Disease Control On Grapes:

I am sure most of you who grow grapes, have some time or another come across some kind of disease on your grapes. Not knowing what to look for and when to expect diseases like powdery mildew and downy mildew infections, it's the reason why so many people fail to have any grapes on their grape vines!

Not only fungus diseases, but also bacterial diseases and insects on your grape vine, will directly influence the quantity and quality of your grapes and because not many grape growers know the symptoms of these diseases, most of the time they wait too long to take action.

The problem is; when you can clearly see the symptoms of diseases on your grape vine (on the shoots, leaves and grapes), it is often too late and 70 % of the damage was done! Therefore, it is better practice to take precautionary measures, than to try and solve the problem when it is visible.

Canopy management to control grape vine diseases:

Controlling diseases and insects starts with a proper canopy management and grape vine manipulation in conjunction with a sound and ongoing occurring spray program. Those of you who owns the Complete Grape Growers Guide, will recall how often I mention sunlight penetration and airflow into the grape vine and the importance of a well balanced grape vine.

Most fungal diseases need humid, hot condition and the existence of free water to spread; therefore grape vine canopy management is of the utmost importance when you grow grapes. Proper airflow and sunlight into the vine will help to reduce the time it takes for grape vines to dry off after heavy dew or unwanted rain and therefore reducing the time the fungus has to develop.

Controlling diseases on grapes is much harder in tropical climates, because the higher humidity and rainfall in those areas, will make the inoculation and the spread of fungus diseases much quicker. Canopy management in these areas is critical!

Another cultural practice to help control diseases of grapes, is a properly set up trellis system. The trellis I use on my farm (the gable trellis system), allows the grape vine to spread its shoots and cover the whole canopy area, making the grape vine less compact - better airflow and sunlight penetration! If you plan to start a vineyard, choosing the right canopy system is VERY important.

Resistance of varieties:

It is a known fact that some grape species and even some grape varieties are more resistant to diseases than other. Take for example muscadine grapes (Vitis rotundifolia), it is a native grape species found in the southeastern United States and grows wild throughout North Carolina. Although Muscadines are not nearly as productive and lovely to look at, as V. labrusca or V. vinifera, it can survive in areas where other grape species will never survive! Note I use the word: "can". Planting or growing muscadines will not safeguard your vines completely free from diseases, but it can help if you live in an area with high humidity and unpredicted (unwanted) rain.

Another example is Flame Seedless and Crimson Seedless - two very popular varieties throughout the world. I grow both of these varieties my self and I can tell you from experience, that although both are red seedless, V. vinifera varieties, Flame Seedless is much more susceptible to berry rot and berry crack after rain, than Crimson Seedless is. On the other hand, Crimson Seedless is more susceptible to powdery mildew than Flame Seedless is.

As said in an earlier blog post, you need to carefully choose the variety you will grow in your climate and/or area and I hope this article gave you some tips when you are new to growing grapes or if you are planning a new vineyard.

Remember one very important thing:

DISEASE CONTROL STARTS WITH PROPER GRAPE VINE CANOPY MANAGEMENT
- CLICK HERE TO LEARN HOW!