Bug vs. Bug
Just like any other agricultural crop, wine grapes face their fair share of harmful insect pests. In our vineyard, the two perennial troublemakers are leafhoppers ((Erythroneura elegantula) and white flies (Bemisia). While they are quite different insects, they do similar damage. They suck the juice out of grape leaf cells, leaving white spots on the leaves. With a large enough infestation, the damage reduces the leaf’s ability to photosynthesize and produce carbohydrates needed to ripen the fruit and keep the vine healthy. Eventually the leaf turns brown and drops, reducing the vine’s vigor. If that were not enough, certain leafhopper species can be vectors for serious pathological diseases that can kill grape vines altogether.
White flies on underside of leaf. Photo Credit: D. Kucharski, K. Kucharska/Shutterstock
However, as an organic vineyard, we do not use chemical insecticides (or herbicides for that matter) for their control. Instead, we rely upon introducing into the vineyard natural predators to theses insects. So, it is Bug v.s. Bug. In the past few years, we have released adult ladybugs (Hippodamia convergens). They are voracious feeders of whitefly eggs. The problem is that once they have been eating for a couple of weeks in the vineyard they tend to fly off. Its rare to get more than a single generation cycle. This year we are trying an insect called Green Lacewing (Chysoperla rufilibris). They are more readily available and often can often provide several life-cycle generations in the vineyard. They come as eggs glued to small paper cards, about 200 eggs per card. We generally use about 5000 eggs per acre, so roughly every 10 plants get a card attached to them.
Lacewing eggs on cards are placed on the vines
They first hatch to crawling nymphs, which are hungry for leafhopper and whitefly eggs. Eventually they morph into flying Lace Wings, capable of covering significantly more territory. We have just today completed our second release of the Lace Wing eggs, the first being about a month ago. So far, the vineyard looks very clean, with no major leafhopper or white fly population. So, these little bugs seem to be doing their job quite well. It is an expensive process compared to chemical spraying, but we are committed to natural pest management. Its better for the vines and its much better for the wine!