Occurrence and Control Methods of Brown Spot Disease and Powdery Mildew in Honeysuckle
Honeysuckle, also known as Erhua or Japanese honeysuckle flower, is a perennial climbing shrub. The dried flower buds of honeysuckle are a widely used antibacterial medicinal material, possessing the effects of clearing heat and detoxifying, promoting meridians and activating collaterals, and reducing inflammation and swelling. With the development and utilization of the medicinal value of honeysuckle, its cultivation has become increasingly widespread. However, the damage caused by brown spot disease and powdery mildew in honeysuckle has also shown an upward trend year by year. The occurrence and control of these 2 diseases are described as follows:
Honeysuckle Brown Spot Disease
Honeysuckle brown spot disease is a leaf disease caused by fungi of the genus Cercospora in the subphylum Deuteromycotina. It occurs commonly and causes serious damage, often resulting in weakened plant growth, and in severe cases, plant death.
I. Occurrence Pattern
The pathogen overwinters on diseased leaves, and the disease mostly occurs in the middle and late stages of plant growth, with August to September being the peak period. This pathogen favors high humidity, and the disease is more severe in rainy years; it is more severe in humid environments.
II. Symptoms and Diagnosis
The leaves are the site of infection. In the early stage of the disease, small brown spots form on the leaves. As the disease progresses, the small brown spots gradually expand into brown round lesions or irregular lesions. Grayish-black mold-like growth appears on the underside of the lesions. When the disease is severe, the leaves drop off.
III. Control Methods
1. Agricultural control: Strengthen field management, and carry out 1 intertillage in each of the 2 seasons of spring and autumn every year. Apply nitrogen fertilizer and phosphate fertilizer 1 time each in spring, late May, and early July every year, and apply farmyard manure 1 time in autumn, to balance the nutrients in the soil, promote healthy plant growth, and enhance disease resistance; in autumn, thoroughly prune diseased branches, sweep up fallen leaves, and take them out of the field in a centralized manner to burn.
2. Chemical control: The agents used are 50% carbendazim 800-1000 times dilution; 50% thiophanate 1000-1500 times dilution; or 1:1:200 Bordeaux mixture for spray control. Spray 1 time during the rainy season, then spray 2 more times, with 1 spray every 10 days.
Honeysuckle Powdery Mildew
Honeysuckle powdery mildew is a disease caused by powdery mildew fungi of the subphylum Ascomycotina. Leaves, flowers, and fruits can all be affected. It occurs commonly and causes serious damage, often resulting in dried branches, and in severe cases, plant death.
I. Occurrence Pattern
The pathogen overwinters as ascocarps on diseased plant residues. In the second year, the ascocarps release ascospores and infect the plants. After the plants are infected, the diseased parts produce conidia for re-infection. When the plants grow too densely, the disease is more severe.
II. Symptoms and Diagnosis
Powdery mildew mainly damages the leaves, flowers, and fruits of honeysuckle. In the early stage of the disease, small white spots appear on the leaves, which later gradually expand into white powdery patches. As the disease continues to develop, the lesions continue to expand and cover the entire leaf, causing the leaves to turn yellow, shrink and deform, until leaf drop occurs. The symptoms on flowers and fruits are similar. When the disease is severe, it can cause flower drop, leaf drop, dried branches, and even plant death.
III. Control Methods
1. Agricultural control: Select disease-resistant varieties, plant at a reasonable density, shape and prune, ensure ventilation and light penetration, and do not allow the plants to become too shaded; when fertilizing, be careful not to apply too much nitrogen, so as to avoid excessive plant growth and more severe disease.
2. Chemical control: Spray with 50% carbendazim wettable powder 500 times dilution, 15% triadimefon wettable powder 1500 times dilution. Use 100 grams of 50% colloidal sulfur, add 100 grams of 90% trichlorfon or 15 grams of 50% dimethoate emulsifiable concentrate, and add 20 kg of water; this can also control anthracnose. Spray 1 time every 7-10 days, for a total of 2-3 sprays.