UC IPM advisor travels Down Under to help stop new California pest
In 2007 light brown apple moth (LBAM), Epiphyas postvittana, was first reported in California. In an effort to learn more about this new pest, North Coast IPM Advisor Lucia Varela took sabbatical leave this year and studied this insect in its native Australia and in New Zealand, where it is an introduced pest.
Varela found that in Australia, LBAM becomes a significant pest of grapes only in cool regions with high humidity; growers keep it in check with timely applications of selective insecticides. In New Zealand, where it is primarily a pest of apples, growers now use an IPM program that combines biological control with reduced-risk pesticides, eliminating the use of broad-spectrum insecticides while significantly reducing damage.
“With a strategic commitment to biological control used as part of an IPM program, California may ultimately achieve the same levels of LBAM control as growers obtain in New Zealand,” Varela said.
LBAM was first reported in New Zealand 1881 where it became a pest of fruit crops, primarily in apples and berries but also a minor pest of grapes, stone fruits, and kiwifruit. Larvae usually feed inside rolled up leaves, but if they web the leaves onto the fruit, they also will feed on the fruit’s surface.
From the 1960s to the 1980s, LBAM developed resistance to broad-spectrum organophosphate insecticides, requiring six to nine insecticide spray applications in apples. As LBAM’s importance as a pest increased, researchers began to focus on biological control to manage it. In the late 1960s they introduced new species from Australia to augment existing native natural enemies.
By the early 1990s, biological control resulted in reduced leafroller populations and lower fruit damage. In the mid- to late 1990s, growers implemented an IPM program for apples, substantially decreasing the use of broad-spectrum insecticides and further enhancing natural control. Damage has decreased to less than 2% in unsprayed trees.
Today only one application is required for apples destined for local markets and about two applications for export markets to countries with zero tolerance for LBAM. Through a combination of natural control and reduced-risk insecticides, New Zealand growers are able to control LBAM and to meet export standards to more than 60 countries.
Lucia Varela, (707) 565-2621
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