Heat Brings Stress, Relief

Two consecutive weeks of extreme heat caused some heat stress and tip burn, particularly on romaine and other sensitive leaf varieties. Growers stepped up irrigation schedules to counter the heat. As a result, many PCAs were turning to aerial applications to apply treatments for pests including aphids, mildew and thrips, which were showing up in only moderate numbers in many Salinas Valley fields.

The heat did help stabilize mildew pressures and other problem brought on by early-season moisture. It also helped keep the usual insect pressures at bay, said Bill Chaney, UCCE Entomology Farm Advisor in Monterey County.

“It has been really quiet insect wise, there’s just not much going on right now,” Chaney said in late July. “This hot weather has slowed down the development of most of the cool-season insects here.”

Heat typically accelerates worm pressures, but Chaney said by late July, worms were not yet a problem.

Gene Spencer, an independent agronomist and PCA in Watsonville, said the heat seemed to bring relief from molds and mildew that forced many PCAs to make additional recommendations this past winter and spring, particularly as crop progress slowed and crops sat in the field for longer stretches.

“It had been a little bit more of a problem. Up until this heat wave, we’ve had weather that was very conducive to molds and mildews,” Spencer said.

Jose Valdez, PCA with D’Arrigo Bros. in Salinas, agreed that disease pressures now remained light.

“Right now the mildew has been pretty calm. We usually get a lot of mildew during the foggy days with cools nights, but the heat as helped us out,” Valdez says.

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