Management
of aphids
Chemical: In the higher hills, where potatoes are grown as rain-fed crop under long-day conditions, only foliar systemic insecticides such as methyl-demeton, dimethoate, thiometon or monocrotophos etc., at 0.03% concentration are recommended for controlling aphids on seed crop. The first spray may be given soon after seeing 1-2 aphids/100 compound leaves on the crop and subsequent 1-2 sprays be given after 10-15 days depending upon the aphids’ pressure. Under irrigated conditions, application of granular systemic insecticides like phorate 10G or carbofuran 3G @ 1.0 -1.5kg a.i./ha is effective for 40-50ays. Granular insecticides applied at planting will not be effective to protect the crop throughout the crop season. Therefore, one to two need- based sprays with any of the above mentioned foliar systemic insecticides at 10 to15 days interval would be needed during the later stages of crop.
Biological: Allograpta favana (Wiedemnn), Episyerphus balteatus (De Geer), Ischiodon scutellaris (Fabricius), S. scripta (Linnaeus) , Sphaerophoria indiana Bigot; Leucopis fumidilarva Tanas, Menochilus sexmaculatus (Fabricus) among the predators and: Aphelinus sp. and Aphidius colemani Viereck among the parasitoids have been reported to be promising. At Shimla, Aphelinus sp has been found to parasitize 100 per cent M.persicae under glass houses conditions.
Integrated management: The integrated management strategies for vectors (mainly aphids) are the need of hour. There is a need to evolve strategies for primary and secondary potato seed growing areas. Some of the approaches suggested are:
1. Planting early bulking and/or maturing cultivars to help seed production programme in areas having short aphid-free periods so that the seed crop may escape the population pressure of aphid vectors.
2. Introduction and conservation of bio-agents that can establish themselves quickly in the crop season and help in checking the initial build up of the vectors.
3. Application of effective insecticides at the right time in recommended manner.
4. Adjustment of planting and harvesting in different potato seed producing areas in a manner that the crop faces none or minimum population-pressure of vectors.