EPIDEMIOLOGY AND MANAGEMENT OF TURCICUM LEAF BLIGHT OF MAIZE CAUSED BY Exserohilum turcicum (Pass.) Leonard and Suggs
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Date
2007-08-31
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University of Agricultural Sciences GKVK, Banglore
Abstract
Turcicum leaf blight disease of maize caused by Exserohilum
turcicum symptoms were recognised by long spindle shaped necrotic
lesions with grey colour centre, immature and chaffy ears. The disease
appeared in severe form in most of the maize growing areas of
Kamataka.
Crop loss estimation studies revealed that, avoidable grain and
stover yield losses in susceptible genotype were to the extent of 52 and
40 per cent, respectively. Linear regression crop loss models were
developed. Arabhavi isolate recorded high virulence. Sixty-five days old
plants found vulnerability to infection. An incubation period of 28 hours
was found ideal for more than 90 per cent spore germination.
Saccharum arundinaceum Retz. was identified as a potential
alternative host to E. turcicum and plays an important role in the
epidemiology of TLB in Karnataka.
Significantly maximum disease severity was noticed in crop sown
on 16^ September. Crop sown between Februaiy and April found least
affected. The weather factors, viz., minimum temperature (11.3-21.4®C),
maximum temperature (26.3-29.4°C), relative humidity (58.7-84.5%) and
rainfall (47.104 mm) were highly favourable for disease epidemic. The
locations, viz., Arabhavi, Dharwad, Devihosur, Sankeshwar and
Nagenahalli were identified as "hot spots' in Kamataka. Significant and
positive correlation existed between rainfall and relative humidity with
spore load.
The genotypes, viz., Allrounder, IB-8501, Cargill 900M, Hi-Shell,
NAC-6004, C-111, KH-517, Kaveri 235 and NK-6240 were identified as
slow blighters. The disease was responsible for photosynthesis loss to the
extent of 89.40 per cent in susceptible genotype.
Fourteen inbrei lines were identified as highly resistant sources.
The QPM genotypes HQFM-4 and HQPM-5 found highly resistant.
Integration of 'olerant hybrid DMH-2 and seed treatment with
carboxin power (2 g/kg) or combined seed treatment with Azospirillum
sp. (25 g/kg) and T^choderma harzianum (6 g/kg) followed by three
sprays with mancoze? (0.25%) was found to be the most effective IDM
package for the management of TLB of maize.
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