Germplasm evaluation of chrysanthemum for resistance to aphid, Macrosiphoniella sanbornii (Gillette)

Chrysanthemum aphid, Macrosiphoniella sanbornii (Gillette) is one of the serious pests of chrysanthemum. Nymphs and adults of aphid colonize under surface of leaves, apical shoots, buds and flowers. They suck sap resulting in devitalization of affected parts. The honeydew excreted by aphids attracts sootymould which adversely affects photosynthetic efficiency of plant In order to find a resistance source, fifty two germplasm/varietal collections of chrysanthemum were evaluated under polyhouse during 2002-04 at Indian Institute of Horticultural Research, Bangalore. The extent of damage was recorded in terms of number of aphids per apical shoot and the percent leaf infestation with aphids. Significant variations were recorded among genotypes in their susceptibility to aphid. Ten collections, viz., ‘Anuradha’, ‘Aparajitha’, ‘Asha’, ‘Chandi’, ‘F-52 ‘Heritage’, PC-31’, ‘Rangoli’, ‘Red stone’ and ‘Usha kiran’ were found to be resistant (mean no. of aphids <5/apical shoot and <10percnt; affected leaves). Among the rest, 21 collections were moderately resistant, 16 were susceptible and 5 were highly susceptible (>25 aphids/shoot and >50% affected leaves).