Control of Downy Mildew in Grapes Caused by Plasmoparaviticola L Using Silver Nano Particles

Grapes (vitisvinifera) is a major horticultural crop in western Maharashtra, India. It contributes about $170 million per annum. It’s export share is about 172000 MT per annum. Downy mildew is one of the most important disease in grapes. For avoiding the financial loss huge quantity of different plant protection products are used every year. However, use of synthetic pesticides is a major obstacle for the grape growers because of the undesirable pesticide residues.

This is especially true for the exporters. Thus there is an urgent need for a disease control agent without synthetic pesticides which are unacceptable due to the foot print in human food.

Silver Nano particle are very well known as antibacterial, anti fungal agents. Their application in plant health care sector is still in a nascent stage. On this background, we undertook a systematic study involving the pathogen - Plasmoparaviticola causing downy mildew in grapes.

Silver Nano particles were produced using bacterial cultures (Bacillus subtilis plus Pediococcus) . Their enzymatic action neutralized the harmful ionic silver and also capped the AgNP. The AgNP were also produced through ‘Green Synthesis (using plant extracts).

The study was done in two parts. In the first study, diseased sample of grape vine leaves were studied in the laboratory. Different concentrations of AgNP were tested against the zoospores of the disease causing fungus Plasmoparaviticola.

In the second part field trials were conducted to confirm the efficacy of AgNP on the leaves affected by Plasmoparaviticola. The leaves affected by downy mildew after spray of AgNP at the concentration of 80 PPM showed death of fungus in 5-6 days.

The healthy leaves were also sprayed with 80PPM AgNP to assess preventive nature of AgNP against attack of Downy Mildew.

The plants treated were free from the attack of Plasmoparaviticola (downy mildew). In some cases which received preventive spray of AgNP, the plant showed attack of down mildew after 2 weeks.