What Causes Abnormal Leaf Color in Rapeseed? Causes and Control Methods Explained in Detail
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 will focus on explaining the causes and control methods of several common abnormal leaf color phenomena for everyone's reference.
1. Red leaves
The red leaf phenomenon in rapeseed is caused by multiple reasons, and the common ones are caused by drought, waterlogging, insect pests and freezing damage. Drought will cause the plant to grow slowly. The plant is short, and the leaf color will gradually turn red. For red leaves caused by drought, water should be applied in time, but the furrow irrigation method should be used, and flood irrigation is not suitable, so as to avoid root rot. In the rainy season, too much rain will cause water accumulation and waterlogging, leading to 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 the control of aphids should be strengthened. In winter, when the temperature suddenly drops below 0 degrees, the leaves will be frozen and turn red. For this, intertillage should be carried out, and 100 kg of plant ash should be spread per mu to reduce freezing damage.
2. Yellow leaves
The main cause of yellow leaves is nitrogen deficiency in the plant. When the plant is deficient in nitrogen, the plant is short, new leaves grow slowly, and the leaf color will gradually become yellow-green or yellow. Some may also spread to the stems and veins. For this, 6-10 kg of urea or 15-20 kg of ammonium bicarbonate can be applied per mu. In addition, sulfur deficiency will cause leaves to turn yellow, generally yellowing of new leaves. Combined with intertillage, 10 kg of gypsum powder can be spread per mu. Too high soil acidity will also cause leaves to turn yellow, and in severe cases the leaves will fall off, which 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 old leaves first, then develops toward the heart leaves. At first, yellow-white spots appear, and brown dead spots appear at the leaf tips. The leaves become thick, hard and brittle, and the leaves will die. When potassium is deficient at the seedling stage, 7-10 kg of potassium chloride can be supplementally applied. When potassium is deficient at the bolting stage, potassium dihydrogen phosphate solution can be sprayed, 2-3 times in a row, with good results.
4. Dark purple leaves
The appearance of dark purple leaves in rapeseed is caused by phosphorus deficiency. It is characterized by slow plant growth, small and few leaves, and no gloss. The petioles are purple, and purple-red spots appear at the edges. In severe cases, they become dark purple and gradually die. At the seedling stage, 25-30 kg of superphosphate can be spread per mu during intertillage, which can effectively supplement the phosphorus element needed by the plant.
The above is an introduction to the causes and control methods of abnormal leaf color in rapeseed. I hope it can help you. If you want to learn more related knowledge, please follow us.