Monday, June 19, 2017

Prolonged Heat Wave Can Really Bug Valley's Crops

Summer is still two days away. But we’re certainly sending off spring with a bang.

It’s HOT, HOT, HOT in the Valley.

The sizzling temperatures we weathered over the weekend are predicted to continue throughout the week, reaching as high as 110 degrees. A week of triple-digit temperatures means things are getting quite buggy for crops, including almonds, alfalfa and cotton.

“Lygus is exploding,” alfalfa and cotton field scout Damien Jelen says.

As we mentioned last week, lygus bugs are a major threat to cotton. They can cause damage from early squaring through cutout and final boll set. The pest will pierce the squares and damage the tissue, eventually causing them to drop. If too many squares drop, the cotton plant will experience too much vegetative growth leading to tall spindly plants and a reduced yield.
Lygus bug damage in cotton. (University of Georgia photo)

In one cotton field, for example, Damien caught nine lygus after 50 passes of his sweep net. That’s not good because the treatment threshold through the end of this month is two lygus per 50 sweeps. The grower is going to have to closely monitor that field and make some hard decisions if the population densities remain high.

Cotton is in an important development period right now.  UC IPM notes: “Success in retaining early squares will greatly determine the final yield; therefore protecting cotton during the early square formation period (June) is critical. Protection during the early season is very complex. Factors such as lygus bug numbers, high susceptibility of cotton, and variability in sampling require the grower to be extremely vigilant and ready to act at an instant.”

If you want to read up on the topic, go to UC IPM online to learn about lygus pest management in cotton. Damien will continue to update us about the state of lygus in our fields.

Almond growers are adding lots of water due to the heat.
Meanwhile, almond field scout Jenna Mayfield reports the growers are keeping their orchards well hydrated. “Everyone is putting on a lot of water. They don’t want to stress the trees.”
Well-irrigated orchards are important for guarding against spider mites, which are a threat for almonds through August.  Mites flourish in warm weather and will hit water-stressed orchards.

“The conditions are ripe for mites,” Jenna says. She reminds growers dusty conditions can trigger mite outbreaks.  So it’s important to water down access roads and watch driving speeds to control dust, she says.

FIELD DAY: Don’t forget Tuesday’s  field day featuring alfalfa pest management tips and an update on pesticide regulatory issues. Sponsored by the San Joaquin Sustainable Farming Project, the free event will be  from 10 a.m. to 12:30 p.m. at Los 3 Pancho Restaurant, 2031 Blossom Street.  Merced County Assistant Agricultural Commissioner Yvette Pellman and Dr. Pete Goodell of UC IPM are the featured speakers. Growers will learn about non-fumigant VOC regulations, chlorphyrifos and worker protection as well as integrating multiple approaches to managing pests in alfalfa. The field day has been approved for continuing education credits. For more information, contact SJSFP Director Marcia Gibbs at (530) 5325 or

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