What causes abnormal leaf color in rapeseed? Cause analysis and control methods
During the growth of rapeseed, poor management or a lack of certain nutrient elements often hinders its growth and development, resulting in abnormal leaf color. Below, the editor explains in detail the causes and control methods of several common abnormal leaf color phenomena, for everyone's reference.
1. Red leaves
Red leaves in rapeseed are caused by several reasons, the common ones being drought, waterlogging damage, insect pests and freezing damage. Drought causes slow plant growth. When the plant is short and small, the leaf color gradually turns red; for red leaves caused by drought, water in time, but use furrow irrigation rather than flood irrigation, so as not to cause root rot. In the rainy season, excessive rain leads to water accumulation and waterlogging, causing root rot and red leaves, so drainage and waterlogging prevention measures should be strengthened during the rainy season. Red leaves caused by insect pests are mainly due to aphids, so aphid control should be strengthened. In winter, when the temperature suddenly drops below 0°C, the leaves are frozen and turn red; for this, carry out intertillage and broadcast 100 kg of plant ash per mu to reduce freezing damage.
2. Yellow leaves
The main cause of yellow leaves is nitrogen deficiency in the plant. When the plant lacks nitrogen, it is short and small, new leaves grow slowly, and the leaf color gradually turns yellow-green or yellow; in some cases it also spreads to the stems and veins. For this, apply 6-10 kg of urea or 15-20 kg of ammonium bicarbonate per mu as topdressing. In addition, sulfur deficiency causes leaves to turn yellow, generally with yellowing of new leaves; combined with intertillage, broadcast 10 kg of gypsum powder per mu. Excessive soil acidity also causes leaves to turn yellow, and in severe cases the leaves drop; it can be adjusted with plant ash and lime powder.
3. Brown leaves
Brown rapeseed leaves indicate potassium deficiency in the plant. It generally starts from the outer leaves and then develops toward the heart leaves; at first yellow-white spots appear, and brown necrotic spots appear at the leaf tips. The leaves become thick, hard and brittle, and the leaves die. When potassium is deficient at the seedling stage, apply 7-10 kg of potassium chloride as a supplement; when potassium is deficient at the bolting stage, spray potassium dihydrogen phosphate solution 2-3 times in a row, with good results.
4. Dark purple leaves
Dark purple leaves in rapeseed are caused by phosphorus deficiency. The characteristics are slow plant growth, few and small leaves without luster, purple leaf stalks, and purple-red spots at the edges; in severe cases they turn dark purple and gradually die. At the seedling stage, carry out intertillage and broadcast 25-30 kg of superphosphate per mu, which can effectively supplement the phosphorus element the plant needs.
The above is an introduction to the causes of abnormal leaf color in rapeseed and the control methods. We hope it helps you. To learn more related knowledge, please stay tuned to us.