Dear Wes: I asked for questions and you listened!

A few months back, about 150 home winemakers attended a WineMaker magazine Backyard Vineyard Online Boot Camp I hosted. The Q&A for the event was great and I offered those that attended the opportunity to reach out with pictures and data of their vineyard problems — a one-question bonus consultation for those that attended. I received a number of inquiries and I will share a selection of the questions, answers, and insight in the following pages. I tried to choose the questions that I thought would have the most benefit for anyone growing grapes on a small scale.

But instead of answering 5–6 short questions, I wanted to take two letters I received and give them the time, space, and love they deserve, as I think this kind of narrative understanding will be more helpful to the readership.

From Kathy in Virginia:
Hello and thanks in advance Wes. I had just a couple questions on the topic of my spray program that I wanted to ask after our class yesterday:

1) I have been told not to spray nutrients in the same spray as my fungicides. When do you like to spray the following:

• Borosol (I have heard just before bloom)?
• Utilize
• Megafol
• Elemax CA
• Elemax MG

Wes: Foliar nutrients are easy to apply if they can be “saddled” in with fungicide sprays. Before you do this, make sure they are compatible by looking at the label or asking a professional agronomist, university, or a local agricultural extension office.

Foliar applications are best used between 6–10 in. (15–25 cm) of new shoot growth, right up to the first appearance of flowers. Zinc can increase fruit set by as much as 10% if sprayed a few weeks before bloom or right when you see the first flower in the vineyard, so watch for cap fall.

It seems that a weekly/10-day fungicide program would give all five of these products a single spray over the 50 days or so between 6-in. (15-cm) shoot growth and bloom. I might suggest using a single product, in order, with each spray, and take notes on how the vines respond; correlating weather and rainfall.

Also, use science to determine optimal nutrient status! The moment of greatest nutrient need (NPK, nitrogen, phosphorous, and potassium being the macronutrients) is at bloom and the best way to determine how close to perfect the vineyard is for said status is to take leaf petiole samples (follow the agricultural lab’s instructions). Take leaves adjacent to flowering clusters. This will show how the vine’s real-time nutrients are impacted at the time of the vine’s greatest need.

2) When is it best to start spraying?

Wes: There is no reason to start applying fungicide until the vine rows show stripes of solid green along the bursting buds. The bud shield needs to open all the way up, and not only do the first leaves need to emerge, there needs to be a growing tip and perhaps a proto-cluster or two. I have included a photo below, of where I would apply the first copper/sulfur mix in my family’s vineyard in California’s Santa Barbara County. Also, follow the label instructions exactly; don’t apply at a higher rate or more frequently than the label suggests. If it says 7–10 days between sprays, spray at seven until you have complete control, and then the next year, go to eight days. Pay attention to the sporulation conditions for your target fungus/rot: (e.g. black rot, powdery mildew, downy mildew, Botrytis, etc.) and make sure you are using a sprayer that is penetrating the outside leaf layers and dousing the fruit and interior of the vines.

3) I have an issue with my leaves seemingly every year (see photo below). It starts with yellowing in late July and ends like the photo shows. I sent them to A&L Crop Solutions for analysis and they were negative for: Grapevine leafroll associated viruses 1,2 and 3, GVB (Grapevine Virus B), fanleaf, and red blotch.

Wes: First, good on you for sending some tissue for lab analysis. Science helps our vineyards thrive and improve, and getting help from professionals should never feel like you’ve failed. It means you want to learn and want to know the truth. Faith does little to improve wine.

Taking out the major viral diseases in grapevines, as you did, I will agree that this is likely environmental marginal foliar necrosis/burn. Looking through all the pictures it is clear that the problem is not systemic, in fact it appears to be ‘patchy’ and focused on areas that might have been sprayed strongly by underpowered equipment (backpack sprayer), and then burned in a summer heat spell. The timing (July) can hint at sulfur toxicity in very hot weather, which can trigger it. You may see about switching from sulfur after bloom (and before hot weather) to a “strobe” or other synthetic fungicide like Rally or Flint, but make sure to rotate the materials, as the mildews and rots can develop a resistance to them. Products like sulfur or copper, or even stylet oil, are elemental by scientific definition, which gives them the benefit of never being resisted by natural selection in the fungus’ mutations.

To recap:

• Start spraying at 4–6 in. (15–25 cm) of average shoot growth after budbreak.
• Use one foliar spray recommended per early spray, and don’t fertilize after set.
• Take petiole samples at bloom for best insight into the vine’s nutrient status.
• Follow all concentration and interval instructions on label.
• Move to a non-sulfur spray during summer/hot weather/post-bloom.
• Watch to see if the marginal leaf scorch persists with non-sulfur spray.

Don’t worry too much about hints of red leaves or any type of damage that is just on the margin of the vine or vineyard (under 5%). This happens in many, many vineyards.

From Matt And Carrie In California:
We are in Carmel Valley of California, Cachagua to be more precise. Nearest to us is Tira Nanza (formerly Gilante), Joullian, Marinus (Bernardus), and Massa (formerly Heller) wineries. In 2016 we purchased the property next door to us that had an existing 1-acre hillside vineyard. The vineyard was originally planted in the 90s with Georis Merlot but the vines were neglected for years and thus very sad. In 2017 with the help of a friend, we took out the old vines and planted four blocks, 1,000 vines total, of Syrah from Duarte Nursery.

• Syrah 05 (French 174) (UberVine) / 5BB
• Syrah 07.1 (French 877) (2010P) (UberVine) / 5BB
• Syrah 08 (Durell) (UberVine) / 5BB
• Syrah 10 (UberVine) / 5BB

Right off the bat things did not go well. Our vines arrived much later than expected and we acclimated our new baby vines in too much shade. Then, less than a week after planting, we had one of the hottest spells of the year with temperatures spiking over 100 °F (38 °C) for several days. Then the following February temperatures were in the 90s °F (mid 30s °C) for a week and the babies began bud break. Then less than two weeks later we had a hard freeze with temperatures around 25 °F (-4 °C) in the vineyard. We lost over 600 vines.

However we were still committed to making this work. We ordered more vines to replace the ones we lost and started anew last year. Unfortunately the nursery somehow lost our 05 so we are expecting those this year. This time around we did create a small nursery in the beds above the vineyard. We evacuated during the Carmel fire with no time to prepare and when we finally came back our vineyard was without water for about a week during some very hot days.

Wes’ summary after a three-hour site visit: The site is a small production winemaker’s dream, but there’s a lot of work to be done. It’s so much easier to imagine the property, the soil, the weather, aspect, challenges, and advantages of your property now that I’ve seen it firsthand.

Details/Action Items: Vineyard

• Sandy soils, expecting good drainage.
• Excellent frost drainage at bottom.
• Low to mow/medium vigor seen and expected. ~2.5 ft. (0.76 m) average cane growth in 2020.
• Looking to up water and fertilization, especially in struggling vines. Suggestion is a 15-15-15 fertilizer (small handful for all vines under emitter two weeks after budbreak), one cup for stunted vines and replants. Second fertilization May 1st.
• Basic water requirements will start at 5–8 gallons/plant/week (20–30 L/plant/week) depending on heat; less water in cool, more in hot. This can go to 10 gallons/plant/week (38 L/plant/week) in heat spikes or if the vines show water deficit status.
• Replant UberVine right after Mother’s Day, or when frost chances are zero.
• Nursery has about 75 very healthy and consistent replants. These should be planted before they wake up. Dig them up carefully, give the roots a ½-in. (13 mm) trim all around, and plant like an Uber.
• On replants, give each vine a mycorrhizae root dip, and pour a little in the wet hole before putting the vine’s roots into the ground. You may want to talk to local nursery if there’s a type of mycorrhizae more suitable for your area.
• PRUNE! You need to get 25–50 vines pruned every day (33 average) to get the vineyard pruned before April 1st. It would be better to do 60–70 to get it done in two weeks.
• Prune stunted but live vines back to the way the vines looked from the nursery, with just a single spur, or two at most, two buds on pencil thick, one bud on smaller wood.
• Prune for hand’s width between upright, vertical spur positions. If cordon arm is sparse or crooked or wrong, you can lay down a new cane as long as the spacing of the buds looks good and the cane is long enough to make an arm.
• Leave two buds per spur (+1 whorl) on robust spurs, one bud (plus whorl) on less vigorous spurs.
• CUT THE SPURS AS LOW AS POSSIBLE to keep most upright and vertical spurs. Don’t let spurs creep higher each year.
• Observe, take pictures, and share. Let me know when you see cotton on the pushing buds and when you first see budbreak, etc.
• Continue/start trapping and gassing gophers and squirrels, shooting them, etc. (Be careful of ricochet towards your other house!) If deer pressure persists, let me know. I love venison and have a 30.06 rifle.

Conclusion

Answering questions via email (Virginia) can be a challenge, but if I get enough data, location, and pictures it can often work and make reasonable improvements in cultural practice and wine quality. Combining email questions with a remote meeting though ZOOM helps a lot to get on the same page and make an action plan, but still has some limitations. (Am I working the crowd for a trip to new destinations? Well, of course. I’m not stupid.) But, as we can see from the correspondence, the combination of email outreach, ZOOM meetings, and possibly a site visit, really opens my eyes to the weather, soil, total vineyard health, as well as doing one hour+ of pruning demonstration, which can’t be done over a laptop.

I hope these examples will give you some ideas about your own grape farming, have taught you something, and if you are ever stuck, do feel free to send some pictures, location, and good beer (or wine!) to me here in California. I’ll answer eventually! [email protected].