Wilcox County Ag

Thrips in Melons and Beans

Were seeing lots of thrips in the field this week and good questions about management. Our watermelons and beans have been a little slow growing with our night temperatures in the 40s and 50s. Here’s a look at some questions from watermelons and beans this week.

Watermelons

Hearing about thrips in watermelons. The good news is that this is NOT a pest of general concern. Thrips Hirt is 2 ways: 1) Disease transmission and 2) Direct feeding injury. In watermelon, they don’t transmit disease like they do in peanut (Tomato Spotted Wilt). Thrips also don’t normally cause direct feeding injury like in cotton.

Can thrips in blooms cause them to abort? This is a great question this week from growers. Scout Coy Harpe found thrips in watermelon blooms, but none were aborting. UGA Vegetable Entomologist Dr. Stormy Sparks says thrips actually can feed in blooms and cause abortion but it’s rare. The number is between 5 and 15 per bloom. That is a wide range, but we’re not even seeing that many now.

Thrips in watermelon blooms. Photo by Coy Harpe

Snap Beans

We were also looking at snap beans with lots of thrips. Coy and I found as many as 10 on a plant. Part of the field was at 2 true leaves and the other was at 1 trifoliate. Imidacloprid was put in furrow at planting.

What is thrips threshold? From day one Dr. Sparks was told that we almost NEVER spray for foliar thrips on snap bean. And this because snap beans grow so fast, it’ll out grow them. Well, they ain’t growing now, and we even wondered if 5 – 10 thrips per plant is slowing them down….

Lots of thrips in snap bean this week, with little to no damage. Warm weather will help plants grow through.

The only thing is we are not seeing much actual damage from thrips. If we WERE seeing damage, we would need to think about treating our YOUNGEST beans only. But with warm weather today and through the week, it is better to wait then out.

Less than 3% or plants show damage from thrips, even with heavy population.