Causes and Control Methods of Magnolia Chlorosis

Also known as chlorosis, it is a common disease of magnolia, and occurs more commonly in areas with alkaline soil. In the northern regions of our country, the disease is relatively severe.

Symptoms

The diseased plant first shows symptoms on the young tender leaves at the top of the shoots. The mesophyll tissue of the diseased leaves turns yellow or pale yellow, while the veins remain green; as the disease progresses, the entire leaf turns yellow to yellow-white, and the leaf margins become gray-brown or brown and necrotic. The condition gradually worsens, the plant grows weak, and eventually dies.

Causes

Magnolia chlorosis is a non-infectious disease, that is, a physiological disease. Its main cause is that the soil is heavy, wet and alkaline, which keeps iron in an insoluble state, causing iron deficiency in the plant and thus the disease.

Control Methods

1. Magnolias should be planted in sunny, well-drained, fertile and loose acidic soil. For potted soil, acidic soil such as mountain soil should be used, and it is best to replace it with new soil once every 1~2 years.

2. In the early stage of the disease, ferrous sulfate (black alum) diluted 30~50 times can be used to irrigate the rhizosphere soil, or "alum fertilizer water" (made by mixing and composting 2.5 kg of ferrous sulfate, 5 kg of soybean cake, and 15 kg of pig manure, then applying it after 10~15 days of fermentation and decomposition ~~ the experience of flower farmers in Yanling, Henan) can be used alternately with clear water for irrigation. A 0.1~0.2% ferrous sulfate aqueous solution can also be sprayed on the leaves.