【摘要】 在建立小黑杨肿茎溃疡病预测模式以后,插条苗根据地茎、苗级、各病情等级的剪穗数量,测算各病情指数的损失量;留床苗则根据苗高、病情等级的损失标准,测算各病情指数的损失量。以此来确定其经济损失阈值和相应的防治指标。结果插条苗病情指数为16时为经济损失阈值,大于17时为防治指标,17—21时要重点防治,21以上时必须全面防治,留床苗病情指数为18时为经济损失阈值,大于19时为防治指标,19—23时要重点防治,23以上时必须全面防治。更多还原

【Abstract】 After establishing the predictive model of the swollen stem canker of Populus simonii×nigra,losses due to different disease index are estimated according to the grades of saplings and quantity of cuttings of each disease intensity for the saplings from cuttings, and the hight of saplings and the criteria of damage of each disease intensity for the roots. Then the economic threshold and the control index are determined.The economic threshold for saplings from cuttings is disease index 16 and the control index is 17. When the disease index is 17 to 21, control can be performed in some serious area, whereas the disease index is above 21, large scale control must be carried out. The ecomonic threshold for saplings from roots is disease index 18 and the control index is I9. When the disease index is around 19 and 23, control can be made in serious area and when it surpasses 23, large scale control must be done.更多还原