Vineyard berms seem little more than narrow barren strips of soil beneath the vines. However, growers will tell you it is one of the most nettlesome areas in producing wine grapes.

Let weeds gain control of that ribbon of bare dirt and those berms become breeding grounds for pests with those same weeds acting like a steel curtain to block pest management control measures.

Left uncontrolled, weeds like marestail can snake up into the vines, damaging fruit.

"Weedy berms not only rob vines of nutrients and water, they also can be pest hotels. Weeds on the berms can suck the vitality out of a vineyard," said Preston Watwood, vineyard manager of 800 acres of General Vineyards Services (GVS) vineyards in the Salinas Valley near Gonzales, Calif.

Kelly McFarland, president of GVS, says Monterey County is a perfect year-round environment for weeds.

"We can have any weed any day of the year," said McFarland. It is warm in the winter and mild in the summer.

"I have found London Rocket in the summer here. Where I grew up farming in the San Joaquin Valley, London Rocket is a winter weed," said McFarland, whose family farms 3,000 acres of wine grapes in Monterey County.

GVS vineyards are broken up into 14 ranches in four different locations in the valley. The company sells wine grapes to about 25 wineries each year.

Eighty percent of GVS’ berm weed control is now chemical, but McFarland wants to switch to more mechanical weed control.

Expenses mount

"The past three years have been tough in the coastal wine grape business and expenses keep going up," said McFarland. "Several years ago I asked my supplier what budget number I should plug in for chemical weed control and he said just add 5 percent to last year’s costs. You do that year after year for 10 years, and it adds up."

GVS has tried non-chemical weed control techniques from flaming to all types of mechanical cultivation from Clemens tillage equipment, Weed Badger, Bezzerides tillage tools and French plows.

"I have even sent crews into vineyards with gasoline weed eaters. You do what you have to do to take care of weeds," said Watwood.

While most mechanical weed control tools work, McFarland said he has not reached his ultimate goal of mechanical tillage that is "so light, so cheap and so simple" that it costs less than herbicides. "We are developing something now in our own shop that we hope will accomplish what we want," said McFarland. "We need to do more research and development to get some time and motion numbers to look at costs before we can determine if it is the answer we are looking for."

Reducing costs is the major focus of McFarland’s efforts to find cheap mechanical cultivation.

"We farm a 20-acre organic block. We get tremendous production off of it, but is costs us a lot more to farm it than a conventional vineyard," said McFarland. "It is easy to make the switch from chemical to mechanical — it just costs a lot more money."

Monterey County is one of the most environmentally scrutinized counties in California and that is also propelling McFarland toward mechanical weed control. "I worry about the growing environmental issues in farming; weed resistance buildup to chemicals; off flavors at the base of the vine and issues like those.

"I really do not see chemicals as being the long term solution to weed control. However, if someone comes along with inexpensive chemistry that addresses some of our concerns, we will be happy to talk with them," added McFarland.

Debatable issue

Chemical weed control vs. mechanical weed control is an ever moving, debatable issue.

"You can talk about the advantages of mechanical cultivation all you want, but there are issues like the cost of steel, cost of fuel, compaction, cost of equipment," said Watwood.

"If you think the prices of gasoline and diesel are going down anytime soon, you are whistling in the graveyard. It is going to get to $3 per gallon before it gets below $2," added McFarland. "There is definitely a cost issue with mechanical cultivation."

The target is also moving because McFarland and Watwood continually strive to reduce chemical weed control costs. For example GVS has built over-the-vine two-row herbicide applicators equipped with color-sensing Weed Seekers to spot treat for weeds with post emergence herbicide. That has dramatically reduced herbicide cost.

"We are also constantly looking for new products that will give us longer pre-emergence residual to reduce not only product cost, but application labor cost as well," said Watwood.

The standard weed control program now is Goal tank mixed with a contact twice a year, in the fall after harvest and before bud break in the spring.

"Ideally, we would like to have a pre-emergence herbicide that would give us good weed control with one application with only maybe a little touch up later with contact. That would cut our labor and material costs in half," he said.

"Goal has served us well. It does a good job on broadleaf weeds and grasses with two applications. However, it has an offensive odor. It stinks, and workers don’t like to use it," said Watwood.

Product testing

Watwood and his father, Bob, have long been involved with product testing and demonstration plots for new products. The family owns a small vineyard for such research.

"There are several new products coming on the market. One we have looked at is Chateau. It does as at least as good if not a better job than Goal," said Watwood.

In moderate weed pressure situations, Watwood has found he can get away with one Chateau application in the fall followed by cleanup spot treatments in the spring with Roundup or another contact. "Chateau has been equal to or better than Goal the last two years we looked at it in our demonstration trials," he said. "And, we like the sanitation qualities of it."

Watwood and McFarland will continue on their cost cutting quest to find cheaper herbicides and equally inexpensive mechanical weed control equipment.

e-mail:hcline@primediabusiness.com