Evaluation of fungicides for the management of chrysanthemum white rust caused by Puccinia horiana Henn.

Abstract

Chrysanthemum white rust is a quarantine pest in many countries. In India, this invasive disease was first reported in Udagamandalam in Tamil Nadu in 2012 and has spread to chrysanthemum growing areas in Tamil Nadu and Karnataka. The disease turns epidemic when the night temperature is lower than 19-20°C. Since the disease is newly emerging in India, an attempt was made to evaluate fungicides for the management of this disease. Field evaluation for two years during 2015-16 and 2016-17 was carried out. Spraying chlorothalonil at 0.2% immediately after the first appearance of the rust pustules and continuing at fortnightly interval during Dec – Jan reduced the infection and prevented further spread. In 2015-16, the PDI in chlorothalonil treated plots did not rise above 10 PDI while in control it reached 78.8 PDI. In 2016-17 also, chlorothalonil was found effective with less than 10 PDI while in control it reached above 70 DPI. The next best chemical was propiconazole with 20 PDI. Myclobutanil which was found effective in Europe was not found effective in our study.