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Edited by Tom Kuhar, Assistant Professor, Dept. of Entomology, Virginia Tech
Weather summary for week ending April 16, 2004, Painter, VA
James T. Custis (Farm Manager, ESAREC)
VERY WET!!! Rain started late PM Saturday 4/10 and we have had measurable rainfall each observation until Thursday AM. The total rainfall this week was 3.32 inches. We have had very little sun until Thursday PM. Maximum air temperature of 64 and minimum of 39 and soil temperatures of 42 to 52 @2" and 45 to 52 @ 4". It has been very windy with max wind gust of 34.4 on Thursday and gust from 20 to 30 mph each day from Sunday on. Next week should be warmer, with more sun and much dryer, with some luck we may be able to get back on the land around the middle or latter part of the week.
White mold on tomato
Christine Waldenmaier (ESAREC)
We recently received a Section 18 for Topsin M fungicide on tomatoes in Virginia, specifically for the control of White mold (also known as Sclerotinia stem rot and timber rot). This disease is caused by the fungus, Sclerotinia sclerotiorum. The fungal infection may cause the collapse of stem tissue near the base of the plant resulting in the death of the plant. It is particularly severe in our area when we have extended cool, wet weather in Spring. When soils are wet and temperatures are in the 50s, like weve had this past week, small cup-shaped fungal structures which hold the spores are formed. With continued wet weather (at least 6 days), these spores may be released to infect dead tissue on or near the plant. This dead tissue may come from frost injury in early Spring or fallen blossoms later in the season. Once the fungus has colonized the dead tissue, healthy tomato stem tissue is susceptible to infection. For the spread of this disease, temperatures need to be in the 60s and continuous wetness is required. Poor air circulation and retention of soil moisture aggravates the disease. Consequently, disease incidence is higher in low-lying areas, and in fields near heavily wooded areas.
For protection of healthy plant tissue, Topsin M needs to be applied preventatively, before disease occurrence during cool, wet weather conditions.
Watermelon weed management Sinbar Section 18 approval for 2004
Jason C. Sanders & Henry P. Wilson (ESAREC)
There are several options available for controlling weeds in watermelons, and these options are based upon whether plastic mulch is used. Black plastic mulch is a very effective control measure for most annual weeds in the bed where watermelons are to be transplanted or seeded. A herbicide application may be necessary to enhance weed control around the planting hole, or if clear plastic is used. Prefar is the sole herbicide available for use under plastic mulch, but weed control can be erratic even at the labeled rate of 5 to 6 quarts per acre. More herbicide options are available for controlling weeds preemergence (PRE) in the middles between the plastic mulched beds. Standard options with a full EPA label include Curbit and Command. Curbit controls annual grasses and small seeded broadleaf weeds which include pigweed and carpetweed. The control of common lambsquarters, spurred anoda, velvetleaf, and jimsonweed can be achieved through the application of Command. A broad spectrum of weeds can be controlled by tank-mixing Curbit and Command, or by using the premix of the two chemicals which is sold as Strategy. There are some disadvantages to using Command and include spray and/or vapor drift, planting restrictions for subsequent crops, and the poor control of morningglory. Due to the void of a safe and effective PRE herbicide, the EPA has approved a Section 18 label in Virginia for the use of Sinbar applied preemergence at a rate of 2 to 3 ounces of product per acre. In conjunction with the Virginia Department of Agriculture, the request for a Section 18 label for Sinbar was submitted to and approved by the EPA. This was an effort to provide growers with a much needed herbicide that lacks the concerns associated with Command and controls larger seeded broadleaf weeds, especially morningglory. One very important thing to note is the fact that Sinbar is labeled at much higher rates for other crops, but the 2 to 3 ounce rate for watermelons should not be exceeded. While the maximum Sinbar labeled rate is 3 oz. of product, the 2 oz. rate is more common and less likely to cause crop injury in watermelons. In the same way Command can be tank-mixed with Curbit to offer a broad spectrum herbicide application, Sinbar and Curbit can be tank-mixed to complement each other. If you desire a copy of the EPAs Section 18 label for Sinbar in PDF format (Adobe Acrobat), please contact Dr. Henry Wilson or DuPont Crop Protection. The full label that comes with the purchased product should be consulted for other pertinent application and safety details.
Sandea is an option as preemergence and/or postemergence (POST) herbicide for row middles. The herbicide suppresses or controls certain broadleaf weeds when applied PRE, but includes the suppression or control of yellow nutsedge when applied POST. There are concerns of reduced activity with Sandea where ALS-resistant weeds are present, and when organophosphate insecticides are applied. The only other POST herbicides available are Select and Poast, which control annual grasses and certain perennial grasses. Watermelons grown without plastic mulch have the same herbicide options available as those grown with plastic mulch. A PRE herbicide applied broadcast is essential and necessary to achieve the desired control of weeds. The PRE application should be Command plus Curbit (Strategy) or Sinbar plus Curbit to maximize the control of both broadleaf and grass weeds. POST weed control options are the same and include Sandea and either Select or Poast. Sandea can only be applied to the row middles and contact with the crop foliage must be minimized, while the two grass herbicides can be applied as a broadcast application that contacts crop foliage. The addition of Sinbar as a much needed herbicide option should greatly aid producers in their weed control program.
Regent - potato Section 18 label request denied
Tom Kuhar (ESAREC)
Although the official letter has not been received, I got a phone call this week stating that the Special Emergency Label (Section 18) request for the use of Regent (fipronil) insecticide on potatoes in Virginia was officially denied by the EPA.
Be aware of carryover/crop rotational restrictions with the use of new seed treatments
Information provided by Joanne Whalen (IPM Coordinator, University of Delaware)
The following rotational restrictions apply to both Poncho 250 and 1250 ( they are both Poncho 600 -- just different rates of loading of clothianidin) -- this is what the labels states:
Poncho 600 - Fields can be replanted immediately with corn, rapeseed and canola. There is a 30-day rotational restriction for cereal grains, nongrass animal feeds, soybeans and dried beans. Do not plant another crop in treated area for at least one year after treated seeds are planted -- so in our area that would mostly affect peas and potatoes after field corn. A bigger issue would be Poncho use on sweet corn where we often double crop limas, snaps, spinach and pickles after early planted sweet corn.
Since there are a number of Platinum labels on vegetables, the Cruiser label is not as restrictive. The active ingredient in Platinum and Cruiser is thiamethoxam. The labels states that treated areas may be planted immediately or as soon as practical for any crop on the label (which now includes snaps and limas); or to cucurbits fruiting vegetables and tuber crops. There is a 120 day restriction for all other crops so it does not affect peas and potatoes planted after field corn. However, spinach could still be an issue after sweet corn treated with Cruiser.
New Asana XL label
Info. provided by Susan K Rick (Dupont)
A new Asana XL label was issued recently - there are quite a few additions that are listed in the attached note below. The new label may be found on the web as well.
Changes to the label:
Change title of the TANK MIXING section to be TANK MIXING & COMPATIBILITY so we are consistent with our other labels. New compatibility statement: "ASANA XL may be tank mixed with DuPont herbicide products when insect populations require control concurrent with the need for weed control. Follow all herbicide and ASANA XL
label directions regarding proper usage. Since formulations may be changed and new ones introduced, it is recommended that users premix a small quantity of a desired tank mix and observe for possible adverse changes (settling out, flocculation, etc.). Avoid mixtures of several materials and very concentrated spray mixtures. For best results, use of spray equipment having continuous agitation is recommended."
Cotton section: add black cutworm (except CA); green stinkbug (except CA); southern green stinkbug (except CA)
Cotton section & Sorghum section: add statement - "Asana XL may be applied at rates of 0.0165 - 0.05 lb. a.i. per acre for control of black cutworm when applied at planting of cotton."
Corn section: add black cutworm (except CA)
Corn section: add statement - "Asana XL may be applied at rates of 0.0165 - 0.05 lb. a.i. per acre for control of black cutworm when applied at planting of corn."
Corn section: add silkfly to sweet corn.
Sorghum section: either remove geographical restriction completely or add AZ.
Soybean section: add soybean aphid (except CA)
Blueberry: add Japanese beetle (except CA)
Caneberries remove geographic restriction (however, retain geographic restriction for root weevils).
Kiwi: add new crop; also place * after Boxelder bug - the * will denote 'suppression only'
Snap bean section: add reduced rate (0.015 lb ai/a) for leafhoppers; add soybean aphid (except CA)
Dry bean section: add soybean aphid (except CA)
Potato section: add reduced rate (0.015 lb ai/a) for leafhoppers
Sweet corn section: add corn silkfly @ 0.05 lb ai/acre
Christmas tree, conifer seed orchards, etc. section: remove (Mistblower) from the Low Volume Sprays column.
Add Mullein bug as a new pest under apple.
Request for information
Tom Kuhar (ESAREC)
Once again, I welcome any contributions from extension agents, crop consultants, or agricultural specialists in Virginia. Any information that might benefit Virginia growers would be greatly appreciated. Please e-mail information directly to me by 5:00 pm on Thursdays for inclusion in the Friday newsletter. Thanks.
Thomas P. Kuhar
Assistant Professor
Department of Entomology
Eastern Shore Agricultural Research & Extension Center
Virginia Polytechnic Institute & State University
33446 Research Drive
Painter, VA 23420
E-mail: tkuhar@vt.edu
Tel: 757-414-0724
FAX: 757-414-0730
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