The holidays are here Fodder Family! For those of you who enjoy a living Christmas tree, perhaps you will try a stump cultured tree this year from one of the many foothill Christmas tree farms.  I often am asked which is more environmentally sustainable, a live Christmas tree or an artificial tree?  A Canadian study found that REAL trees, though not perfect, have fewer impacts on climate change and resource depletion than artificial trees.  Stump culture is the practice of cutting a tree leaving the stump with whorls of lower branches to regenerate new sprouts that will grow into a harvestable tree.  It is an old technique (coppicing, a similar practice used in European woodlands, is thought to be thousands of years old) that can provide Choose n' Cut Christmas tree growers with several harvests off of the same stump, saving time and money, and using fewer resources.  Some consumers like the stump culture concept since they consider the tree is not “killed”, it is “renewed”.  

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

the farm sells out every year, often just after the Thanksgiving weekend.  Mike, who learned from his Dad Omar McGee-a Christmas Tree grower pioneer in the region, grows a wide selection of White, Noble, ‘Silver Tip' (Red), Canaan, Nordmann and Turkish “true” fir (Abies sp.), and Douglas fir (Pseudotsuga sp.), all using stump culture. 

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.   

Nurse branches, left to providephotosynthates to the growing sprouts, are trimmed back but not completely removed as the sprouts grow up.  Omar McGee referred to this as leaving a “bird's nest” owing to the look of the branches surrounding the bottom of the stump.  Mike uses his experience to go through a process of elimination in determining which growing sprout to keep and when to cut the others, as competing branches and sprouts are gradually removed or cut back.  He often begins by asking himself “What don't I want?” to prune off competing sprouts and eliminate misshapen stump trees.  

A happy customer measures a 12 foot white fir grown using stump culture.

 

 

 

 

“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.

 

Fodder Farmers, Applicators, Supervisors and PCAs! Do you need continuing education credits for your license renewal? Or do you just want to increase your knowledge on your air blast sprayer? If so, then I have something for you!

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 interactive course, developed by UCIPM online course design experts Petr Kosina and Cheryl Reynolds, is presented in narrated text, photos, video clips and animation to engage you!  You will learn the basic principles of spray calibration, review the basic components of a sprayer, perform calculations needed for calibration, and take a look at how factors such as droplet size, nozzle type, and weather conditions influence drift and spray coverage. This course also explains the conditions for pesticide applications under the 2018 Pesticide Use Near Schoolsites regulation.

 

 

 

The course is organized into 5 modules:

1. Why proper calibration is critical for your operation's success.
2. Equipment: Parts of an axial fan* air blast sprayer.
3. The calibration formula-how to measure the variables and do the math.
4. Spray drift: droplet size, fan speed, weather, and how to manage.
5. 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

charge).  Create a new account or simply use your existing Google or Microsoft account for login.

 

 

Fodder Family! There was a time, not too long ago, when California wine growers and geeks scrunched up their nose and asked "Smoke taint, is that really a thing?"  Back before the 2013 Rim Fire (257,314 acres burned), the 2014 King Fire (97,717 ac), the 2015 Rough Fire (151,663 ac), the 2016 Chimney Fire (46,344 ac), the 2017 Thomas Fire (281,893 ac), the 2018 Mendocino Complex (459,123 ac), the 2019 Kincade Fire (77,758 ac), and most certainly before this horrific year of wildfires-SCU, LNU Lightning, North and August Complex Fires (over 2 million acres burned).  Back before Purple Air was on everyone's phone like the weather and when home air purifiers were still on the shelf at the local big box store.  Back before Napa's ETS labs had a 40 day backlog for processing smoke taint samples and the term "smoke" was associated with a pleasant tobacco like character picked up in complex red wines.  But, like climate change, smoke taint has been creeping in as an issue we can no longer ignore.  The Aussies knew it first, of course. And now, armed with $2 million of newly awarded research funds, West Coast USDA and University researchers have added winegrape smoke taint to their list of critical wine industry issues to address.  Anita Oberholster, our UCCE Enology Specialist at UCDavis, is one of the researchers doing just that.  Anita recently shared some critical information on smoke taint during the California Alliance of Winegrape Growers (CAWG) hosted webinar on Wildfire and Smoke Exposure Events. 

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

FREE VPs and a lot of BOUND VPs.  The BOUND VPs are extracted and released during winemaking and can not be detected before wine is made.  This is why it is recommended that winemakers concerned about the possibility of smoke taint make a small micro-fermentation batch of wine and test that, as well as testing berries, for volatile phenols of smoke taint.  There are seven FREE VP compounds available for testing in berries and six BOUND VP precursors. While Anita's research has shown good correlation between guaiacol, one of the VPs found and tested for in berries, and full smoke VP panels, she cautions that this work is based on a small number of samples and more research is needed.

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.  

 

Entomologists have a unique toolbox of gadgets designed to trap and collect otherwise hard to nab insects.  Beating, sweeping, sucking, and carefully brushing, these scientists have no lack of creativity when it comes to collecting what most people can't even see.  Yet these collections are critical keys to unravel the mystery of crop-threatening disease, where insects often play the role of "vectoring", or spreading, the pathogen.   Enter the "D-Vac", a modified leafblower designed to suck up insects from otherwise hard to get to places-like grapevine canopies!  Recently I joined Kelsey McCalla, Post-doctoral researcher, and Kristen Flores, Lab manager and Junior Specialist, both hailing from UC Specialist Kent Daane's lab in Berkeley, on the hunt in the foothills for clues to the insect vectors responsible for transmitting Grapevine red blotch associated virus (GRBaV).  I'm so happy to have engaged the Daane lab to include our foothill region in the nationwide collaborative research to understand the spread of this disease.  The research is critical to managing it.

Red blotch symptoms in Vermentino, a white grape variety

GRBaV, or simply "red blotch", the DNA virus identified in 2011 causing disease in grapes that was a mystery for so long, continues to vex the research community.  While tremendous progress has been made on understanding the effect of the disease on delaying grape berry ripening and physiology, we still have not confirmed a vector or vectors, as it may be, responsible for the spread of this disease evident in so many of our vineyards. Awhile back you may remember my post about the exciting discovery by Bahder, Zalom and Sudarshana that the three-cornered alfalfa treehopper was a red blotch vector.  Oddly enough, that greenhouse study has not yet been replicated by other researchers seeking to duplicate, and confirm, the treehopper as a red blotch vector. 

Kristen Flores takes down yellow sticky traps

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.

I spy with my little eye...a three cornered alfalfa treehopper sucked up by the D-vac!