Wednesday, June 7, 2017

Texas South Plains Cotton: Thrips Numbers on the Rise in Spots

Cotton ranges from seed just placed in soil to four true leaf stage in South Plains region. In most areas thrips pressure remains low, however, we are seeing some hotspots in counties north of Lubbock where thrips numbers are well beyond economically damaging levels. As the wheat is drying down and becoming an unfavorable host for thrips, adults are taking flight on breezes and winds to young cotton plants. Thrips feed on the lower surface of cotyledons first or any exposed true leaves before moving to the very tender terminal bud or growing point of developing seedlings. With their piercing-sucking mount parts, they stab and rasp away at plant surfaces causing severe scaring and then suck up the plant juices.
Young cotton leaves damaged by thrips

Controlling thrips at an early stage is very important as we try to protect these young and rapidly developing plants from damage. Excessive amounts of damage to these first leaves or growing point can have a huge impact on how the plant develops later and ultimately performs. Preventive insecticidal seed treatments provide control up to 3 weeks after planting. However, this can vary with growing conditions and the weather.

Once the plant reaches the 3 to 4 true leaf stage, with a healthy growing point and true leaves, growth accelerates rapidly and the risk of thrips damage usually starts to decrease. However, the plants will need to reach pinhead square stage before they are truly past economic thrips damage.

During the plant’s early growth stages, growers should apply foliar insecticide at a threshold level of 1 thrips per true leaf. When scouting for thrips, there is truly no substitute for whole plant inspections from a representative sample from across the whole field. More information on thrips management can be found at: http://lubbock.tamu.edu/files/2017/05/ENTO-069_fn.pdf

Check out our video to know how to scout for thrips: https://www.youtube.com/watch?v=uD2dIDQmRb0

Suhas Vyavhare, Texas A&M AgriLife Extension Service