Garlic is widely cultivated in Utter Pradesh, Haryana, Punjab, Madhya Pradesh, Gujarat, Rajasthan, Orissa and Maharashtra. The crop, like others, is infested with several pests among which onion thrips is a major one.
Both nymphs and adults suck the leaf sap and cause injury to the crop.
They remain in dense clusters at bottom of leaves and whorls and feed by lacerating the tissues and sucking the oozing cell sap.
InfestationThe infestation results in a spotted appearance on the leaves, subsequently turning into silver coloured blotches. The leaf tips fade and the basal portions get blighted and distorted from tip downwards and finally the plant dries up. Infested plants yield less by small sized bulbs.
Adults are slender, yellowish brown and measure about 1mm in length with narrow fringed wings. Eggs are laid singly in tender leaves by making slits with sharp ovipositors by the females. A single female lays 40-50 eggs which hatch after 4-9 days. The entire life cycle is completed in 11-21 days. There are more than ten generations per year. The pest occurs on garlic from November to May and migrates to other crops from June.
ManagementVarieties with open type growth and circular leaf structure are not preferred by the pest.
Tolerant varieties of garlic viz. G-2, G-19, LCG-1, Ooty-1 can be grown.
High doses of nitrogenous fertilizers and close planting should be avoided.
Clean cultivation, regular hoeing and flooding of infested field will check the pest population.
Insect predators like green lacewing fly and tiny ladybird beetles check the population of this pest in nature.
Spraying of insecticides at rate of (10 thrips/plant) is advised.
Application of monocrotophos 0.036 per cent, formothion 0.025 per cent, dimethoate 0.03 per cent, profenofos or malathion 0.05 per cent, methyl demeton 0.025 per cent , , carbaryl 0.1 per cent or phorate 10G at 10kg/hectare can help.
(J. Jayaraj, Associate Professor and R.K. Murali Baskaran, Professor & Head, Dept. of Entomology, Agricultural College and Research Institute, Madurai 625 104, email: vu2jrj@rediffmail.com, phone: 0452- 2422956 Extn: 214.)
