Almond pest management challenges

Times were much simpler three and four decades ago. People were thrilled to get their first (black-and-white) television set. Homes had a single, wired telephone. The family sedan was filled with 20 cent-per-gallon gas at the nearby “full-service” station.

Veteran pest control advisers (PCAs) fondly remember simpler times on and off the farm when job duties were just as important but less complex. PCAs today are armed with an arsenal of knowledge on numerous pests and diseases, a broad range of crop protection materials with various active ingredients, and ever-changing, more complicated regulations.

“PCAs must consider environmental issues and how pest control technology can impact air and water quality, endangered species, international markets, maximum residue levels, bees and pollinators, and production costs,” said Gabriele Ludwig, associate director of environmental affairs for the Almond Board of California (ABC), Modesto, Calif.

Ludwig discussed hot-button pest management issues faced by California’s almond industry during the 2009 California Association of Pest Control Advisers annual meeting in Sparks, Nev., in October.

Almonds are California’s largest horticultural crop and the top U.S. horticulture export crop with an estimated $2.3 billion annual value. Acreage in 2008 totaled about 680,000 bearing acres and 115,000 non-bearing acres, according to the National Agricultural Statistics Service.

Regulations governing this valuable nut industry and others continue to get more complicated including rules to reduce volatile organic compounds (VOCs) in the San Joaquin Valley (SJV). VOCs are gases emitted from a variety of chemicals used by various industries including agriculture which can create smog and reduce air quality.

Ludwig says pesticides were once perceived as the sixth largest VOC source.

Two classes of farm pesticides are primarily responsible for VOCs including the inert ingredients in emulsifiable-concentrate (EC) formulations plus soil fumigants.

The California Department of Pesticide Regulation (DPR) set maximum limits on VOC emissions in the SJV in January 2008 for the annual calendar period from May 1 – Oct. 1. DPR calculates emissions in 2005 and 2006 would have exceeded the cap. The rule also limits how soil fumigants are applied.

“Pretty much anything and everything in the San Joaquin Valley is being examined to reduce the precursors to smog, including farm pesticides,” Ludwig said. “Roughly two-thirds of the pesticide VOC emissions in the SJV are from EC formulations where there are often other formulations or pesticide choices available,” Ludwig said.

“If PCAs and growers can opt for lower VOC-emitting formulations then it’s a good idea to make a change,” Ludwig said. “If the cap is exceeded, DPR will likely further restrict the use of soil fumigants.”

VOC regulations on soil fumigants currently require the use of tarps for methyl bromide (MeBr) and chloropicrin. In addition to VOC regulations, various other federal and state regulations impact soil fumigant use. Under the Clean Air Act, MeBr production is basically phased out in the U.S. There are two exemptions: for critical uses and quarantine and pre-shipment uses a limited production of MeBr is allowed.

“Almonds still have a critical use exemption for methyl bromide, but specific conditions are required for pre-plant use,” Ludwig said. “In addition, the Environmental Protection Agency plans changes to product labels for soil fumigants to reduce bystander exposure.”

The easier label changes will start in 2010, Ludwig says. The more difficult changes in 2011 will require significant buffer zones, monitoring, and/or notifying neighbors within a certain distance of the product application.

The ABC funds research to reduce emissions or reduce the amount of fumigant required. ABC is funded by a three-cent-per-pound almond assessment. The ABC has spent about $17 million on science-based production and environmental research since 1973.

“Among the possible options studied through Almond Board-funded research include utilizing soil moisture, placing water on the soil surface, adding sodium thiosulfate as a soil amendment to the surface, and assessing less permeable tarps — all to reduce emissions, plus more site-specific applications and improved resistant rootstocks,” Ludwig said.

“Tarps are expensive, but they may be a way to maintain these tools at acceptable emission levels.”

Other air quality challenges include a California Air Resources Board planned requirement to retrofit or replace equipment with cleaner burning motors to lower particulate matter and nitrous oxide emissions.

Growers can also expect higher prices for fossil-based fuels tied to a California requirement to reduce greenhouse gas emissions by 25 percent to 1990 levels by the year 2020.

Challenges in ground and surface water quality continue to evolve. The Irrigated Lands Regulatory Program requires monitoring of surface waters primarily influenced by agriculture. Three years of data indicate pesticides regularly showed up. Water boards want to know what actions growers are taking to prevent surface water contamination.

“ABC-funded research focuses on mitigation measures to allow growers the continued use of effective pesticides while minimizing the movement into waterways,” Ludwig said. “Possible actions as an outcome of the research include the installation of settlement basins and vegetative buffer strips, improved aerial sprayer calibration, and integrated pest management through fine-tuning pest biology research.”

Other challenges facing the almond industry include ever-changing international maximum pesticide residue levels, plus how pesticides and honey bees interact; an issue brought to the forefront by Colony Collapse Disorder.

While pesticide product labels may have a “bee warning” that explains the possible acute toxicity for adult bees, Ludwig says labels fail to explain the potential impact on bee larvae. U.S. research is looking at the sub-lethal effects on bees.

“Emerging data indicates some pesticides have sub-lethal effects and some don’t,” Ludwig said. “This is not just an insecticide issue; it’s also a fungicide and herbicide issue.”

ABC has funded pollinator research for 20 years with a focus on honey bee health.

“A sustainable almond industry will cease to exist without honey bees,” Ludwig said. “We’re focusing on improved bee nutrition and health including pest management in hives.”

In addition, USDA’s Natural Resources Conservation Service encourages growers to develop or maintain pollinator habitat that extends beyond honeybees to include native pollinators including butterflies, insects, birds, and bats; though habitat close to growing areas can make pesticide applications more complicated, Ludwig says.

ABC production research also focuses on pathology and nematology including the efficacy of new fungicides and how to better rotate different chemistries to reduce resistance development.

Successful entomology research continues to focus on the navel orangeworm (NOW). “The navel orangeworm remains the primary pest in almonds; not just from the damage to the almond but its implications for food safety by aflatoxin,” Ludwig told the PCAs.

Years of ABC-funded research have reduced average NOW damage in almonds from about 8.8 percent of the total crop to about 1 percent; accomplished mainly through a combination of winter sanitation, prompt harvest, and pest control tools.

On the issue of sustainability, Ludwig emphasizes the almond industry remains sustainable.

“You don’t have fourth or fifth generation almond growers without being sustainable,” Ludwig said.

ABC almond grower focus groups in 2005 developed the following sustainability definition: “Sustainable almond farming utilizes production practices that are economically viable and are based upon scientific research, common sense and a respect for the environment, neighbors and employees. The result is a plentiful, healthy and safe food product.”

The challenge, Ludwig says, is how to bridge the knowledge gap between farmers and non-farmers. The ABC embraces developing a sustainability-based, grower-focused self assessment, an educational tool to help the almond industry make the best choices and then sharing the results with regulators and customers.

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TAGS: Tree Nuts
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