在梨树每年的生产周期内,农民喷施农药的次数常在10次以上,但多半是针对虫害和病菌引发的病害,而对生理性的病害却比较忽视,使之对产量和品质都造成不同程度的影响。梨树生产上常见的生理性病害有黄叶病、小叶病和红叶病。黄叶病最初表现为叶肉褪色失绿,比正常叶片要小,叶脉附近的叶肉仍呈绿色,外 Pear trees in the annual production cycle, the number of pesticides spraying farmers often more than 10 times, but mostly for pests and diseases caused by germs, but physiological diseases are neglected, so that the yield and quality are caused Different degrees of influence. Common pear physiological diseases are yellow leaf disease, leaf disease and red leaf disease. The first manifestation of yellow leaf fission green leaf chlorosis, smaller than normal leaves, veins near the leaf vein is still green, outside