Cotton: understanding mites and hot weather

Midsouth cotton farmers and their advisors have learned a good deal about spider mites over the last three or four years. For whatever reason, mites have become a problem through a wide part of the region (and some of those possible reasons are noted in an article of mine that appeared recently in Progressive Farmer). You won’t find mites in every field this season. But if they develop and aren’t treated, mites can quickly become a full-blown economic problem.

As several people pointed out in this week’s AgFax: Midsouth Cotton, more proactive treatments were made this year for mites, compared to last year when mites ran amok across many of the region’s cotton fields. This year, nobody waited to see what would happen with mites nor did anyone bank on a driving rain to suppress the tiny, eight-legged beasts.

To some extent, growers in northeast Arkansas and the Tennessee River Valley of Alabama have taken that approach for several years. And in Arkansas – where products like Zephyr have been available for several years – growers have been willing to treat with what are still considered high-dollar, “western” products.

The idea of treating early (and spending more) has been more widely adopted in the rest of the Midsouth this year, and it’s credited with helping contain spider mites this season.

Hot and dry weather, of course, spur on mites. There’s a common misconception that spider mites actually like those conditions, as evidenced by the fact that mites are an ongoing problem in places like Arizona and the San Joaquin Valley (SJV) of California.

But, as one of our long-time contacts in the SJV pointed out this week, spider mites multiply rapidly in hot, dry weather as a survival mechanism.

“They hit those kinds of conditions, with blazing temperatures and no moisture, and they go into a panic mode, thinking they are going to die,” said Vern Crawford, a PCA with Wilbur-Ellis Co. in Shafter, which is in the southern SJV near Bakersfield. “It’s basically a state of fecundity. They can’t lay eggs fast enough."

Several years ago, we published a couple of charts in our California cotton report that show just how fast mites can proliferate as temperatures climb. Click here to bring up that page.