- Author: Oleg Daugovish
We have many highly salt sensitive crops in Ventura County: strawberry, avocados, blueberries. Rainwater, the purest kind, is excellent for leaching salts, but, in years with low rainfall, salt accumulation and resulting toxicity is a big concern.
Plant reaction to salts varies among varieties, stages of growths and environmental conditions and, perhaps most importantly, with the type of salts that they are exposed to. We typically determine salinity of water and soil by measuring Electrical Conductivity (EC): the more salts are present the greater is the capacity to conduct electric current. In fact, there are guidelines for most crops that show at which EC level you would expect negative effects on plant growth and productivity. Yet there seems to be a discrepancy between the guidelines and what actually happens in the field. For example, University of California (UC) guidelines suggest that strawberry injury and yield reductions can occur at EC=1 dS/m. However, in several Ventura County fields we have healthy productive strawberry in soils with EC >4 dS/m. These large differences in tolerable EC levels result from the fact that the guidelines were developed using sodium chloride, while Ventura county soils/waters most frequently have calcium and sulfates as primary components of EC. Recent studies at UC Riverside showed the specific negative chloride effect on strawberry fruit production, while studies elsewhere have documented that sodium can also be more harmful than other ions such as calcium and potassium. Because we have calcium-rich soil, and even irrigation water often contains calcium sulfate, our crops can manage well even with EC levels well above 1 dS/m. In fact calcium and magnesium help to counteract the negative effects of sodium in the soil salt solution.
In a demonstration, we wanted to show that a very salty water (EC=20 dS/m) will have different effects on mature strawberry plants depending on the ion composition of the salts in that water. Indeed, after four days of watering with sodium chloride solution, the plants had severe injury symptoms and were dying. However, the same salt concentration of potassium sulfate only resulted in slight marginal leaf burn and mild stunting. Plants irrigated with distilled water (that imitated rain water) looked perfect, of course.
The important points of these demonstrations and field evaluations were:
- EC values in water or soil analyses only show total salinity and one needs to look at specific ions in the report to evaluate the potential effects on sensitive plants.
- Sodium and chloride are a lot more damaging that potassium and sulfate and we’re planning to evaluate several other salts and develop realistic thresholds for safe strawberry production in their presence.
- At high concentrations in the root zone fertilizers (such as potassium sulfate, a ‘safer’ salt) can injure plants and reduce their productivity
- Typical irrigation with drip lines placed between planting rows does not affect salts in the root system, unless excessive amount of water are applied to induce leaching.
- Author: Chris M. Webb
UC Farm Advisor Oleg Daugovish will hold an Irrigation field day Thursday, April 19 from 9:00 am to 11:15 am.
Scheduled topics include:
- Update on conditional waiver and requirements for irrigated lands in Ventura County
- Evaluation of three differing irrigation regimes in California strawberry
- Salts and soil analyses in strawberry beds under different irrigation regimes
- Soil test results interpretation and corrective management
- View experiment plots onsite
VCALIG educational credits have been requested from the Los Angeles Regional Water Quality Control Board.
There is no cost to attend. If you have questions, require translation into Spanish, or to register please contact Oleg Daugovish at 805.645.1454 or odaguovish@ucdavis.edu. More information can be found on the agenda.
In the event of rain, the meeting will be held at the UCCE Conference Room located at 669 County Square Drive in Ventura.
- Author: Chris M. Webb
On April 20, 2012 California State University, Channel Islands will host a symposium titled, ‘Agriculture in the Golden State: Challenges in Feeding California in the 21st Century.’
Strong and sustainable agricultural production is important to all of us, and to our future. UCCE Ventura County researchers Oleg Daugovish and Ben Faber will speak at the symposium.
From the event organizers:
"California is the nation’s top agricultural producer generating over $30 billion annually. However, the ability of growers to feed California and beyond is continually being challenged by the introductions of new insect pests, drug resistant pathogens, and environmental concerns at the urban-agricultural interface. CI sits within one of the top ten agriculturally important counties in California, which produces much of the States’ strawberries, raspberries, citrus, and avocados. Given our location, it is important that everyone learn about the issues affecting agriculture locally and statewide."
To learn more about this year's symposium, or to register please visit this page of the CSU Channel Islands website.
- Author: Chris M. Webb
On the morning of Tuesday, April 3 Oleg Daugovish will hold a fumigant alternatives and soil-borne pathogens field day. This event will be simultaneously translated into Spanish.
Scheduled topics include:
- Regulatory update on soil fumigation
- Alternative fumigants research update
- Soil borne pathogens Macrophomina and Fusarium: biology and management in strawberry
- Advances in steam application technology for soil disinfestation
- Update on Anaerobic Soil Disinfestation studies
- Research update from the California Strawberry Commission
- In-progress results from experiment on display
- View the plots with fumigant alternative treatments
Continuing education credits have been approved from DPR (Department of Pesticide Regulation).
Lunch and refreshments will be provided. Additional details can be found on the agenda.
To insure your participation, or if you have questions, please contact Oleg Daugovish at (805) 645-1454 or odaugovish@ucdavis.edu.
- Author: Chris M. Webb
The California Weed Science Society (CWSS) is offering scholarships to support undergraduate and graduate students with an interest in weed or invasive plant management.
To be eligible for these awards the student must be pursuing a degree at an accredited 2-year college or 4-year university in California and be enrolled through the spring 2012 term. Preference will be given to students that demonstrate a strong interest in weed or invasive plant management.
All awards will be given at the discretion of CWSS.
CWSS Scholarships: Academic scholarships up to $2000 are available for undergraduate and graduate students.
- CWSS Internships: The internship is an award of $3000 for an 8-week full-time internship with a University of California farm advisor or other off-campus research personnel with responsibilities in weed or invasive plant management.
- CWSS Undergraduate Research Awards: The undergraduate research award is a grant up to $2000 to support a research project related to weed or invasive plant management.
All applications must be received by April 1, 2012.
For additional information and instructions on how to apply contact Oleg Daugovish at odaugovish@ucdavis.edu.