Role of weather on <i>Alternaria</i> Leaf Blight Disease and its effect on Yield and Yield Components of Mustard

Abstract

Alternaria leaf blight disease caused by Alternaria brassicae in mustard (Brassica juncea (L) Czern and Coss) was studied in two crop seasons, 1992 and 1993 in Nepal at Nawalpur, Sarlahi (Tarai) and Khumaltar, Lalitpur (mid hill). At Nawalpur, epidemics of the disease was recorded for both seasons. Weather conditions like humidity, temperature and frequent rainfall played key role for the epidemics. In experimental fields, the disease appeared first in mid-December when the relative humidity was more than 80% with maximum temperature ranging between 18-25 0 C and minimum between 10-14 0 C. At Khumaltar, incidence of the disease was low in both seasons due to low average temperature from December to February. Among cultivars, Krishna and Pusabold were less susceptible than Varuna. Both mancozeb and iprodione had effectively reduced disease in the sprayed plots and increased seed yield by 48% and 130% respectively. The correlation between disease severity and yield, and yield components was negative and highly significant. Average yield loss was estimated to be in the range of 32 to 57%. Seed infection was also significantly higher in non sprayed treatment than sprayed one. The disease showed a negative effect on oil content causing losses on oil between 4.2 to 4.5%.

Assessment of Different Brassica Germplasms Against Alternariablight and Its Management Using Naturally Occurring Chemicals

“…Many scientists worked on control Alternaria leaf blight of brassica by different plant extracts and chemicals. Our results are in agreement with [8,13] who checked the efficacy of plant extracts obtained from garlic, neem leaf, ginger and onion bulb against Alternaria brasicae. It was observed that the application of plant extracts show significant result to increase the seed germination as compare to untreated control.…”

Implication of Meteorological Parameters on the Incidence of Purple Blotch of Onion under Odisha Condition

“…However, maximum temperature, maximum RH, number of rainy days and wind velocity were found to be statistically significant with respect to disease development which supports the findings of Cova and Rodriguez (2001), Delahaut and Walt (2004) and Shrestha et al, (2005) (Table 4). The maximum temperature alone contributed 49.28% towards the disease development followed by minimum temperature (23.88%) and then wind velocity (21.82%).…”

Prevalence, Incidence and Management of Alternaria Blight of Rape-Seed and Mustard (Brassica juncea L) through Resistance and Integrated Approach

“…Average yield loss in the range of 32-57 per cent due to Alternaria blight has been reported from Nepal (Shrestha et al, 2005). Besides India, disease is reported to be of major economic importance in Australia, France and Poland and of moderate importance in Canada and United Kingdom (Sharma and Kolte, 1994;Verma and Saharan, 1994;Barman and Bhagavati, 1995).…”