West Plains
IPM Update


news about integrated pest management in hockley and cochran counties
Kerry Siders, EA-IPM
(806) 894-2406 (phone)
(806) 638-5635(mobile)
(806) 897-3104 (FAX)
E-Mail: k-siders@tamu.edu   http://lubbock.tamu.edu/ipm  
Vol. 7, No. 4
1212 Houston Street, Suite 2, Levelland, TX 79336
June 4 , 2002

IN THIS ISSUE:

* Crop and Insect Situation
* Thrips
* How did IPM come about? What are the tactics or control methods used in IPM? What are the goals of IPM for Agriculture?

CROP & INSECT SITUATION
In the last issue of the West Plains IPM Update newsletter I was concerned about heat units. Well, we are now generating sufficient heat units. The last seven days we have averaged 16.7 heat units (DD 60's) per day. My main concern now is that we have sufficient moisture to go along with the heat.

For the month of May, in Levelland, we received 0.06 inches of precipitation. The crops generally planted before May 15th this year have rooted down into fairly good soil moisture below 6 inches. Acreage planted after May 15th are struggling in droughty conditions or have not germinated at all.

Compounding the problem for area cotton which has germinated is that the at-plant insecticide may not be providing protection against thrips. The insecticide may be sitting in a dry zone of the soil. Products such as Temik need moisture in order for uptake into the plant to occur and subsequent control of thrips. Some producers have begun to irrigate because of the dry conditions, this will allow for reactivation of the soil insecticide.

As I write this newsletter rain chances are good hopefully we will all receive a good amount of rainfall to benefit all crops and possibly wash-away and drown the thrips. We continue to find grasshoppers; the survey scouts are picking up some light numbers of beet army-worms in northwestern Cochran county; and a few cotton bollworm eggs found in southeastern Hockley.

THRIPS
Thrips are slender, straw colored insects about 1/15 inch long, with piercing and sucking mouthparts. Adults are winged and capable of drifting long distances in the wind. Thrips attack leaves, leaf buds and very small squares and may cause a silvering of the lower leaf surface, deformed or blackened leaves, terminal loss and square loss. Under some conditions, heavy infestations may reduce stands, stunt plants and delay fruiting and maturity. Thrips damage is most evident during cool, wet periods when small cotton is growing slowly. Thrips damage often is further compounded by plant damage resulting from rain, wind, blowing sand and diseases.
Under favorable growing conditions, cotton can sometimes recover completely from early thrips damage. In many areas thrips are considered minor cotton pests. Thrips problems are more prevalent in areas with large winter wheat acreages and where producers plant prior to late May or early June. Research has demonstrated that cotton varieties with hairy leaves are less injured by thrips than smooth-leaf varieties.

 
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Management and decision making. In areas with a history of frequent, heavy thrips infestations, the use of systemic insecticides should be seriously considered. Research has shown that the application of foliar sprays after significant thrips damage has occurred generally does not result in increased yields. Where post emergence sprays are to be used, fields should be scouted as often as twice a week as cotton emerges. Thrips can migrate in heavy numbers from adjacent weeds or crops, especially small grains, and cause significant damage within a few days and prior to the appearance of true leaves.

Early infestations often reduce yield more than later infestations. Thrips often infest the folded small leaves of the plant terminal and are difficult to count unless the terminal area is dissected. This is especially true during rainy, windy conditions. The decision to apply insecticide should be based on the number of thrips present and the stage of plant development. The number of thrips per plant to use as a treatment level increases as plants add more leaves. Control may be justified when the average number of thrips counted per plant is equal to the number of true leaves present at the time of inspection. One thrips per plant should be used as the treatment level from plant emergence, through the cotyledon stage, to the first true leaf. Inspections should begin once cotton has reached approximately 50 percent stand emergence. Insecticidal control is rarely justified once plants reach the 5- to 7-true-leaf stage, or when plants begin to square.

HOW DID IPM COME ABOUT?
The concept and impetus for IPM grew out of the discontent with using a purely insecticidal approach to insect control in many areas in the 1950's. Overuse of insecticides resulted in insects that were resistant to insecticides, resurgence of pests after treatment and occurrence of secondary pests that became a problem only after the natural enemies that had been keeping them in check were killed by insecticides. "Integrated control" was developed emphasizing use of selective insecticides so that natural enemies were conserved in the system. This "integration" of control techniques was expanded in later years to include other management options such as resistant crop varieties, crop rotation and other tactics and to include weed and diseases as pests in addition to insects.

WHAT ARE THE TACTICS OR CONTROL METHODS USED IN IPM?
The tactics or methods used in IPM include one or a combination of the following:

* Cultural control (crop rotation, use of locally adapted or pest resistant/tolerant varieties, sanitation, manipulating planting/harvest dates to avoid pests)

* Biological control (protect, enhance or import natural enemies of pests)

* Mechanical control (cultivation, trapping, pest exclusion)

* Chemical control (insect growth regulators, pheromones, biological/chemical pesticides)

WHAT ARE THE GOALS OF IPM FOR AGRICULTURE?
* Ensure abundant, high quality food and fiber
* Increase net profits
* Maintain or improve environmental quality
* Reduce production risks


West Plains IPM Update is a publication of the Texas Agricultural Extension Service IPM Program in Hockley and Cochran Counties.

Editor: Kerry Siders
Production: Patty Castaneda


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