What causes autumn yellowing in citrus? Causes and solutions
As autumn arrives, some citrus plants develop yellowing, which is known as autumn yellowing. Autumn yellowing is a fairly common phenomenon, and it is also one that gives fruit growers headaches. It is related to how well the fruit trees grow and affects both yield and quality, so what causes autumn yellowing in citrus? Let's take a look.
1. Nutritional imbalance
Autumn is the fruit enlargement and ripening stage, which requires a large amount of nutrients. The same is true for the sprouting of autumn shoots, and root hair growth is also at its peak at this time. If the plant's nutrient supply is insufficient, or because too many fruits are set on the tree, nutritional imbalance can result. Especially when trace elements are lacking, autumn yellowing occurs. Common nutritional problems generally involve deficiencies of elements such as zinc, iron and magnesium.
2. Root damage
The root system is an important organ for the plant to obtain nutrients, and the growth and development of the planted tree cannot do without it. If the root system is damaged, its absorption capacity declines, and since the plant needs many nutrients, autumn yellowing is very likely to occur. The main factors that damage the root system are high temperature and drought, waterlogging that rots the roots, soil compaction, and root burning caused by high fertilizer concentration. Keep these factors that cause root damage firmly in mind.
3. Pests and diseases
Damage from pests and diseases is also one of the causes of autumn yellowing. They harm the plant's leaves, twigs and root system, affect the plant's photosynthesis and respiration, hinder nutrient synthesis and nutrient absorption, and cause autumn yellowing in the plant. The main pests and diseases are root rot and nematode disease. The former causes the root system to rot and, in severe cases, the planted tree to die; the latter parasitizes the root system in the later stage, causing the roots to be covered with knots so that they cannot absorb nutrients normally.
4. Soil pH imbalance
An imbalanced soil pH value reduces the solubility of trace elements such as phosphorus, magnesium and zinc, causing deficiency symptoms in the plant and producing a phenomenon consistent with nutritional imbalance; while too high a pH value increases the solubility of elements such as aluminum, manganese and copper, causing poisoning in the plant and leading to yellowing.
5. Poor soil capacity to retain fertilizer and water
Poor soil aggregate structure causes water to evaporate easily and fertility to be lost easily. Its capacity to retain fertilizer and water declines, and its air permeability also becomes worse, affecting the normal respiration of the root system and hindering root growth. In addition, the massive loss of nutrient elements easily causes deficiency symptoms in the plant, namely normal yellowing.
6. Solutions
For the autumn yellowing phenomenon caused by the various nutritional factors above, the solution mainly revolves around improving the soil and nourishing the roots. First, reasonably increase the application of organic fertilizer to increase the organic matter in the soil, raise the content of trace elements, improve the soil structure, and enhance the soil's capacity to retain fertilizer and water. In addition, an imbalanced pH value can also be adjusted through fertilizer.
The above are the causes and solutions of autumn yellowing in citrus. We hope it can help you. To learn more about citrus cultivation knowledge, please follow us.