经济阈值(economic threshold)
指应该采取防治措施时的发病数量,此时防治可防止发病数量超过允许的经济损害水平(economic injury level),防治费用不高于因病害减轻所获得的收益。损失预测结果可用以确定发病数量是否已经接近或达到经济阈值。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
免费的网站请分享给朋友吧