Implications of epidemiological studies on strategies for control of powdery mildew and anthracnose.
Joubert M. H.
Author Affiliation: CSFRI Private Bag X11208, Nelspruit 1200, South Africa.
Yearbook - South African Mango Growers' Association 11 : 26-28
Abstract : Different strategies were used to study the epidemiology of powdery mildew, caused by Oidium mangiferae, and anthracnose, caused by Colletotrichum gloeosporioides [Glomerella cingulata], in mango. Powdery mildew incidence was monitored by calculating the area of inflorescence covered by mildew as a percentage of the total inflorescences studied (70) in an unsprayed orchard in Nelspruit during the 1990 season. The epidemiology of anthracnose was studied using detached mango leaves inoculated with G. cingulata and incubated at 26°C for 5 d to determine which developmental stage was most susceptible to anthracnose infection. The first symptoms of powdery mildew were seen at the beginning of Aug. approx. 1 week after the first spores were released and 50% of inflorescences were in full bloom. A peak in disease incidence appeared in the first week in Sep., when spore release was at a max. Full bloom and fruit set to pea size stages were the most susceptible. Studies on anthracnose showed that lesions on leaves were important sources of inoculum for the infection in blossoms and fruit and it is suggested that susceptible leaves should also be sprayed. Spraying in the last flush of the season (bronze-brown leaves) may reduce inoculum levels to an extent which would reduce the percentage of infection in the flowers and fruit of the following season.