番茄白粉病田间扩展流行规律与药剂防治试验

通过2年对番茄白粉病田间扩展流行动态调查和药剂防治试验研究，结果表明：番茄白粉病菌首先由中心病株下部叶片向上部作垂直扩散，随后进行水平传播，且顺垄传播快；在甘肃省张掖市一般7月中旬至下旬开始出现，田间蔓延快;环境条件适宜时，从植株上部叶片显症到发病率达91.5%仅需5 d。田间防治试验表明，喷药7 d后，24%噻呋酰胺悬浮剂1 200倍液、15%三唑酮可湿性粉剂750倍液、30%苯醚甲环唑•丙环唑乳油2 000倍液和62.25%代森锰锌•腈菌唑可湿性粉剂600倍液防效达到最大,依次为83.4%、81.4%、81.3%和68.7%，而喷药10 d后40%氟硅唑乳油3个浓度梯度（3 000、5 000倍液和7 000倍液）的药效均达到最高值，依次为72.2%、73.3%和78.5%，表明40%氟硅唑乳油持效期较长，药效稳定。

Expansion dynamics of the tomato powdery mildew and chemical control tests in the field

Through investigations of the expansion dynamics of the tomato powdery mildew in the field during 2006-2007, the results showed that the disease spread firstly from the lower leaves to the upper leaves at the primary infection focus, and then to the nearby plants. Generally, the symptoms emerged in mid or late July in the field in Zhangye city of Gansu Province, followed by rapid dispersion. From emerging symptom at the upper leaves to the incidence rate of 91.5%, it needed only 5 days, when the environment was optimum for the tomato powdery mildew. Chemical control tests showed that the control efficiency of 24% thifluzamide 1∶1 200 dilution, 15% triadimefon 1∶750 dilution, 30% difenoconazole•propiconazole 1∶2 000 dilution and 62.25% mancozeb•myclobutanil 1∶600 dilution reached the maximum at the 7th day, which were 83.4%, 81.4%, 81.3% and 68.7%, respectively. However, at the 10th day, the control efficiency of 40% flusilazole at three concentration gradients (1∶3000, 1∶5 000 and 1∶7000 dilution) reached the maximum (72.2%, 73.3% and 78.5%, respectively), which indicated that 40% flusilazole had longer duration and was more stable in efficacy.