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Garden Article March 23, 2019

If you have a grape vine or two in your yard let this be the year that you get grapes by getting an early start on the control of Black Rot, which mummifies the grapes and renders them useless. Black rot is one of the most serious diseases of grapes in the eastern United States. Crop losses can range from 5 to 80 percent, depending on the amount of disease in the vineyard, the weather, and variety susceptibility. The fungus can infect all green parts of the vine. Most damaging is the effect on fruit. Later fruit infections can destroy many grapes, even the entire crop.

Black rot on grapes. Prevent this from Happening this summer by taking action in the early spring


When weather conditions are exceptionally favorable for black rot, many home gardeners have problems.Even if you are doing all the right things such as proper pruning and removing diseased plant material, the disease may be ruining your grape harvest. If so, consider using a fungicide starting early in the spring to protect your fruit.

First, meaning now, before the buds swell, remove all infected prunings and mummified berries. They should be burned, and/or buried in the soil before new growth begins in the spring. If black rot has been a problem the previous year, early season fungicide sprays should be timed to prevent the earliest infections. Should infections become numerous, protecting against fruit rot is very difficult later in the growing season. So spraying now is very important to a successful grape crop.

The black rot fungus overwinters in mummified fruit on the vineyard floor or in old fruit clusters that hang in the vines. The fungus can also overwinter within cane lesions. Spores of the fungus are produced within the diseased fruit and infect leaves, blossoms, and young fruit during spring rains. Fruit infections occur from mid-bloom until the berries begins to color. Mature leaves and ripe fruit are not susceptible. Very few fruit or leaves are infected after late July, and none are infected after the end of August. Black rot infections depend on the temperature and the length of time the leaves are wet. Infections occur if susceptible tissue remains wet for a sufficient length of time, depending on temperature.

Where black rot is a problem follow this spray schedule for its control:

New Shoot–when new shoot growth averages 4 inches. Spray with Captan plus Mancozeb.  Apply these fungicides every 14 days after the “New Shoot” spray up to and including the “Before Ripening” spray. During long rainy periods, shorten the interval to 7 to 10 days between sprays. Spray in the rain, if necessary, to maintain the schedule of applications. Be sure to read the label before making pesticide applications.

Before Bloom–just before blossoms open.  Spray with Captan plus Mancozeb along with Sevin for the control of leaf hoppers.  Do Not Spray Sevin or any other insecticide when blossoms are open and bees are present.

Post-Bloom–immediately after bloom.  Mancozeb plus Dipel plus Imidacloprid for the control of berry moth.

First Cover–apply 10 days after Post-Bloom: Captan + Sulfur plus same as Post-Bloom for the control of Black Rot, Powdery Mildew, Boytris Rot and Japanese Beetles.

Second Cover–apply 3 weeks after First Cover. Captan + Sulfur for the control of fruit rots.

Third Cover–late July or early August.  Captan + Sulfur for the control of fruit rots

Before Ripening–10 days before picking.  Captan + Sulfur for the control of fruit rots

Garden Tip: Fertilize grapes now with 4 cups of Sustane Organic Fertilizer. During the season mix Fish Emulsion with applied sprays.

.Dave Vargo is the owner of   Kiski Plaza Garden & Feed Center (724-845-8201) in Leechburg.  Products mentioned in the article are available at the garden center.  Any questions call or email dvargokiski@comcast.net.  Like us on Facebook @kiskigardencenter.