Matheron M E, Porchas M
The University of Arizona, Yuma Agricultural Center, Yuma 85364.
Plant Dis. 2005 Jan;89(1):50-54. doi: 10.1094/PD-89-0050.
The effect of soil temperature and moisture on eruptive germination and viability of sclerotia of Sclerotinia minor and S. sclerotiorum in field soil was examined. In two trials at constant temperatures, the proportion of sclerotia of both pathogens that germinated in wet soil ( ≥-0.02 MPa) tended to decrease as soil temperature increased from 15 to 40°C, with no germination of sclerotia of S. minor and S. sclerotiorum detected after 1 and 2 weeks, respectively, at 40°C. In contrast, after 1 to 4 weeks in dry soil ( ≤-100 MPa) at 40°C, germination of sclerotia of S. minor and S. sclerotiorum ranged from 28 to 55% and 42 to 77%, respectively. In field trials, the germination rate of sclerotia of S. minor and S. sclerotiorum after 2 to 8 weeks in irrigated soil on the surface or buried at a depth of 5 cm was significantly lower than that for sclerotia maintained in dry soil at the same depths. On the other hand, after burial at a depth of 10 cm, germination of sclerotia in irrigated and dry soil did not differ significantly after 2 to 8 weeks for S. minor and after 2, 4, and 8 weeks for S. sclerotiorum. For both pathogens, germination of sclerotia from 2 to 8 weeks in irrigated soil with a mean temperature of 32°C was significantly lower than that for sclerotia in irrigated soil with a mean temperature of 26°C. In microplot trials conducted in July and August, no sclerotia of S. minor and S. sclerotiorum germinated after 2 and 3 weeks, respectively, after recovery from flooded soil with mean soil temperatures ranging from 30 to 33°C. A flood irrigation is often applied to fields for salt management during July or August in the Yuma lettuce production region. Results from these studies suggest that maintaining this flooding event for 2 to 3 weeks in fields with a history of lettuce drop caused by S. minor and S. sclerotiorum could significantly reduce the population of viable sclerotia.
研究了土壤温度和湿度对田间土壤中小核盘菌和核盘菌菌核的爆发性萌发及活力的影响。在两个恒温试验中，随着土壤温度从15℃升高到40℃，两种病原菌的菌核在湿润土壤（≥ -0.02 MPa）中的萌发比例均呈下降趋势，在40℃时，小核盘菌和核盘菌的菌核分别在1周和2周后未检测到萌发。相反，在40℃的干燥土壤（≤ -100 MPa）中放置1至4周后，小核盘菌和核盘菌菌核的萌发率分别为28%至55%和42%至77%。在田间试验中，小核盘菌和核盘菌的菌核在灌溉土壤表面或埋于5厘米深处2至8周后的萌发率显著低于在相同深度的干燥土壤中保存的菌核。另一方面，埋于10厘米深处后，小核盘菌在灌溉和干燥土壤中2至8周后的菌核萌发率无显著差异，核盘菌在2、4和8周后的菌核萌发率也无显著差异。对于这两种病原菌，在平均温度为32℃的灌溉土壤中2至8周的菌核萌发率显著低于平均温度为26℃的灌溉土壤中的菌核萌发率。在7月和8月进行的小区试验中，从小核盘菌和核盘菌引起生菜菌核病的历史田块中回收后，小核盘菌和核盘菌的菌核分别在2周和3周后均未萌发，此时土壤平均温度为30℃至33℃。在尤马生菜产区，7月或8月经常对田地进行漫灌以进行盐分管理。这些研究结果表明，在有小核盘菌和核盘菌引起生菜菌核病历史的田块中，将这种漫灌事件维持2至3周可显著减少存活菌核的数量。
