Pathogen and control methods of loofah ring spot disease

Here is a detailed introduction to loofah ring spot disease and how to better prevent it:

Loofah

The scientific name is Luffa cylindrica (L.) Roem. The synonym is L.aculangula (L.) Roxb. It is an annual climbing herbaceous plant of the Cucurbitaceae family. The melon peel can be used as medicine. In addition, the leaves, vines, roots and seeds can also be used as medicine. It has the effects of clearing away heat and detoxification, promoting blood circulation and unblocking meridians, promoting diuresis and reducing swelling, and relieving cough and reducing phlegm. It is distributed throughout the country.

symptom

It mainly harms leaves. The diseased part initially appears as water-soaked brown spots with wavy edges. Several waves form concentric rings. The area around the spots turns green or yellow areas appear. When the humidity is high, dirty gray hyphae appear on the surface, which later turns into olive green. Sometimes small black dots can be seen on the spots, which are the conidiophores of the pathogen.

pathogen

Dip10dia natalensis Pole-Evans is also called Diplodia natalensis or Diplodia natalensis, belonging to the subphylum Ascomycota. The conidiophores are pear-shaped or oblate, black, smooth, and 290-522 μm in size; the conidiophores are cylindrical, unbranched, colorless, and 8.4-19×2.8-5.6 (μm) in size; the conidia are brown when mature, oblong, bicellular, with longitudinal stripes on the surface, and 21-29.4×11.9-15.4 (μm) in size. In the past, the fungus mainly infected citrus, apple, pear, hevea, tea and other plants, causing fruit rot and branch blight. Now it is found that the fungus can infect loofah and cause ring spot disease.

Transmission route and disease conditions The pathogen overwinters in the form of mycelium and pycnidia on diseased remains. When conditions are suitable the following year, conidia are released from the pycnidia and spread in the field through wind and rain. In the southern citrus growing areas, the pathogen can spread from citrus orchards to vegetable fields, and the spores can invade from leaves after germination. The disease is more likely to occur when the temperature is 27-29℃, the humidity is high, or there are large changes in dryness, wetness, coldness and heat.

Prevention and treatment methods

(1) Choose moisture-tolerant and disease-resistant varieties.

(2) Select high-dryness land for planting, apply compost fermented with Japanese enzyme bacteria, strengthen field management, and improve disease resistance.

(3) Pay attention to timely prevention and control of melon-guarding and stink bug pests to prevent them from invading through wounds.

(4) Drain water promptly after rain to prevent moisture retention.

(5) At the early stage of the disease, spray 300 times of 30% basic copper sulfate suspension or 500 times of 36% methyl thiophanate suspension plus 1000 times of 75% thiophanate-methyl wettable powder or 1500 times of 50% benomyl wettable powder. Spray 60-70L of the correct solution per 667m2, once every 7-10 days, and control 2-3 times in succession. Stop using the drug 7 days before harvest.