- (Public Value) UCANR: Promoting economic prosperity in California
Avocado Varieties like GEM, Maluma, and Future Varieties
& Rootstock Update
CAS/CAC/UC Seminar Series
Mary Lu Arpaia and Eric Focht of UC Riverside Botany will cover the horticultural characteristics of the Hass-like varieties - how they grow in different circumstances relative to ‘Hass'. Patricia Manosalva of UCR Plant Pathology will cover the avocado rootstock breeding program and the efficacy of root rot chemicals, new and old.
June 10, 9-11 AM, Wednesday. A virtual seminar, viewed on your own computer at home or work.
The registration page is here and it's free:
Evaluating claims of new products that could potentially improve yield and tree health is a daunting task. Every week I get calls and literature from people promoting fertilizers and techniques that "resist insects," "reduce salt levels in the soil," "increase crop quality," "release that natural fertility of your soil," and numerous other claims. There just is not enough time in the day to approach each and every one of these materials or techniques, even though some may, in fact, be promising.
So what does a grower do? You hear about a new product. It only costs $20 an acre to apply. Might as well fly it on all 50 acres. But then, how do you know it has done anything? What results do you have to compare it with? Last year's yield which was miserable? We know how variable avocado yields are, so last year's harvest may not be a good comparison.
When we conduct field trials, we assume a clear comparison is available to test the effects of the treatment. With field trials, there are usually small plots, repeated several times (at least three), and arranged in an apparent haphazard (random) fashion. The reason is threefold: 1) to account for variability in the field, 2) to prevent a systematic bias in favor of one treatment over another and 3) to see if differences in treatments are due to chance or to the superiority of the treatment.
How are observational trials different from replicated one? The big difference is that they are not replicated. Each treatment occurs only once, so we have no measure of the natural variability in the field or trees. As a result, we risk thinking we have a difference due to treatment which is actually due to field variability. Without replication there is no way to tell.
Let's examine this replication idea a little more closely. We had a frost trial where we applied copper or a water control spray to young trees in November. Copper is a noted bactericide and the idea was to control the frost-nucleating bacteria. Forty trees, randomly spaced in the orchard were sprayed with either a dilute copper spray according to instructions or water alone. We evaluated frost damage to the trees in January. The first counts showed 40% frost damage with the copper spray and 60% with the water alone. Great. Let's go out and spray the whole orchard next year with copper. However, successive counts showed 50% frost damage with the copper and only 30% from the water. In the end, there was no significant difference to trees that had been sprayed with either material.
These results show the natural variability in biological systems and demonstrate the disadvantages in looking at results from a non-replicated trial based on a single year. This becomes even more important when interpreting information from a trial site different from your own. If every grower sprayed a non-replicated treatment at their own ranch, the risk of coming to the wrong conclusion about that treatment at each location is still 50%. Just like flipping a coin. Is that worth spending money on?
As each of the variables (soil type, irrigation quality, management, etc.) increases, the risk of making a poor decision about a product or practice increases, as well. You can see that there are difficulties associated with relating information from a non-replicated trial based on a single year of data at a different location to your own situation.
How does someone go about evaluating a new practice or material at home without going through all the complications of a complicated research trial? Mary Bianchi, retired Farm Advisor in San Luis Obispo and I came up with a little checklist.
- Be conservative in your approach and critical observations. Resist the urge to spray the whole grove. Leave something, so that a comparison can be made. Preferably run a side-by-side comparison.
- Use consistent farming practices across all areas of the trial.
- Compare the new practice to one which is a standard for your operation.
- Don't bias your results by implementing the new practice where it stands to have the best effect anyway. For example, don't spray boron on the trees that always give a good yield.
- Run the test more than one year and in more than one location, especially if the new practice is costly.
- Talk to the industry and use the experience of others in different locations as a check on your own experience. A good place to swap ideas is at the California Avocado Society/CA Avocado Commission/University of California Cooperative Extension sponsored bimonthly meetings.
Research does not need to be complicated, but it needs to be thought out before hand with consistent data collection and given time. And time is critical, especially for nutrient studies and with a tree like avocado, that has a prolonged bloom with alternate bearing and usually more than one crop at a time. The effects of application timing at a given rate might not be determined for several years of crop yield. Persistence is the key to experimentation. Unless it's a pesticide trial, do you see results in the first year.
It's not really like this!!
Air Blast Sprayer Calibration
June 9, 3-4 PM
During this one hour live webinar, UCCE Farm Advisors Lynn Wunderlich and Franz Niederholzer will explain the importance of proper calibration and go through the steps of properly calibrating an air blast sprayer. This information is critical for PCAs, applicators, and growers of trees and vines so that pesticides are applied to the target crop at the proper application rate with good coverage and minimal drift.
One DPR CE unit (other) and one CCA CE unit (IPM) are pending.
Nozzle components from an air-blast sprayer being examined during a training class.
Efficient and precise irrigation management is critical if California producers are to maximize crop quality, conserve water, and protect the environment. The use of evapotranspiration (ET) estimates is a significant component of irrigation management. ET refers to the sum of water lost from the soil (evaporation) as well as that used by the crop (transpiration). While the California Irrigation Management Information System (CIMIS) network of weather stations derive daily ET values, there is a perception that CIMIS does not produce accurate ET estimates for all locations. This view is particularly prevalent in the canyons of Ventura County where weather conditions differ substantially compared to CIMIS locations. Since avocado and citrus thrive in these areas, it was concerning when it was determined that ET scheduling is not widely used.
That is, a Ventura County Resource Conservation District (RCD) review of California Department of Food and Agricultural State Water Efficiency and Enhancement Program (CDFA SWEEP) projects concluded that Ventura County growers substantially lagged their state-wide peers with respect to implementing ET-based irrigation scheduling (14% versus 44%).
RCD seeks to reverse the low implementation of ET-based irrigation scheduling within Ventura County by using simple, rugged on-site ET devices (atmometers) to determine on-site ET values. These on-site values will be compared to CIMIS values to determine local correction factors and develop refined ET maps for the canyon and valley areas. RCD will present these results at outreach events and provide workshops demonstrating how ET data, whether from CIMIS or on-site atmometers, can be used for irrigation management.
PHOTO: Atmometer Test/Calibration Site @ UC Hansen
Lemon growers are seeing good production this year, but the market for choice lemons has been ruined by COVID-19 food-service industry losses.
“We've seen 20 to 25 percent decrease in fruit movement, and that's mainly attributable to the decline in the food-service industry,” according to Ventura County lemon grower Will Pidduck.
Ironically, it is otherwise a good year for lemons in Ventura County. “We're growing great quality fruit. The quantity is great,” said Pidduck.
However, with the coronavirus pandemic forcing the closure of restaurants, schools, cruise lines and other commercial food-service operations, the market for an entire class and size of lemon has all but vanished.
“That's a big hit,” Pidduck said. As a fourth-generation citrus grower in the Ventura area, Pidduck also grows mandarins, oranges and avocados, but is primarily a lemon grower.
“A large portion of the choice fruit goes to the food-service industry. And without that industry, it's bad. The movement has slowed dramatically on the choice fruit,” Pidduck said. “We're still moving the fancy, the higher quality fruit. But for the choice and some smaller-sized fruit, it definitely slowed way down.”