What are the symptoms of tomato gray mold and how is it controlled?

Tomato gray mold is a fungal disease caused by the pathogen Botrytis cinerea, which belongs to the subdivision Deuteromycotina. In addition to infecting tomatoes, it can also infect many other vegetable crops such as cucumber, pepper, eggplant and Chinese chives. The flowers, fruits, leaves and stems of tomatoes can all be affected.What are the symptoms of tomato gray mold? How is it treated?

1. What are the symptoms of tomato gray mold?

Leaf symptoms start from the leaf tip, with lesions developing inward in a “V” shape. They are initially water-soaked and light brown, large and with irregular edges, bearing concentric rings of alternating light and dark shades. When humid, a small amount of gray mold grows on the surface, and the leaf finally withers and dies. When fruits are affected, in most cases the remaining flowers, stigmas or sepals are infected first, and the infection then spreads to the fruit or the fruit stalk, causing the rind to turn grayish white and soft-rot, with a gray mold layer growing on the surface of the diseased part; the fruits infect one another.

2. How is tomato gray mold treated?

1. Scientific ventilation: ventilate briefly in the early morning first to let out moisture; then close the greenhouse to raise the temperature, and only vent again at noon. In the afternoon, extend the ventilation time appropriately to lower the humidity inside the greenhouse and prevent dew from forming on the plant leaves. At the same time, plant at a reasonable density, prune and remove side shoots in good time, clean the greenhouse film regularly, and improve ventilation and light penetration.

2. Water and fertilizer management: use drip irrigation or concealed irrigation under the film as far as possible, strictly control watering, and water in the morning on a sunny day. Fertilize in a balanced way to prevent premature aging of the plants and promote strong seedlings.

3. Real-time monitoring: when diseased plants, leaves or fruits are found, remove them from the greenhouse in good time and dispose of them in a centralized way.

4. Chemical control methods

When dipping flowers, add gray mold control agents in proportion. For example: add 1% of agents such as Limeikang, Shijiale or Nongliling to the prepared flower-dipping solution; this can prevent the pathogen from infecting the fruit through the declining parts of the tomato flowers.

At the early stage of the disease, spray chemical agents for control. You can choose 65% metalaxyl wettable powder at 1000 times dilution, 40% Shijiale suspension concentrate at 1200 times dilution, 50% Nongliling suspension concentrate at 2000 times dilution, 50% Sumilex wettable powder at 1000 times dilution, etc. Spray once every 7 days, for 3~4 times in a row. Alternatively, use 45% chlorothalonil smoke agent or 10% Sumilex smoke agent to fumigate the greenhouse, and after applying the agent in the evening, keep the greenhouse closed overnight to ensure the efficacy.

Notes:

1. Strictly follow the pesticide use standards, and at the same time pay attention to rotating the agents to avoid developing resistance.

2. When the humidity inside the greenhouse is relatively high, use smoke agents for control as far as possible.