What to Do When Grape Leaves Turn Yellow
Grape leaf yellowing is a common abnormal phenomenon in the cultivation process, directly affecting the efficiency of photosynthesis and fruit quality. This article systematically analyzes the causes of yellow leaves in different cultivation scenarios, combined with 20 years of horticultural experience, providing a comprehensive solution from environmental regulation to nutritional management.
Key Points for Preventing and Treating Yellow Leaves in Grapes
One, Light Adjustment and Water Management
Environmental yellow leaf characteristics: Leaf edges become crispy and curl, often occurring at noon in summer. Research shows that when the environmental temperature exceeds 35℃ and the air humidity is below 40%, the water loss rate of grape leaves can reach three times the normal value.
Advanced solutions: 1. For potted plants, use double-layer shading nets (shading rate 50%-70%) combined with morning sprinkling. 2. For field-grown parks, it is recommended to build adjustable shading shelters to maintain an average daily sunlight duration of 6-8 hours. 3. Choose early morning or evening for watering to avoid leaf burns caused by high temperatures at noon.
Two, Root Care and Irrigation Optimization
Water damage yellow leaf diagnosis: Lower old leaves turn yellow first, and be alert when the soil moisture content is continuously >25%. Research data shows that积水 for more than 72 hours will lead to an 80% reduction in root oxygen content.
Systematic improvement solutions: • Establish drainage ditches: Maintain a slope ratio of 3%-5%. • Improve soil structure: Mix in 30% coarse sand + 20% humus soil. • Intelligent irrigation system: Use soil moisture sensors to control irrigation frequency.
Three, Precision Fertilization Technology System
Nutritional yellow leaf diagnosis: Synchronous yellowing of new and old leaves is often due to nitrogen deficiency, and chlorosis between leaf veins is usually due to iron deficiency. Experiments have shown that when the nitrogen content in leaves is <2.5%, the photosynthetic rate decreases by 40%.
Nutritional management solutions: 1. Base fertilizer plan: Apply decomposed sheep manure (3kg/plant) + superphosphate (200g/plant) in autumn. 2. Top-dressing strategy: High nitrogen fertilizer (N-P-K=20-10-10) during the germination period, balanced fertilizer (15-15-15) during the fruit expansion period. 3. Foliar application: 0.2% ferrous sulfate + 0.3% urea solution, spray every 10 days.
By implementing a three-level environmental monitoring system (light/water/nutrition) and regular leaf nutrient testing (recommended once a month), the incidence of yellow leaves can be effectively controlled to below 5%. It is recommended that growers establish cultivation logs to record daily environmental parameters and plant changes, achieving precision management.