Monday, August 27, 2012

Valley Ag, Pests Really Cooking with Hot August Nights & Days

In some fields, cotton bolls are opening early this season.
It has been a weird week in the Valley. Perhaps Mother Nature has concocted a little weird science with these blistering triple-digit temperatures we’ve been having here.

Tomatoes and melons are ripening at a meteoric pace, forcing growers to accelerate their harvesting plans. Alfalfa plants are turning to seed. Cotton bolls are starting to open earlier than normal. And crop-threatening pests are exploding on the scene.

What started as a fairly calm, normal season earlier this summer could be turning a little weird for cotton growers as we approach the fall equinox.

Let me put my weather cap on and give everyone a recap: Despite a few record-breaking high temperatures in early June, the overall weather was fairly normal for the month and provided ideal growing conditions for cotton; July remained routine with no surprises; and then there is August with 18-straight days of triple-digit temperatures before finally dropping into the 90s on Saturday. In fact, just five days have been under 100 degrees this month, according to the National Weather Service. We could be back to triple digits Tuesday.  W 

The result: I’ve seen the first bolls already open up. That’s a little early. Usually, bolls open sometime in the first week of September. If this keeps up, we could be in for an early harvest.

To ease the heat-induced stress on the plants, some growers have started to add an extra dose of water to their crop. This extra irrigation is aimed at slowing the down boll opening.
First open boll.

In the meantime, aphid and whitefly counts are on the rise. The pests are migrating from nearby fields due to the accelerated tomato and melon harvests. Also, the heat wave also is causing some alfalfa to dry out fast and go to seed, prompting pests to seek more lush habitats such as nearby cotton fields.

Meanwhile, a few anxious growers are moving ahead and treating their cotton fields. I suggest growers hold off a few days before spraying, especially if the bolls are still closed.  By being patient and monitoring the fields, the aphid counts could drop few in a few days – beneficial insects may come in and help keep pests under control. In addition, growers should run the numbers, comparing the percentage of open bolls and pest counts to help them determine threshold for treatment. Go online and check out UC IPM’s monitoring aphids and whiteflies guidelines covering the first open boll to preharvest.
The alfalfa season is starting to wind down in the Valley.

Right now, I’m generally seeing 15 to 20 percent infestation in fields. The treatment threshold is about 30 to 40 percent infestation.

In the alfalfa, some plants are flowering and ready to turn to seed. In that case, growers may lose out on getting one more cutting. Other growers are hoping for two more cuttings before closing out the season. On the pest front, I’m seeing an uptick in beet armyworms. UC IPM also offers tips about monitoring for armyworms in alfalfa.
Almonds are approaching hullsplit in this orchard.
Almond field scout Jenna Horine reports an explosion of spider mites in some orchards. Some areas are hit harder than others. Harvest timing still varies, with some growers still waiting for hullsplit while others are well into their nut harvest. In dealing with mites, long-time entomologist and almond expert Walt Bentley tells us that growers they can’t do anything about mites if harvest has started.

Some growers are still  waiting for the harvest.

If they haven’t started to harvest, growers may be able to treat with a short pre-harvest interval miticide. This would have to be done by air. Growers should consult their pest control advisors. For the most part, he says, “We will probably have to sit through this and get the harvest done. This shouldn’t hurt this year’s crop and won’t hurt next year’s.” Thanks for the tips Walt.Th 

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