downy mildew of grapes

downy mildew of grapes

1. Downy mildew of grapes distributed worldwide where the grapes are grown in humid condition.
2. The Plasmopora viticola attacks on fruits and leaf of the grapes plants and also cause dwarfing and killing the young shoots.
3. The downy mildew of grapes is caused by Plasmopora viticola.

downy mildew symptoms 

1. On the upper surface of the bay leaf developed yellowish gray spot from the lower surface of the spores downy growth of fungus appear these nacrotic areas may causes.
2. The leaf of the grapes turn to become brown and the infected leaf may finally die. Barriers turn brown and may also be attacked.
3.  Mildew pathogen is not indused storage decay.

Causal Organism of downy mildew of grapes

1. Plasmopora viticola
2. The conidiophore branches at the right angle and are in irregularly spaced.
3. Intercellular space in mycelium has mycelium ranifers in it and sets haustoria globose into infected tissue.
4. Through One stoma 4-6 sporangiophores arise each sporangiophores producing 4-6 branches nearly right angle to make branches, after that 2-3 secondary branches are produce from each such branches.
5. Sporangia germinates through resting spores or zoospores are produce as a result of fertilization between Anthredia and oogonia.

Disease Cycle of downy mildew of grapes

The fungus over twinter through. Oospores on the infected plant. Oospores germinates at a temp range of 20°c to 25°c penetration take place through stomata on lower surface of the leaves. For the production of sporangial the incubation periods is about 5-8 days after infection, depending upon the humidity and the temperature

Downy mildew of grapes life cycle

Sporangia is responsible for the secondary infection  and this is germinates by the means of zoospore.

Controls of downy mildew of grapes

1. The infected leaves of sanetary precaution and the fallen things should be destroyed.
2. Use resistance variety of crops.
3. The most commonly used spray of fungicides are as follows; Biltox 50,Captan, Bordeaux mixture etc