Terry - Yoakum IPM Update

Texas Agricultural Extension Service
The Texas A&M University System

T-Y IPM NEWS

news about integrated pest management in Terry and Yoakum counties

Scott A. Russell, EA-IPM

Telephone: (806) 637-4060

Mobile: (806) 893-1041

Fax: (806) 637-2588

E-Mail: sarussel@tamu.edu

http://lubbock.tamu.edu/ipm

http://www.tpma.org

Vol. 2, No. 5

209 South Fifth Street, Brownfield, TX 79316

June 21, 2001

General Situation:
Heat, wind and dry weather conditions are having their impact on this season's crop, much more so than anyone would like to see. Irrigated fields are being watered while dryland fields are drying out even more. Some of our area dryland fields had enough moisture to germinate and emerge, but are now struggling. Cotton growth ranges from 4 true leaves on the later replanted fields to 7 nodes with several matchhead sized squares. Several fields have lost a number of first position squares, not all of which can be attributed to insects. Pest numbers and variety are down this week. Grasshopper numbers seem to be dropping as do the beet armyworms. We did not find any beet army worm larvae in scouting program fields this week, reports from private consultants are that they are also seeing fewer.

Cotton Fleahoppers:
Again this week we found a couple of fields in the scouting program which had economic infestations of cotton fleahoppers. One field in particular, which had a less than economic infestation last week, jumped up to 21 fleahoppers per 100 terminals and the square retention dropped dramatically.

This illustrates the importance of scouting the field regularly and doing it well. Fleahoppers feed on the tender portions of plants (newest growth) and small squares. Pinhead and smaller squares are the most susceptible to damage. Damaged squares will die and turn black. See last weeks newsletter for details on scouting for fleahoppers and economic thresholds.

Tarnished Plant Bugs (Lygus spp.):
A few lygus are showing up in fields, but not nearly as many as I had expected, that is not to say we won't see more of them in the near future. Lygus bugs are attracted to succulent growth; their feeding results in shedding of squares and small bolls, stunted growth and boll deformation. Sampling for lygus is most effectively done using the drop cloth. An off white cloth 36 x 42 inches works well, one can staple small strips of wood along the short sides for easier handling. With the cloth stretched between two adjacent rows, mark 18 inches of row bordering the cloth and vigorously shake the plants in that 18 inches toward the cloth. Sample both rows bordering the cloth, this will equal 3 row feet per sample.

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Count all lygus nymphs and adults which fall onto the cloth. Repeat this procedure in atleast 20 locations to equal 60 row feet sampled.

Adults lygus are 1/4 inch long, have a conspicuous triangle in the center of the back, are winged and vary in color from pale green to yellowish brown with reddish brown to black markings. Immature lygus bugs are called nymphs. They are uniformly pale green with red-tipped antennae; late instars have four conspicuous black spots on the thorax and one large black spot near the base of the abdomen. The nymph's wings are not developed, but nymphs can move rapidly and are difficult to detect in cotton foliage. Small nymphs may be confused with aphids, cotton fleahoppers and leaf hopper nymphs.

The need for lygus bug control is determined by their abundance in relation to the fruiting condition of the cotton plants. During the first week of squaring, the economic threshold is 1 lygus bug adult or nymph per three feet of row combined with less than 90 percent square set. In the second week of squaring, the economic threshold is 1 lygus bug adult or nymph per three feet of row combined with less than 85 percent square set. In the third week of squaring, the economic threshold is 1 lygus bug adult or nymph per three feet of row combined with less than 75 percent square set. After the third week of squaring, the economic threshold is 2 lygus bug adults or nymphs per three feet of row with less than acceptable fruit retention.

There are several products labeled for the control of fleahoppers and / or lygus bugs. Please refer to the Texas Agricultural Extension Service (TAEX) publication "Suggested Insecticides for Managing Cotton Insects in the High Plains, Rolling Plains and Trans Pecos Area of Texas 2001", TAEX publication number E-6A. This guide is available here at the office or on the internet at: http://insects.tamu.edu/extension/ag_and_field.html.

False Chinch Bugs:
We have had numerous samples of false chinch bugs brought into the office. Most have been from home lawns adjacent to pasture. These pests can be a problem in cotton. Due to the tremendous numbers (100,000 plus) moving out of the drying grasses and weeds, they can reduce stand counts if they begin feeding on cotton. This takes hounds of insects per plant. I am unaware of any damages in Terry and Yoakum Counties at this time. Watch the edge rows for the first signs of these pests, but don't be eager to treat as they may not do significant damage.

T-Y IPM News is a publication of the Texas Agricultural Extension Service IPM Program in Terry and Yoakum Counties.
Editor: Scott A. Russell EA-IPM, Terry & Yoakum Counties	Production: Bea Pippin

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