西洋杜鹃的病虫害虽然不多,但常见的叶片黄化症,由于病因多,致使农民束手无策,并造成重大损失。笔者经几年的调查发现,这类病害以生理性病因为主,也有少量的侵染性病菌或虫害,且侵染性病害在逐年扩大。现总结如下:一、非侵染性病害(又称生理病害)1.气候不良主要病因有温湿度突变、有害气体和冻害等。温湿度突变常发生于3～4月间。早春低温阴雨,常伴随时晴时雨,中午温度骤升,花农不经意把温棚两头大棚全部打开,造成棚内温度骤降,引起花苗叶部水分短时间内大量损失。严重者,出现叶片萎蔫、黄化、凋落、枯死。有害气体常发生于2～3月间的花苗。在长时间的冬季保温生长条件下,加上一些花农采用地栽后上钵入棚,施用一些有机肥作定植基肥,棚内交换空气少,而积累了有毒气体如CO_2、H_2S等,造成了叶片黄化——叶片尖端干枯——叶片凋落。 Western Rhododendron pests and diseases are not many, but the common leaf etiology, due to multiple causes, resulting in peasants helpless and caused heavy losses. The author after several years of investigation found that such diseases mainly physiological reasons, but also a small amount of invasive bacteria or pests, and infectious diseases are expanding year by year. Are summarized as follows: First, the non-infectious diseases (also known as physiological diseases) 1. The main causes of poor climate temperature and humidity mutations, harmful gases and frost damage. Temperature and humidity mutations often occur in 3 to 4 months. Early spring low temperature rainy, often accompanied by sunny rain, noon temperature soar, flower growers inadvertently open the greenhouse of the two sheds, resulting in greenhouse temperature plunge, causing a large number of leaf flower water loss within a short time. In severe cases, leaves wilting, yellowing, litter, dead. Harmful gases often occur in February to March flower seedlings. Under long-term winter heat-preservation and growth conditions, some flower-growers used the planted pots and put some organic fertilizers on the base for planting the base fertilizer. There was less exchange air in the shed, and toxic gases such as CO_2 and H_2S accumulated, resulting in Leaf yellowing - leaf tip dry - leaf litter.