CHIKMAGALUR: Coffee growers in the Malnad districts of Chikmagalur, Hassan and Kodagu are a worried lot as their crops, especially Arabica plants, are susceptible to Coffee Leaf Rusr (CLR).
Severity and damage of CLR is more in the areas where Arabica coffee is grown below 1000 m MSL. The CLR affects the yield by reducing photosynthetic efficiency due to defoliation and loss of vigour of the plants. Coffee Growers’s Association office-bearer M S Lingappa Gowda told Express that the growers in Chikmagalur largely grow Arabica plant, which is more susceptible to the disease than Robusta.
“The infection causes berries to fall resulting in the loss of yield. Arabica is already affected by white stem borer worrying farmers. This is another worry,” he said.
However , the Coffee research station of Balehonnur has advised planters to cultivate rust tolerant Chandragiri coffee variety, grow arabica under optimum shade, prune the coffee bushes after harvest and before blossom shower, spray freshly prepared Bordeaux mixture and application of Triadimefon during monsoon break to prevent defoliation.
In severely affected areas, loss of foliage will be up to 50 per cent and berries up to 70 per cent. Hemileia Vastatrix is an obligate parasite and affects only coffee crops. The pathogen forms uredospores, telitispores and basidiospores in its life cycle but the pepetuation is only through underspores formed abundantly on the infected leaves under favourable conditions.
The pathogen exists in the form of races and so far 45 races are reported. Due to its ability to exist in the form of different races, newly developed resistant coffee varieties are subjected to infection. Spread of the disease is by dispersal of spores by wind, water and by insects, mites and human beings to a little extent. According to scientists of Central Coffee Research Institute (CCRI), the main symptoms of CLR are development of pale yellow lesions under the leaves and spots turning yellow to orange with powdery mass of the uredospores of the pathogen.