By now you  have probably heard about the Light Brown Apple Moth. The tiny moth and its offspring, leaf-rolling caterpillars, have caused quite a stir around the state. Because of its threat to agriculture, aerial spray programs were proposed to attempt to eradicate it.

Here in Napa, no aerial spray program has been implemented. Instead, the Napa County Agriculture Commissioner, in cooperation with the California Department of Food and Agriculture and the United States Department of Agriculture, have formed the Light Brown Apple Moth Quarantine Program.

At a recent meeting, attended by local landscape pest control businesses, landscape contractors, tree services and maintenance gardeners who haul brush and garden debris, Ag Commissioner personnel explained the potential damage that the moth could do and the importance of professional cooperation to prevent it.

The bottom line is: Professionals will not be authorized to move plant material and green waste from properties unless they obtain a compliance agreement. 

Even though I rarely haul brush and garden waste in the course of my work, I obtained a compliance agreement ( and it was absolutely free.)

Light Brown Apple Moth (Epiphyas postvittana), a native to Australia, is now widely distributed through New Zealand, the United Kingdom, Ireland, New Caledonia, and, since 2007, 15 counties in California.  Findings in Napa County include the Carneros district, American Canyon, Napa, Yountville and St. Helena. 

The Ag Commissioner’s office states that since state and federal eradication measures cannot proceed, because of current legal actions and the need for environmental review, a quarantine program must be implemented, including all landscape professionals working in the quarantine area. 

That area, as shown on a map handed out at the orientation meeting, includes virtually all of Napa Valley south of Pratt Avenue in St. Helena.

A USDA pest alert distributed at the meeting states that crop losses attributed to the Light Brown Apple Moth in New Zealand range from 5 to 20 percent, so it’s a serious cause for concern in agricultural areas where it it is expected to thrive if it gets the chance — including California, the Southwest and Southeast U.S.

Active at night, year-round in mild climates, the Light Brown Apple Moth adults rest during the day.  To feed, the larvae roll themselves up with a protective web in green leaves of trees and various green plants, including weeds. The economic threat comes from their feeding on fruit. The pest alert states that it has few “natural enemies in the U.S and reproduces at extremely rapid rates.” 

Prunings from infested landscape plants — even pulled-up weeds — may harbor adult moths, larvae or eggs. Infestations are spread naturally by the adults, which fly, and could be increased dramatically by infested foliage and fruit transported in yard waste, nursery shipments and agricultural crops leaving infested areas.

Under the Compliance Agreement there are various requirements, depending on the nature of each business. They apply to yard waste and chipped brush generated in the infested zone. Summarized as simply as possible, a typical landscape maintenance business or tree service has the following requirements: 

  • Cover yard waste loads so they don’t spill out of the truck or trailer.

  • Take yard waste directly to facilities that are under a Compliance Agreement or leave the yard waste or chipped brush on site. (No hauling of chips from one site to another! That’s a significant limitation for tree services.  Can a moth survive a pass through the wood chipper?)

  • Thoroughly clean out and leave all yard waste at the facility.

  • Keep a copy of the the compliance agreement in each truck, keep records for two years of all yard waste disposal, and have them available for inspection.

  • Notify the Cooperative Program (Ag. Commissioner’s office) within 24 hours after a spill.

There are many other requirements, which apply to the various types of business establishments such as nurseries, and ag. crop transporters. 

So, think about it, be careful and call the County Ag Commissioner’s office if you have questions. A seemingly innocent basket of fruit or a small load of clippings or weeds, could introduce Light Brown Apple Moth to a new area.

In other tree news, I’ve just learned of a growing threat to black walnuts, those magnificent shade trees I wrote about earlier this year, and possibly to English walnuts as well.

In a professional discussion group e-mail, Mark Porter, a certified arborist from Riverside, mentioned that a newly discovered disease problem has been identified and is infecting and killing hundreds of black walnut trees in the western states. He provided a link to UC Davis for information.

Known as “Thousand Cankers” the disease is introduced into black walnut trees by the tiny “walnut twig beetle” (Pityopthorus jugandis), which is native to California, New Mexico, Arizona and Mexico. It’s about as small as a mechanical pencil point. The infectious agent is a fungus in the genus Geosmithia.  When thousands of the tiny beetles infect a tree, they infect it with thousands of fungal cankers.

UC Davis Department of Entomology chair, Lynn Kimsey warns in a newsletter (July 2, 2009)  that black walnuts could go the way of the American chestnut or American elm.” That means decimation or worse.

Already, many of the large black walnut trees lining the streets and county roads around Davis are dead or dying and there are several symptomatic  English walnuts at the USDA National Germplasm collection in Winters.

Colorado State University is leading research on the new disease, and UC Davis researchers are participating in a federally funded project to collect diseased branches throughout California.

Be on the lookout for declining black walnut trees and, if you’re interested, take a look at the UC Davis entomology newsletter (http://entomology.ucdavis.edu/news/walnuttwigbeetle.html).

Bill Pramuk is a registered consulting arborist. Visit his Web site, www.billpramuk.com, e-mail questions to info@billpramuk.com, or call him at 226-2884.