentucky. Thus far, it does not appear to be a significant threat to tall fescue in Kentucky, but we are continuing to monitor this. The disease can be so explosive and so destructive that I have seen no choice but to recommend that managers of high-maintenance swards of perennial rye be prepared in mid- to late summer to apply fungicides preventively for this disease, should conditions warrant.
I have been scouting all summer for this fungus on several host plants. With the help of several county agents and Paul Bachi (Plant Disease Diagnostician at the UKREC), we found it on German foxtail millet in several fields in southern and western Kentucky in mid-July. However, in spite of regular scouting in a number of locations in central Kentucky, I had not yet found it on either ryegrass or large crabgrass until late last week, when we detected a low level of active disease on perennial rye on a golf course in Lexington.
Recent cool weather has definitely been unfavorable for disease development and very favorable for growth of a cool-season grass like perennial rye. Temperatures for this week are not forecasted to exceed the upper 80's. Given the situation at this moment (8:30 AM Monday, 25 Aug 97), it is very possible that there will be no benefit to spraying at this late date. Can I guarantee that there will be no benefit to spraying? No, we don’t know enough about this disease yet to make that claim. However, I do feel that no more than one spray is needed, if even that. We just need to get to mid-September without any substantial disease activity to get past the need to treat. By then, nights are cool and long, and I don’t perceive there to be much risk from the disease. I wish to know about any severe outbreaks of this disease for the remainder of the season, particularly those that occur later than my experience suggest will happen.
Superintendents who manage high-maintenance perennial rye should monitor the situation closely, and consider their recent history of the disease. If an extended period of warm, humid weather is forecasted, a single spray may be justified. Labeled products that are reasonably effective include Daconil Ultrex and Banner MAXX.
Tar spot is visible on maples in Kentucky now. Some people worry when they observe thick, crusty black splotches and spots on the leaves of their maple trees. The leaves of red, silver, and sugar maples may show symptoms and signs of either of two species of Rhytisma, cause of tar spot disease. Tar spot begins in early summer as light green or yellow spots on the leaves. The disease becomes very noticeable in late summer when the raised, tar-like fungal stroma develop on the upper surface of the leaves. R. acerinum, found more frequently in Kentucky, causes a black splotch approximately 1/4 - 3/4 inch across, while a related fungus, R. punctatum, appears as a cluster of tiny black spots.
New infections begin from spores produced on fallen leaves that were diseased last season. There apparently is no secondary cycle of disease during the growing season. Withered leaves with many spots may drop from the tree, but normally they are too few and appear too late to affect the health of the tree. Thus, raking up and destroying diseased leaves, the source of primary inoculum for next year, should be all that is needed to manage tar spot. It is possible that one might worry if tar spot disease disappeared from the landscape. R. acerinum is reported to be sensitive to low levels of sulfur dioxide air pollution, thus tar spot is uncommon in certain urban and industrial areas.
Other species of Rhytisma may cause tar spots on tuliptrees, hollies, and willows. I have noticed that tar spot occurs in England on sycamore maple and in France on willows where it causes a fairly substantial blotch.
Foreign grain beetles are very small (about 1/16-inch long), reddish brown, and are often mistaken for flour beetles or other stored product insects. The key characteristic to look for in identifying this beetle is the presence of a slight projection or knob on each front corner of the segment directly behind the head. A microscope or good quality hand lens is necessary to see this character.
Foreign grain beetles are frequently problems in new houses (less than 5 years old). These beetles are one of a group of beetles called "fungus beetles" that feed on the molds and fungi that grow on poorly seasoned lumber or wet plaster and wall board. If they are found infesting flour, grain, or other stored products, the products are generally moldy or in poor condition.
When new homes are built, damp wood is often covered with molds or mildew which attracts the beetles. The beetles are also attracted to accumulations of sawdust trapped behind walls during construction. Eggs are laid on this food material and the larvae develop on the surface fungi. The adults usually become a problem in late summer when they move out of wall voids and are attracted to windows and lights. Foreign grain beetles can also be associated with plumbing leaks, condensation problems, or poor ventilation.
There is no fast or easy way to get rid of foreign grain beetles. Control is difficult because the breeding source of the beetles (sawdust, etc) is sealed up within the walls. The ultimate solution is time (and patience). Most new homes dry out naturally within the first 1-4 years, and the fungi and molds disappear along with the beetles. Drying time can be enhanced by increasing ventilation, e.g., by use of fans and air conditioning. Homeowners can gain some relief with directed applications of aerosol sprays containing pyrethrins, but such treatments would need to be repeated frequently as the beetles continue to emerge. A vacuum cleaner works just as well and removes any visible beetles which are Present. Pest control companies may be able to provide additional relief by locating the infested wall areas or source of dampness (usually next to where the beetles are most abundant) and injecting residual aerosols or dusts into cracks and crevices along baseboards and into the wall voids.
If the homeowner can tolerate the beetles during the period when they are most active (late summer) the problem will usually resolve itself. Some comfort can be taken in the fact that foreign grain beetles are only a nuisance by their presence, i.e., they do not bite or damage wood, fabric or stored food in sound condition.
| Princeton | |
| European Corn Borer | 4 |
| Corn Earworm | 51 |
| Fall Armyworm | 3 |
| Tobacco Budworm | 8 |
Lee Townsend
Extension Entomologist