What is the best pesticide for controlling leaf blight in plants?

Leaf blight is a disease that mainly harms the leaves of plants. If it is not controlled, the disease will spread from one leaf to the leaves of the entire plant, causing all the leaves of the plant to dry up and fall off. So, when leaf blight occurs in plants, what is the best pesticide to use?

1. A brief introduction to leaf blight!

1. When does leaf blight occur?

Leaf blight can occur from July to October. It mostly starts from infections at the leaf margins and leaf tips. High temperature and high humidity, as well as poor ventilation, are all favorable to the occurrence of the disease. Plants with weak growth vigor are affected more severely, and the lower leaves of the plant are more severely affected.

2. What are the symptoms of leaf blight?

Leaf blight mostly starts from infections at the leaf margins and leaf tips. The lesions grow from small to large and are irregular in shape. At first, the diseased leaves turn yellow, then brown, and gradually spread from local areas to the entire leaf vein, showing brown to reddish-brown lesions along the leaf margins. Afterward, black downy material or small black spots appear on both sides of the diseased leaves.

2. Which plants can develop leaf blight?

Generally speaking, almost all plants with leaves can develop leaf blight, such as cucumber, garlic, watermelon, strawberry, Chinese rose, osmanthus, camellia, orchid, rice, wheat, and so on. In some cases, leaf blight can also occur on new shoots, branches, and fruits.

1. Cucumber leaf blight: It usually occurs during the low-temperature period in early spring. The suitable temperature range for the disease is 3-30°C, and the most suitable environmental temperature for the disease is 8-20°C, with relative humidity above 95%. The incubation period of the disease is 7-15 days. It mainly harms the leaves. The lesions are round or irregularly round, 1-2 mm in diameter, brown, with or without a yellow halo around the edge. Grayish-brown or dark-brown mold-like material grows on the surface of the lesions. In severe cases, the diseased leaves wither and die.

2. Strawberry leaf blight: It mostly occurs in autumn and early spring in weather with more rain and dew. It mainly harms the leaves, and the petioles, calyxes, and fruit stalks can also be infected. At the early stage of the disease, small dull purple-brown spots appear on the leaf surface, and the spots gradually expand. When the disease is severe, the entire leaf surface is covered with lesions, and in the later stage the whole leaf becomes yellowish-brown to dark brown. After the petiole or fruit stalk is affected, the lesions are dark brown, slightly sunken, brittle, and easy to break.

3. Osmanthus leaf blight: It mostly occurs from July to November. The optimum temperature for development is about 27°C. Humid and stuffy conditions, poor ventilation, or weak plant growth all lead to more severe disease. It generally occurs at the leaf margins and leaf tips of osmanthus leaves. It begins as small light-brown spots and then gradually expands into irregular large patches. If several lesions connect, 1/3-1/2 of the whole leaf dries up. The lesions are grayish-brown to reddish-brown, and in the later stage many small black spots are scattered on the diseased parts.

4. Wheat leaf blight: It mostly begins to occur at the heading stage of wheat. Low temperature and high humidity conditions are favorable to the occurrence and spread of this disease. It mainly harms the leaves and leaf sheaths. At the early stage of the disease, oval light-yellow to light-green small spots grow on the leaves, and then rapidly expand to form irregular yellowish-white to yellowish-brown large patches. It generally starts from the lower leaves, which become diseased and die, and gradually develops upward, causing the plant to weaken and even die.

3. What is the best pesticide for leaf blight?

1. If leaf blight occurs in plants, you can use Bordeaux mixture at 1:1:100, 50% thiophanate at 500-800 times dilution, 50% carbendazim wettable powder at 1000 times dilution (or 40% suspension concentrate at 600-800 times dilution), 50% benlate at 1000-1500 times dilution, 65% zineb at 500 times dilution, and other pesticides. They can be selected for use or used alternately. Spray once about every 10 days, and several consecutive sprays can effectively control it.

2. In addition to using pesticides for control, usually apply sufficient base fertilizer to improve disease resistance. Clean the drainage ditches in time to prevent water accumulation after rain, so as not to provide good conditions for the disease. Ventilate frequently to reduce leaf surface humidity and reduce infection opportunities. Remove diseased leaves in time and clear away fallen diseased leaves to reduce sources of infection. Use disease-free seeds and advocate crop rotation to prevent the disease from continuing to infect.

The above is an introduction to leaf blight and its control methods. If leaf blight occurs, pesticides can be used for control, and attention should also be paid at ordinary times so as not to create conditions for the occurrence of leaf blight, thereby reducing the spread of pathogens.