Ampelographer attacks fungal diseases at ‘Grape Expectations’

by Richard Skelly

MONROE TOWNSHIP, NJ – Lucie Morton, a Virginia-based international viticultural consultant, spoke in early March at the Rutgers Cooperative Extension Service’s “Grape Expectations” annual conference for Garden State wine makers and grape growers. The conference is a massive celebration of New Jersey wines.

Morton is an internationally recognized ampelographer, lecturer, consultant, research collaborator and author. Her higher education in viticulture occurred in Europe, while her practical education began as vineyard manager on the family farm along the banks of the Potomac River, Virginia-side. Recently, she has been working with geologists to show the need for revising potassium recommendations based on soil analyses and with plant pathologists to better understand wood fungi that also impact developing fruit clusters.

Morton’s talk was titled “Cabernet Franc – A Multifarious Star Grape for the East,” but it was wide-ranging and jam-packed with all kinds of cutting-edge information related to fungal diseases faced by owners and managers in Mid-Atlantic vineyards.

“When people ask me about how many acres of grapes there are in Virginia, I say I don’t know. I’m too busy looking under the microscope at the fungi that were on our grapes in 2018,” she said.

An ampelographer, she explained, is a fancier term for a grapevine botanist, and she joked it comes in useful in stumping people at cocktail parties. One thing that is required to be one of 10 practicing ampelographers in the world today, as she is, “is to use your eyes to see what is in front of you … I look at vines, I talk to vines and I see things,” Morton explained.

“Because I knew about rootstocks when the California industry made a big mistake to plant a rootstock that failed spectacularly – AXR-1 – I wrote an article, ‘The Myth of the Universal Rootstock,’” she explained, noting everybody in California was blaming the rootstock genotype, arguing it was not adapted to California climates. When she looked closely at these rootstocks, “I noticed that when you cut them in cross sections instead of nice clear sap, they had these tarry black spots coming out. So I’m out there showing this to people and they’re saying ‘We’re going to call this Morton’s Disease’ and I said ‘No you’re not. We’re going to call it black rot.’”

After getting tired of being such a Debbie Downer about grape diseases, “I started working with some hydrogeologists on potassium nutrition. It really bothered me that Virginia Tech, Penn State and others were telling East Coast grape growers you need 200 parts per million in your soil of potassium,” she opined. “I said to myself ‘Who am I going to believe, the grapevines or some agronomist?’ and it’s always stood me in good stead in my career to believe the grapevine.”

The Virginia Wine Research Board has funded Morton and her experiments with some hydrogeologists for four years now.

“I can assure you, you should never ever add one drop of potassium fertilizer to your soil unless your vines ask you for it with a deficiency, because one of the leading problems we have here is maintaining lower pHs in our fruit,” she argued.

“We all need to look at the herbicides, the insecticides, the fungicides we’re putting in our vineyards,” she continued, “and for that reason I don’t think we should turn our back on classic Native American grapes, French-American hybrids, new varieties. We must continue to look at them, evaluate them and bring them into our programs.”

Unlike northern California, which has relatively predictable weather patterns ideal for growing grapes, “the big deal for us is our weather” on the East coast, she said. “If you’re a New Jersey Extension agent, you may have one guy who’s being killed by downy mildew and the other guy isn’t, and a lot of times it’s simply because the rainfall was different at different times of the year. We just have to live with the fact that you know the weather in your area.” She encouraged Garden State and New York State vineyard owners to have their own weather stations and monitor things closely.

Vineyard owners talk in terms of varietal resistance, she said, but not enough in terms of clonal resistance. She learned from vineyard owners in Ontario that a clone of Sauvignon Blanc is more winter hardy than a clone she uses in Virginia.

“This is farther south, same root stock, different winter hardiness, so when I see it growing in Maryland and guys in Ontario confirm it as more winter hardy, I tend to believe it, and I’m starting to believe that clones matter,” she argued. Morton also argued that Bordeaux grapes in Mid-Atlantic states increase in winter hardiness as they get older, and that nice, thicker vines get the vigor under control.

She also pointed out the necessity for good canopy management. “Shaded fruit is one of the greatest causes of low color I see in Cabernet franc, and it’s super susceptible to red blotch. With merlot, the fruit will get downy mildew first,” she noted.

Morton offered up what she thinks is a good mix for vineyard owners in New Jersey. “There’s no question the Bordeaux blends do very well for us here and we’ve won prizes and consumers love them. I’d also say Cab franc and merlot are important, Cab sauvignon less so,” she said, adding she spends a lot of time looking at leaves and then vines, “because when you’re an ampelographer, looking at the fruit is considered cheating.”

Another kernel of advice she offered was to carefully monitor and manage the young vines. “I used to ride horses, and some of them you need to kick to get them going and other ones you need to pull them back [and rein them in], and fruit is the way you reduce vigor on the vine. We all know if you over-crop a young vine, that’s the worst thing you can do because you’ll have a debilitated root system.”

Morton urged growers to think about how to prune each vine as an individual, especially when they’re two and three years old.

“I do it based on how many shoots they grow and how many buds it will take to give it a little more for the next year but not too many,” she said, adding that none of the pruning literature she’s reviewed for East Coast growers seems to offer much guidance for this sort of viticulture.

If vineyard owners do good vertical management and don’t let vines shade each other, their vineyards start to come into uniformity, because they’re kept all in the same leaf area. Owners thin the fruit out to what they should be yielding, she added.

Morton recalled how when she started in the 1970s, many vineyard owners thought pruning and growing cordons was easy, but she now refers to these grapevines as “mildew hotels.”

In summing up, she urged growers “you have to take your time in pruning and re-establishing older vineyards. You have to know where you’re going and how you’re going to get there.”

Finally, she reminded “Grape Expectations” conference attendees “that what happens in the vineyard does not stay in the vineyard.”