Powdery mildew on grapes

Powdery mildew on grapes

Get rid of powdery mildew on wine and grapes! Find out here which household remedies or natural sprays work well against the fungal disease.

Grapes are becoming increasingly common to grow in gardens at home. Regardless if the grapes are later processed into juice or wine, a powdery mildew infestation can endanger the entire harvest. It is of secondary importance whether you are dealing with powdery mildew or downy mildew. Both pathogens can cause considerable damage. With a few tips, however, you can get the mildew plague under control and prevent it from becoming superfluous.

Powdery mildew vs. downy mildew

One of the main characteristics of powdery mildew is the grey to white fungal coating on both young shoots and leaves. Infested grapes stop growing and dry out, whereas larger berries burst open and can be infested by other pathogens. Compared to that, downy mildew causes round yellow spots with an oily sheen to appear on the underside of the leaves. Downy mildew appears exclusively on the underside of leaves. The grapes are not spared the wrath of downy mildew either, they dry out and become leathery after a mildew infestation. Since grapes are perennial, both types of mildew can unfortunately survive the winter on the plants unscathed. If a mildew outbreak is untreated, it is highly probable that a new breakout will occur next season.

Preventing mildew on grapes

By abiding by the following rules the mildew will be less likely to gain a foothold on your plants in the first place. Grape vines should be given enough space so that air circulation is provided. Densely growing shoots and foliage considerably increase the probability of an outbreak. However, choice of the grape variety can determine the success of the harvest. Powdery and downy mildew are imported diseases, which is why native European grape varieties lack resistance to the fungus. The following varieties are very susceptible to powdery mildew: ‘Portugieser’, ‘Elbling’, ‘Kerner’, ‘Trollinger’, ‘Silvaner’, ‘Muskateller’. Grape varieties such as ‘Müller-Thurgau’, ‘Gutedel’, ‘Portugieser’, ‘Limberger’ are more likely to be infested with downy mildew. By the way, grape berries are no longer edible even with a slight mildew infestation because they develop a very unpleasant taste.

Using baking powder and milk against mildew

Mildew, regardless of whether it is powdery or downy, sticks extremely stubbornly to grape vines. In early spring the fungus begins to grow again and is likely to infest the fresh new shoots of grape plants. There are many cures that the internet tries to offer to the desperate gardeners. However, household remedies such as baking powder or milk are rarely of any help against mildew. It is possible, though, to treat mildew with natural sprays. Copper based preparations are the best way to go. The spray should be applied to the affected plants several times, otherwise the mildew can survive. To increase the likelihood of the treatment’s success we advise to read the instructions manual of the product carefully. Resistant grape varieties are often less susceptible to mildew and are more easily treated when infected.



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