Biology, Cop rotation, Infestation, Mustard, Delayed sowing, Management, Tomato
Orobanche or broomrape obligate, troublesome root parasite which completely depends on the host plant to complete its life cycle. The host plants of Orobanche includes crucifers such as oilseed rape (Brassica spp.), broad bean (Vicia faba) and other crops belonging to Apiaceae, Asteraceae, and Solanaceae families. In India, Orobanche has emerged as a major threat to rapeseed mustard production. Many farmers have abandoned the cultivation of mustard under the threat of this parasitic weed. Orobanche infestation is mostly confined to major mustard growing states of northern Rajasthan, Haryana, Punjab, Western UP, and North East Madhya Pradesh. In Andhra Pardesh, 50% area under tabacco (40,000 ha) is infested with Orobanche and causing 50% crop losses. In Karnataka state, 90% area under tobacco is infested with this weed with 50-60% yield losses. Tomato crop is also infested with Orobanche spp. in Mewat and Bhiwani districts of Haryana. Depending upon the extent of infestation, environmental factors, soil fertility, and the crops’ response damage from Orobanche can range from zero to complete crop failure. Orobanche aegyptiaca is the most dominating species in India; however, localized infestation of two other species namely O. cernua and O. ramosa has also been observed to some extent. In spite of continuous and extensive research by the scientists, no single method for effective and economical management of Orobanche is available. Integration of cultural, preventive and chemical methods is required in spite of its costly inputs. Following methods may be adopted in integration fashion: crop rotation with non-host crops like wheat, barley and chickpea depending on the irrigation facilities; delayed sowing (25 October - 10 November) of mustard supplemented with higher seed rate; use of organic manures in combination with increased fertilizer N dose for enhancing crop vigour; two sprays of glyphosate at 25 g/ha at 30 DAS and 50 g/ha at 55 days after sowing provided the crop does not experience any moisture stress at the time of spray; and hand removal/pulling of left-over emerging shoots before flowering to reduce weed seed bank in the soil