Q. I’ve heard that Los Osos and part of the Nipomo Mesa have been placed under a plant transportation quarantine that even affects home gardeners. Is that true? - John Normanly, Nipomo
A. The answer, unfortunately, is yes. These are the local quarantine areas where a nasty, invasive, and broadly destructive pest has been recently found. Native to Australia, the Light Brown Apple Moth (Epiphyas postvittana) was identified in California in 2007, the first time ever in the continental United States, and since then in coastal areas ranging from Los Angeles to Sonoma. Although called an “apple moth,” this pest is equally damaging to hundreds of plant species including most fruits and many vegetables, trees and landscape plants; if unchecked it poses a serious threat to commercial food crops.
The moth is a “leaf-roller” capable of two to four generations per year. The female moth nightly lays a cluster of 20 to 50 eggs on the underside of a leaf. The resulting immature larvae disperse across the plant, select a feeding sight, make a silken tent and begin to feed. Adult larvae web (“roll”) leaves together into a tent, and often feed on flower buds or burrow into nearby fruit. The reproductive cycle continues throughout the year with immature larvae overwintering in mummified fruit, leaf litter and other garden wastes.
For the home gardener, preventing the spread of the moth is essential. If you live within the quarantined areas, removing and properly disposing of garden wastes, either by composting or green waste disposal, is a necessary first step to preventing infestation. Pheromone baits are being hung by the California Department of Food and Agriculture and are an effective method to confuse the moths, interrupting their mating cycle. Broad spectrum insecticides are not recommended since they kill many beneficial insects including the apple moth’s natural predators. If you do live within the quarantine, don’t give away plants, fruit, and vegetables or cut foliage that you have grown in your own yard. They may carry a very unwelcome guest.
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The quarantine boundaries for Los Osos and the Nipomo Mesa may be found at http://pi.cdfa.ca.gov/. Scroll down to SLO County and click on the link.