A highly refined integrated mite management program was developed with funding from the Almond Board in 1984 The program introduced the presenceabsence technique for monitoring mites

A highly refined integrated mite management program was developed with funding from the Almond Board in 1984. The program introduced the presence-absence technique for monitoring mites.

40 years in almond pest management – a retrospective

Almond yields have more than doubled over the past 40 years, and damage from navel orangeworm has gone from a high of 8.8 percent down to 1 percent or less. Here’s how it happened.

This year marks the 40th anniversary of the Almond Board of California’s (ABC’s) Production Research Program. It’s no coincidence that almond yields have more than doubled over the past 40 years, and damage from navel orangeworm has gone from a high of 8.8 percent down to 1 percent or less in the most recent crop.

Here’s how it happened.

In 1972, the Federal Marketing Order for almonds was revised so that the ABC could establish and fund production research projects. By the next year, a cooperative research program was begun between ABC, University of California and USDA. At the time, the focus was on managing NOW, a very serious problem for the industry.

NOW – The First Milestone

Cooperative research with UC and USDA resulted in a “Four Point Program” for addressing navel orangeworm, which is the foundation of practices used today that have brought damage down to a new low, reducing direct crop losses and associated aflatoxin risk.

The four points are:

·      Winter sanitation

·      Dormant sprays

·      In-season sprays

·      Timely harvest

More recently, as a result of 35 years of dedicated research by several experts, a NOW pheromone is commercially available for use in traps and for mating disruption. Now, work is being done to develop the use of almond plant volatiles, or kairomones, to disrupt ovipositioning. Combining the two techniques has the potential to increase trap attractiveness to both males and females, disrupting both mating and egg laying, and possibly leading to an attract-and-kill technique.

Ongoing research has also resulted in the refinement of programs for NOW control using in-season reduced-risk pesticides with minimal impact on beneficials. Newer materials fit in both spring and hullsplit sprays, with added efficacy on peach twig borer in the spring application.

More recent research shows that for winter sanitation, mummy nuts should be removed down to two or fewer per tree, and harvest should take place as soon as possible after nuts are mature to avoid egg laying for a third generation of NOW.

These discoveries came about under ABC-supported research, which has been leveraged by the 2008 – 2012 USDA Area-wide Pest Management Project for NOW, a funding partnership between ABC and USDA Agricultural Research Service.

Integrated Mite Management

Web-spinning mites are an ongoing concern in California’s almond orchards. In 1984, another milestone was reached with the publication of “Managing Mites in Almonds – an Integrated Approach.”  With funding from ABC, researchers developed a highly refined integrated mite management program that relies on monitoring and treatment thresholds along with effective mite predators to be sure miticides are applied prescriptively only when needed.

This program introduced the spider mite “presence-absence” sampling technique, which allows PCAs and growers to determine mite treatment thresholds and apply miticides accordingly.

Since 1984, new miticides have come on the market, and ABC-supported research has determined which products work best, the optimum application timing, and the effects of each on the western predatory mite and other mite predators.

The integrated mite management program was quickly followed, in 1985, by the first edition of the UC “Integrated Pest Management for Almonds.” Now in its second edition in print, much of this information is also available online as the UC IPM pest management guidelines (http://www.ipm.ucdavis.edu). These guidelines are constantly updated, thanks to support from ABC.

Pest Management Partnerships

In 1998, the Almond Pest Management Alliance (PMA) was initiated by ABC and continued until 2005 in a funding partnership with the California Department of Pesticide Regulation (CDPR) and U.S. EPA to evaluate the possibility of reducing pesticide use in California Almonds. 

The PMA was a cooperative effort among industry stakeholders, including ABC, the Almond Hullers and Processors Association, the UC Statewide IPM Program, UC Cooperative Extension, pest control advisers and growers, CDPR, and U.S. EPA.

The almond PMA resulted in the widely used “Seasonal Guide to Environmentally Responsible Pest Management Practices in Almonds.”

Another partnership program, which was initiated in1993 to help protect water resources, is the Biologically Integrated Orchard System (BIOS).

Applying research conducted under the Almond Pest Mangement Alliance and the BIOS programs, California Almond growers were able to reduce dormant organophosphate (OP) sprays by more than 50%, resulting in lower costs and less potential for runoff into waterways.

To reduce dormant OP sprays, alternate timings and materials were researched. For instance, it was found that peach twig borer treatments could be made effectively at delayed dormant or in the spring, as well as bloom sprays with B.t. kurstaki.

Research continues on the impact of reduced-risk insecticides and fungicides applied at bloom on honey bees; current recommendations are to avoid insecticide bloom sprays tank-mixed with fungicides, and to time bloom fungicides when there is no pollen available and bees are not foraging.

Future Challenges

The work of the Production Research Committee is never done. Here are some of the challenges that lie ahead:

Plant bugs. Without the use of dormant sprays, leaffooted bug and stink bug populations are being treated with OPs and pyrethroids in the spring. Will this disrupt IPM systems? What effect will this have on surface water and air quality?

Growers need a monitoring program to determine the need for and timing of treatments for plant bugs.

Spider mites. Is resistance developing for abamectin? How effective are newer miticides, and what is their impact on predatory (beneficial) mites? Which miticides should be used at different times of the season?

How can growers predict in-season spider mite populations and areas where mite problems could flare?

Answers to these and many other questions will be forthcoming, thanks to the growers whose leadership 40 years ago led to the cumulative investment to date of $19.8 million to address production issues and needs of California’s almond growers.


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