By Certis Biologicals
Diseases in fruit are inevitable – from weather to environmental issues that arise, grape crops face a multitude of threats, but they don’t have to overtake your crops.
Although disease pressure had been low over the past few years, proper prevention is ideal for when it will become a challenge again in the future.
It’s important to take a practical approach to disease management in grapes by recognizing what you can and can’t control, and then preparing through preventive measures along with ways to protect yield and boost healthy crops throughout the growing season.
What You Can’t Control in Grape Crops
We want to get the bad news out of the way, so let’s start with what you can’t control. Diseases are typically caused by pathogenic fungi that cause rot and decay of the vines and fruit, and they tend to sneak in unannounced.
Depending on the location of your grapevines, some of these seasonal obstacles will apply, while others will not, but having a well-rounded understanding of what causes disease and how to approach management will help throughout the growing season.
Weather patterns affect the growth of grapes and can be unpredictable, so they often affect fruits at various stages of growth and can cause the onset of disease before growers realize it’s happening.
Rainfall and Drought
While too much rainfall can cause risks to yield and quality of grapes such as rotting, extreme drought can cause vines to stop producing. Although most grapes are drought-tolerant, they can be negatively affected over multiple seasons of drought stress.
Temperatures and Other Environmental Factors
Extreme temperatures can also affect the growth of fruit, causing them to ripen too quickly or more slowly, which changes the flavors of the grapes.
Weather-driven diseases should not be an ever-present problem each growing season. Biological fungicides are an excellent choice to include alone or within an IPM program to increase effectiveness in fighting disease or to combat resistance.
Smoke taint can also be a major problem for grape growers. Wildfires have ravaged areas like California and the smoke can permeate grape skins to ruin the taste of the grapes. Unfortunately, you can’t just rinse off smoke taint because the smoke bonds with the sugars inside of the fruit, and many growers cannot tell if the grapes have been affected or not.
Winemakers often send samples of grapes and juice to research institutions or private companies to be tested because they do not smell or affect the product until it goes into production to make wine. Some wines have a smoky flavor that naturally exist, but heavy smoke exposure can ruin crops.
What You Can Control in Grape Crops
Since grapes are perennial crops, grape growers can plan to stay ahead of diseases caused by external factors by implementing programs that help prevent the spread of disease.
Common diseases in grapes include Downy Mildew, Powdery Mildew, Bunch Rot, Leafy Spot, Botrytis spp., Xanthomonas ssp, Sclerotinia spp., Mold (white), Blight, and more.
Implementing preventive applications of an effective fungicide before bloom and through 2-4 weeks after bloom aids in disease management. Follow-up applications can be made to control or suppress fungal and bacterial plant diseases.
Grapes may develop resistance to certain fungicides, which can prevent them from being effective in disease control. Biofungicides are an effective method for IPM (integrated pest management) programs to promote sustainable disease control and to reduce resistance to other active ingredients.
Choosing products with multiple modes of action can also help increase effectiveness to ensure that the method combats disease throughout the growing season.
Prevention and Preparation is the Best Medicine
Although there are a variety of factors that are out of your control, advanced preparation for disease control and preventive methods throughout the growing season will decrease disease pressure in grapes.
Disease-causing fungi can rapidly colonize a plant surface, so preventive fungicides are effective prior to the onset of diseases. Preventive fungicides have an upfront cost, but they also reduce the incidence of disease and minimize the need for costly post-infection practices after plants have been infected, which can also lead to greater loss in yield and profits.
Double Nickel® LC is a technologically advanced broad spectrum biological fungicide and bactericide featuring active ingredient Bacillus amyloliquefaciens strain D747. It is OMRI listed and safe for use in organic production or as part of an IPM program to control or suppress over 90 different fungal and bacterial diseases and is tested to be effective on grapes. Because Double Nickel features complex modes of action, resistance to the active ingredient is unlikely to occur. This makes the product effective for use in organic production as well as useful in an integrated disease management program.
Lead more about Double Nickel® LC.