Effective prevention and control of rhododendron chlorosis

Rhododendron chlorosis is a physiological disease, but the reasons for the formation of chlorosis are complex, such as prevention and treatment, often futile, so we must carefully observe, determine the condition, find out the cause, and then prescribe the right medicine to be effective. The symptoms, causes, effective prevention and treatment measures of rhododendron chlorosis are described as follows:

First, iron deficiency.

1. Soil iron deficiency: the formation of chlorophyll requires elements such as iron and nitrogen, and the phenomenon of chlorosis caused by soil iron deficiency often occurs, so it is very important to supplement the iron element in the soil. Ferrous sulfate powder can be evenly spread on the surface of the basin soil. 30 cm in diameter basin can be 1.5 grams, and so on, and then spray water to dissolve the water, can also dissolve into the water irrigation, the concentration is 1%, or add zinc sulfate, borax, etc. Until it recovers. Plants with thicker trunks can also be slowly injected into the trunk with 0.75% ferrous sulfate for control.

2. When the soil or water is alkaline, when the pH value increases, it seriously affects the root absorption of nitrogen and iron, and the leaves yellowing and falling off gradually from bottom to top. Vinegar should first be used to neutralize the alkalinity of water, so the pH value should be reduced to 5-6, and then irrigated. The soil can be modified or replaced by the methods described in item 1 or 2. In severe cases, 0.3% citric acid can be added to the ferrous sulfate solution and applied evenly to increase the lasting effect of adhesion.

Second, choose the cultivated soil.

Acid sandy loam with loose, good drainage and rich humus should be used. 7 parts of rotten leaf soil, 2 parts of garden soil, 1 part of sandy soil, mixed preparation, and a small amount (about 50 grams per basin) of sesame sauce residue and bone powder should be used as cultivation soil; do not use calcareous alkaline soil or poorly drained clayey soil; in the process of cultivation and management, dry but not crack, tide but not wet, can promote the germination of new roots.

Third, pay attention to the prevention of fat damage.

The rhododendron root is as thin as silk, and its response to fertilizer concentration is extremely sensitive, and excessive concentration will lead to yellowing, shedding, and even death, especially once you get chlorosis, you should stop fertilization immediately; fertilization outside the root has a certain role, but does not solve the fundamental problem. If it is stable for a period of time, you can apply fertilizer only after the new green branches are lignified, otherwise it is still possible to yellowing again.

Fourth, be willing to remove the buds.

Plants suffering from chlorosis cannot bloom well even if their buds mature, but because flowering consumes a lot of nutrients and affects the recovery of diseased plants, all buds, big or small, should be removed as soon as possible.

Fifth, the light must be suitable.

The formation of chlorophyll needs light, only sufficient sunlight can make the leaves show normal green, lack of light will make the leaves yellowing. However, the root system of the diseased plant is weak, and the leaves are easy to wilt under the strong light, so the sun should be shaded in the high temperature season in summer and autumn, and the light should be increased in late autumn, winter and spring to facilitate the recovery of the diseased plant.

In short, once azaleas get yellowing, they should patiently improve their conservation conditions, adopt the above-mentioned effective prevention and control measures, prepare for half a year to a year or so, and take meticulous care to make the diseased plants come back to life.