EARLY FLOAT PLANT PESTS
By Lee Townsend

Sowbugs or pillbugs and ants have been reported in float bed trays. Sowbugs tend to be scavengers that feed in decaying organic matter but they can feed on fine feeder roots or leaf tissue. Much of their damage can be burrowing into the media and uprooting small seedlings. Once in the trays, they can remain there and cause significant loss of small seedlings. Sevin Bait may provide control of these small crustaceans. They are likely to be very abundant under the plastic lining of float beds. Close clipping of grass to increase air circulation and application of the bait is about the best control option.

Ants may be present in some float systems. It is not clear as to what is attracting them or maintaining their interest. Check for trails to locate nests in the soil around the production beds and treat them directly.

For more information about tobacco pests, visit "Insect Management Recommendations".

SEED TREATMENTS ARE MOST IMPORTANT FOR EARLY PLANTING
By Paul Vincelli

Of the numerous organisms that attack corn seeds and seedlings, Pythium ultimum is the most common and most destructive. P. ultimum is very commonly present in agricultural soils. It can cause seed decay, preemergence damping off, and postemergence damping off of corn. It can also infect root hairs and young rootlets of older plants, causing reduced vigor of developing plants, which can ultimately affect yields in continuous corn situations.

P. ultimum is most active and destructive in the kind of weather in the kind of soil conditions experienced last week and forecasted for early this week for most of Kentucky: wet and cold. Specifically, the risk of stand loss from P. ultimum is greatest when soil is saturated with temperatures in the 40'sF. At temperatures of 50F, the young corn plant begins to have enough physiological activity to be able to resist these infections, and so is more likely to overcome any infections that might occur. This is the basis for the UK recommendation to plant corn when the soil temperature at a two-inch depth is at least 50F at sunrise for 3-4 days (basically, one is simply checking soil temperature at the depth of the corn seed at the coldest time of the day).

Corn seedings made in late March and early April are at greatest risk of attack by P. ultimum. For early seedings, improving soil drainage is the best cultural control available. Seed treatments are inexpensive and valuable chemical options for minimizing the risk of Pythium stand loss in cool, wet soils. Of the various seed treatments available, metalaxyl is specifically active against Pythium organisms and in my opinion, is the best choice for early seedings. Metalaxyl is found in several products, including Allegiance and Apron. Most of the corn seed sold in Kentucky is treated with metalaxyl. However, when making early season seedings, it is best to check and be sure the seed being purchased is treated with metalaxyl.

MUSK THISTLE CONTROL IN KENTUCKY PASTURES
By J. D. Green

One of the most troublesome weed problems in Kentucky pastures and hayfields are thistles. Thistle plants can interfere with livestock grazing and limit the amount of available forage. The spring and early summer months is when thistles become a major problem for land owners and livestock producers who graze cattle or produce hay.

Musk thistle, also called nodding thistle, is the most common type of thistle plant found in Kentucky. It is considered a noxious weed because of its ability to reproduce rapidly and limit pasture production. Musk thistle only reproduces by seed. Therefore, the major aspect of any control efforts is to prevent or limit seed production.

The primary growth period of the plant is generally in the spring through the early summer months. However, most seed germinate in the fall and form a rosette which grows close to the ground, often growing unnoticed until the spring months. The leaf surface is waxy in appearance and contain spines along the leaf margins. Flower stalks develop in the spring followed by bright purple to reddish flowers, which bloom in late May to early June. The seed, which are produced for the next generation, develop soon after flowering and are easily carried by wind and spread to other areas as well.

The most important step in long-term control of musk thistle is to prevent flowering, and the production and spread of new seed. This can be accomplished by using various mechanical, biological, or chemical control methods.

For mechanical control efforts mowing, clipping pastures, or even hand-grubbing can be used. These control methods should be initiated before flowers begin to open. Some regrowth and production of flowers can occur after mowing, but seed production will be notably less than if a mechanical control method had not been used. Thistle plants mowed or removed by hand after flowers have bloomed contain enough energy reserves that these plants will still produce viable seed.

A reduction in musk thistle populations can also be obtained through biological control methods. Two different insects are known to inhibit thistle growth and development, the Thistle-Head Weevil and the Thistle Rosette Weevil. The Thistle-Head Weevil can be found during the spring in many counties throughout central Kentucky. These insects feed on the maturing seed inside the developing flower head. The impact of the Thistle-Head Weevil will not eliminate all seed production, but can significantly reduce the amount of seed produced by individual plants in areas where the insect has become established.

Broadleaf herbicides labeled for use in pastures can be applied in grass pastures and non-cropland areas for control of musk thistle rosettes. However, for herbicides to be effective the timing of the application is critical. Best results can be obtained if herbicides are applied to plants that are in the early rosette stage of growth and actively growing. Therefore, the best times for herbicide application is in the early spring or fall. Application of herbicides in the spring should be made during March and April when thistle plants are actively growing. In the fall, apply herbicides in October or early November following new seed germination. When plants are in the rosette stage they are more susceptible to herbicide applications.

Herbicides which can be used in pastures include 2,4- D, Banvel, Crossbow, Redeem R&P, and Weedmaster. For spring herbicide applications apply when air temperatures are above 55 F for 2 to 3 days. Complete spray coverage of the plant is also important. When herbicides are applied after flower stalks elongate, control will be less effective and inconsistent. When using herbicides for control, consult the waiting period on the product label for livestock grazing restrictions following herbicide application. Avoid spraying near crops such as tobacco, vegetables, or ornamental plantings. Also, avoid spray drift by not spraying on windy days or days with extremely high temperature and high humidity.

WHEAT FUNGICIDE STATUS FOR 2002
By Don Hershman

As the spring begins to unfold, I wanted to update you on the wheat fungicide situation for 2002. Actually, there is not much new to say and that is my main point. This winter a couple of fungicide manufacturers indicated to me that they expected to have new product labels for use this spring. I am not mentioning any names here so as not to get your hopes up or down in regards to any particular fungicide. There is still some hope that additional labels will be granted, but time is running out for the 2002 crop. Stay tuned.

As it now stands, the main fungicides for use this year are Tilt, PropiMax, Stratego, and Quadris. Tilt, a Syngenta product, and PropiMax, a Dow AgroSciences product, are for all practical purposes the same fungicide. Price, existing marketing incentives/tactics, and availability will play major roles in determining which product farmers use in 2002. The active ingredient in both these products, propiconazole, has been an outstanding performer in Kentucky, but there is a major drawback, -- that being that products containing propiconazole must be applied by the time the flag leaves of a crop have emerged. For a variety of complicated reasons, Kentucky does NOT have 24C label which allows application of propiconazole later than flag leaf emergence.

The Bayer product, Stratego, also contains propiconazole and is subject to the same time of application restriction as Tilt and PropiMax. However, Stratego has an additional active ingredient, trifloxystrobin. Triloxystrobin alters the disease control aspects of Stratego slightly compared with Tilt/PropiMax, but in my opinion there is not a great deal of difference in regards to disease control between the three fungicides. Again, price, marketing incentives/tactics and availability will determine how much Stratego is used in 2002.

Quadris is a Syngenta product containing the active ingredient azoxystrobin. In my experience, Quadris is an excellent fungicide and the label allows use of the product up to crop flowering. The fact is, that of the products I have mentioned in this article, only Quadris can be legally applied after crop flag leaf emergence. This is a very strong selling point since most research we have conducted through the years indicates that the period from boot stage to flowering is usually the best time to apply foliar fungicides in Kentucky. The big limitation with Quadris is its price. It is very expensive compared with the other products and this is not likely to change. This is because wheat is a secondary market for Quadris, but it is priced for use in labeled higher value primary crops (e.g., many vegetable crops). Because of the price, I would be surprised if much Quadris is used on wheat in Kentucky unless Syngenta provides a major marketing incentive (which in effect would be an unofficial price reduction).

If I hear of any changes in the wheat fungicide situation, I will be certain to pass that information along as soon as possible.

ARE KENTUCKY APPLES ALREADY INFECTED WITH APPLE SCAB DISEASE?
By John Hartman

Last week, from March 17 - 20, most of Kentucky experienced continuous rainfall and wet, misty conditions with temperatures averaging 45-50 F., depending on location. In some apple orchards, especially in southern and western Kentucky, green leaf tissue of some of the early varieties was just then emerging from swollen buds. After this prolonged wetness of newly emerging leaves, growers should expect that some apple scab infections have already occurred. Most apple growers know that it is extremely important to avoid primary scab infections. However, with good disease management approaches, even these established infections can be suppressed.

Apple scab disease development. During winter and early spring, the scab fungus develops in fallen leaves that were infected the previous season. Primary scab spores (ascospores) mature in early spring about the time that leaves start to emerge. When leaves on the orchard floor have been wetted by at least 0.01 inches of rain for at least 30 minutes, ascospores are released and carried by air currents to newly emerging leaves and blossoms. The maximum rate of spore discharge is reached after 2 to 3 hours of wetness; after 6 hours, 75 percent of the ascospores that are mature during that wetness period will have been discharged. In general, maximum ascospore discharge and maximum susceptibility of leaves and fruit occur between tight cluster and 10 days after petal fall, however, some infection can also occur now, as green tissue is just emerging.

The time required for infection depends on the temperature and duration of the "wetting period," the period during which leaves on the tree are continuously wet from rain or dew. When the infection process is not inhibited by a fungicide, primary scab lesions appear 9 to 17 days after infection depending on the temperature. The "Mills Table" is valuable for determining when conditions are favorable for infection and for deciding when fungicides with "after-infection" activity should be used. A modified version of the Mills Table, shown below, has been validated in the field over several years and locations.

Modified Mills Table. Approximate minimum number of hours of leaf wetting required for primary apple scab infection at various temperatures.a

	Degree of Infection			Lesion Appearance (Days)c
Average Temp.(°F)	Light(hr)b	Moderate (hr)	Heavy(hr)
78	13	17	26	-
77	11	14	21	-
76	9½	12	19	-
63 to 75	9	12	18	9
62	9	12	19	10
61	9	13	20	10
60	92	13	20	11
59	10	13	21	12
58	10	14	21	12
57	10	14	22	13
56	11	15	22	13
55	11	16	24	14
54	1½	16	24	14
53	12	17	25	15
52	12	18	26	15
51	13	18	27	16
50	14	19	29	16
49	14½	20	30	17
48	15	20	30	17
47	17	23	35	17
46	19	25	38	17
45	20	27	41	17
44	22	30	45	17
43	25	34	51	17
42	30	40	60	17

a From W. D. Mills, Cornell University as modified by A. L. Jones, Michigan State University.
b The infection period is considered to start at the beginning of the rain.
c Number of days required for lesions to appear after infection has been initiated.

Thus, with last week's extended leaf wetness (more than 30 or 40 hours), heavy infections were possible on those varieties already showing green tissue. Within each primary scab lesion (caused by one ascospore), thousands of secondary spores (conidia) will be produced, each of which is capable of causing a new infection. Conidia are spread by splashing rain and by wind. Germination and infection by conidia occur under about the same conditions as for ascospores. Additional conidia are produced all season long from established scab lesions.

Control of Apple Scab. The key to successful apple scab control is to prevent primary infection by ascospores. Infections by ascospores occurring prior to tight cluster can cause significant losses because conidia are produced just as leaves and fruit reach maximum susceptibility. If ascospores are prevented from establishing infections early in the season, no further scab control is needed after ascospores are depleted. However, if scab is established early in the season, a grower must fight secondary infections throughout the summer. The number of conidia produced by just a few scab lesions is greater than the total number of ascospores produced in an entire acre of leaf litter in most commercial orchards.

Four general fungicidal approaches to primary scab control are:

1. Standard Protectant Program (7-day interval). Protectant fungicides must be applied at approximately 7-day intervals during primary scab "season" because growing clusters and terminals are continually producing new tissues that need protection.
2. Extended Sterol Inhibitor/Protectant Program (10-day interval not to exceed 14 days). This combination program utilizes both protectant and after-infection scab fungicide activities and should result in fewer sprays than the standard protectant program. The first scab spray of the season is a protectant fungicide applied between green tip and half-inch green. Sterol-inhibiting (SI) fungicides are not recommended in the first spray because there is not enough leaf tissue exposed to take up the systemic fungicide. At tight cluster, scab pressure is high, and the first SI/protectant combination spray is made. The SI/protectant combination provides approximately 5 to 6 days of protection and 3 to 4 days of curative activity, thus extending the spray interval to 10 days. The 10- day spray intervals are continued until after petal fall.
3. Post-infection Program (spray intervals based on weather monitoring and disease prediction program). This program can significantly reduce the number of fungicide applications, but it should be used only by growers who are accurately monitoring infection periods with electronic weather measuring devices and computers. It is not recommended in orchards with high levels of scab inoculum from the previous year.
4. New York IPM (Integrated Reduced Spray) Program. This is a minimal spray program. As is the case for the post-infection program, it is not recommended in orchards that had much scab the previous year. The first fungicide application is delayed 1 to 3 weeks; a total of four applications of an SI fungicide is made at: 1) tight cluster (with oil); 2) pink (with insecticide); 3) petal fall (with insecticide); and 4) first cover (with insecticide). Including a protectant with the SI should delay development of resistance to the SI. Because this is a minimal spray program, spray coverage must be nearly perfect. The timing of the four applications is dictated by the weather (spraying when conditions will allow optimal coverage) and timing of insect and mite control rather than by infection periods.

For more details on apple scab control, consult the Kentucky Commercial Tree Fruit Spray Guide 2002 (ID-92) and Midwest Tree Fruit Pest Management Handbook (ID-93) available at Kentucky County Extension Offices.

HEAVY RAINS CAN FORCE CREATURES INDOORS
By Lee Townsend

Heavy rains and saturated soil will force many creatures to escape to high ground. Expect visits from crickets, millipedes, centipedes, sowbugs, earthworms, slugs, and in some parts of the state - scorpions. Large numbers of the less mobile, such as earthworms and slugs, may accumulate on driveways and hard surfaces. The better crawlers can enter homes and buildings under or around doorways, garage doors, basement windows, and crawl space vents. Most will move back outdoors as water levels recede and soils begin to dry. In general, the unwanted invaders will be a temporary nuisance and can be scooped up or swatted and discarded as they are encountered. When practical, place sticky cards around these entry points to capture them.

Slugs, millipedes, and sowbugs are examples of creatures that like wet areas and they may remain for some time in mulched beds and thick grass along foundations. This means that they can continue to enter structures for a much longer period of time. Clipping overgrowth and thinning or pulling back mulch will remove cover and allow the area to dry out more quickly.

Cloudy skies and cool temperatures will favor slug damage to landscape and vegetable plants. Slug baits (containing metaldehyde) can be used according to label directions to help reduce slug numbers.

EARTHWORM PESTS
By Lee Townsend

Several specimens of earthworm media have been sent in over the past few weeks. The samples have had two common factors - very high moisture content and grain mites. Grain mites are very small (1/64 - 1/32 inch), slow-moving, pearly white mites with some long fine "hairs" on their abdomen. These mites can feed on a variety of processed or finely ground grains, wheat germ, yeast, cheese, powdered milk, flour, or mold spores. They develop rapidly in 90% humidity and a temperature of about 77o F. Grain mites require a minimum relative humidity of about 65% so dry air is their enemy. They do not attack earthworms but their waste, shed exoskeletons, and dead mites can quickly foul the earthworm media. Overcrowding from heavy infestations will force mites to move off in search of other food sources. This "spill over" can produce a fine dust-like layer of these mites on areas around the worm beds. Some people can have an allergic reaction from exposure to the mites or their shed exoskeletons.

Also, there have been reports of red mites in worm beds. There is a red mite that is a parasite of earthworms. They attach themselves to worms and remove body fluids and can feed on earthworm egg capsules. These mites first appear as small white or gray clusters, resembling mold. Magnification will reveal clusters of juvenile red mites in various stages of development. The adult red mite is has an egg-shaped body, is bright red, and has eight legs

Here are some factors associated with mites in earthworm beds.

1) Too much water - Beds that are too wet create conditions that are more favorable to mites than to earthworms. Avoid excessively wet beds by adjusting watering schedules, improving drainage, and turning bedding frequently.

2) Overfeeding - Too much food can cause an accumulation that will ferment. This will lower the pH of the beds. Adjust feeding schedules so that all feed is consumed within a few days.

3) Excessively wet or fleshy feed - Vegetable matter with a high moisture content favors high mite populations. Limit the use of such feed, and if high mite populations are discovered, do not add any more until the mite population is under control.

These conditions also will favor problems with flies and other insects. Pest prevention is the greatest control program and pest exclusion, through screening, is the greatest tool. There are no pesticides that are labeled for mite (or general pest control) in worm beds. There is information on mite management alternatives at www.bae.ncsu.edu/people/faculty/sherman/miteworm.html.

Lee Townsend
Extension Entomologist

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