Iron deficiency chlorosis of rhododendron

Rhododendron iron deficiency chlorosis, also known as yellow leaf disease, chlorosis, is a common disease of potted rhododendron.

Symptom

The disease often occurs on tender shoots and new leaves. At the initial stage, the mesophyll between the veins faded and lost its luster, and then gradually became yellow and white, but the veins remained green, making the green on the leaves reticulate. Then the yellowing degree increased gradually, except for the larger veins, the whole leaf turned yellow and white, and when it was serious, it scorched inward along the leaf and leaf edge.

Cause of disease

Rhododendron iron deficiency chlorosis is a physiological disease, mainly because soil iron deficiency or iron can not be absorbed and utilized, so it affects the synthesis of chlorophyll and makes the leaves turn yellowish green.

In general, there are the following aspects: in calcareous alkaline soil, the soluble divalent iron that can be used is transformed into insoluble trivalent iron salt and precipitated, so that the roots cannot be absorbed; potted flowers are watered frequently, resulting in excessive leaching and loss of soluble iron in the soil. In the areas with heavy soil viscosity, poor drainage or high groundwater level, the root development is affected, the normal physiological activities of the roots can not be carried out, and the ability of the roots to absorb iron is reduced.

Prevention and cure method

Cuckoos like acid and alkali, should avoid planting in alkaline and calcium-rich soil; garden open field planting, do not go near cement, brick walls or places where lime has been used. Potted rhododendron should use acidic soil, which can be replaced by alkaline soil; when rhododendron is planted in nursery, compost, green manure or other organic fertilizers can be used, and the organic acid produced in these fertilizers can dissolve insoluble iron in the soil and make it easier for plants to absorb.

Or mixed with ferrous sulfate in fertilizer, the preparation is: ferrous sulfate 2.5-3 cm, oil meal 5-7.5 cm, dung 10-15 kg, water 200-250 jin, mixed, after its maturity into black can be used. This method has a good effect.

In the slightly alkaline soil, 0.1-0.2% potassium dihydrogen phosphate solution can be irrigated, and the ph value of this solution is 4.7, which can turn the alkaline soil into an acidic soil, and the yellowing of tender leaves can be treated. At the same time, there are phosphorus and potassium elements in potassium dihydrogen acid. conducive to flowering and increase the number of flowers.

Regular application of ferrous sulfate solution will cause too much sulfur and effective iron in the soil and poison plants. Disodium ethylenediamine tetraacetate 0.14 g, ferrous sulfate 0.1 g (chemically pure) can be mixed into 500 ml tap water and foliar sprayed, the leaves should be sprayed on the front and back, once every 3 days, several times, good results can be obtained.