This has been a challenging year for thrips.

To date we have treated significantly more acres with foliar sprays than normal. Granted, thrips infestations vary across the state, but as a whole this is a tough thrips year. So why is damage so bad? 

Cotton planted in late April and early May grew off slowly which exacerbated (made worse) plant injury symptoms associated from thrips feeding. Thrips numbers were only moderate during the first half of May but plant injury was severe in some areas. 

Thrips feed in the terminal bud and when cotton is not growing rapidly the thrips are feeding on the same unfurled leaf for an extended time resulting in increased damage symptoms. 

We have observed in research trials that a slow growing seedling incurs significantly greater damage than a rapidly growing seedling with similar thrips infestations.

Slow growing seedlings have also extended the time which plants are susceptible to thrips. Seedlings are susceptible to thrips until they reach the 4-leaf stage and are growing rapidly. Recall that seed treatments are only active on thrips for about 3 weeks and much of our early planted cotton has taken 4-5 weeks to reach the 4-leaf stage.

Beginning late last week (about May 23), thrips numbers significantly increased in many areas. We normally expect the peak in thrips populations to occur earlier, but the peak appears to be later than normal (maybe 2 weeks later) this year. 

Historically, thrips numbers taper off on cotton planted after May 10, but this year the peak has been delayed and we can only hope numbers will taper off soon. 

Another factor which may explain the recent surge in thrips infestations is the dry conditions we are experiencing. Thrips reproduce and build populations on many different host plants. After a moderately wet spring, alternate host plants have begun to dry down and thrips are on the move looking for a green plant.