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Journey to harvest … and beyond!

Journey to harvest … and beyond!

Cover crops and weeds

By Squire Fridell

What is a cover crop?

As conscientious Stewards of the Land, we try to be as eco-friendly as possible, but nothing in farming (or life) is perfect … so we simply weigh the pros and cons of every decision and try to make the best possible “sustainable” choice for the environment, for our crop, for our health, and for the health of the land. Part of that sustainability plan in our vineyards is planting a cover crop of select beneficial plants between the rows of grapevines.

Why is a cover crop sustainable?

A cover crop planted between the vineyard rows will hold the soil together and reduce the possibility of erosion. It will also help choke out unwanted weeds and will supply valuable nutrients to the soil. That’s sustainability!

How do you maintain a cover crop?

Some farmers choose not to plant any cover crop between the vineyard rows (usually because the ground is flat with little chance of erosion); some will tractor-disk (rototill) each row every year and then reseed the cover crop; some will disk only the alternate rows and then reseed; and some vineyards choose to let that cover crop continue unmowed. (Drive around and see for yourself!) There are choices, but most wine grape farmers believe a cover crop of some kind is a good idea.

What about all that pretty mustard you see all over wine country? Is that a good cover crop?

Napa takes great pride in their “Mustard Festival” each year, but (as in everything else) using mustard as a cover crop is one of many options, so we weigh the pros and cons. Mustard may be very pretty, but if the plants grow three feet tall, they will also have a three-foot root system. And where do those long mustard roots travel? The roots travel as fast as they can, right to the emitters, robbing both water and nutrients from the grapevine. (It’s called “hydrotropism” and the most stunted grapevines in any vineyard are those that are close to any surrounding oak trees that have sent their roots out searching for water.) So is mustard good for grapevines? It depends on who you ask, but methinks not.

Do farmers have to maintain their cover crop?

Both our vineyards here at GlenLyon are on a hillside and we are very concerned with erosion, so disking the vineyard rows wouldn’t be the best idea for us. Instead, we have a permanent cover crop of four mixed beneficial seeds: two clovers, a fescue, and a brome. These low-profile plants reseed the soil and then grow back beautifully each year after the rains begin. Our cover crop is low-growing, nice and green, attracts beneficial insects, and prevents erosion. We also mow that low-lying cover crop twice, the last time during early spring, to keep any possible freezing air flowing (since cool air is low and warm air rises). This reduces the chance of a spring frost that can damage new grapevine green tissue growth. The timing of those mows is important so that the plants will reseed themselves for the following season.

What about weeds?

A weed is simply a plant that is growing in the wrong location. Any weed that is provided by Mother Nature (or an overzealous cover crop spillover) and grows underneath our drip emitters, thus competing for water and nutrients, is considered a weed. It is unwanted and should be removed.

How do you get rid of those unwanted weeds?

We, like most other grape growers here in our valley, are trying to be as environmentally conscious, sustainable, and organic as possible. At the same time, we want our vineyards to be efficient, tidy, and goodlooking. That means getting rid of any overlapping cover crop and weed-row growth under the drip line. Like almost everyone else, we used to “strip spray” a glyphosate herbicide product called Roundup. Like many other winegrowers, we made a decision a number of years ago to quit using it. But by choosing not to use an herbicide, we were then faced with a big problem: What should we do about that pesky under-vine weed growth that steals our water and nutrients? Again, choices abound. Any number of chemical substitutes have been tried (“Weed Slayer” being one; it was originally deemed “organic,” but has since lost that favored status). Many farmers and homeowners use machines called string trimmers. They are efficient (and noisy!), but is using a gasoline and oil mixture environmentally sound? (Plus, the weed still comes back next season because the root system is intact.) Some use propane blow torches (again … good for the environment?). One of the best ways to ensure the weed won’t come

back is hand-hoeing, but in a hillside vineyard, this labor-intensive process will eliminate the dirt berms and possibly cause erosion.

So how do you control those unwanted weeds under the drip line? Early this spring, we invested in a (very costly) Italian-made tractor-bolt-on unit made by Rinieri (see below, then Google it to see the video). It is called a “biodynamic under-vine cultivator” and we are in love with it! (It was also wife-Suzy’s combination birthday, Mother’s Day, and Christmas gift.) We drive the tractor up and down the vineyard rows, roto-tilling the soil eight inches on each side of the vines to a depth of two inches, thus eliminating both the weeds and the root systems, but never touching the grapevines. Since our upper vineyard soil has not been disturbed since we originally deep-ripped the ground over two decades ago before planting those vines, the ground has grown pretty hard, so we are finding that the machine needs two passes on each row. There is a lot of churned-up rock to remove after tilling, so I figure it will take us three full seasons until the vineyard is perfect, but as our eco-friendly-obsessed daughter says, “It’s much better than using RoundUp, Dad!”

So, there you go. Come on by and I’ll show you how wife-Suzy’s new combination gift works!

“Just Drink It!”

Mustard grows between vines beside Sonoma Highway in Glen EllenPhoto by Paul Goguen

Overgrown weeds choke out the vines.Photo by Squire Fridell