- Author: Lynn Wunderlich
Brian Leahy, Dept. of Pesticide Regulation Director, was a keynote speaker. Brian discussed proposed regulations (they're not final yet) concerning pesticide use around schools and the forthcoming requirement for annual field worker safety training to begin in 2017. (Currently annual safety training is required for applicators, and field worker training is required every 5 years or when the field worker is new.) DPR has just updated the pesticide safety leaflets for field workers (A-9 series) and pesticide handlers (A-8 series). You can go to get a PDF of the English A-9 here, or the Spanish A-9 here. And to the English A-8 here, or the Spanish A-8 here. These should be filled out and posted.
Parry Klassen, Exec. Director for CURES, discussed water quality and compliance with the Central Valley Regional Water Quality Control Board's irrigated lands program. All growers who apply irrigation to their commercial crop land are required to comply, and one way you can do this is by joining your regional coalition (hopefully everyone out there is already a coalition member). If you need more information on where your local coalition is (there are several covering the watersheds within the Central Sierra region), you can contact me or click here.
My colleague Franz Niederholzer, who many of you have heard speak at my spray tech meetings, always does an excellent job of presenting the practical benefits of sprayer calibration and targeting the spray. Franz emphasized that spray applications during the dormant season, when trees have little to no canopy, are a different animal and require adjustments to fan speed and/or travel speed to avoid drift.
I spoke about the drift control nozzle choices growers have when spraying weeds, a thing we might be doing a lot of this coming spring because of all the rain germinating all of those pesky weed seeds. I demonstrated, with the help of Alan of PBM Sprayers, air-induction (AI) and turbulence chamber nozzles. These nozzles will deliver the same flow rate as a standard XR fan nozzle, but the droplet sizes these AI and turbulence nozzles produce are much larger than the fines of a standard XR. Larger droplets drift less!
- Author: Lynn Wunderlich
California Dept. of Water Resources climatologist Michael Anderson kicked off the meeting by attempting to answer the question: "Is the Drought over in California?" The answer is "no", since, even with the rainfall we've received so far, we are not yet seeing near-average run-off accumulating in our reservoirs. This is the result of 4 years of drought and what it takes to actually refill soil profiles enough to accumulate run-off. Michael expects the current El Nino to continue to kick in strong, especially in February, with above average precipitation expected. The freezing elevation level is going to be a key component of whether we accumulate enough snowpack to alleviate our drought in 2016.
Amos Naor, a researcher from the Golan Research Institute in Israel, discussed why plant based stress measurements (stem water potential (SWP) measurements obtained with a pressure chamber) are valuable even when we have soil based sensors and ET0 information. His research in apples, nectarine and pear have shown that the pressure chamber measurements are much less variable than those obtained by dendrometers or tensiometers; and SWP measurements respond more quickly to changes in irrigation regimes, giving the user quicker feedback. Soil moisture variability can be quite large, especially in drip irrigated fields. But the pressure chamber measurements are useless, Naor said, without an established threshold for when growers should use the information to irrigate-this is the key and one I hope to work with foothill grape growers to establish for their blocks. Naor also found that apple crop load can also effect stem water potential measurements-the higher the crop load, the more stressed. I'm uncertain if research has shown this is also true for grapes.
Ken Shackel, UC Davis Plant Science professor and recognized "father" of SWP measurements, described how much
Several speakers addressed irrigation water quality, especially with regards to salinity, an issue that, thankfully, foothill growers don't have to deal with. A number of techniques and models used to estimate and measure soil properties affecting soil water infiltration were discussed. The Israelis have found treated wastewater a valuable and effective water resource, although long term use of wastewater presents challenges due to soil degradation.
The meeting concluded with several grower panels, organized by commodity. Susan Farrington, of Villa Toscano winery and vineyard located in Amador County, accepted my invitation to participate in the wine and table grape grower panel. Susan and her team have experimented this past year with using the pressure chamber, and also use neutron probe soil moisture measurements to make irrigation decisions. Like many foothill growers, they are plagued by problems of iron in their water. After years of sending crews in to change drippers, Villa Toscano is installing a chemical injection system to help keep the iron in solution and hopefully improve their irrigation system's distribution uniformity. Irrigation system distribution uniformity is critical for irrigation efficiency, and is a topic we will revisit in the future. Stay tuned!
- Author: Lynn Wunderlich
The press of the recent resurgence of Pierce's Disease (PD) in North Coast grown grapevines has gotten some foothill grower's attention. But I have never seen a case of PD in grapes grown here. Why? We think that grapevines grown in the colder climate of the foothills benefit from a little understood phenomenon called "cold curing". What is this "cold curing"? The idea is that freezing temperatures cause vine stress that triggers an increase of some phenolic compounds in the xylem, or water conducting tissue. PD is a disease caused by the bacterium Xylella fastidiosa that resides in the xylem. But in cold-cured vines, we think the increased levels of xylem phenolics interfere with the growth of the Xylella bacterium such that disease
Cold curing phenomenon has been studied by the late UC Davis plant pathologist Bruce Kirkpatrick, who contributed much to the science of plant diseases like PD. Bruce, along with Richard Bostock (UCD Plant Pathology) and Andy Waterhouse (UCD Vit and Enology) did work back in 2009 to try to identify the compounds in grape xylem sap responsible for cold curing. That work, funded by the American Vineyard Foundation, was continued in 2010 by Waterhouse, visiting scholar Blandine Cretin, and Mauri Anderson, who works in Andy's lab. I collaborated for a part of the study by locating El Dorado growers to provide five "cold" vineyard sites for comparison (same variety, clone and rootstock) with warmer climate sites in Yolo county that were also sampled. We sampled the canes of vines seasonally, and the Waterhouse lab analyzed the cane xylem sap for phenolic compounds. We looked at Cabernet Sauvignon, Barbera, Pinot Noir, Petite Sirah, Chardonnay and Merlot. The Waterhouse group focused on the 'flavonol' group of phenolics, and found that indeed, the vines grown in colder El Dorado county had 50-120% higher yearly concentration of flavonols than their warmer counterparts grown in Yolo, as reported in a poster presented at the American Society for Enology and Viticulture (ASEV) conference in 2012 (Anderson et al. 2012). Unfortunately, this work was not funded further, so the exact mechanism of cold-curing remains unknown. Interestingly, the current resurgence of PD in the North Coast region is thought to be associated with last season's mild winter temperatures-affecting either the vectors and/or the growth of Xylella.
- Author: Lynn Wunderlich
A few of you growers out there have told me in the past "Lynn, if you want it to rain, hold a field meeting!"
So it is in this spirit that my very first blog post forecast a warm winter right before the major snow dump in the Sierra over the holidays! Indeed the Department of Water Resource's (DWR) California Data Exchange Center (CDEC), my go-to site for up to the minute hydrological information, shows the latest snow data for the American River Basin range sites at 52 to 67 inches of snow! This includes the snow stations at upper and lower Carson Pass, Aloha and Echo lakes, and Tamarack flat. The snow currently has an 18-30% water content and is at 31-60% (depending on the location) of April 1 historic records. According to the CDEC, the April 1 historic average is based on measurements from 1951-2000.
A little closer to home, all of that snow in the Sierra amounted to a good drenching of rain to ring in the New Year. The following stations recorded December rainfall amounts:
Camino CIMIS: 7.41in.
Diamond Springs CIMIS: 6.99 in.
Plymouth CIMIS: 6.49 in.
And our PMI stations recorded December rainfall totals:
Lava Cap PMI: 9.56 in.
Fairplay PMI: 5.8 in.
Amador Eagle: 6.16 in.
Amador Renwood: 5.47 in.
Calaveras Ironstone: 10.17 in. (Wow! this one surprised me, as Calaveras often has lower precip. than further North).
A very good start to the new year. Let's hope the cold weather sticks around.
- Author: Lynn Wunderlich
In years past, I've collaborated with several local Christmas tree growers and Pacific
Merry Christmas and Happy Holidays everyone!
/table>