Regarding Thrips and Herbicide Injury

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E-Mail string concerning thrips control and herbicide Injury. You may experience something similar over the next week or so. 

Question: 

I was contacted today about a grower that has peanuts that have some Valor damage and has thrips feeding on the peanuts. These are peanuts that were planted on May 8. They put down 4.5 lbs. of Thimet to the acre. They also, sprayed a 1/3 of pound of Orthene on Tuesday (May 20) and today were finding about 15 thrips per sq. ft. What type of recommendation would you recommend with already applied Orthene and having Valor damage to help control the thrips. Thank You.

Jordan Answer: 

I am going to copy Rick for his input. 6 oz is low in my opinion but used by a lot of people. In some of our work last year we saw very good results with 10 oz. Rick can provide much better perspective. May 20 was just the other day so more time might be needed for control. Temps will warm over the next few days and peanut growth should improve.

Brandenburg Answer: 

David is correct in that 1/3 lb of Orthene is a light rate. The thrips numbers this early in the season sound really high. We’ve not seen that yet this year. I am very surprised given the Thimet in furrow and the Orthene spray to hear about numbers that high. But it is what it is and what we need now is a means to move forward. Orthene is very sensitive to UV degradation so it is unlikely the grower can apply another 1/3 lb and feel confident he will get the benefit of a 2/3 lb treatment. The first application of essentially gone. However, the effects of the treatment will linger on the population and there may still be a reduction in numbers. One thing that happens when we get plant injury from a pesticide is that the injury to the plant reduces uptake of products like Thimet so control isn’t as good as it should be. Thimet has proven pretty reliable for us and I would think it is going to get the job done as well as the kick in the pants form the low rate of Orthene. The easy way out is to have the grower treat again with a higher rate of Orthene, but my guess is that with or without the additional spray the peanuts are going to recover. I’m not standing there looking at them, so it is a little bit hard to make a call, but good growing conditions do wonders. Hope this helps.

Article first appeared as North Carolina Peanut Note (PNNC-2014-053)