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tration and water holding capacity, Smither-Kopperl said. Some of these species also host pollinators and ben- eficial insects, and can help in pest and weed suppression. She said it is important to keep in mind variability in seed size and to choose equipment that is compatible for planting. Seed size determines op- timum planting depth; seed planting depth is commonly twice the diameter of the seed. Cary Crum, a crop consultant with California Ag Solutions Inc. in Madera, said it’s best to eliminate glyphosate from a production system using cover crops, and to treat the cover cropwith the same attention paid to a primary crop. Crum advised farmers to take care in timing mowing and mowing frequency, and to have a termination plan. He said plant ing can be done by broadcasting seed, using a convention- al or no-till drill and applying by air. Planting too early in the fall may mean a lack of rain results in poor germination, he said, or that seeds germinate but die for lack of moisture. The webinar is available on YouTube by searching for its title: Cover Crops in Orchard Systems Workshop. (Denni s Pol lock i s a repor t er in F r e s no . He ma y b e c on t a c t e d a t agcompollock@yahoo.com.)
Margaret Smither-Kopperl, manag- er of the Madera/Chowchilla Resource Conservation District, talked of cover crop selections and management in the Central Valley. She described site preparation and use of a no-till drill and tillage aimed at creating a firm seed bed. Next comes dr i l l ing or broadcast ing seed. She called good soil-to-seed contact essen- tial for success. Smither-Kopperl said other consid- erations include whether the cover crop will be entirely rainfed or if an irrigation systemwill be used. “Drip or microsprinklers in orchards can lead to twoenvironments: growthun- der the trees, desert in the rows,” she said. Cool-season cover crops can be plant- ed in the fall or early spring, Smither- Kopperl said, and will tolerate cold tem- peratures and some temperatures below freezing. Warm temperatures will cause plants tomature, set seed and die. There are varying degrees of drought tolerance, depending on species and cultivar. Warm-season cover crops are plant- ed in spring, after danger of frost has passed, and may be planted through the summer to early fal l , she said. Freezing temperatures will kill these crops. They tolerate high summer tem- peratures and have varying degrees of
Participants in an orchard tour organized by the Madera/Chowchilla Resource Conservation District observe plantings of cover crops in a Madera County almond orchard.
drought tolerance, again depending on species and cultivar. Smither-Kopperl said cereals and grasses have vigorous root systems, are good for soil building, reduce erosion, increase water infiltration and holding capacity, concentrate nitrogen andphos- phorus, increase nutrient cycling and suppress weeds and diseases.
Legumes are good for nitrogen fixa- tion, nutrient cycling, developing amain taproot and improvingwater infiltration, she said, noting that some species sup- port pollinators and beneficial insects, and aid in pest and weed suppression. Brassica and radish provide strong taproots, reduce soi l compact ion, scavenge ni t rogen, increase inf i l -
CALIFORNIA’S CITRUS INDUSTRY INNOVATES TO COMBAT DEADLY PLANT DISEASE F or nearly 10 years, a deadly citrus tree disease called
Sponsored by the Citrus Pest & Disease Prevention Program
Huanglongbing (HLB) has been present in backyard citrus trees throughout Southern California; however, as of today there has not yet been a detection in a commercial citrus grove in the state. Due in part to proactive regulatory measures put in place by the Citrus Pest & Disease Prevention Division (CPDPD) and endorsed by the Citrus Pest & Disease Prevention Committee (CPDPC), researchers across the state from the Data Analysis and Tactical Operations Center (DATOC) have found encouraging results that support the conclusion that these requirements are making a measurable difference. As part of its efforts to prevent the spread of the pest and disease, the CPDPC, along with regulators and members of the scientific community, continually evaluate the current regulations and discuss potential improvements that can help keep HLB out of commercial groves and major citrus growing regions. In 2017, the CPDPC made a recommendation to California’s secretary of agriculture to impose tarping requirements on trucks transporting bulk citrus. This tarping regulation enforced the requirement that all bulk loads of citrus be fully enclosed or covered whenever in transit to a packing facility from the field. California’s packinghouses, including coastal and Southern California counties, ship more than 63 million pounds of bulk citrus into the San Joaquin Valley annually for processing. A considerable quantity of fruit also moves to packinghouses in Ventura County from across the state. In years past, ACP detections in the San Joaquin Valley had soared as ACP presumably “hitchhiked” on trucks that weren’t properly covered, coming from Southern California into the valley and threatening the livelihood of commercial groves throughout California along the way.
Source: DATOC
As DATOC researchers reviewed ACP trapping data along major transportation routes before and after tarping regulations for bulk citrus shipments were in place, the data showed the tarping regulation was accomplishing its intended goal of reducing ACP movement throughout the state. While this is encouraging news, and a testament to the important actions citrus growers, packers and transporters are investing in to stop ACP movement and prevent HLB from taking hold, growers must continue to remain vigilant. “This simple solution to a potentially devastating problem shows the power our industry has when we work together,” said Jim Gorden, chairman of the CPDPC. “It’s up to all of us to stay informed, follow regulatory requirements and continue to look for new solutions to help us stay one step ahead of this deadly adversary.”
8 Ag Alert May 26, 2021
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