Voracious Mites Invade Fillmore Avocado Grove : Agriculture: County has yet to confirm the infestation. Pest has turned up in Moorpark, Somis and San Diego.


A Fillmore avocado grove has apparently been infested with a voracious mite that has already invaded other groves in Ventura County and has caused major crop damage in San Diego, officials said Tuesday.

“I inspected the grove this morning,” said Dave Machlitt, the pest control consultant who discovered the mite in Moorpark and Somis orchards. “It’s a positive. It’s the perseae mite.”

Although Ventura County agriculture officials have not confirmed the Fillmore infestation, based on conversations and past reports from Machlitt “we’re 95% to 98% certain it’s the perseae mite,” said Phil Phillips, the county’s pest management adviser with the University of California.

“The potential is there for some serious damage,” Phillips said. “But whether it will be as severe as San Diego is somewhat in question.”


Machlitt said trees scattered over two to three acres in the Fillmore grove, located on an isolated ranch in the hills above the city, had been infected by the Olygonichus perseae mite.

The mite attacks the underside of avocado leaves, draining them of life-giving chlorophyll. Once the leaves are dead, the fruit is left unprotected from the sun and eventually withers and drops from the tree.

Machlitt speculated that the mite had migrated to the Fillmore grove a year or more ago because the infestation was much greater there than in Moorpark and Somis.

“This is the most advanced infestation,” he said. “It’s been here a lot longer than the other two finds.”


Machlitt said the owner of the Fillmore ranch became concerned about his crop after hearing reports last week about the infested groves in Moorpark and Somis. He said the rancher suspected his crop had been infected, but was not certain about the type of pest or the extent of the infestation.

“It’s really kind of hard to see if you don’t know what you’re looking for,” Machlitt said.

David Buettner, the county’s deputy agricultural commissioner, said he expects there will be more reports of perseae mite infestations as people learn about it.

“I don’t think what we’re seeing is the rapid spread of the mite,” he said. “I think it’s more that people are becoming aware that the pest has arrived in Ventura County.”


Still, Buettner said agriculture officials remain concerned over how entrenched the pest is in the county, which is the second largest producer of avocados in the state behind San Diego. Avocado sales in Ventura County totaled $30 million last year.

“It’s a significant threat to the industry,” Buettner said.

Machlitt said he plans today to release 20,000 “predator” mites in the Moorpark grove to do battle with the perseae mite there. The laboratory-bred Galendromus helveolus mite is the natural enemy of the perseae and is being used to combat the avocado-loving pest in Riverside and San Diego counties.

Entomologists and county agriculture officials believe the perseae mite is probably being spread by attaching itself to farming equipment and the clothes or picking bags of fieldworkers. The reason, they said, is the perseae mites discovered in Ventura County were all found near “bin-rows,” where the fruit is collected and packed for transportation.


To slow the spread of infestation, Phillips advises growers to regularly sterilize farming equipment, picking crates and bags. Workers should also be careful that mites have not attached themselves to their clothes.

Phillips said the main advantage Ventura County has over Riverside and San Diego is that it has more rainfall and cooler temperatures, which would help reduce the population of the subtropical pest that is believed to have migrated from Peru or Mexico.

Machlitt said he will speak about combative measures being taken against the avocado-destroying mite at a special meeting of growers and agriculture officials to be held at the Ventura County Government Center on Thursday. The meeting begins at 8:30 a.m., but Machlitt is not scheduled to speak until about 11 a.m.