- Author: Pamela Kan-Rice
Two UC Cooperative Extension scientists have been selected as Presidential Chairs for Tree Nuts at University of California Agriculture and Natural Resources.
The endowed chairs will give the two scientists a dedicated source of funding for five years for their ongoing agricultural research. UC Agriculture and Natural Resources established the two $1 million endowments in 2015. Half of the funds for the endowed chairs was donated by the California Pistachio Research Board and the other half was provided by UC Office of the President.
“The California Pistachio Research Board appreciated the opportunity to create these Presidential Chairs with the dedicated flexible funding it provides the scientists,” said Bob Klein, manager of the California Pistachio Research Board. “Mae and Giulia have stellar research records, have a history of research on California pistachios, and deserved both consideration and the award of these Chairs. The Board was pleased with the previous incumbents and is now looking forward to working with both Giulia and Mae in their programs on Genetics and Soil Science/Water Relations.”
Marino, who joined UC ANR in 2020, is based at UC Kearney Agricultural Research & Extension Center in Parlier. Her research integrates germplasm preservation and evaluation with tree physiology to improve orchard system profitability and abiotic-stress resilience. She explores the interactions between cultivar-rootstock traits, soil conditions and management practices.
“The program has the objectives of increasing the genetic diversity of the scion and rootstock cultivars used by the pistachio industry to improve grower returns and reduce its susceptibility to climate change,” Marino continued. “Rootstock projects include novel rootstocks more tolerant of boron in irrigation water, dwarfing rootstocks for higher early yields and more efficient use of pruning and harvest inputs. Scion objectives include novel scions for higher yield and trees less sensitive to inadequate winter chilling.”
One of her current research lines focuses on the characterization of low vigor cultivars and/or rootstocks to increase orchard planting density and reduce management costs in olive, pistachio and almond. She develops protocols for irrigation management based on genotype-specific physiological responses to water stress. Marino also studies the impact of saline sodic soil conditions on pistachio physiology and of low winter chill on cherry and pistachio tree and fruit physiology.
Marino earned a doctoral degree in fruit and forestry tree systems and master's and bachelor's degrees in agricultural science, all from the University of Palermo in Italy.
“As Presidential Chair, I will utilize these generous funds from the Pistachio Research Board to augment my collaborative outreach extension and applied research efforts to understand
and develop solutions to soil and water quality problems faced by pistachio growers and other nut crop producers across the San Joaquin Valley,” Culumber said.
She is collaborating on a CDFA Fertilizer Research and Education Program project that provides irrigation and nitrogen management training for certified crop advisors and growers to adopt practices that conserve water and protect water quality. She is also studying how to improve estimates of crop evapotranspiration and forecasting for major California crops for more precise irrigation. Culumber is leading research on the effects of whole orchard recycling on air quality and climate resilience, soil health, tree growth and productivity in second-generation orchards.
Culumber earned a Ph.D. in soil science and agroecology and a master's in plant science and molecular ecology, both from Utah State University, and a bachelor's in biology from University of Wisconsin-Stevens Point.
Bruce D. Lampinen, UC Cooperative Extension integrated orchard management, walnut and almond specialist in the UC Davis Department of Plant Sciences, received the first Presidential Chair for Tree Nut Soil Science and Plant Water Relations. Craig Kallsen, UC Cooperative Extension farm advisor in Kern County who specializes in fruit and nut crops, received the Presidential Chair for Tree Nut Genetics.
- Author: Steve Haring
- Posted by: Gale Perez
Over the last few years, UC Davis Weed Science has been testing cover crops for weed suppression in nut orchards. The most recent project we've been working on has trialed several cover crop programs using cereal rye in walnut orchards. These cover crop programs represent a range of several management philosophies, from a basic, low-input program to a high-intensity forage intercrop. So far, we are finding that a variety of winter cover crop programs can provide some level of winter weed suppression, but cover crops are not (and may never be) a complete vegetation management solution for the orchard floor.
Weed scientists have been thinking a lot more about cover crops recently. Because of renewed concerns about herbicide-resistant weeds and, therefore, increased interest in IPM, we have been trying to understand how to replace unwanted weeds with desirable plants. Researchers in annual cropping systems have been leading this charge, even going so far as developing cover crop systems that use neither herbicides nor tillage.
In California, many recent cover crop discussions have focused on management goals other than weed suppression, especially in orchard systems. Research has examined the benefits and challenges of cover crops related to soil health, water management, insect pests, and other facets of the agroecosystem. If weed suppression is a specific management goal, more management recommendations are needed to make cover crops feasible in the unique environment of a California orchard.
A large part of this feasibility challenge is related to the logistical demands of adding an additional layer of crop management on top of an existing orchard system. Will the cover crop provide any benefit if it is simply planted in the orchard and left until spring? Will it pay to use other inputs on the cover crop, such as fertilizers, herbicides, or additional irrigation? We started an experiment to try to answer some of these questions.
We planted cereal rye into a walnut orchard in Davis, CA in November 2019 (photo 1). There were four different cover crop programs based around cereal rye, as well as a bare-floor treatment where the rye was sprayed out with herbicides. A basic cover crop program had 50 lbs/acre rye planted into the orchard alley and no other inputs. A boosted cover crop program had the same rye planting with some starter irrigation and a nitrogen topdress in the spring (photo 2). A multi-species cover crop program had additional mustard and legume species planted along with the rye cover crop. Finally, a forage crop program was planted with 100 lbs/acre rye that received starter irrigation, a postemergent application of carfentrazone, and fertilizer at planting and in the spring.
In April 2020, we harvested orchard floor vegetation from two 0.25 m2 quadrat samples within each cover crop treatment plot. The harvested samples were separated, so that we could measure what proportion of the sample's mass came from weeds compared to cover crops. Then, the cover crops were terminated by mowing with a flail mower, except for the forage treatment which was swathed, baled, and removed (photo 3). At the time of harvest, the cereal rye was post-anthesis and taller than 7' in spots (photo 4). Weed species present at this time predominantly included Italian ryegrass (Lolium multiflorum), hare barley (Hordeum murinum ssp. leporinum), whitestem filaree (Erodium moschatum), and California burclover (Medicago polymorpha). We also monitored the experiment after harvest to evaluate cover crop regrowth and the effects of cover crop residue on summer weed emergence, which included predominately field bindweed (Convolvulus arvensis), spotted spurge (Euphorbia maculata), yellow nutsedge (Cyperus esculentus), and bermudagrass (Cynodon dactylon) in this orchard.
All of the cover crop treatments reduced weed biomass when compared to the bare ground treatment. However, none of the cover crop treatments consistently reduced weed biomass more than any other treatment (table 1). While the two treatments receiving supplemental fertilizer and irrigation (i.e. the boosted cover crop and the forage crop) appear to have produced slightly higher cover crop biomass than the other two treatments, these differences weren't large enough to be considered significant. The forage crop treatment did demonstrate more cereal rye regrowth after termination than other treatments, but we are still evaluating the effects of each treatment's residual effects on summer weed emergence. While the cover crop does leave significant residue in the orchard initially, it seems to break down fairly quickly and evenly across the orchard floor (photo 5).
This experiment supports the idea that a weed-suppressing cover crop can be used to displace unwanted vegetation. While we understand that any cultivated cover crop can outcompete weeds for resources like light, water, and nutrients, we are still trying to draw conclusions about how management actions related to these resources affect competition between weeds and cover crops. Orchards are complex, ecological systems, and many relationships may exist between horticultural management, cover crops, and weeds.
Early cover crop establishment might be one management practice that does have a direct relationship with weed suppression, based on other cover crop studies, including some of our own research in almond orchards (see Almond Cover Crop website). Management practices that help a cover crop emerge, and access resources, ahead of weeds can help minimize the resources available for weeds to take. Think about the logistics of planting a winter cover crop early enough to get ahead of winter weed emergence. Timing, equipment availability, and other management goals are all important when planning for an orchard cover crop.
The first year of this study demonstrated that cover crops have some level of weed suppression across a variety of management systems but that impacts were not dramatic after only one season. However, cover cropping is a cultural practice that affects the whole orchard ecosystem. We expect that several consecutive years of cover cropping may lead to cumulative effects such as a reduced weed seed bank or different winter weed species in the plant community. We will be repeating this experiment beginning in early winter 2020. Contact Steve Haring (sharing@ucdavis.edu) if you are interested in becoming involved in this project or learning more!
Steve Haring is a graduate student in the Hanson Lab (Weed Science Program, Dept. of Plant Sciences) at UC Davis.
- Posted by: Gale Perez
- Author: Sonia Rios
The University of California Cooperative Extension in conjunction with the California Macadamia Society and the Gold Crown Macadamia Association will hold their Annual Field Day on Saturday 30 September 2017, 8:45 A.M. to 1:30 P.M. at the home of Thomas & Bobbi Rastle's, 1115 Valencia Drive, Escondido, California.
We will have classes on topics germane to the macadamia industry, with plenty of opportunities for you to ask questions, both general in nature and about the specifics of your operations. We will also be serving a continental breakfast and a delicious lunch. Please plan to join us for a fun and information filled day.
Directions:
From I-5 & I-15, Exit on 78 east, Right on Broadway in Escondido, Left on Washington Ave, Right on Ash Street (it will become San Pasqual Valley Road), Right on Summit Drive, Right on Valencia Drive to 1115.
From I-15 north, Exit Via Rancho Parkway east (it becomes Bear Valley Parkway), Right on San Pasqual Valley Road, (Note: it is about four miles to San Pasqual Valley Road – Do Not Take San Pasqual Road), Right on Summit Drive, Right on Valencia Drive to 1115.
Cost: $20.00 per person if you pre-pay by 10 September 2017, $25.00 per person after that.
Visit www.macnuts.org/fieldday.htm for a registration form. Mail registration form along with your check to:
California Macadamia Society, P. O. Box 1298, Fallbrook, CA 92088
Questions? (760) 728-8081/Cell 760-580-5516 or RussellFarms@Roadrunner.com
Visit http://www.macnuts.org/fieldday.htm.
- Author: Elizabeth J Fichtner
- Author: Mohammad Yaghmour
Tulare and Kings Counties have over 200,000 combined acres of nuts, valued near $1 billion, approaching harvest. To promote worker and community safety during the harvest season, UCCE Tulare County joined with the Kings County Farm Bureau and the Tulare County Farm Bureau to host a Nut Harvest Safety Seminar at the Kings County Fairgrounds on July 19, 2017. The event, conducted in both English and Spanish, attracted over 100 attendees. Due to positive feedback and consistent annual attendance, the program has been offered for three consecutive years. Additional program sponsors include American Pistachio Growers and State Compensation Insurance Fund.
Topics covered include equipment and road safety, as well as chemical safety and prevention of heat stress. Course content was presented by Officers Chris Tuttle and Luis Guillen, California Highway Patrol, Martha Sanchez, Department of Pesticide Regulation, and Joe Zavala, Patrick Taylor, Paul Williams, and Annette Casares, State Compensation Insurance Fund.
Photo Credit: Barbara Martin, Kings County Farm Bureau Community Relations Coordinator
Photo Captions:
Photo 1. Annette Casares led discussion on equipment safety.
Photo 2: Officer Chris Tuttle educated attendees on the influence of alcohol consumption on physical performance.
Photo 3. UCCE Farm Advisors Elizabeth Fichtner and Mohammad Yaghmour assisted with advertisement and registration.
Photo Credit: Barbara Martin, Kings County Farm Bureau Community Relations Coordinator
