Management of downy mildew of grape caused by Plasmopara viticola with new formulation of fungicides and plant strengtheners.
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Date
2015-05-30
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Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani
Abstract
known edible fruit crop. Most commercial grape belongs two genus Vitis which contain
about 60 species found mainly in the temperate zones of Northern Hemisphere and
distributed almost equally in America and Asia. Grape is affected by many fungal,
bacterial and viral diseases. Downy mildew is one of the prevalent disease caused by
Plasmopara viticola increased at faster rate in most part of grape growing areas.
A Preliminary survey was carried out in Osmanabad and Latur districts during
2014-15 to find out the incidence and severity of downy mildew of grapes. Among these
districts, average mean per cent disease incidence and severity of Osmanabad was
recorded as 48.37 and 30.18 per cent, respectively, whereas, in Latur district, average
mean per cent disease incidence and severity was recorded as 46.66 and 38.46 per cent,
respectively.
Different fungicides were tested at 0.1, 0.15 and 0.2 per cent concentration against
Plasmopara viticola in-vitro condition by cavity slide technique. Azoxystrobin recorded
maximum spore inhibition of 88.12, 90.82 and 95.16 per cent at 0.1, 0.15 and 0.2 per cent
concentration, respectively.
Different fungicides were tested at 0.1, 0.15 and 0.25 per cent concentration invivo
condition against downy mildew disease. Among all the fungicides, Azoxystrobin
was found significantly superior in controlling downy mildew disease. Azoxystrobin
recorded at maximum per cent disease control of 67.77, 66.72 and 67.72 per cent at 0.1,
0.15 and 0.25 per cent concentration.
Different plant strengtheners were tested at 0.15 and 0.25 per cent concentration
in-vivo condition against downy mildew disease. Among all plant strengtheners, Salicylic
acid was found superior in controlling downy mildew disease. Salicylic acid recorded
55.77 and 63.58 per cent disease control at 0.15 and 0.25 per cent concentration,
respectively.
At all the concentration of fungicides tested, Azoxystrobin was found
significantly superior in fruit setting and fruit yield. It recorded fruit yield of 9.74,11.32
and 13.46 kg/plant at 0.1, 0.15 and 0.25 per cent respectively. At all concentration of the
plant strengtheners tested, Salicylic acid was found significantly superior in fruit setting;
fruit yield per plant and yield per ha. The second best treatment in yield character was of
Amino acid.
Different varieties of grapes were screened for downy mildew disease severity
under natural conditions. None of the variety was found immune and highly resistant.
Manik chaman, Sonaka, Sharad seedless, Nanasaheb purple and winery varieties viz.
Sauvignon block and Semiion were found tolerant to downy mildew disease, whereas,
Thompson seedless and Tas-e- Ganesh varieties were found susceptible to downy
mildew disease in natural condition.
At 0.1 and 0.15 percent concentrations of fungicide, Pyraclostrobin + Metiram
recorded maximum ICBR, whereas, at 0.25 per cent concentration, Fenamidon +
Mancozeb treatment recorded maximum ICBR. In plant strengthener, Cystin + Folic
acid was found significantly superior in incremental cost benefit ratio at 0.15 per cent
concentration, whereas, Tricontanol treatment recorded maximum ICBR at 0.25 per
cent concentration.
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