What pesticide has good control effects on tobacco bacterial wilt?

Tobacco bacterial wilt is one of the main diseases of tobacco in tropical and subtropical regions, and it occurs in Shandong, Henan, Shaanxi and Liaoning provinces. So what pesticide should be used for tobacco bacterial wilt? What are the symptoms?

What pesticide should be used for tobacco bacterial wilt?

There is currently no pesticide to treat tobacco bacterial wilt; it can only be prevented in advance. Before planting, apply 2-2.5 kg per mu, or 50% phoxim granules at 2-3 kg per mu, by hole application or furrow application; after planting tobacco, in the early stage of bacterial wilt, agricultural streptomycin 4000-fold solution, 77% copper hydroxide wettable powder 400-fold solution, and 50% DT wettable powder 500-fold solution can be used alternately, drenching the roots once every 7-10 days for 2-3 consecutive times.

What are the symptoms of tobacco bacterial wilt?

1. Bacterial wilt is a vascular bundle disease. Because the plant wilts quickly after infection, the wilted leaves have not yet faded in the early stage and remain grayish green, so it is called bacterial wilt.

On the exterior of the stem of diseased plants, longitudinal black streaks can be seen, which may extend to the top of the plant. Sometimes one side of the diseased plant wilts first, and the corresponding side of the root system turns black and rots, which is called “half-side madness”. In severe cases, large water-soaked necrotic spots appear on the leaves. In the middle and late stages of the disease, all leaves wilt. When the stem of a diseased plant is cut open, the vascular bundles can be seen turning brown; in the parts with higher water content, when squeezed by hand, yellow sap can be seen exuding from the vessels, which is bacterial ooze. In the later stage, the pith of the diseased stem becomes honeycomb-like or completely rots into a hollow cavity.

2. The pathogenic bacteria mainly overwinter in the soil and on diseased residues left in the soil, and can also latent-overwinter in seeds or other host plants. The pathogen is mainly spread through the flow of irrigation water, feeding by underground pests, contaminated fertilizer, and contaminated production tools. The main entry routes for the pathogen are wounds, such as insect injury, mechanical injury, and scorch injury.

In addition to using pesticides to control tobacco bacterial wilt, it is also necessary to select disease-resistant varieties and do a good job in clearing the garden and crop rotation.