萝卜患了黑腐病,从表面上看是好的,但用刀切开后可见萝卜心发黑。黑腐病是萝卜的一大病害,一般发病率达40％左右,常造成整个萝卜空心而不能吃用。此种病是由“甘兰黄色杆菌”引起的,主要由种子传播,当带菌种子的幼苗出土时,种皮上的黄色杆菌便从子叶的气孔腔侵入叶内,然后逐渐进入维管束。病菌在维管束内大量繁殖,苗期造成幼苗死亡,以后则使茎、叶、块根、肉质发黑变空。防治方法:轮作是防治黑腐病的关键。种过白菜、油菜、芥菜等十字花科作物的土地,应相 Radish suffering from black rot, on the surface is good, but after sawing carrot radish black heart. Black rot is a major disease of radish, the general incidence of about 40%, often resulting in the whole radish hollow and can not eat. The disease is caused by “Kalan Huang bacillus” and is mainly transmitted by seeds. When the seedlings with the contaminated seeds are excavated, the yellow bacillus on the seed coat invades the leaves from the stomatal cavity of the cotyledons and then gradually enters the vascular bundles. Bacteria multiply in the vascular bundles, seedlings caused by seedlings died, after the stem, leaves, roots, flesh black and empty. Prevention and treatment methods: rotation is the key to control black rot. Planting cabbage, rapeseed, mustard and other cruciferous crops land should be phase