Members of the local agricultural business industry received information on cover crops and pest management when presentations by two farming organizations combined into one seminar at Blythe City Hall on February 21.
The Palo Verde Resource Conservation District (PVRCD) contributed a “Cover Crop/Soil Health Workshop” comprised of four speakers, while the Progressive Farmers contributed a special presentation, “Low Desert Alfalfa Insect Pest Management Update.”
District Conservationist Sam Cobb of the Natural Resources Conservation Service (NRCS) opened the seminar by introducing the PVRCD speakers and their topics: Heather Dial, manager of the Arizona NRCS Plant Materials Center in Tucson, “Cover Crop Desert Species Research and Soil Health Benefits”; Kathryn Prince, NRCS partner biologist, “Using Cover Crops for Pest Control and Beneficial Insects”; Farm Advisor Jose Aguiar from University of California Cooperative Extension (UCCE) Riverside, “Cover Cropping in the Desert”; and Brooks Engelhardt, NRCS area resource conservationist/agronomist, “Cover Crops and the Environmental Quality Incentives Program (EQIP).”
Dial explained that Tucson’s NRCS Plant Materials Center has focused on finding appropriate cover crops for a given region rather than evaluating long-term soil health benefits. Cover crops, she said, benefit soil health by reducing erosion, increasing soil organic matter and improving infiltration and water-holding capacity. Crop mixes, she added, have shown to be more beneficial than just one type of crop.
In current experiments by Dial’s organization, a combination of cow pea, sorghum sudan, sesame and sunflower is being used as an effective summer cover crop, while purple top turnip, winter barley, winter triticale, Austrian winter pea and buckwheat can be effective in the winter. If a cover crop can be left in the ground for as little as six weeks, it can benefit soil health, Dial said.
Prince introduced the work of the Xerces Society, which studies insects and their habitats. Its programs include pollinator conservation and agricultural biodiversity, as well as pesticide policy and regulation, among others. Less than 1 percent of insects are considered “pests,” Prince said, and $4.5 to $12 billion is the annual value of natural pest suppression – in other words, using beneficial insects that prey on the pests as a natural and more affordable solution to chemical pest control.
Predatory ground beetles, for example, can live for years, are mainly nocturnal, consume their body weight in prey daily and especially like to eat destructive caterpillars and slugs, Prince said. Seed-feeding beetles, she added, are voracious consumers of weed seeds, averaging 37 to 104 seeds consumed per day. Lady beetles are also effective predators and even help spread flower pollen.
Aguiar explained that while cover crops provide strong benefits for farmlands, they are an added expense for farmers and require careful management. Nevertheless, he said, they have been shown to be highly effective for desert date, grape and citrus plantings, as well as vegetable fields during summer fallowing and provide a break from monoculture.
The potential benefits of cover crops are broad and varied, he said. They add organic matter to the soil, enhance mycorrhizal numbers, suppress weeds and nematodes, reduce erosion, increase infiltration of water, decrease soil nutrient loss and attract beneficial insects. Aguiar cautioned that cover crops that have not done well in UCCE Riverside’s desert trials are crotalaria, lab lab, guar and soybeans.
Engelhardt reported that the planet is experiencing its most destructive soil erosion phenomenon worldwide, necessitating the need for critical soil maintenance by such means as use of cover crops. The soil loss in the United States alone is 5 million metric tons per year, he said, caused two-thirds by water erosion and one-third by wind erosion. The majority of the erosion occurs on productive agricultural lands, he noted.
EQIP, developed by NRCS, addresses resource concerns related to soil, water, air and other resource issues on private land, he explained. It is voluntary and provides agricultural producers technical and financial assistance to promote agricultural production and environmental quality while helping producers meet environmental requirements.
Following a break for lunch, provided by PVRCD and American Ag-Credit, seminar attendees reconvened for the Progressive Farmers presentation.
Michael Rethwisch, the UCCE crop production and entomological advisor for the Palo Verde Valley, began his presentation on the growing destructiveness of several types of alfalfa pests and their seasonal prevalence. Key among them, he said, are the alfalfa weevil (January to April and June to July); blue alfalfa aphid (January to April); pea aphid (January to April); cowpea aphid (November to February); alfalfa caterpillar (July to September); armyworms (June to October); and leafhoppers/three-cornered alfalfa hoppers (May to December).
Alfalfa grows all year round and can have insect pests at every cutting, Rethwisch reported, and the possibility of new pests continues. In addition, current insect controls on the whole are somewhat losing effectiveness, perhaps due to multiple exposures to the same class of chemical pesticides and lack of effective alternatives. As a result, he said, insecticide rotations will need to be utilized to keep current chemistries viable as long as possible. Newer chemistries, he added, are probably going to be more expensive due to increased costs for registrations.
Discussion on local agricultural pest control will continue at the next Progressive Farmers’ meeting from noon to 1 p.m, Thursday, March 21, in the lunch room of the Riverside County Administration Building at 290 N. Broadway in Blythe. The presentation will be “2019 Updates Regarding Pesticides and Related Riverside County Programs” by Robert Mulherin, Riverside County deputy agricultural commissioner. Call (760) 921-5050 and leave a message to register for the lunch meeting.