The Reasons for Yellow Spots on crabapple花 Leaves
As a common ornamental plant in gardens, crabapple花 leaves with yellow spots severely affect their ornamental value. The yellow spot disease not only impairs photosynthesis but may also lead to overall plant weakness. This article will analyze two typical disease characteristics from a pathological perspective and provide a systematic prevention and treatment plan.
Pathological Analysis of crabapple花 Yellow Spot Disease
Symptoms and Countermeasures of Rust Disease Infection
Rust disease belongs to the Basidiomycota fungal disease and becomes active when temperatures rise in April. Initially, it appears as orange-yellow pinpoint spots on the leaf surface, which develop into circular spots 2-3mm in diameter as the disease progresses, with yellowish-white spore piles forming on the leaf back. The pathogen has a characteristic of alternating hosts, so cross-infection with nearby pine and cypress plants should be watched.
Key points for prevention and treatment: 1. Isolate pine and cypress plants within a radius of 50 meters; 2. Check and remove diseased leaves weekly, and disinfect tools with 75% alcohol; 3. Alternate the use of 25% triazole cream oil 1500 times liquid and 12.5% myclobutanil microemulsion 2000 times liquid, focusing on spraying the leaf back.
Mechanism Analysis of Brown Spot Disease Onset
Brown spot disease caused by Deuteromycetes fungi has an incidence rate as high as 80% during the rainy season. Initially, it presents as small white circular spots, which expand into irregular brown spots with obvious concentric patterns after 3-5 days. When humidity is greater than 75% and temperature is between 20-25°C, the reproduction rate of conidiospores increases by three times.
Prevention and treatment plan: 1. Maintain a plant spacing of ≥80cm to ensure ventilation; 2. Spray 1:1:200 Bordeaux mixture at the initial stage of the disease; 3. Use 50% iprodione wettable powder 800 times liquid when severe, focusing on treating lower leaves.
Comprehensive Control System for crabapple花 Yellow Spots
Establish a three-level system of prevention, monitoring, and management: spray lime sulfur before spring germination to clean the garden; install temperature and humidity sensors for real-time environmental monitoring; use yellow boards to attract and kill disease vectors such as aphids. Regularly supplementing calcium and magnesium trace elements can enhance the thickness of the leaf cuticle, reducing the probability of infection by 30%.
By implementing the above systematic control measures, along with monthly foliar applications of biostimulants such as seaweed extract, the development of crabapple花 yellow spot disease can be effectively controlled. It is recommended to establish a disease log to record the timing and effectiveness of each application, providing data support for long-term maintenance.