Effect of Sowing Dates on the Bacterial Leaf Spot of Bottle Gourd and Pumpkin Caused by Xanthomonas cucurbitae

Abstract

An experiment was conducted at Experimental Farm, College of Horticulture and Forestry, Neri, Hamirpur during May 2019 to October, 2019 cropping season to study the effect of different sowing dates viz., 17th May (1st), 7th June (2nd), 27 June (3rd) and 17th July (4th) on the development of bacterial leaf spot of bottle gourd and pumpkin caused by Xanthomonas cucurbitae. It was observed that the mean disease severity in both bottle gourd and pumpkin crops decreased with delay in the date of sowing from mid May (40.15 and 31.73%, respectively) to the end of June (27th June, 31.65 and 27.06%, respectively) or mid July (17th July, 23.32 and 20.13%, respectively). The disease incidence was also found to be minimum in the fourth (31.31%) and third (39.60%) dates of sowing in case of bottle gourd fruits and no incidence of the bacterial spot was recorded in case of pumpkin fruits. In the case of bottle gourd, the expected yield loss was minimum in crops sown mid July (31.44%) while in pumpkin, the fruit yield was more in mid July (9.59 kg vine-1) sown crop in comparison to mid May and early June sown crops. So, it was concluded that late June and mid July sown crops of both bottle gourd and pumpkin are less vulnerable to the disease leading to reduced crop losses and higher yield.

Bacterial Leaf Spot of Cucurbits: A Menace to Cultivation

“…It was found that disease severity decreased with a delay in date of sowing from mid-May to the end of June (27th June) or mid-July (17th July) in pumpkin and bottle gourd [21]. A high disease severity was recorded in early sown (17 May and 7 June) crops [44]. Development of bacterial spots of bottle gourd and pumpkin was favoured by temperatures ranging between 30 and 35°C and relative humidity more than 80 per cent [21].…”

“…A similar survey was conducted in Illinois, USA, between 2010 and 2011 in pumpkin fields, which demonstrated the prevalence of bacterial spots in the field on infected fruits with 25 per cent disease incidence on an average. The survey in Jammu and Kashmir, India, including 27 areas revealed disease severity ranging from 14.5 to 33.4 per cent [24]. Bacterial leaf spot was also recorded to be a predominant disease in 60 per cent of fields of pumpkin surveyed on Caribbean Island with 30 per cent disease incidence in the rainy season [25].…”

“…Temperatures between 25 and30°C with 90 per cent relative air humidity are favourable conditions for disease development [34]. Disease incidence reaches its peak at the end of July and the beginning of August [44].…”

“…These chemical compounds or biocontrol agents may be used in combination with other methods to manage X. cucurbitae in pumpkins. It was found that a chemical combination comprising streptocycline (100 ppm) + captan (2500 ppm) proved effective in controlling the pathogen and disease both under in vitro and pot house conditions [49].…”