Stag’s Leap Wine Cellars

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Stag’s Leap Wine Cellars

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The sharpshooter, a "bad bug", caught early by the trap crop of corn planted adjacent to our estate vineyard.

Integrated Pest Management: It’s A Bug’s Life

When most people look at a vineyard, they see an orderly series of vine rows marching off to a distant vanishing point. But for Kirk Grace, Vineyard Manager at Stag’s Leap Wine Cellars, the sight is something more akin to the movie “A Bug’s Life.” He knows that beneath the neatness and symmetry there is a wealth of activity —animal, plant, and insect life. It’s a world-within-a-world, and although most people are unacquainted with it, in spring, it preoccupies Kirk on a daily basis.

“A healthy vineyard is made up of much more than just the vines,” says Kirk. “It’s a complete ecosystem, where vines co-exist with other plants, animals and insects.” But when it comes to the insects, Kirk notes “there are definitely good bugs and bad bugs.”

What makes a bug harmful to a vineyard? Some, like Phylloxera, feed on vine roots, which can lead to reduced or poor growth. Others, like the grape leafhopper, prefer the leaves, which can cause defoliation and severe crop damage. And still others serve as vectors, or carriers, of diseases that can stunt the growth of or even destroy vines, such as the sharpshooter. Thankfully, however, there are a plethora of good bugs as well, working to mitigate the damage wrought by the bad bugs. This is a key component of the widely used system known as integrated pest management (IPM).

“IPM seeks to minimize damage to crops caused by plant pests while also preserving the environment. It involves a number of complementary strategies, but one of the most important utilizes natural biological controls to reign in pest populations,” says Kirk. In other words, finding ways to promote beneficial insects that feed on the harmful ones. Good bugs do more than just eat bad bugs. They interact with the environment as parasites and as predators, eating everything from funguses to pollen, taking advantage of whatever niche they can fill. The honey bee is one of the most celebrated beneficial bugs, but as Kirk notes, there are many unsung heroes in this category (including the ladybug featured on the cover). He should know; he spends a great deal of time encouraging good bugs to make their homes in the Stag’s Leap Wine Cellars vineyards.

Occasionally he does this directly, purchasing beneficial mites to prey on pest mites as part of a practice called augmentation. Most often it’s a matter of creating the proper environment in the vineyard for the good bugs to thrive. With an “if you build it they will come” philosophy, Kirk seeks to mimic ideal natural conditions in the vineyard. “Call me idealistic,” he says, “but I believe if you do this the good guys will outnumber the bad guys.”

In this battle between “good” and “evil,” one of Kirk’s most potent weapons is cover crops. Farming between the vine rows has many benefits, including erosion control, weed suppression, and soil structure improvement, but cover crops also make a great home for beneficial insects. In fact, the type of cover crop a vineyard manager uses is often chosen for its ability to attract certain types of insects.

Using insects as predators is a farming tool that dates back several centuries, but the use of IPM has become more widespread and sophisticated in recent decades. There’s always more to learn, and Kirk often attends workshops and talks to other viticulturists to stay current. Some of his best information however, comes from what he calls the “older texts” – books and pamphlets that are long since out of print. Why refer to older texts? “They didn’t have as many tools back then, and so they tended to be more resourceful.”