Vine Midew ,also known as fog or blast among other names, is a Cryptogamic disease caused by the Plasmopara viticola fungus.
It attacks all the green organs of the plant and is very feared due to the damage it can cause in the harvests. Therefore, it is very important to know its cycle and to recognize its symptoms in time to be able to act.
Below we review those key points that we must know to avoid the disease or minimize its damage.
- Annual cycle of the fungus
The fungus develops within the infected tissues.
During the winter, it is mainly conserved in the dead leaves in the form of oospores and, it is in the spring ,when the favorable conditions of temperature and humidity usually occur so that they are mature. From there will come the zoospores that are the contaminating organs that will produce the primary contaminations.
After an incubation time (between one or two weeks, depending on humidity and temperature conditions) , the first visible symptoms will appear at this time, when secondary contamination may occur due to new infections.
In autumn, it will form oospores again to preserve itself during winter.
- Conditions for its development
As we have already mentioned, the fungus will develop when the conditions are favorable and they normally occur in the spring.
These conditions can be summarized in the so-called “rule of three 10”.
- Vine shoots with a length of 10 cm or more.
- Temperatures above 10 cm.
- Rainfall of more than 10 mm.
- Signs that warn us of your presence.
- Leaves: In the beam ,first appreciate some yellowish spots called oil spots produced by the filaments of the fungus, that later will acquire a mosaic shape and, on the underside, a whitish fuzz will appear.
- Bunches: Immediately after flowering, the fungus attacks the rachis making it curve in an S-shape, causing it to dry completely or partially, and presenting the characteristic whitish fuzz. When the grain is over the size of a pea, the fungus causes it to darken, wrinkle, and eventually dry.When the grain is over the size of a pea, the fungus causes it to darken, wrinkle, and eventually dry.
Pay special attention to the flowers and freshly curdled grains because at that time they are very sensitive to the attack of the fungus and the entire bunch could be lost.
- Vine mildew how to fight it naturally.
The fundamental thing is always prevention. It is necessary to promote the aeration of the vineyard by making green trimmings or pruning, eliminate the leaves that could be affected and choose those varieties that are more resistant to the disease.
From IDAI NATURE we propose the use of OROCIDE ( Register number :ES-00867), a natural and effective solution against mildew that does not create resistance and is formulated from orange oil.