- Author: Lynn Wunderlich
When cutting into the spurs, we see green tissue. But when some of the buds (those not pushing at all) are dissected, the primary bud appears brown-indicating dead tissue. Many of the growers told me that they think this is due to fall frost-and they are right!! (although I admit I was slow to believe it until I looked at the data)!
A look at our fall temperatures and corroborating news from our friends in Lodi agree: unusual early November temperatures in some locations dipped into the low 20s. This occurred at Amador stations and in Calaveras, but not in ElDorado county.
What confuses the situation at first glance is that not every vineyard is affected-and some are more severely affected-those that are dry farmed and certain varieties like Zinfandel- than others. Furthermore when we cut into the cordons of some vines, trunk disease is evident. Stress, from drought and often made worse by disease or root damage that further
To help foothill growers understand what happened and what to do about it, I invited Kaan Kurtural, UCDavis Viticulture Specialist, and Akif Eskalen, UCDavis Plant Pathology Specialist, to a field day (the first in person meeting held since Covid!) at Don Potter's vineyard on May 26.
Kaan explained that what we are seeing in the foothills in not unique-many vineyards in California are
Kaan suggested the grower avoid fertilizer this year, since the vine's color is good, and need only sucker up to knee high to allow for herbicide applications to the berm. Irrigation is critical this year (as always), and will help grow a canopy that will "feed" the structure of the vine. And while crop is very light this year, the good news is that the vines will recover for next year. Cutting the irrigation by early September (or after one post-harvest irrigation in a "normal" year) will help the vines get ready for cold temperatures.
Kaan clarified that 110R-a popular rootstock used in the foothills-is considered "drought tolerant" because it doesn't completely evacuate water from it's vessels-it limits root "leakiness" under drought. 3309 is considered the most cold tolerant rootstock; and scions on 3309 always come out last since the rootstock doesn't "wake up". So, the rootstock can influence the scion, and the scion also will have an effect on when bud break occurs. Much to discuss again about rootstocks!-added attendee Tia Russell, Duarte nursery. Indeed-we will visit this in the future...
Akif Eskalen then talked to the group about trunk diseases, since the symptoms of trunk disease, poor shoot growth, can be confused with cold, dry weather issues; and, when investigating the poor growth this year, many vines with trunk disease were found incidentally. The fungi responsible form spores in the winter
Akif and his lab have worked on testing many pruning wound protectants that are sprayed onto the pruning wounds soon after the cut is made. One of those that looks promising is Bio-Tam, a formulation of beneficial fungi called Trichoderma. The Bio-Tam can be applied using a sprayer-no hand painting of wounds!
All in all, another challenging year for grape growers. Many are re-evaluating their operations to look for cost savings. Thankfully, as Kaan said, "grapevines are very hard to kill", so if growers can ride out the season, the vines will continue to be there for us to nurture, harvest, and enjoy!
- Author: Lynn Wunderlich
Mike McGee grows Christmas trees in El Dorado county and has been using stump culture on his 19 acre Choose n' Cut Farm for 36 years. According to Mike, stump culture reduces the time to harvest for a White Fir from 8-10 years to 5-7 years. One stump can provide as many as eight harvested trees.
If you want a Christmas tree from McGee Tree Farm, you'd better plan on getting it early. Located at 3,000 feet elevation
For those of you who think growing Christmas trees is as easy as planting a few conifers and forgetting about them, beware. Christmas tree production and stump culture takes work to produce a good looking tree. The cut, number of nurse branches, and selection of final tree sprout all affect the resulting success and tree quality. McGee goes back to each harvested stump in January and recuts the stump using a sharp saw to produce a clean cut. He then paints the stump using a 4 inch roller and an elastomeric coating, which is dense and will stretch. The coating helps to prevent the stump from rotting until the tree's nature sap overgrows it, sealing the stump.
The bigger the tree stump, the more nurse branches that are left. Typically this means leaving 10-12 branches around a white fir. New trees will grow up from either a nurse branch limb that turns up-not desirable due to the bend in the bottom- or a new sprout which will grow straighter, and is therefore more desirable than a tree grown from a turned up limb. The limbs fold up and shade the cut stump, nature's way of protecting the cuts that heal better when they have shade.
“Every tree is a perfect tree”, McGee once told me, who actively grooms his trees to keep the farm looking neat. Stump culture work is best done during the dormant season when branches are still pliable and green, before the summer heat. In this way, cut branches are easy to pick up off the ground by hand, before they are dried out and too prickly to handle.
“On my farm, everything is an experiment”, McGee told me. “Growers have to try it and find out for themselves. Maybe what works for me won't work the same for them.” Opening a week early this year to thin out the crowds during Covid-19, the full parking lot at McGee Tree Farm tells me this experiment is working just fine.
- Author: Lynn Wunderlich
UC Cooperative Extension, UCIPM, and the Spray Application Pest Management Alliance Team, with support from California's Department of Pesticide Regulation (DPR) Pest Management Alliance grants program, have developed a comprehensive online course for calibrating air blast sprayers!
Co-authored by myself and my colleague Franz Niederholzer, UCCE Farm Advisor in Colusa/Sutter/Yuba counties, this unique course is for anyone involved in spray decision making in perennial crops (trees and vines). Calibration is the process of setting up, maintaining, and rechecking a desired spray volume, measured in gallons per acre. It is the basis for a safe and effective pesticide application and is used by every grower-conventional to organic-who uses pesticides in their crop to help manage pests.
The course is organized into 5 modules:
- Why proper calibration is critical for your operation's success.
- Equipment: Parts of an axial fan* air blast sprayer.
- The calibration formula-how to measure the variables and do the math.
- Spray drift: droplet size, fan speed, weather, and how to manage.
- Spray team communication.
*We are working on a venturi (air-shear) sprayer module option which should be available soon.
- 2.5 California DPR CE credits have been approved (2.0 other, 0.5 laws). You must complete all of the course modules and pass the final exam with at least 70% to receive your CEUs.
With the support of DPR's Pest Management Alliance grants, this course is now available for FREE, until December 31, 2020.
You must have an account first in eXtension campus (available without
- Author: Lynn Wunderlich
Smoke taint in wine is defined as a lingering retro-nasal character (some describe as licking an ashtray-yeck!) and is not to be confused with “tobacco” flavors some grapes and wines may impart. White wines, which are less complex than reds, often show smoke compounds more since the offending smoke cannot "hide" in the oak or wine matrix. When you taste a wine, saliva picks up the smoke compounds with the other flavors. Interestingly, approximately 20-25% of wine drinkers can't pick up smoke in a tainted wine.
How does smoke taint a wine? When lignin, found in woody plants, is burned, volatile phenols (VPs) are released that absorb to grapevine leaves and berries. The VPs are absorbed through the berry skin and become BOUND inside. So, there are both FREE and BOUND volatile phenols in grapes affected from smoke exposure. For the wine industry, predicting smoke taint is tricky. The amounts of VPs present in smoke affected grapes are not related; there may be little to no
What's a grower to do? While washing ash off of fruit may help with flavors directly from ash, washing will not reduce smoke taint. And, so far, there are no known vineyard treatments (sprays) that have been shown to reduce taint. Spraying anything with a spreader/sticker adjuvant, even oil, during a fire event may even increase smoke taint uptake. Possibly the best thing a wine grape grower can do is get clear on their winery contract with relation to criteria for rejection, and insure their crop against possible losses, from smoke taint.
So far, most of the 2020 wildfires are far from foothill vineyards. And, since most of the taint research is related to "fresh" smoke (in close proximity to an active fire), I'm hopeful that 2020 foothill wines will escape with little smoke taint. Years ago, after the 2013 Rim Fire that burned in Tuolumne County, I visited Yosemite Cellars owners Cheryl and Ron Harms. They boldly made a Rim Fire Red with smoke tainted fruit from that vintage. Cheryl said for a time, it was a favorite with young wine drinkers. They loved the smokey flavor, reminiscent of an expensive Scotch, she said.
- Author: Lynn Wunderlich
The Daane lab joins Houston Wilson and other researchers on a nationwide search to confirm the three cornered alfalfa treehopper as a red blotch vector and/or identify other insects that are spreading the disease. Part of that work includes sampling for suspect insects using the D-vac and yellow sticky traps in vineyards where red blotch spread is evident. The trap count information is used to understand the life cycles of these potential vectors. Wilson, who was one of several speakers covering red blotch research progress during my 2020 Foothill Grape Day, recently published a newsletter on his work of the seasonal ecology of the treehopper in North Coast vineyards. Our foothill monitoring will help us understand if the insect's life cycle is similar here as compared to what is known to occur in the cooler N. Coast.
And no, those vineyard fall colors are not a good thing! This is the time of the year when GRBaV symptoms become evident in red varieties in the vineyard-the characteristic red "blotches" on the leaves for which the disease is named begin to show in summer and become more visible as harvest nears and the season progresses. (Note: the disease affects both white and red varieties. In whites, the "blotches" are yellow and more difficult to see). While diseased vineyards turn red, healthy vines remain green, then gold, in fall.
Thanks to the hard work of those like McCalla and Flores, even during this time of the pandemic (and wearing masks while working outdoors in summer heat is not fun, let me tell you), we will get closer to solving the red blotch mystery.