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Texas Agricultural Extension Service The Texas A&M University System Plains Pest Management Newsletter |
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News about Integrated Pest Management in Hale-Swisher Counties. Greg Cronholm, Extension Agent - IPM, 122 East 6th, P.O. Box 680, Plainview, TX., 79073-0680, 806-291-5273 |
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Web Site: http://entowww.tamu.edu |
E-Mail:
g-cronholm@tamu.edu
August 1, 2001 |
Cotton ranges from early bloom to past peak bloom. The few scattered showers this past week provided very little relief for our extended drought. Temperatures have continued to range from 97 to over 100 F. The banded-winged whitefly has been on the increase in many fields over the past few weeks. When one walks through the field adult whiteflies look like snowflakes flying from the plants as you walk down the rows. The adult whitefly is about 1/16" and looks like a miniature white moth. Females lay eggs on the underside of the leaf, generally in the terminal. One of our local consultants, David Winters discovered some very high egg densities on cotton in the Springlake/Earth area. Egg lays were estimated to be about 4000 per leaf. This was confirmed in our office. Needless to say that if this population survives, the field could be in trouble. The nymphal stage of the whitefly is round to oval shaped and becomes immobile after a suitable feeding site is found. They are flat on the leaf surface and are usually translucent. The nymphs secrete honeydew similar to the honeydew from cotton aphids. |
So far honeydew from this pest has been light, but that could change rapidly as populations increase. We do not know what the economic threshold is for this pest in Texas. With populations of 10 to 15 per leaf it is difficult to see any appreciable damage or honeydew at this time. Control of this whitefly species should not be a problem like its close relative the silverleaf whitefly. Products expected to be effective would be Capture, Danitol, Phaser or Thiodan, Monitor and Orthene. Other pyrethroids may also be effective. Cotton bollworm infestations are spotty, but we should see a gradual increase over the next 2 ½ weeks as corn is no longer an acceptable host. With the reduced corn acreage adult flights may be reduced and limited to local areas. So far only one of our traps has had high counts. The heat has reduced some of our beneficial populations, but overall there should be enough to have an impact on light to moderate bollworm infestations. Beet armyworms,
cotton aphids and boll weevils generally remain light over
the area. Predators have helped cotton growers a great deal to control
cotton aphids and beet armyworms this year. Punctured square counts
from boll weevils remain low; but can increase rapidly as adult weevils
emerge from punctured squares. The extreme heat we have had is known
to be detrimental to boll weevil survival in squares where they fall
on the hot soil. This may be a factor in keeping populations low. |
Cotton|
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CORN Corn remains somewhat stressed under the current drought conditions. Spider mites range from very light to fields reaching or passing economic thresholds as described in last weeks newsletter. Southwestern corn borer trap collections remained high as of Monday (7/30/01). Continue to scout for eggs and larvae over the next one to two weeks. European corn borer remain light with an occasional egg mass reported. Adult collections in traps also remain low. SORGHUM A few headworms are now being found, but generally counts are at the one per 20 sorghum heads. Greenbugs have continued to increase in a number of area fields. The economic threshold at heading is when we average greater than 2 leaf kill on more than 20% of the plants. With drought stressed sorghum greenbugs can sometimes be more difficult to control. Under our current conditions it is suggested that all greenbug insecticides be applied in 4 to 5 gallons of water per acre by aerial application. Coverage is very important. Under wet conditions 3 gallons per acre has been adequate. Please report any control failure to my office, since we are interested in monitoring for resistance. Continue to scout for sorghum midge in blooming fields. So far populations have been very light. |
SUNFLOWERS Dr. Pat Porter, Extension Entomologist had reports of sunflowers infested with stalk/stem girdlers from around the Bula, TX area.
We suspect that it is Dectes texanus, which is our most common stalk
girdler. The best solution for this problem is to not plant sunflowers
back on sunflower or soybean ground. Soybeans are also a host for
this pest. Also planting adjacent to old fields from the previous
year could be a problem. It is best to move about 1/4 mile from the
previous years sunflower or soybean crop.
Greg Cronholm,
Extension Agent - IPM,  Posted at this web site by: texagnet Internet Services. |
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