北元大队位于河曲县黄河岸边,地势平坦,土地肥沃。1974年建苹果园174亩,3,100株。建园后行间每年间种油菜和瓜类,全年浇水7—8次,每年亩施化肥70斤,农家肥30担,幼树生长旺盛。但在76年春季,发现新梢生长缓慢,叶片淡绿发黄,同时还有卷缩现象。经过挖根观察,发现根部表皮变褐,不少韧皮部和木质 North yuan brigade is located in the Yellow River bank of Hequ County, flat, fertile land. 174 acres of apple orchard built in 1974, 3,100 strains. After the park built between the rows of rapeseed and melons every year, 7-8 times a year watering, fertilizer 70 kg per mu, farmer fertilizer 30, saplings grow vigorously. However, in the spring of 1976, it was found that the shoots grew slowly, the leaves were pale green and yellow, and there was curling. After digging root observation, found that the root of the epidermis brown, a lot of phloem and wood