What are the types of grape yellow leaf disease
Grape yellow leaf disease is a typical physiological disease that troubles grape growers, and its symptoms and pathogen characteristics directly affect grape yield and fruit quality. This article provides scientific coping strategies for grape growers, from pathological characteristics, pathogenic causes to systematic prevention and treatment measures.
Analysis of the pathogenesis of grape yellow leaf disease
Single pathogen characteristics
The disease is caused by iron deficiency chlorosis, with the initial symptoms showing reticulate yellowing of the new shoots' leaves. As the disease progresses, more than 90% of the leaves turn yellowish-white, the development of the grape clusters stagnates, and fruit drop occurs, which is fundamentally different from fungal diseases.
Three main pathogenic inducements
1. Variety defects: Varieties like 'Jufeng' have finer xylem vessels, reducing the efficiency of iron transport by 30%-40%. 2. Climatic influence: Continuous rainfall in autumn and winter causes root damage, resulting in a 50% decrease in iron absorption rate during the following year's germination period.3. Soil imbalance: When the pH value is greater than 7.5, the available iron content in the soil is below the critical value of 2mg/kg.
Systematic management plan for grape yellow leaf disease
Emergency treatment measures
At the initial stage of the disease, foliar application of a compound solution of 0.3% ferrous sulfate and 0.15% citric acid, 7 days/interval for 3 consecutive times, combined with injecting EDDHA chelated iron solution (concentration 1:200) into the main stem can increase the utilization rate of iron elements to 85%.
Soil improvement plan
In autumn, apply 50kg of sulfur powder per mu to adjust the soil pH value, combined with the application of 3m³ of decomposed sheep manure per mu to increase the organic matter content, which can increase the availability of iron elements by 2-3 times.
Daily maintenance specifications
1. Thoroughly remove diseased and residual bodies within a radius of 2 meters during the winter clean-up. 2. Spray iron-containing foliar fertilizer during the new shoot stage for prevention.3. Regularly inject EDTA-Fe nutrient solution into the drip irrigation system.
By adopting a three-pronged approach of variety improvement, soil repair, and precise iron supplementation, the incidence of grape yellow leaf disease can be reduced by over 75%. It is recommended to establish an annual control calendar, combined with leaf nutrient testing for dynamic management, to ensure the sustainable and healthy production of the grape garden.