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柑桔幼树退化病,亦叫枯萎病、沙丘退化病或柠檬根退化病,可能是佛州最具破坏性的病害。其典型症状与干旱或营养不良引起的相似。佛州自1874年起即出现此病。4年内调查21个病果园,有223株10—40年生的树发病,即平均每年损失树5—12%。如以1979年每株15年生树的平均价值为59.37美元计,则园主每年每英亩果园将损失285—772元。佛州的柑桔业每年损失超过451,000,000元。而树的价值1979年后已经增加。虽然许多人多年来曾向满意地解决幼树退化病作了研究,並未确证病原,亦未成功地将病传至健树上。本文是叙述用一种由轧棉花机废渣制成的含高氮的腐殖质,防治田间幼树退化病的6年的研究结果。
Degradation of citrus young trees, also known as blight, dune degeneration or lemon degeneration, may be the most devastating disease in Florida. The typical symptoms are similar to those caused by drought or malnutrition. Florida from 1874 onwards that the disease. Twenty-one diseased orchards were surveyed in 4 years, and 223 trees aged 10-40 were affected, accounting for an average of 5-12% of trees lost each year. For example, if the average value of 15-year-old trees per plant in 1979 was 59.37 U.S. dollars, the owner would lose 285-772 yuan per acre orchard each year. Citrus industry in Florida lost more than 451,000,000 yuan annually. The value of trees has increased since 1979. Although many have studied satisfactorily the degeneration of saplings for many years, they have not confirmed the pathogens and have not succeeded in transmitting the disease to the trees. This article describes the results of a six-year study of the prevention and treatment of degenerative diseases in field saplings using a high-nitrogen-containing humus made from cotton gin waste.