What Causes the Dry Leaves of Dahlia
Dahlias are loved by horticulture enthusiasts for their vibrant flowers, but the issue of withered leaves often troubleshoots plant growers. This article will analyze the three core causes through visualization and illustration guidance to systematically solve the problem of leaf scorching in dahlias.
I. Leaf Dehydration Caused by Improper Water Management
1.1 The Mechanism of Damage from Overwatering
The root system of dahlias consists of tubers, and waterlogging can lead to cellular asphyxiation. Data shows that soil moisture above 70% for three consecutive days can cause yellow leaves. Special attention should be paid to the drainage holes of potted plants during the rainy season, and it is recommended to raise the ridges by 20cm for ground planting.
1.2 Scientific Water Supplement Plan
In spring and autumn, maintain a watering cycle of 3-5 days, and in summer, water twice a day in the morning and evening, but reduce the amount of water by 30% each time. It is recommended to use the bamboo stake method: insert the bamboo stake into the soil for 5 minutes and then pull it out. If the tip is moist, there is no need to water.
II. Physiological Leaf Withering Due to Nutritional Imbalance
2.1 Identification of Fertilizer Damage Characteristics
Fertilizer concentration exceeding 0.3% can cause salt burn roots,表现为 leaf edges turning brown and spreading towards the center. Special care should be taken to avoid fertilizing during the high-temperature noon hours, as root absorption efficiency decreases by 80% at this time.
2.2 Precise Fertilization Strategy
Use 12-12-12 slow-release fertilizer with nitrogen, phosphorus, and potassium during the growing period, and switch to a high-phosphorus and potassium formula during the budding period. Water thoroughly after fertilizing and it is recommended to use the circular groove application method, digging a groove 15cm away from the main stem to bury the fertilizer.
III. Control System for Pathogenic Leaf Withering
3.1 Diagnosis of Dahlia Dark Stripe Disease
The disease initially presents as brown net-like patterns on the back of the leaves, and the spread accelerates when humidity is above 85%. Microscopic observation reveals that the conidiomata are black-brown spherical structures.
3.2 Comprehensive Control Plan
Immediately disinfect the pruning shears with alcohol when a diseased leaf is found and apply sulfur powder to the wound. For chemical control, it is recommended to use 75% chlorothalonil 800 times liquid + 0.1% organic silicon synergist, focusing on the back of the leaves, and applying the treatment for 3 consecutive times at 7-day intervals.
By precisely controlling the amount of watering, adopting scientific fertilization methods, and establishing a disease warning mechanism, the problem of dry leaves in dahlias can be effectively prevented. It is recommended to check the thickness of the leaf cuticle monthly and maintain a ventilation index of above 2.5m/s to keep dahlias in a healthy and vibrant state for viewing.