Introduction of comprehensive control methods of tomato scab

Tomato planting process is very easy to be affected by scab disease, this disease occurs once for tomato plants, fruits and so on have great harm, for growers appear loss is inevitable. Let's learn about the comprehensive control methods of tomato scab disease.

Symptoms of tomato scab

Tomato scab mainly damaged leaves, stems and fruits. The disease occurs first on the lower leaves near the ground, and dark green water-stained spots appear at the beginning of the disease, with obvious edges, and then gradually expand into irregular dark brown withered spots at the edges, slightly depressed in the middle, surrounded by yellow chlorotic zones, the expansion of disease spots is often limited by veins, the diseased leaves gradually turn yellow and shrink, and the diseased parts dry and become brittle and fall off at the later stage; The stem is damaged, often before the stem groove appears water-like small spots, then along the plant up and down expansion, the disease spot is long, slightly depressed in the middle, brown, late disease part cork raised, forming a nearly round rough dead spot; fruit damage, more than fruit surface formed raised round white spots, after the disease middle depression for dark brown or black brown raised ring spots, serious disease spots connected into irregular scab shaped chunks, fruit coloring before and young fruit expansion stage more serious disease. If the joint of fruit and fruit stalk is damaged, it is easy to cause fruit drop.

II. Introduction of comprehensive control methods of tomato scab

1. Prevention should start from seedling

In planting areas with factory seedling conditions, growers should try their best to purchase and order seedlings from competent seedling enterprises and cooperatives. If you buy seeds from ordinary channels, you should soak them with liquid medicine. You cannot use soil or substrate planted with eggplant vegetables. If there is livestock manure mixed in the seedling substrate, you need to fully decompose before you can use it.

2. Land selection and preparation, high ridge cultivation

It is advisable to select loam land with good drainage as tomato seedling and cultivation land; when planting in the field, it is necessary to excavate waist ditches and surrounding ditches, make a ridge surface of about 1.2 m wide, and open a ditch of 30 cm deep and 20 cm wide at the bottom between adjacent planting ridges to facilitate drainage and humidity reduction.

3. Strengthen field management and apply fertilizer reasonably

Strengthen field management, loosen soil and weed should be shallow rather than deep, so as not to hurt roots and cause wounds, and prevent excessive water shortage or excessive humidity of plots; fertilization, weeding, pruning and branching should not be carried out before rain and dew on tomato leaves to prevent disease transmission; Central diseased plants, diseased branches and leaves and diseased fruits should be removed in time during the growth period. Since the disease generally extends upward from the lower part of the plant, timely cleaning of diseased branches and leaves can not only increase ventilation and light transmission, but also reduce the reinfection of pathogenic bacteria. When fertilizing,"apply enough base fertilizer, apply seedling fertilizer early, apply bud fertilizer heavily", apply enough base fertilizer at one time, base fertilizer is mainly decomposed manure or compost, try to use less chemical fertilizer, avoid partial application of nitrogen fertilizer, apply enough phosphorus and potassium fertilizer, and enhance its disease resistance.

4. Irrigation under film

In tomato planting areas where conditions are available, drip irrigation under film should be adopted, which not only can reasonably save water, reduce labor intensity, improve field microclimate, but also reduce the damage of pests and weeds. Generally, about 15 days before planting, soil moisture shall be opened and dropper shall be laid according to terrain. For plots with more weeds in the last crop, herbicides such as paraquat can be sprayed according to the instructions for use, and then black or silver-gray film shall be covered, and the film shall be sealed and compacted with soil. Some pathogenic bacteria and weeds can be killed by film mulching in advance combined with high temperature in summer and autumn in Yunnan hot zone. Drip irrigation under mulch can control the water demand of tomato in different growth stages, and it is also found that this measure greatly reduces the occurrence and prevalence of diseases, which is worthy of popularization in production areas.