Department of Horticulture, Punjab Agricultural University, Ludhiana
Online published on 20 March, 2012.
The investigations were conducted at Punjab Agricultural University, Ludhiana during 1999 to 2001. The infestation of guava shoot borer, Microcolona technographa Meyrick at four locations varied from 46–66 per cent on full-grown trees whereas, it was 63–97 per cent on nursery plants. The apical buds of full-grown trees were more preferred (83.2%) to that of nursery plants (69.8%) while the infestation on auxiliary buds (62.7%), leaf petiole (37.4%) and leaf mid-rib (16.3%) of nursery plants was more compared to full-grown trees. The number of larvae and holes per shoot on nursery plants (2.9±1.2 larvae and 6.8±2.1 holes) were significantly high in full-grown trees (1.2±0.9 larvae and 2.6±1.3 holes). The pest remained active from mid April to November with its peak period of infestation from mid July to mid August. The effect of abiotic factors showed that mean temperature (r= 0.48 and 0.47, respectively with per cent infestation and fresh holes bored) and relative humidity (r=0.37 and 0.34) had significant impact on build up of shoot borer population. The selections showing more infestation had more number of holes and vice-versa. Among 31 genotypes, four selections viz., Red Flesh (Faizabad), Sardar Guava, Dharwar and Annu Ishkwala showing 14–20 per cent infestation were moderately resistant. Monocrotophos, chlorpyriphos, quinalphos and endosulfan each @ 0.1 per cent were found effective in reducing the pest infestation significantly.
Guava Microcolona technographa, Susceptibility
