Abstract: The impacts of the meteorological factors on the occurrence of the colletotrichum gloeosporioides Penz of Chinese Wolfberry (Lycium chinense) in Ningxia were studied to determine the discriminant indexes and their thresholds. The results of a four years experiment indicated that the key meteorological factors influencing outbreak of the colletotrichum gloeosporioides were the mean relative humidity and the precipitation, including rainfall and available precipitation days during 28 days before mature period, and the mean wind speed during 12 days before mature period. Based on the index of colletotrichum gloeosporioides occurrence, the discriminant index of meteorological factors was determined by methods of k-means cluster and artificial judgement. The accuracy of discriminance was with 66% tested by historic data.

Key words: Colletotrichum gloeosporioides Penz, Colletotrichum gloeosporioides Penz, Discriminance, Meteorological index