Climatic Characteristics of Disease by Colletotrichum gloeosporioides Penz on China Wolfberry in Yinchuan

The Colletotrichum gloeosporioides Penz is a fatal disease in Ningxia wolfberries, by which heavy economicloss is caused by deeply influencing its quality and yield. As an original habitat, it is very important to understand the biological characters of Colletotrichum gloeosporioides Penz, as well as its meteorological conditions and climate rules, so as to release the hazard of disease by decreasing the yield loss and the quality decline by means of effective and timely prevention and cure. After separating and breeding, effects of environmental conditions on the mycelia growth, sporulation, conidial germination of Collectotrichum gloeosporioides Penz are studied and its lethal temperature is detected by controllable climate boxes in 2004. The problems of the mycelia growth, number of sporulation and conidial germination in connection with different temperature, humidity, pH, carbon resource, nitrogen resource are obtained. The suitable and limited temperature and humidity index on every growth and sporulation stage is also set up.Based on meteorological conditions and its indexes on invaded Colletotrichum gloeosporioides Penz into branches of Lycium barbarum L, which are collected into laboratory and grow on the field during the growing season in 2004 and 2005, it is obtained that those meteorological conditions and indexes are the cause of the invasion and expansion by different amount of rainfall supply. According to perennial climatic data in the main planting areas, the status and time of disease of Lycium barbarum L caused by Colletotrichum gloeosporioides Penz have been simulated in each year from 1971 to 2000 in Ningxia.The results show that the suitable temperatures for mycelia growth are 22—31℃, the maximum and the minimum temperatures are 10℃ and 37℃ respectively. The same is for sporulation, but it is not for conidial germination whose suitable temperatures are 16—37℃ and extremum values are 10℃ and 40℃. The lethal temperature is 50℃, much different from the former researchers. The limit humidity for conidial germination is lower than 80% and the suitable one is upper 90%. The invasion of Colletotrichum gloeosporioides Penz to the leaf, flower and fruit is suitable under the temperatures of 28—32℃. The lower and the upper temperatures are 20℃ and 35℃ respectively. The injection experiments under different amount of precipitations in the field show that 5 mm, 10 mm, 20 mm and 40 mm are indexes that cause Lycium barbarum L anthracnose occurrence, diffuseness, popularity and expansion respectively.Suitable climatic condition for anthracnose occurrence of different degrees almost appears every year in growing season, mainly from middle July to early September.The frequency is over 70% that the conditions suitable for anthracnose occurrence are from the end of July to the end of August in the total 30 years, especially in the period of last three times of fruit gathering in the summer-fruit crown season. The climatic conditions in early June aren't suitable for the development of anthracnose and the highest incidence rate of disease is in August. The main cause that results in the lower and unstable yield in autumn may not be the inadequate of heat resource, but the destructive disease by Colletotrichum gloeosporioides Penz. The severe anthracnose occurs in the middle of 1970s, early and middle of 1990s in the 20th century. However, the relatively slight diseases appear in late 1980s and 1990s in the 20th century, but individual heavy diseases also happen in those period. By means of investigation, the results are true which indicates that meteorological indexes obtained through experiments are reliable.