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West Plains |
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| Kerry Siders, EA-IPM |
(806)
894-2406 (phone)
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(806) 638-5635(mobile)
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(806) 897-3104 (FAX)
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| E-Mail: k-siders@tamu.edu | http://lubbock.tamu.edu/ipm | ||||
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| Vol. 7, No. 10 |
1212
Houston Street, Suite 2, Levelland, TX 79336
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July
24, 2002
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CROP
& INSECT SITUATION Cotton bollworm numbers this week range from 0 to 12,000 larvae per acre. Egg laying has been light the past few days; however, with full moon and other factors such as moth trap catches we should keep close watch for continued worm pressure. Beneficial insect such as crab spiders, and lady bugs are highly variable. Scouts have found beet armyworms, yellow stripped armyworms, whiteflies, |
lygus, fleahoppers, and cotton aphids all in very low numbers. I mention this to make a point about the complexity of decision making when treating for bollworms. Please ask for help from me or someone who is a professional pest manager and can put as many of these factors together. Bacterial blight has been noted in several fields over the past month. This disease causes angular lesions to leaves. Eventually death and defoliation of leaves occurs. In the boll-rot phase of bacterial blight, lesions on bolls tend to be circular, dark green, and water-soaked or greasy when young. Two or more lesion often become confluent. Spots rapidly become sunken, brown, and dry in the center, with a dark-red margin, and attain a diameter of about 3/8 inch. The causal agent, Xanthomonas campestris, is a true parasite, but is an exception to the rule that rue parasites can breach the unbroken cuticle of the boll. X. campestris does , however, penetrate stomata, or enters through nectaries; it is conveyed by spattering droplets or rain, or carries by insects. Once within the boll, the bacteria multiply rapidly, killing and causing collapse of tissues, and spreading through the mass of developing fibers. Affected locks fail to fluff out. This results in spots yellow fiber that may cause reduced grade. The drier weather had definitely helped slow this down and has limited its spread ; however, sprinkler systems can continue the incidence of this disease. |
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Educational programs conducted by the Texas Agricultural Extension Service serve people of all ages regardless of socioeconomic level, race, color, sex, religion, handicap or national origin. The information given herein is for educational purposes only. References to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Cooperative Extension Service is implied. |
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The Texas A&M University
System, U.S. Department of Agriculture, and the Commissioners Courts
of Texas Cooperating
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Typically, cotton varieties are bred to be tolerant to this problem.
No labeled treatments are available. We have just a few days left to set a square which may result in a bloom by August 20-25. That would be our historic average of last effective bloom date for a harvestable boll to be formed. It takes 21-23 days for a pinhead size square to develop into a bloom. However, any new growth at this point would detract from the needs of fruit already developing. The cotton bollworms along with yellow stripped armyworms can also be found in peanuts. We are finding around 3-4 per row foot. This is about half of what the threshold would be for requiring treatment. No disease problems have been noted to-date in peanuts. Although we have gone through a period when conditions were right. Growing conditions for peanuts have been excellent. Most fields have very good peg and pod development. No soil bourne insects have been noted the last week.
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* The synthetic pyrethroid insectidides recommended for control of bollworms also will control boll weevil. However, application intervals similar to those recommended for the traditional phosphate insecticides (3 to 5 days under heavy pressure) are necessary to provide adequate control. When treatments are to be made for a bollworm-boll weevil complex a suggested treatment regime is to use a pyrethroid followed 3 to 5 days later by a phosphate or carbamate boll weevil insecticide. Since pyrethroids are not more effective than organophosphates or carbamates for boll weevil control, but are more effective for bllworm control, they should be saved for bollworm management. We do not recommend using pyrethroids for boll weevil control alone or for early season pests because increased use may contribute to the development of resistance to pyrethroids. Bifenthrin suppresses spider mites when used for control of bollworms. The use of synthetic pyrethroid insecticides may increase cotton aphid numbers.
 Posted at this web site by: texagnet Internet Services.
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