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Edited by Tom Kuhar, Assistant Professor, Dept. of Entomology, Virginia Tech
Greetings crop producers, researchers, extension personnel, and crop consultants,
Weather summary for week ending May 14, 2004 Painter, VA
James T. Custis (Farm Manager, ESAREC)
HOT, DRY and WINDY!!!!
We had 0.05" rain last Saturday am and no rain since. Highs in the mid 80 's each day and lows in the mid 50's on the weekend, then lows in the mid 60's the rest of the week. We need some rain, we are stating to irrigate now.
Blacklight and Pheromone Insect Traps
Jack Speese & Tom Kuhar (ESAREC)
Weekly catch:
Blacklight trap (BLT) in Painter, VA: 56 European corn borer moths, 57 green stink bugs, 3 cutworm moths
BLT in Cheriton, VA: 420 ECB moths, 2 black cutworms, 1 spotted cutworm, 1 corn earworm
In summary, the first generation European corn borer moth flight is very heavy on the Eastern Shore, green stink bug adult activity is picking up.
Reflex Herbicide Receives Section 18 Registration for Snap Beans in Virginia
(Henry Wilson & Jason Sanders, ESAREC)
We are pleased to announce that we have received approval from the EPA for the use of Reflex for post-emergence weed control in snap beans in Virginia. This registration pertains to the 2004 crop. Our research indicates that Reflex affectively controls numerous broadleaf weeds in snap beans when mixed with 1 qt of non-ionic surfactant per 100 gallons of water. Since Reflex is not highly effective on common lambsquarters, our data support reducing the Reflex rate to 0.5 pt/A and adding 1 pt/A of Basagran herbicide. Some temporary snap bean response may occur with the use of Reflex, but snap beans recover rapidly and weed control has been good. Plan to time the application between the one and three trifoliate growth stages. A copy of the supplemental label can be obtained by e-mailing Dr. Henry Wilson at hwilson@vt.edu.
Potato Disease Control
Christine Waldenmaier (ESAREC)
Late Blight : We have accumulated 18 disease severity values (DSV) in lower Northampton County and 14 DSV in upper Accomack County since April 15th. The first fungicide spray according to the Blitecast computer model should go on after the accumulation of 18 DSV. I understand that some of the growers in lower Northampton County have already applied fungicide. For these growers, a second application can wait until we get at least 1.2 inches of rain. We have found in the past that irrigation in this warm, dry weather generally does not affect leaf wetness or relative humidity for long enough to influence disease severity values.
Growers in upper Northampton County or upper Accomack County can hold off the fungicide, or apply a general, all purpose fungicide such as one of the mancozeb containing fungicides or Polyram if they want to get over the field before the potatoes close-in across the rows.
Early Blight - We have accumulated about half the disease severity values needed for the first early blight spray. Protectant fungicides applied for late blight will also protect against early blight.
Insect activity in potatoes on the Eastern Shore
Tom Kuhar (ESAREC)
The potato crop is looking beautiful on the Shore. However, insect activity on the crop is really picking up. We are seeing a very high density of European corn borer egg masses on potato plants. There was probably an average of 1 ECB egg mass per plant found on our potatoes this week in Painter. A single egg mass will yield 20 or more neonate ECB larvae in a few days. Given this observation and the high moth catch that we are picking up at blacklight traps, I would recommend scheduling an insecticide application for ECB control on potatoes at this time. The proper timing of ECB sprays is critical. Apply first spray when 10% of the stems have entry holes in fresh market varieties or 25% in processing varieties. Historically, the first spray usually goes on around mid-May. Avaunt, Ambush, Baythroid, Furadan, Penncap, Pounce, Monitor or Spintor will provide effective corn borer control when applied in a timely manner. A follow-up spray may be needed in a week or two.
In addition to ECB, Colorado potato beetles are actively laying eggs with early larvae feeding away on some plants, and the first potato leafhopper adults are appearing in relatively high numbers for this time of the year. If potatoes were treated at planting with Admire, Platinum, Gaucho, or Cruiser, then they should be adequately protected against both of these pests for most of the season.
If potatoes were not treated with any of the aforementioned products at planting then fields should be scouted weekly. A control measure is recommended if 50 CPB adults or 200 larvae are found per 50 randomly-sampled plants. A control measure is also recommended if 1 potato leafhopper adult per sweep with a sweep net or 10 nymphs per 10 leaves are found. If a rescue foliar treatment is needed, please consult the recent addition of the Commercial Vegetable Production Recommendations Manual (VCE Publication No. 456-420) for labeled foliar insecticides there are numerous options. Two products, however, that will control both Colorado potato beetle and potato leafhopper are Provado 1.6 F at 3.75 fl oz/A and Actara 25 WDG at 1.5 oz/A.
Update on thrips in cotton and peanuts in Tidewater, VA
Ames Herbert (Virginia Tech Tidewater AREC)
It is still a bit premature, but all indications are that we are in line for another year with fairly intensive thrips pressure on cotton and peanut. We are seeing a lot of adults on volunteer peanut plants, a sure sign of trouble ahead. Also, we are using a series of 3 X 5-inch yellow sticky cards, placed on wire stands about 6 inches above the ground, to monitor adult thrips populations as they fly into a peanut field test here at the Center. The cards indicate that adult thrips have been present since at least April 19 (the earliest card sample) and numbers have increased from an average of 2.5 per card to 30 per card as of May 13. Im not saying that the thrips population is higher than normal just normally high with ample numbers to cause yield problems in both cotton and peanut if they are not well managed.
Weather plays a large role in the ultimate impact that thrips have on these crops. Weather affects both the thrips numbers and their development, and the uptake of in-furrow or seed-applied insecticides by seedlings. We typically see the worst case scenario when cool, dry conditions prevail for the first 2 weeks after cotton emergence. Cool weather slows plant growth and the combination of slow grow and dry soil can inhibit insecticide uptake. So far this season, although we have had a few early cool nights, warmer temperatures have been more common. We are definitely on the dry side (at least as of this update). Cotton is germinating well, stands are excellent, but if the dry weather continues, plant growth will slow, which will allow thrips to inflict more damage to seedlings. If it remains warm and we get some rain showers, both cotton and peanut plants will rapidly grow out of the thrips injury susceptibility period.
With what appears to be a relatively large thrips population, growers need to take precautions and plan for a good management program. There is no single best program, but several options provide good results. At this point, the decision regarding seed treatment versus in-furrow application is past history. What should be next? Based on several years experience and seeing a lot of field test results, the best approach is to make a single post emergence foliar application, either broadcast or banded. Banding works best, but most growers broadcast so they can tank mix the insecticide with a herbicide. Either way, the object is to wet the seedlings with a good concentration of whatever insecticide is selected.
Proper timing of the single foliar treatment is important to achieve the best result. In cotton, we have found that over most years, we get the best result when we spray when the first true leaf is about the size of a dime. We recommend treating if more than 10 percent of plants show thrips damage symptoms - crinkled leaves, deformed buds (newly formed leaf), blackened buds. More than 10 percent seedling damage implies that whatever seed or in-furrow treatment was applied is not adequate which can be due to many things including slow insecticide uptake or slow seedling growth, as mentioned above. In peanut, we recommend treating if 25 percent of the leaves show damage, and at least some of the terminal buds are blackened and of course, thrips are still active.
What is the best product and rate? Again, there are options. In peanut, there are really only 2 products that we have done much research with: Orthene 97 and Karate Z. With Orthene 97, we recommend 6-12 oz/acre (broadcast), but have had consistently good results with the 6 oz rate. With Karate Z, we recommend 1.28-1.92 oz/acre, but have had consistently good results with the 1.28 oz rate. In cotton, there are more options. We have had the most experience with Orthene 97 at 4-6 oz (broadcast) and Karate Z at 0.96-1.28. Our most consistent results have been with the higher rates for both of these products. We recommend a single foliar application (if the above mentioned plant damage justifies it) using the higher rates. A single higher rate spray will usually provide enough control to protect plants until they reach the less susceptible growth stages. More than one treatment can result in triggering additional problems like aphids or spider mites. This is an especially important consideration this year, as it appears we may be going into a dry season. Decisions like cutting the rate and splitting the treatment, half now and half in 1 or 2 weeks is NOT a good plan. GO ONCE, HIT HARD AND BACK OFF.
Eastern Shore AREC Field Days, June 28 & June 29
Henry Wilson (ESAREC)
Please come and join us for the Eastern Shore Field Day and Weed Tour held at the Virginia Tech Eastern Shore Agricultural Research and Extension Center (AREC), Painter, VA. The Field Day starts at 4:30 p.m. on June 28 with tours of research in vegetables, including potatoes and snap beans, and a BBQ dinner will be provided following the tours. The Weed Tour starts at 9:00 a.m. on June 29, and includes weed management research in corn, cotton, potatoes, soybeans, snap beans, and wheat. For more information contact Jason Sanders (757-414-0724 ext. 42 or jcsander@vt.edu) or Henry Wilson (757-414-0724 ext. 13 or hwilson@vt.edu). Information can also be obtained from the Eastern Shore ARECs website at http://arecs.vaes.vt.edu/arec.cfm?webname=painter.
Asparagus beetles
Tom Kuhar (ESAREC)
Asparagus beetle densities have been quite high over the past week or two. This year is the first year that I have gotten calls or walk-ins about asparagus beetles, and I received three over the past week or two. Low rates of Sevin, Lannate, Ambush, or Pounce usually will provide effective control of beetles. Make sure to read the Days to Harvest Interval on the label, as asparagus spears may be harvested daily this time of year.
Using Admire 2F as a transplant drench
Information provided by Dr. Shelby Fleischer (Penn State University)
For growers transplanting some or all of their vine crops, the following article from, explains the rates for treating flats. "To control cucumber beetle invasion at transplanting, we recommend using Admire at a very low rate (0.02 ml/plant) to treat transplants about 1 day prior to planting in the field. To treat a flat of 200 transplants with Admire at this rate, a grower would need to dilute 4 ml (0.135 fl oz) of Admire in a volume of water sufficient to soak the soil mix evenly. This treatment will protect the plants for a short period of time (about 2 weeks) and after that should be followed by field application. [Water plants lightly after application to avoid leaching insecticide out of the media.] To help make other conversions, just multiply 0.02 ml per plant times the number of plants in your flat. For example, use 20 ml (0.7 fl oz) to treat 1000 transplants. (This rate is just a little higher than suggested for tomato transplants, which is 15 ml [or 0.5 fl oz] per 1000 transplants.) You can convert ml to fl oz by dividing ml by 29.6 (there is 29.6 ml in one fl oz). Be careful of phytotoxicity burning the plants at higher rates. We observed burning of leaf margins at 0.04 ml/melon plant at the 2-leaf stage, although these plants did grow out of this in about 2 weeks."
2004 Wye Research Centers Spring Strawberry Twilight Meeting
Information provided by Debby Dant & Michael Newell (U. MD Coop. Extension)
The 2004 Wye Research Centers Spring Strawberry Twilight Meeting will be held at the University of Maryland Wye Research and Education Center in Queenstown, MD on Thursday, May 20, 2004, at 6:00 PM. University and USDA Small Fruit Specialist will be available for questions.
What will I see?
Pre-registration not required.
For more information and directions: Contact: Debby Dant at 410-827-8056, ddant@umd.edu or Michael Newell at 410-827-7388, mnewell@umd.edu
Information request from VA Ext. Agents
Tom Kuhar (ESAREC)
To Virginia Cooperative Extension Ag. agents, we would love hear from you regarding crop pest activity in your county or region. Send me a quick e-mail by the end of the day on Thursdays. Passing on your information or observations may help other growers and ag. workers around the state. Thank you.
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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