Studies on powdery mildew of sunflower caused by Erysiphe cichoracearum DC.
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Date
2009
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UAS, Dharwad
Abstract
Sunflower is one of the important oilseed crops of India. Among biotic stresses powdery
mildew caused by Erysiphe cichoracearum is economically important disease. Roving survey was
conducted during late kharif and rabi seasons of 2008 in seven districts of Northern Karnataka.
Maximum disease severity was noticed in Koppal (74.11%) and Haveri district (66.61%). Least
severity was noticed in Bagalkot (30.94%) and Belgaum district (34.11%).
The plants of 50 days old were highly susceptible to the infection of
E. cichoracearum. The per cent reduction of chlorophyll a, chlorophyll b and total chlorophyll was
more in susceptible variety than in resistant cultivar. In susceptible variety higher amount of total
sugar, reducing sugar and non-reducing sugar were recorded than in resistant cultivar. Whereas, nonreducing
and total sugar were synthesized at faster rate in susceptible cultivar than in resistant cultivar.
Healthy leaves of resistant cultivar had 1.362 mg/g of total phenols and it was increased to
4.817 mg/g after infection. Total phenols were accumulated at faster rate in resistant cultivar (253.63%)
than in susceptible cultivar (230.70%).
Among the 91 germplasm lines screened under artificial epiphytotic condition seven lines viz.,
GMU601, 602, 605, 664, 672, 684 and 697 were found resistant against powdery mildew.
In case of in vitro evaluation of botanicals and organics, azadirachtin (0.5%) and NSKE (5%)
were found most effective in inhibiting conidial germination. Whereas, in field azadirachtin (69.07%
and 7.11 q/ha) and NSKE (66.93% and 7.00 q/ha) managed the disease and increased yield
significantly.
In field evaluation of fungicides, two sprays of difenconazole at 0.05 per cent
(3.56, 9.53 q/ha), propiconazole at 0.1 per cent (4.44, 9.47 q/ha) found superior as they recorded the
lowest per cent disease index and higher seed yield. Highest cost benefit ratio was observed in
propiconazole (1:6.86), difenconazole (1:6.13) and hexaconazole (1: 6.12).