Ventura County UCCE Staff Research Associate Maren Mochizuki shares current research which hopes to provide an organic method to kill plant pathogens and weed seeds in production agriculture.

Synthetic chemicals to fumigate soil have been used in some production agricultural systems, to kill plant pathogens and weed seed before planting crops.  Here in Ventura County, this is a common practice for strawberry production.  Joji Muramoto, Associate Researcher at UC Santa Cruz and Oleg Daugovish, Ventura County UCCE Farm Advisor and Maren Mochizuki, Ventura County UCCE Staff Research Associate are investigating an organic method to treat soil before planting by creating anaerobic, or oxygen-free, conditions.  Most organisms, including plant pathogens, cannot survive without oxygen.

We incorporated rice bran from the Central Valley into the soil as a carbon source to trigger microbial activity.  To test the applicability within a strawberry production system, we created planting beds topped with plastic mulch.  The beds needed to be well-sealed to ensure no air leaks that could add oxygen.  Using drip irrigation, we added sufficient water to the beds to fill all soil pores, further pushing out any air/oxygen.  Each day we monitor the soil environment with sensors measuring soil water content, temperature, and the level of anaerobic conditions and add more water as needed.  At the end of three weeks, we will evaluate the survival of a significant plant pathogen, Verticillium dahliae.

ASD Sensors

ASD beds

Below you will find a summary of what we did last month. By no means does this summary capture all that we accomplished or began, but it gives a nice glimpse of what we do.

1. Research Activities

This is a sampling of the research activity conducted in June.

• Established an experiment testing an herbicide for management of yellow nutsedge, a major weed in production agriculture costing Ventura County growers thousands of dollars annually to control.  For more information on nutsedge and its impact, please read previous blog posts.
• Established an experiment testing an organic method of soil disinfestations by creating anaerobic conditions in strawberry beds and monitoring effects on plant pathogen Verticillium dahliae.  This research makes direct contributions by addressing the issue of seeking alternatives to fumigants such as methyl bromide.
• Finished four field trials that evaluate management options for four pests detrimental to the strawberry industry. Management strategies included physical, thermal and chemical control measures.
• Initiated a project with CA Dept. of Food and Agriculture and local strawberry growers to introduce a biocontrol agent for Lygus bug, the #1 insect pest for strawberries and significant for other row crops.
• We are continuing research on minimizing irrigation needs for strawberries, which addresses both economic and environmental issues.

2. Educational Activities

This is a sampling of the educational activities conducted in June.

A. Grower/Clientele Education

• Jim Downer presented sessions at a regional meeting on nutrition of palms and diseases of shade trees. 100 in attendance.
• Ben Faber participated in a program at UC Riverside on Asian Citrus Psyllid (ACP), which poses a significant threat to the citrus industry.  It was clear that fruit from affected areas coming into Ventura County packing houses could be a host for the psyllid.   Ben spoke to Henry Gonzales about this and as a result the import of lemons from Imperial County (quarantine area) to Ventura for repacking has been restricted to reduce the likelihood of introducing the pest here.   Both Faber and Rose Hayden-Smith participated in a meeting that brought packers together with the Ag Commissioner, where they hammered out a solution/agreement.
• Ben Faber delivered two grower workshops, one on avocado irrigation and the other on techniques to reduce surface water contamination.
• Rose Hayden-Smith presented her research on gardening and community development at a City of Minneapolis/IATP event attended by more than 100 people.  She also presented a two-hour workshop on Victory Gardens, past and present, to a sold-out audience in Minneapolis.  She offered a talk on gardening trends and public policy in Oxnard to an audience of 75.  Earlier in the month, she facilitated an Urban Agriculture Symposium for 175 people in Chicago, which generated public policy recommendations for the USDA.
• Monique Myers presented the Ventura County RESTOR Project at the National Marine Educators conference in Monterey.
• Monique Myers organized a focus group for Ventura City/County Planners and city storm water experts addressing low impact development and emergency safety issues.
• 4-H staff trained staff at Pt. Mugu and Port Hueneme Naval Bases in the basics of 4-H program management.  Also trained new 4-H club leaders.

B. Youth Education

• Monique Myers directed/facilitated the last of 8 RESTOR teacher/student field trips to Ormond Beach (~70 students per trip).  RESTOR is a grant-funded wetlands/ecological restoration program linking teachers and youth with science education and community service opportunities.
• Monique Myers led a RESTOR Project field trip with 28 student essay contest winners and their teachers on the NOAA research vessel Shearwater.
• 4-H held a Science, Engineering and Technology Day at the military base.
• 4-H held events at both military bases kicking off the new 4-H programs there.

3. Publications

• UCCE staff. Launched a UCCE/Farm Advisor blog  http://ucanr.org/blogs/venturacountyucce/
• UCCE staff.  Produced a new UCCE/Farm Advisor educational brochure.
• Daugovish, Oleg and Maren Mochizuki submitted a paper to HortTechnology detailing the potential for carbon dioxide to be taken up by raspberry plants to boost productivity instead of being released to the atmosphere as a greenhouse gas.   We hope this method will gain attention as one of the ways to tackle a global issue on a local scale.
• Downer, James and Maren Mochizuki. 
  • Two manuscripts accepted to HortTechnology.
    • Pruning landscape palms
    • Diseases of palms.
• Downer, James.  Landscape Notes – Landscaping Trees.  Available at http://ceventura.ucdavis.edu/newsletterfiles/Landscape_Notes17660.pdf
• Downer, James: Article on mulches in Western Arborist Magazine.
• Downer, James,   Article on a new pest, the Date Bug, in Southwest Trees and Turf Magazine.
• Faber, Ben and Newman, Julie, et al.  2009.  Re-evaluation of the roles of honeybees and wind on pollination in avocado.  J. of Hort Science and Biotech (84)3:255-260.
• Faber, Ben and Newman, Julie, et al. 2009. Farm Water Quality Planning Project – From Education to Implementation.  Statewide Conf., Sacramento April 27-30.
• Faber, Ben. 2009. Cherry Vinegar Fly in Ventura County.  VC Farm Bureau Newsletter 41(7): 2-3.
• Hayden-Smith, Rose, et al.  Proceedings of the Chicago Urban Agriculture Symposium.  Includes policy recommendations for the USDA and other cities relating to urban agriculture. http://www.chicagobotanic.org/wed/index.php
• Myers, Monique, et al. Differences in benthic cover inside and outside marine protected areas on the Great Barrier Reef: influence of protection or disturbance history? was published on-line (in advance of printing) this week in Aquatic Conservation. (http://www3.interscience.wiley.com/journal/84503925/issue)
• Newman, Julie.  Wrote an article for Greenhouse Management & Production, a national grower magazine
• Monique Myers and Sabrina Drill won an Award of Merit from the 2009 Ecology Awards for their Quagga Mussel manual.

Ventura County UCCE Staff Research Associate Maren Mochizuki shares with us more information about yellow nutsedge, and what is being done to help minimize the problems it causes to local growers.

Managing yellow nutsedge costs local growers many thousands of dollars per year (see previous blog posting on yellow nutsedge for more information). Nutsedge is sharp enough to poke through plastic mulch installed on strawberry and vegetable beds. Once a shoot germinates through plastic, it can produce underground storage structures for reproduction (tubers) so that even if the shoot is removed, many tubers remain to sprout into new plants.

Nutsedge through plastic

To block shoot germination and prevent the production of more tubers, we (Oleg Daugovish, Ventura County UCCE Farm Advisor and Maren Mochizuki, Ventura County UCCE Staff Research Associate, in collaboration with Reiter Affiliated Companies) installed mechanical barriers underneath the plastic mulch of strawberry beds, including Tyvek homewrap, landscape weed barrier mat, and a layer of recycled paper roll between two layers of plastic.

All of these barriers prevented germination of yellow nutsedge in commercial strawberry fields compared to control beds with no barriers, but the plastic/paper/plastic treatment has the lowest cost per acre. Minimizing production of yellow nutsedge tubers reduces weed-crop competition and costly hand-weeding, improving the grower’s bottom line.

Today our Staff Research Associate, Maren Mochizuki, will share with us a glimpse inside a recent day as our office works to better understand the growth patterns of the yellow nutsedge.

Yellow nutsedge is a difficult weed to control because the plant produces new shoots via underground stems called tubers (similar to a potato); a few plants can turn quickly into an infestation!  Costly and labor-intensive hand weeding has been the only means of management because current herbicides are not effective.

Strawberry bed with yellow nutsedge

To understand the underground growth of this weed, we (Oleg Daugovish, Ventura County UCCE Farm Advisor; Emmanuel Gonzalez, Ventura County UCCE Lab Assistant; and Maren Mochizuki, Ventura County UCCE Staff Research Associate) sliced a cross section of an infested strawberry bed.  We were hoping to answer the following questions: How deep are the tubers?  About how many tubers are produced from each shoot?

After cutting the cross section and pushing it onto a bed of nails to hold it, we were able to lift it onto the truck tailgate and drive it to a water source to wash a few cubic feet of soil from the nutsedge underground stem/root system.  We were surprised to find that the tubers were not as deep as we expected (no deeper than 8 inches) and we counted several hundred tubers from our cross section, or about 3 per plant.

Yellow nutsedge tubers

The research team has another multi-year study using mechanical barriers such as layering plastic mulch, then paper, and another layer of plastic prevents germination of yellow nutsedge in strawberry beds as they continue to develop ways to handle this problematic weed. The mechanical barrier study will be featured in tomorrow’s blog posting.