A Detailed Guide to the Latest Control Methods for Cucumber Leaf Blight
Cucumber leaf blight mainly damages the leaves. Symptoms on young leaves are not obvious. On mature leaves, yellowed areas appear on the leaf surface, along with deformed water-soaked chlorotic spots that gradually enlarge into nearly round or polygonal brown spots, 1-2 mm in diameter, surrounded by a chlorotic halo. On the underside of diseased leaves in the early morning or on cloudy days, short sections of clear veins are very likely to appear. Let us take a look below at the control methods for cucumber leaf blight!
Occurrence Pattern of Cucumber Leaf Blight
The pathogen mainly overwinters in the soil as mycelium with diseased plant residues. In the following spring, it produces conidia, which spread through airflow and cause infection. Then conidia are produced on diseased leaves for secondary infection. Weak plants, waterlogged fields, and high humidity easily trigger the occurrence of this disease.
Characteristics of Cucumber Leaf Blight Occurrence
The pathogen prefers a low-temperature and high-humidity environment. The suitable temperature range for disease occurrence is 3-30°C, and the most suitable environmental temperature for occurrence is 8-20°C, with relative humidity above 95%. The most suitable growth stages for occurrence are from the seedling stage to the adult plant stage. The incubation period of the disease is 7-15 days. It occurs only in protected cultivation, usually only during the low-temperature period in early spring. When the greenhouse temperature exceeds 25°C, the disease is inhibited.
Control Methods for Cucumber Leaf Blight
1. Apply sufficient base fertilizer, drain promptly after rain, and ensure ventilation and light penetration between plants and rows.
2. Collect seeds from disease-free seed-bearing plants and select disease-free seeds.
3. In protected cultivation greenhouses, clean ditches promptly to prevent water accumulation after rain, ventilate and exchange air in a timely manner, adopt light and frequent watering in fertilizer and water management, water and fertilize in the morning on sunny days, and open the greenhouse promptly for ventilation to reduce humidity.
4. Advocate crop rotation with non-Cucurbitaceae crops every other year to reduce the sources of pathogens in the field.
5. During the peak period of disease occurrence, promptly remove diseased and old leaves. After harvest, clean the field, remove diseased plant residues, take them out of the field and bury them deeply or burn them, and plow the soil deeply to accelerate the decomposition and rotting of diseased plant residues.
6. Before watering or on the morning of a sunny day after rain, use Bordeaux mixture (1:1:200) for spray prevention, or use mancozeb for control in the early stage of disease occurrence.