綠矾对防治苹果黃叶病效应的初步研究

A PRELIMINARY STUDY ON THE EFFECTS OF FERROUS SULPHATE FOR CONTROLLING CHLOROTIC DISORDER OF APPLE TREE

以适当浓度的綠矾溶液;或以綠矾——檸檬酸混合溶液浸泡病株树根,效果显著,病株复綠快速,惟不能持久。若以綠矾——有机混合肥料施于根区,防治效果良好,效力持久,但复綠較慢。综合利用这两种施用方法,卽:先用綠矾溶液浸泡树根;后用綠矾——有机混合肥料施于根区,則可达到防病快速持久的目的。

1. The chlorosis in apple seedling was corrected by an immersion of individual roots of chlorotic tree in the field for 40 minutes in 0.8 or 1.6 per cent of ferrous sulphate solution or in 0.5 or 0.8 per cent of a mixture of ferrous sulphate and citric acid in 1:1 ratio. Injuries were produced by treatment with 0.5 or 0.8 per cent of the mixture and with 1.6 per cent of ferrous sulphate. 2. The application of a mixture of solutions of ferrous sulphate and citric acid, at the concentrations of 0.2, 0.5, 0.8 per cent respectively, to the soil around the chlorotic apple seeding at the rate of a liter per tree, gave little or no control. 3. The application of a mixture of 250-gram ferrous sulphates and 2,500-gram cotton-seedmeal to the root zone, with subsequent heavy watering, corrected severe chlorosis of small apple trees (four-old tree) within a month. Their curative effect last a year. 4. 1 per cent of ferrous sulphate solution was applied around the chlorotic tree, at a rate of 50 liters per tree so that some of their roots were immersed. Then a mixture of 500 grams of ferrous sulphate mixed with 25 kilograms of manure was applied to the roots. It gave consistently good results in correcting chlorosis. The curative effect of this method last about a year. 5. The application of manure alone to the root zone was ineffective under our experimental conditions.