MANAGEMENT OF POWDERY MILDEW DISEASE {Erysiphe cruciferarum Opiz ex. Junell) OF MUSTARD [Brassica juncea (L.) Czern. & Coss.] 1692
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Date
2012-07
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JAU,JUNAGADH
Abstract
Indian mustard (Brassica juncea (L.) Czern. & Coss.) is the
most important oilseed crop of India. Like other crops, rapeseed
and mustard are attacked by a number of fungal, bacterial and
virus diseases, which are considered economically important.
Among them, powdery mildew caused by Erysiphe cruciferarum
Opiz ex. Junell is an important disease particularly in the
Saurashtra region of Gujarat. Hence, present investigation was
carried out to assess losses due to this disease and to develop
feasible management options.
The initial symptoms of powdery mildew disease appeared
with minute visible and almost circular fungal colony on upper
surface of lower most leaf and progressed towards upper leaves
on both the surfaces, stems, branches and siliquaes. Eventually
whole plant covered with white powdery fungal growth showing a
dusty appearance. In advanced stage, purple blue patches were
seen on the stems. Heavily infected leaves turned pale yellow,
dried and shedded. Infected siliquae produced shriveled seeds.
Heavily infected plant showed early maturity.
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The conidiophores were erect, stout and ellipsoid to
cylindrical in shape and measured 67.4 + 6.2 pm with a
moderately straight foot cell bearing 2-3 conidia in chain.
Conidia were unicellular, hyaline, elliptical to cylindrical in
shape and measured 26.5-39.8 pm x 12.4-16.6 pm in size
without fibrosin bodies.
Estimation of seed yield, oil, protein and test weight loss
due to E. cruciferarum was 22.50, 7.26, 21.74 and 21.52 per
cent, respectively when no control measures were adopted. The
avoidable yield loss 23.48 per cent and net profit of Rs.9,390 per
hectare was achieved by spraying the crop with hexaconazole @
0.005 per cent.
Screening of 13 entries against powdery mildew in vivo
showed that the entries GM-2 was highly susceptible, while GM-
1 and GM-3 showed susceptible reaction. The entries HNS-0004,
lSN-129 and NUDB-26-11 were moderately susceptible and GSL-
1 and GSL-861-212 exhibited resistant reaction. DLSC-3, Kiran,
NPC-3, NPC-111 and NPJ-87 exhibited highly resistant reaction.
The effect of maximum air temperature on disease
development exhibited positive and significant relationship with
per cent disease intensity (PDI) while minimum air temperature
with PDI was found non significant. The morning relative
humidity was significantly negatively correlated with PDI and
afternoon relative humidity was highly negatively significant In
multiple regression analysis, maximum temperature (°C) and
afternoon relative humidity were highly significant to disease
development.
In laboratory screening of systemic fungicides, non
systemic fungicides, insecticides and phytoextracts,
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hexaconazole, dinocap, methyl-o-demeton and clove extract of
garlic [Allium sativum) were found better with 84.10, 79.98,
54.97 and 74.08 per cent inhibition of spore germination,
respectively.
In field evaluation of different fungicides, the minimum per
cent disease intensity (PDI) 28.17 and a maximum yield of 2225
kg/ha was recorded in the treatment of hexaconazole with 54.17
per cent disease control and 30.04 per cent yield increase. The
highest incremental cost benefit ratio (ICBR) of 1:4.63 was
obtained in four sprays of hexaconazole 0.005 per cent followed
by wettable sulphur 0.2 per cent (1:3.36) and penconazole 0.010
per cent (1:1.07).
The maximum oil (34.37%), protein (18.05%) and test
weight (5.39 g) was also recorded in the treatment of
hexaconazole (0.005%). Similarly, oil, protein and test weight
increase were 11.95, 26.05 and 22.78 per cent, respectively.
Neem leaf extract proved to be the most effective
biopesticide and recorded 38.35 PDI with 44.20 per cent disease
control and 2013 kg/ha seed yield with 21.41 per cent yield
increase. The highest ICBR of 1:5.19 was found in four sprays of
neem leaf extract and followed by neem seed kernel extract
(1:3.72) and azadirachtin (1:1.08).
The maximum per cent oil (33.97), protein (16.69) and test
weight (5.38 g) and per cent increase in oil (9.97), protein (15.34)
and test weight (23.68) were recorded in neem leaf extract
treatment under field conditions.
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Keywords
MANAGEMENT OF POWDERY MILDEW DISEASE