Area-Wide Treatments for Ventura ACP

Apr 18, 2018

For the past 18 months, a team led by University of California research entomologist Beth Grafton-Cardwell has been conducting an Asian citrus psyllid monitoring project to determine the efficacy of Ventura County's area-wide ACP suppression strategy. Based on her analysis of the survey data, Dr. Grafton-Cardwell has recommended changes in the area-wide management (AWM) protocol to provide better control of the invasive pest. The Ventura County ACP-HLB Task Force has endorsed her recommendations and incorporated them into the AWM schedule for 2018-2019.

The primary change will be the addition of a second fall treatment, which may be a perimeter spray, for lemons and mandarins. Fall is when ACP populations reach their highest level, and the research data indicate a single pesticide application is inadequate. The research data also show that ACP is most abundant on grove perimeters, and only expands into the center rows when the population is large. In recognition of this, the new Task Force protocol allows one of the two fall applications to be applied to only the grove perimeter, as long as the grower, grove manager or PCA/PCO has scouted the orchard and determined that center rows are free of ACP nymphs on flush. The other fall application, however, must cover the entire grove.

As in previous cycles, the treatment window for each psyllid management area (PMA) will last three weeks, but it now will overlap with the next window by two weeks instead of one. This will compress each treatment cycle from four months in length to two and a half months, heightening the area-wide effect. (See below for the schedule.)

The annual AWM program for lemons and mandarins will now consist of four applications: a coordinated AWM whole-orchard treatment in winter, individual applications of an ACP-effective material (either alone or piggybacked on a spray for another pest) in late spring-early summer, and two coordinated AWM treatments in late summer and fall (one of which may be a perimeter spray).

The annual cycle for oranges, which do not flush year-round, remains two coordinated applications, one during the first fall window and one in the winter. For organic growers, each "treatment" must consist of two applications of Entrust and oil or Pyganic and oil, or other approved alternative material, to compensate for their limited residual activity. The list of approved materials for both conventional and organic operations is at

Members of the Ventura County citrus community are invited to a workshop to learn more about these changes, and the research data upon which they are based. The workshop will be from 9:30 to 11:30 a.m. on Thursday, April 26, at the Agriculture Museum, 929 Railroad Ave., Santa Paula. Attendance is free, but advance registration is required. Please register online at:

During the workshop, Dr. Grafton-Cardwell will present findings from her continuing survey of ACP populations across the county, including data on the effects of AWM pesticide treatments on ACP abundance. Other speakers will present updates on the statewide Citrus Pest and Disease Prevention Program, the status of Huanglongbing disease in California, and grower participation in the local ACP suppression effort.

The Task Force is also planning outdoor workshops to help grove owners, managers or farm employees develop an effective ACP scouting strategy. Topics will include how to scout for ACP, and how to identify symptoms of HLB. More information will be distributed in coming weeks.

The following is the new schedule for Fall 2018 and Winter 2019 treatments, organized by groups of PMAs. Overview maps of Ventura County's PMA boundaries are available at

Individual maps of Ventura County's PMA boundaries, along with many other documents pertaining to the Ventura County AWM program, can be viewed or downloaded at

As was the case with the previous AWM treatment cycles, growers will be notified about the date of their treatment window either by their packinghouse field reps, their PCAs or by the Ventura County grower liaisons: Sandra Zwaal ( and Cressida Silvers ( It will be up to growers to work with their PCAs and applicators to schedule those treatments.