天水地区葡萄霜霉病田间病情、孢子囊数量动态及病害始发关键因子分析

葡萄霜霉病是为害天水地区葡萄的主要病害,为明确当前环境条件下天水地区田间霜霉病发生、霜霉病菌孢子囊数量时间动态及病害初始发生的关键因子,本研究采用捕孢法及病害定点调查,对葡萄生长期田间霜霉病菌孢子囊数量及霜霉病发生动态进行了观测,用农田小气候自动观测仪记录田间气象数据。结果表明,天水地区葡萄霜霉病菌孢子囊始见期一般为7月初左右,若条件适宜,7月下旬至8月下旬为扩散盛期,9月以后进入快速消退期;田间病害始发期为7月上中旬,条件适宜时8月中下旬进入盛发期。在田间检测到霜霉病菌孢子囊后7 d左右田间开始见到霜霉病斑,从病害始发期至盛发期田间病情扩展与霜霉菌孢子囊数量呈显著正相关;葡萄霜霉病的发生与温度、相对湿度、降水等气象因子密切相关,其中有效降水是影响葡萄霜霉病初始发生及蔓延流行的关键气象因子。

Dynamics of disease and sporangium quantity,key factors analysis of grape downy mildew initial occurrence in Tianshui area

Grape downy mildew is a major disease on grapes in Tianshui area. To clear the temporal dynamics of sporangium quantity and disease, the key factors to the disease initial occurrence, sporangia of Plasmopara viticola dispersal were observed using the spore-trapping machine and the disease state were investigated during the grape growing season in Tianshui area. At the same time, meteorological data were recorded in the field by automatic microclimate recording instrument. The results showed that the sporangium of P. viticola in Tianshui area was generally observed around the beginning of July. If conditions were suitable, it would be the quickly spreading period from late July to late August, and would enter the rapid decreasing period after September. The disease in the field initially occurred in the early or middle July, and reached its peak in the middle or late August when the conditions were suitable. Disease began to appear about 7 d after the sporangia of P. viticola were detected in the field, and there was a significant positive correlation between the disease index and the number of sporangium. The grape downy mildew is closely related to the meteorological factors of temperature, relative humidity, and rainfall, effective rainfall is the key factor to disease initial occurrence and spreading.