Mealybug in grapes: where a nematode product fits

Mealybug is one of the longest-running problems in the vineyard. It sucks sap from the vine, leaves a sticky honeydew, and spoils bunches. Growers who have fought it season after season know how quickly it returns after a spray.

Why it is hard to control

Mealybug does not sit in the open. It shelters under bark, in the folds of the vine and inside clusters, where a spray often does not reach it well. Green Care Agro’s field videos also point out that mealybug can begin in the soil as well as on the vine. That is why growers also treat the soil and not only the vine.

What nematodes do

Killoryx+ is made of entomopathogenic nematodes (EPNs): microscopic worms that hunt insect pests in moist soil. They enter the pest through natural openings, release a symbiotic bacterium that kills the host within 24 to 48 hours, then multiply inside it and move on to find the next one. Because it is a living biological agent and not a chemical, it leaves no chemical pesticide residue and does not build the kind of resistance that repeated chemical spraying can. Killoryx+ is made by Green Care Agro with technology licensed by ICAR-NBAIR.

What independent research shows

A review by South African researchers of nematodes against above-ground pests in vineyards and orchards reports that mealybug is a good target in the laboratory: up to 90% mortality of vine mealybug females in laboratory tests and 88% in a glasshouse. In a semi-field vineyard trial the result was lower, at 66% mortality, and it varied with the nematode concentration and the time of application. The review adds that nematodes are held back by dryness and strong sun: humidity matters most, and they should be applied early in the morning or late in the afternoon. It also notes that mealybug hiding in sheltered places, such as under bark, is a good target because it is protected from sun and drying.

This was research on a different nematode species, in South Africa, and it does not promise a result in your vineyard. What it does give is a clear rule: moisture, shade and timing decide how well nematodes work. (Platt, Stokwe and Malan, South African Journal of Enology and Viticulture, 2020)

How Killoryx+ is applied

The directions follow that rule.

1. Soak the 250 g in water for 4 hours.
2. Mix it into 200 litres of water. One 250 g can covers 1 acre.
3. Apply in the evening, on moist soil and away from strong sun, through the drip line, or as a spray where you see mealybug on the vine.

Putting it through the drip line reaches the pest in and near the soil, which is why growers use drip. Spraying in the evening covers what you can see on the plant. The dose is the same either way.

What to expect

Nematodes are a living agent and they work over days, not minutes. Look under the bark and in the clusters before you apply, and again a week or two later, so you can see the change for yourself. Keep the soil moist, and apply on a fresh evening rather than on a hot, dry afternoon. If mealybug is heavy, talk to us before the season gets ahead of you.

Putting it with the rest of the grape programme

Mealybug is one part of a vineyard programme. After pruning, the same growers use Ready Kav Paste on the canes for even bud break and to help control flea beetle. See the grapes page for the full order.

Getting it for your vineyard

Killoryx+ comes in a 250 g can. See the dose and pack details or the mealybug page, or get in touch with your village, acreage and the stage of your vines. Dealer and bulk enquiries are welcome.