Monday, July 13, 2015

Dusty Roads Might Stir Up Mite Trouble for Almond Trees

Every year, we talk about dusty roads and spider mites, especially during the hot summer months.

Kicking up dust will stir up mite populations.

These pests will reproduce quickly in hot weather and are most populous from June to September. Dusty conditions can trigger outbreaks.

To help control mites, growers should “apply water to pathways and other dusty areas at regular intervals,” UC IPM says. “Water- stressed trees and plants are less tolerant of spider mite damage. Be sure to provide adequate irrigation.”

Mites feed tree leaves and can lead to defoliation in the most severe situations. Major mite damage can cause a loss in yield.

Example of a web spinning mite issue.
Of course, keeping dust down on roads and providing trees and plants with enough water becomes a little problematic – and costly – for farmers during a severe drought. But growers have little choice because watering down roads and watering crops is matter of economic survival.

Field scout Jenna Horine sees out water trucks out regularly sprinkling H2O agua on dirt roads around melon fields bordering almond orchards. The melon harvest is in full swing, which means lots of trucks running in and out of the fields.

“It’s important to keep the dust down,” Jenna says. The recent heat wave was driving up mite numbers in the almond orchards. However, Jenna notes that most growers have applied miticides in their hullsplit treatments. That has kept mites under control for now.

Check beneficial populations before treatment.
Of  course, non-chemical, biological ways are effective in controlling mites too. UC IPM advisors point out growers could hold back on second miticide applications to give beneficial insects a chance to build their population to knock down mites. Under this approach, growers have to be comfortable enough to tolerate some amount of leaf damage to give beneficials enough time to gobble up the mite population. Yes, it’s a good practice to check on the beneficial insect population in the orchard before deciding to spray.

Cotton plants, too, can suffer mite damage – in which leaves turn yellow or red and then drop. This condition could hamper development of cotton squares and bolls, causing them to fall to the ground. Whole plants can become defoliated. Early plant and fruit development are when mites become the biggest threat.
Cotton fields are receiving the second irrigation of the season.

Field scout Carlos At the moment, Silva says lygus bugs have been in check in most fields. Plant development – around 10 to 11 fruiting branches – and fruit retention is good.
“Everything is growing quickly,” Carlos says, pointing out cotton plants are getting their second helping of irrigation water this season.

Field Day AlertDon't forget the summer Alfalfa Field Day on Wednesday from 10 a.m. to 12:30 p.m. at Bowles Farming at the intersection of Hereford Road and Bisignani Road in Los Banos. The speakers are UC IPM advisor Dr. Pete Goodell on insect management; UCCE Davis alfalfa extension specialist Dr. Dan Putman on current issues, including weeds, water quality and availability and summer retirement of alfalfa fields; Merced County Deputy Agricultural Commissioner Sean Runyon on an update of chlorpyrifos regulations; and Cannon Michael of Bowles Farming. Continuing education credits for farmers and PCAs, including 30 minutes of regulations, will be available. For more information contact Marcia Gibbs at (530) 370-5325 or

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