Greetings Fodder Family! How have you been? Well, I hope!  I've been busy too and I've got stories to tell!

Over the years as Farm Advisor here (gosh, 19 years this October) my job has changed in many ways with the times.  Recently, I have answered more and more inquiries from those who own a parcel and are wondering about agricultural development or those who are looking to purchase.  The foothills, it seems to me, are becoming impacted by a growing California population and those who may be priced out of other locations and seek a rural lifestyle.

But the "what can I grow?" question, as I call it, is more complicated to answer than some anticipate.  The key is to not have any preconceived notions (this isn't the Valley nor is it the North Coast) and to be open to exploring the opportunities, and challenges, the foothill landscape offers.  The foothills are kind of like Nebraska, whose new slogan is "Honestly, it's not for everyone" (true!)

The first step to evaluating a property's suitability for agricultural development is to understand the natural resources that parcel offers.  The most important: soils, water, microclimate.  Enter an amazing resource...the Natural Resource Conservation Service (NRCS) Web Soil Survey! I recently received word that after 12 (or more) years of work, the Calaveras and Tuolumne county soil series maps have been added to our NRCS database and included in the Web Soil Survey (WSS).  Calaveras and Tuolumne had been the only 2 California counties for which the soils were not mapped previously.  This work, led by our local Tuolumne county NRCS office headed by Theresa Kunch and her team of soil scientists, represents a wonderful resource for anyone interested in land, for any reason.

Last fall I asked Andrew Brown, NRCS  Soil Scientist and one of the staff in the Sonora office, to help me explain local

soils while visiting a landowner.  While visiting his office, Andrew gave me a brief tour of their soil library, where samples of soil class types are stored (sort of like looking at a soil scientist's version of a pinned insect collection!) Each box has a sample of that soil series collected at each "horizon" (unique soil that changes with depth). This is like looking at what a soil pit dug with a backhoe would show you if you had dug to the bedrock of that series.  Soil color

The archived Red Apple soil series

and texture and the size and shape of soil particles give an indication of the soil's fertility.

Whenever I get the "what can I grow on my property?" question, I encourage the landowner to dig a soil pit to get a good look at their soils, BEFORE they plant.  Soil depth, texture and percent rock (some of the foothill soils have alot of rocks!) all contribute to a soil's water holding capacity.  Soil is, in some ways, a key to water, and water is a limiting factor in agricultural productivity.  Understanding the soil will help greatly with planting decisions, such as spacing, rootstock, and soil amendments.  

Take a look at the soil survey map available online, then go out and dig your pits.  Using the WSS may not be easy the first time around, although there are excellent instructions (begin by defining your AOL "area of interest") on the web page.  I also really like the UC Davis California Soil Web Resource app, created by our UCANR Toby O'Geen and his lab and is newly updated for use on a mobile phone or tablet.  I just bookmarked it on my phone homepage, for easy access when I'm out in the field. Check it out!

 

 

 

Everyone, and I mean EVERY one,  is all smiles as the 2018 California foothill winegrape harvest sails in on cool weather after a bit of a tumultuous season.  Winemakers were giddy and growers still energetic (a rarity come October) as I visited several foothill vineyards to learn how the season wrapped up. 

"Beautiful acidity" in the later red varieties was the common theme as the cooler August and September temperatures

allowed fruit to hang and develop flavors.  "The main thing to note is that we're using a lot fewer acid additions than in some years past", said Michael Long, winemaker at Amador Cellars.  "Our Zinfandel, Mourvedre and Aglianico is still hanging, with pH around 3.5 and great acidity."  

Although some foothill Zinfandel remained unsold, a continuing trend following last year's Zinfandel dive, demand for Cedarville's organic fruit is up.  "Buyers are very interested in our Zin", Jonathan said, "and some winemakers in the area are showing a renewed interest in Cab. as well, which is so great to see".  

Other than in frosted locations, yields came in at average to slightly above, although crop estimates may have been misleading early on. 

Challenges of the season included a high powdery mildew index in the cooler, higher elevations (perhaps the price paid for the payoff in slower ripening later), and mites, especially in some Zinfandel blocks and often brought on by heat and drought conditions.  Some growers buck the miticide train and choose to use biological control to combat mite outbreaks.  "We've been releasing 6 spotted thrips for years", Ann Kraemer, Shake Ridge Vineyards and Yorba Wines, told me.  6 spotted thrips is a generalist predator, which means it will prey on any soft bodied insect it can, including leafhopper nymphs.  It has the ability to get under the webbing of spider mites to attack them, making it an excellent mite predator! 

But how cool was it really? After hearing all of this praise for a "cooler" season, I compared the weather data from 2018 to the previous 4 years using the Plymouth CIMIS station located in the Shenandoah Valley in Amador.  Turns out, July had a warmer minimum temp. (62°F) than the previous 4 July minimum temps. But indeed, average minimum temperatures dropped to 55°F come August and stayed cool in September too ( 2018 data shown in dark solid line in graphs).  Average monthly maximum temperatures were less than last year (which held record highs), but still slightly higher than the previous other 3 years.

 

 

 

 

 

 

Concern about smoke due to the Ferguson and Mendocino Complex  fires made for an "oppressive" July-when some days air particulate matter counts were deemed unsafe to work and crews were sent home early-all blew away by August as clear skies ushered in the first whites.  

As we made it through her vineyard blocks, Ann made one more keen observation.  "There were fewer birds this year.  My owl boxes are empty and even when putting out netting I noticed there didn't seem to be as many birds as usual." One (unproven) theory: the high summer smoke affected the bird population, causing them to fly less or leave. 

Now that the fruit is almost all in, let's hope the rainy season comes, and our owls return, soon.

 

With mounting pressure on growers to account for their precious water use, irrigation tools are relevant now more than ever.  Daniele Zaccaria, UC Irrigation Specialist, brought his impressive International team of student researchers and scientists to the foothills August 10 to discuss their study findings and grower friendly irrigation tools at a UCCE field day.  About twenty growers made the trip over to meet with us at Safari vineyards in Pilot Hill, where we have been gathering data for 4 years on the effect of aspect and slope on vine water use.

Tools for scheduling irrigation fall into three categories: we can monitor the weather, the soil or the plant.  Monitoring weather includes the classic estimation of crop evapotranspiration (ET) using reference ET data (ET₀), based on the amount of water an area of well-watered grass uses, and multiplying that number by a suitable crop coefficient (K_c) to determine how much water a crop has used during any given time period.  The idea being, if you can estimate what a crop has used, you will know how much water to replace with irrigation. The reference ET₀ depends on temperature and other local weather factors and is available online (for free, you only need to create a login) from 

CIMIS (CA. Irrigation Management Information System).  CIMIS stations measure the grass ET in different locations, there are currently 2 CIMIS stations in El Dorado County (Camino and Diamond Springs) and one in Plymouth. 

If we were growing corn or apples or almonds or practically anything else it would end there; you would have the ET₀ from CIMIS and a crop coefficient given based on research and you would multiply the two and then, voila!, you would have an estimate of how much water your crop has used.  But alas, winegrape production is more complicated.  This is because winegrapes, as most of you know, are not irrigated to "full ET".  We typically impose an irrigation deficit to winegrapes at key times of the year to increase the quality of the crop and intensify flavors in the berry skins.  So, for winegrapes, we multiply the reference ET₀ by a crop coefficient and then by yet another factor for "stress".  The stress factor is one that a grower determines (say, 70%).

The final equation is: ET_{grapes-stress}=ET₀ * K_c-grapes* K_stress

Furthermore, the crop coefficient is not one number, but a number multiplied by the amount of shading present.  This grape coefficient was developed based on research conducted in the Valley (where it is FLAT) by our very own UC Irrigation Specialist Larry Williams and Jim Ayars, in which they found a good correlation between the percent shading and the crop coefficient.  The formula they published in 2005 is K_{c grapes}= 0.017 * % shaded area.

But how do we get shaded area? And does this formula really work on sloped vineyards?  While many growers may eyeball

percent shading, Kristen Shapiro and Sloane Rice demonstrated the "Paso Panel" developed by my UCCE colleague and gadget whiz by his own right Mark Battany. Kristen and Sloane have been using Mark's Paso Panel to estimate percent shading in this sloped vineyard site, and have so far found that the Williams/Ayars model to predict K_c does not seem to work accurately on hillside vineyards.

There are several ways we can monitor the plant to determine vine water needs.  One of the most tried and true is to measure stem or leaf water potential using a pressure chamber.  Guilia Marino, a plant physiologist who hails from Sicily, demonstrated using a pressure chamber to measure vine stress.  To use a pressure chamber, a leaf is bagged (when measuring STEM water potential), allowed to equilibrate for at least 10 minutes, then the petiole is cut and the cut bagged leaf is placed in a chamber.  The chamber is sealed, pressure is applied, and a hand lens is used to note the pressure at which water is pressed out of the cut petiole.  Guilia likened using the pressure chamber to taking the blood pressure of the vine.  If the vine is under alot of stress, it will take more pressure (higher negative reading) to force water out of the xylem of the cut petiole.  I've done some work using the pressure chamber and I think it is an excellent tool for growers to use in the foothills, because it avoids the variability we frequently see in soils and focuses on what the plant is actually receiving.

Soil moisture sensors are, perhaps, the oldest technology we have and if placed properly, can give us good information about soil conditions in their location.  Pedro Lima of Brazil has been using Watermark sensors to measure soil moisture on the two slopes at Safari vineyards at several depths.  The sensors consist of porous media that require good contact with the soil, so proper installation is critical. Data from the sensors is uploaded to a station so that the sensors themselves remain undisturbed.  The sensor data has shown different tension, likely because the soils on the two slopes are different.  One other important note: beware of rodents chewing your sensor wires! Pedro noted that something (hmmm) was nibbling on the sensor wires which disrupted data collection.  I think these are great tools for young vineyards, when the roots haven't yet penetrated to greater depths.

But ET isn't only about crop transpiration.  Camilo Souto demonstrated his work measuring soil evaporation (the "E" in ET) using buried canisters and weighing them periodically to determine the component of soil evaporation.  Camilo noted that the top 4 inches of soil is where most evaporation occurs and he has estimated that evaporation of moisture from the soil accounts for 20-30% of seasonal ET!

The Zaccaria Team ended our field day by discussing how critically important it is for growers to begin using a tool, if they are not already, to better understand water use in their own vineyards.  Not only for improving winegrape quality, but as competition for water resources increases, the cost of water will surely continue to rise (consider the cost of running a pump) and with it the increase in regulations that require growers to demonstrate their good stewardship of water.  Our growing future depends on it.  

Hello Fodder Family! Whoosh, the 2018 season is beginning to move fast now that things have finally warmed up (wasn't that cool spring weather nice, though?).  Last time here I wrote about a relatively LARGE (in physical body terms, that is) pest of grapevines, today I want to tell you about a tiny one...

On a farm call recently, I was reminded of a pest I've come to know pretty well since my appointment here in the foothills: Grape Phylloxera (Daktulosphaeria vitifoliae).   I'm still surprised when growers are taken aback from the discovery of Phylloxera on their own-rooted vines that are declining ("REALLY? PHYLLOXERA?").  Yes, really.  When I first started here as Farm Advisor for viticulture many folks told me that there was NO Phylloxera in the foothills, even though my predecessor, Donna Hirschfelt, knew that phylloxera was here and had spoken about it.  And although vines in decline can be due to many different pests (canker, gophers, and Armillaria to name a few), often when I come upon own rooted vines (i.e. those who are not grafted onto rootstock and so have Vitis vinifera as the root) I am able to find phylloxera on the roots.

How can this tiny insect take down these large vines?  Phylloxera is an aphid like insect that feeds on the roots

of V. vinifera.  Sometimes called "European grape", vinifera is the Vitis species we grow on the top half of the vine and includes all of the cultivars like Cabernet, Zinfandel, Viognier, Rousanne, Chardonnay, Mourvedre, etc. etc. (oh my gosh...so many wines, so little time!) that we like to sip with our dinner! 

Phylloxera is native to N. America, so no, we did not get phylloxera from France.  Rather, we unwittingly gave it to the Europeans for which they will never forgive us. When feeding, the phylloxera cause swelling of the roots and their feeding damages the root system so that fungi can infect and decay the roots.  This is why phylloxera infested vines are so stunted and stressed, after awhile, they have little functional root system left.  Thank goodness the plant breeders have come to the rescue to breed hybrids of other Vitis species for our rootstocks, such as V. rupestris (St. George) and V. riparia which are resistant (but NOT immune) to phylloxera.  Andy Walker, our very own UC Davis Viticulture breeder, gave an excellent talk on rootstocks and phylloxera a few years ago at my 2013 Foothill Grape Day.  His presentation is posted on my webpage with all the other Foothill Grape Day presentations our speakers have granted me the OK to post. A great resource if you ever want to check back for some fun facts!

By the way, there are many ways that phylloxera can spread.  Since our rootstock hybrids are not immune, phylloxera can enter a vineyard on the roots of grafted vines.  From there, phylloxera nymphs or crawlers will periodically climb their way up to the soil surface, where they can easily be carried by the wind.  They can also be picked up on the bottoms of boots and equipment, which is why I always carry a spray bottle of clorox in my truck to spray my boot bottoms off after being in a phylloxera field.

A few years ago, Kent Daane (UC Berkeley Entomology Specialist and biological control whiz) wondered if phylloxera might be spreading around leafroll (this was back before we knew the ID of red blotch).  I collaborated with Kent and his then assistant Christina Wistrom in a study where we looked at foothill sites that had both phylloxera AND grapevine leafroll virus.  Thankfully, we found no evidence that phylloxera spreads leafroll (but mealybugs, including grape and Gill's mealybug, do).

As own-rooted vines that are many years old are declining, and as the cost of farming these vines continues to increase, we are seeing many older vineyards being replanted in the foothills.  This is sad to me, mainly because of the family history in many of these vineyards that are as much as 130 years old!  Some winemakers would also argue that these vines produce superior wine, although I think this is in part due to the low yields making fruit highly concentrated (and, for most, growers are paid by the ton, not so much by the age of the vineyard).  But phylloxera is a pest that cannot be managed indefinitely, it eventually will win.  Some growers choose to apply a systemic insecticide for phylloxera management, but these do not kill the phylloxera eggs.  So, we are gradually seeing our historic foothill vineyard landscape change as older, historic own-rooted vineyards are replaced.

Change, though, can sometimes bring unexpected and good things (I often have to remind myself of this).  Rootstocks today provide growers a large choice of attributes that can help dial in quality for a given "site capacity".  Replanting also gives growers and their winemakers an opportunity to try new varieties that may have a better consumer niche and price for the grower.  And, most importantly, the increase in YIELD that comes with phylloxera free vineyards will allow our foothill industry to stay vibrant and alive!