Prevention and cure to the michelia alba Fe deficiency

Michelia alba belongs to heliophilous species, like light and a little acid soil which is fertile, good dewatering and is rich in humus, and avoid bad dewatering and wet land. It will grow well if fertilizing before flowering, ferrous sulfate can prevent yellow leaves.
The iron deficiency symptom starts in the early May, leaves turn diminish and old leaves still keep green, new leaves’ vein is green but mesophyll turns yellow even white. In the late June, the leaf margin turns dried-up, the whole leaf withers. As to the iron activity is weak in the plants so that it can’t be transferred to the new leaf, so the new leaf will be yellow if it is deficient of iron. Leaves wither and tree vigour is weak, so that it can’t form blossom bud, and the whole trees can’t bloom and lose ornamental value. We can the following prevention and cure methods: 

1/ Foliage fertilizer: Time for foliage time is in the morning or evening for better. Put 0.3% ferrous sulfate into it and spraying equally. It’s needed that the pros and cons of leaves till the leaf drips, and do not spray in the same place for long, or fertilizer damage will occur.
2/ Punching and perfusion: In the shadow of crown, punching with 40cm deep for every 50cm, and dilute ferrous sulfate to 50 times and inject it into holes till it’s full, every 15 days a time, 4-5 times is OK. Add some ferment manure and urea liquid at the same time. Fertilize with two methods, new leaves will turn green in 15 days.

3/ Base fertilizer is made after autumn or before spring sprouting. Apply manure in small holes or furrow application. Don’t hurt roots, it’s very fragile and will take much time to recover. Change the furrow position every two years. Ways of radiation furrow application is: Dig a furrow 1m away from trunk, 30-40cm in deep is better. Mix ferrous sulfate and thoroughly decomposed organic fertilizer at the proportion of 1:5, add some compound fertilizer at the same time, and watering so that they can solute thoroughly, and then cover the soil. The quantities, fertilizer volume and methods should be made according to the tree’s ages. For DBH is 12cm tree, 5-8 furrows are needed, and 2.5kgs of ferrous sulfate, 12.5kgs of organic fertilizer and 3kgs of compound fertilizer are needed. Cyclic annular furrow application is suitable to young trees.

The above three methods can receive very good effects, for trees who are lack of iron, we should apply foliage fertilizer when leaves come out, add some ferrous sulfate, spraying every 7 days. The michelia alba will recover after 2 or 3 years.