Pathogenicity test of Alternaria brassicae (Berk.) Sacc. using artificial inoculation methods on common varieties of rapeseed-mustard in Punjab region

Abstract

To develop the precision, sensitivity for pathogenicity testing, a comparison was carried out among three different
artificial inoculation methods namely foliar spraying method, drop method and biocontrol+foliar spray method for
pathogenesis studies. The pathogen A. brassicae was isolated and from infected mustard plants. The drop inoculation
method was most ideal as this fixed the inoculum on the target site. Drop method produces significantly higher number
of disease lesions than the other inoculation methods and has the advantage of being accurate and precise. The number
of initial disease lesions in drop method was highest in all of the time intervals of observation namely 71 in B. juncea
(Giriraj), 59 in B. juncea (RLC-3), 53 in B. napus (GSC-7), 73 in B. nigra (PC-6) at 120h after pathogen inoculation
compared to other methods respectively. The results in this particular study indicates that two varieties B. juncea (RLC-
3) and B. napus (GSC-7) showed some tolerance as compared to other two varieties B. juncea (Giriraj) and B. nigra (PC-
6).The biocontrol agent used in particular study showed that the tolerance can be induced in the plants using Trichoderma
viride. As the number of lesions and pathogenicity caused by A. brassicae was reduced considerably when the culture
of T. viride was used.