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Pre-emptive pest control is big business for ag

Bob Aguilar is a common sight at the local UPS and Federal Express offices in Merced. He goes there almost every day — but not to send a package or pick one up. Aguilar is looking for plants coming into the county that may harbor pests.

Aguilar, along with 16 other biologists, works for the Merced County Agriculture Commissioner’s office making sure that the pests in the county are kept under control, and that no new ones come in.

And that is serious work. An infestation of the wrong type of insect or plant could put a screeching halt to the $2 billion ag industry in the county. If the wrong pests end up here, other states and countries could impose embargoes on products from the county.

“There are huge additional costs when you have export requirements,” Robinson said.One of the first plants that came under the scrutiny of the county was the puncture vine in the 1960s. Two separate types of weevils were brought in to deal with the painful plant, and its numbers plummeted.

“These programs are not designed to eradicate. When doing biological control we are trying to reduce the population of the pests,” Robinson said.

When the county experienced an invasion of the ash whitefly in the early 1990s, the ag commissioner’s office was inundated with calls from the public.

“We had tons of calls from joggers who were getting facefulls of the bugs,” Aguilar said. In order to fight the whitefly, which affected local ash trees and the ornamental pear trees that line Merced’s streets, the county introduced a tiny parasitic wasp.

Aguilar said that a small number of the wasps was imported and a seed colony established. When there were enough wasps, they were gathered by the biologists and released throughout the city.“This program went like gangbusters. Within one or two seasons we couldn’t find any white ash flies,” Aguilar recalled.

Other bugs that are problems in the county include the grapeleaf skeletonizer and the red gum lerp psyllid. The grapeleaf skeletonizer affects grapevines, and the lerp psyllid almost devastated Merced County’s eucalyptus trees at the end of the 1990s.

But it isn’t just bugs that are bad for the county’s ag producers. For cattle ranchers, a big problem is yellowstar thistle. This prickly plant can take over grazing grounds, and the county uses five beneficial insects and a rust fungus that are released to control the plant.

In order to keep pests out, Aguilar and his fellow biologists spend a lot of their time making sure that those pests don’t get here in the first place. The biologists go to local package stores, checking any packages that look as if they may contain plants.

The biologists also have to check every bee hive that comes from any of the southern states into Merced County. In the past, the hives inadvertently introduced the southern fire ant, a stinging species found in the Snelling area a few years ago. Now every hive has to be tipped upside down and checked for the little red stingers.

The insect most in the spotlight now is the light brown apple moth, which has established itself in the Bay Area. Robinson said that the county has laid traps to see if the moth is in the area, but none has yet been found. Unfortunately, the moth is devastating to more than just apple trees - it likes many other plants.

County biologists do more than just check for pests, although that’s a big part of their jobs. They also check egg houses for quality, along with checking growers and the chemicals that are sprayed on their fields.

“We do a lot that people don’t realize,” Aguilar said.

Robinson said pest control is extremely important in Merced County, which depends on agriculture for many of its jobs.

“There will always be pests,” Robinson conceded. “We want to keep them at a level where they aren’t really a problem.”

Reporter Carol Reiter can be reached at (209) 385-2486 or creiter@mercedsun-star.com

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