Prevalence and management of leaf spots of sorghum
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was conducted at Forage Research Farm and Pathology
Laboratory of Department of Plant Breeding and Genetics, PAU, Ludhiana during Kharif
2012. Leaf spots were prevalent in Ropar, Hoshiarpur, Jalandhar, Ludhiana, Moga and
Faridkot but intensity was more in Hoshiarpur and Ropar. Grey leaf spot was widely and
severely distributed than zonate leaf spot and anthracnose. Fungi associated with leaf spots
were identified as Cercospora sorghi causing grey leaf spot, Gloeocercospora sorghi causing
zonate leaf spot and Colletotrichum graminicola causing anthracnose of sorghum. The fungi
associated with these leaf spots has also been detected as part of seed mycoflora and might
play role in primary infection. Development of leaf spots revealed that grey leaf spot appeared
in first week of July, whereas zonate leaf spot and anthracnose appeared in field in second
week of August and end of July respectively with maximum per cent disease index (PDI) of
39.67 (grey leaf spot), 20.42 (zonate leaf spot) and 11.75 (anthracnose) towards the end of the
season. Relative humidity and rainfall were positively correlated, whereas temperature was
significantly and negatively correlated with develoopment of leaf spots. Grey leaf spot was
predominant on all dates of sowing but intensity of all the leaf spots was high in timely and
the late sown. Of 119 germplasm accessions, 7 (94001 A, NS 1008-A, SSG 226, SSG 241,
SSG 253, SGL 244 and SGL 98-12) showed multiple disease resistance against these leaf
spots. Under in vitro conditions, Emisan @ 2.5g/kg seed showed the lowest infection by
different mycoflora, whereas under in vivo conditions seed treatment with Emisan @ 2.5g/kg
seed and Bavistin @ 3g/kg seed recorded minimum leaf spot intensity in both forage and
grain crops. These treatments also showed increase in yield.
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