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Downy Mildew Redux

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stcoemgen

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Downy Mildew Redux

Last year I wrote that downy mildew was relatively uncommon in our vineyard. However, it has been cool and raining regularly since mid July this year, with another 3.5 cm last night and more rain predicted through the weekend. Ideal conditions for downy mildew.

And not too unexpectedly, there has been a lot of downy mildew in our vineyards this year. Not so much in the classic “oily spot” form, but in the much worse circumstance of significant leaf attack and vine defoliation caused by this fungus. I only spray with certified organic fungicide solutions. For powdery mildew this is sulfur, and for downy mildew the spray is historically copper sulfate. While there are other new and modern organic options these are not yet available in Hungary (more on that in a separate post).

While I always notice some small amount of fungus in the vineyard, regular spraying normally keeps fungus under control and with the ideal to avoid larger infestations. But organic solutions are contact fungicides, meaning they are only effective if they contact the fungus on a leaf or grape cluster. Rain will wash off the fungicide spray. And with this very wet year it has been a battle royal, as the below images demonstrate.

Pinot Gris leaves that received copper sulfate spray.
Pinot Gris leaves that received copper sulfate spray. You can notice some spray residue as the slightly blue-gray spots on the leaves, and most observable on the lower leaf.
Now showing part of the lower grape leaf covered by the upper leaf and what fungal damage occurred due to the contact fungicide not being applied due to this physical coverage.
Now showing part of the lower grape leaf covered by the upper leaf and what fungal damage occurred due to the contact fungicide not being applied to half of the leaf surface due to this physical coverage.
Multiple fungus attacks on grape cluster.
Multiple fungus attacks on grape cluster. Showing both powder and downy mildew damage. This grape cluster was buried in the vine under leaves and none of the contact fungicide spray reached it. So it gives a good example of what our entire vineyard would look like without spraying.
The heaviest leaf damage and defoliation has been to the Turán. Which is why I still consider this an experimental vine type in our vineyard.
The heaviest leaf damage and defoliation has been to the Turán. Which is why I still consider this an experimental vine type in our vineyard.

 

 

One response to “Downy Mildew Redux”

  1. Weather That Is Good For Mushrooms Is Bad For Wine | Crafting wine, life and home in Hungary Avatar
    Weather That Is Good For Mushrooms Is Bad For Wine | Crafting wine, life and home in Hungary

    […] vines were hit hard with moisture loving downy mildew in July and August, and this month grape clusters have been hit with Botrytis bunch rot. Botrytis […]

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