What to Do About Rape Seedling Stunting? A Detailed Guide to Targeted Prevention and Control
After transplanting and seedling recovery, rape (Brassica napus) sometimes shows stunting in the early field growth stage, with symptoms such as reddened or yellowed leaves, curled leaf centers, slow or halted growth, and poor development. To prevent and control rape stunting, targeted measures must be taken based on investigating its causes. Stunting caused by drought or waterlogging - drought not only...
After transplanting and seedling recovery, rape (Brassica napus) sometimes shows stunting in the early field growth stage, with symptoms such as reddened or yellowed leaves, curled leaf centers, slow or halted growth, and poor development. To prevent and control rape stunting, targeted measures must be taken based on investigating its causes.
Stunting caused by drought or waterlogging - Drought not only causes a lack of water in the plants, but also comes with nutrient deficiency symptoms such as red or purple leaves. In field surveys, the topsoil turns white and hard, and may even crack; on sunny days at noon the plants may wilt. Stunting can also be caused by poor drainage in the transplanted field, or by continuous rainy weather after transplanting, which causes oxygen deficiency. For drought-induced stunting in no-till transplanted fields, furrow irrigation can be used, filling the furrows to 2/3 of their depth and letting the water soak into the soil; in plowed transplanted fields, watering (sprinkling) to combat drought can be used, combined with topdressing, that is, applying a dilute fertilizer solution; for stunting caused by waterlogging, the drainage ditches should be cleared or deepened to lower the groundwater level. Combined with intertillage, apply plant ash or decomposed barnyard (compost) manure to raise soil temperature.
Stunting caused by fertilizer deficiency - Plants are short, leaves are narrow and yellow-green, and in severe cases the leaves at the stem base turn red, indicating nitrogen deficiency. Quickly supplement with fast-acting nitrogen fertilizer: apply 15 kg of ammonium bicarbonate per mu together with dilute manure water. If the upper leaves are dark green and lusterless, the lower leaves are purplish red, leaf emergence is slow, and the root system develops poorly, these are symptoms of phosphorus deficiency. For this, spray 0.3% monopotassium phosphate solution on the leaves 2 to 3 times, once every 3 to 5 days. At the same time, apply 25 kg of superphosphate or 30 to 40 kg of calcium magnesium phosphate per mu. Before application, the phosphate fertilizer can be mixed with organic fertilizer, composted and fermented, and applied after decomposition. Stunting can also be caused by boron deficiency, showing as slow plant growth, and in severe cases root rot, dead heart, and purple leaves. For this, spray 30 to 40 kg of 0.1% borax solution per mu on the leaves, or drench the root zone with 0.5 to 1.0 kg of borax per mu mixed with 100 to 150 kg of water.
Stunting caused by pests and diseases - The common cause is severe damage by aphids, which causes plants to shrivel and can also induce viral disease. To address this, strictly guard against aphid damage. When local aphid damage is found, spray with 100% aphid-whitefly net (imidacloprid, Yibianjing, Kangfuduo, Dagongchen) at 2500 to 3000 times dilution; when viral disease symptoms are found, promptly spray with 5% Junduqing at 300 to 400 times dilution 2 to 3 times, once every 7 to 10 days. Also pay attention to using 2.5% Decis to control cabbage caterpillars and other pests.
Stunting caused by soil compaction - Due to compaction, the plant root system develops poorly. Do a good job of intertillage: the first time, hoe shallowly and finely to loosen the topsoil; the second time, hoe shallowly around the plants to scrape weeds, and hoe deeply between the rows to loosen the soil and remove weeds.