Control techniques of Tomato powdery mildew

Tomato powdery mildew is mainly harmful to leaves, petioles, stems and fruits can also be killed sometimes, the leaves appear white mildew spots, scattered, and then gradually expand into white powder spots, and connect with each other into powdery mildew spots of different sizes, the whole leaf surface is covered with powdery mildew, like being sprinkled with a thin layer of flour, let's take a look at the prevention and control techniques of tomato powdery mildew.

Symptoms of tomato powdery mildew

There are two common manifestations of tomato powdery mildew, one is the initial appearance of small radial powder spots on the front of the leaves, that is, hyphae and conidia and conidia, then expand into round powder spots, and the white powdery matter gradually encrypts and expands, and in severe cases, it is covered with the whole leaf. In another symptom, the pink spot on the front of the leaf is not obvious at the beginning, but there are yellow patches with inconspicuous edges, and a sparse mildew layer can be seen carefully. After the disease spot expands, the white mildew layer becomes more and more obvious, and covers the whole leaf. In the later stage, the whole leaf turns brown and dies.

Occurrence regularity of tomato powdery mildew

In the north of China, the pathogen overwinters mainly as asexual spores on winter tomatoes, and it can also overwinter on the ground with the remains of the disease. when the conditions are suitable, the ascospores scattered from the closed cysts spread with the airflow, and then produce conidia in the diseased part, and the mature conidia fall behind and re-infect through the air flow. In the perennial tomato planting area in the south, the pathogen had no obvious overwintering phenomenon, and the conidia were produced continuously. The optimum temperature for conidia germination of tomato was 20: 25 ℃, and that of powdery mildew in Tatar was 15: 30 ℃. Open fields mostly occur in June-July or September-October, while greenhouses or plastic greenhouses are more common in March-June or October-November.

Control techniques of Tomato powdery mildew

1. Breeding varieties resistant to powdery mildew and strengthening the management of temperature and humidity in greenhouse. Remove the disease and residue in time after harvest to reduce the source of overwintering bacteria. In the early stage of the disease, the shed can choose the dust method or smoke method, spray more than 10% 100 dust agents in the evening, 1 kg per mu each time, or apply 45% chlorothalonil smoke remover, 250 grams per mu each time, and light it with dark fire for one night.

2. Open field or greenhouse can choose 15% triadimefon (triadimefon) wettable powder 500x, 40% Fuxing EC 100008000x, 10% high water soluble granules 1500 times, 30% Teflin wettable powder 1500002000 times, 50% sulfur suspension 20000x. Or 50% triadimefon EC 500 times 600 times, 2% Wuyisin water agent or 2% agricultural anti-120 water agents 150 times, 25% enemy emulsifiable concentrate 3000 times, 15% triadimefon (triadimefon) wettable powder 2000 times, 25% chlorpromazine demulsifiable oil 4000 times, interval 7~15d1, continuous prevention and treatment for 2 times for 3 times.