How to prevent and control tomato Fusarium wilt? A detailed introduction to the key technical points

Tomato is a nutritious food with a rather distinctive taste; it can be eaten raw or cooked, and can also be processed into all kinds of foods. Tomatoes are grown in many parts of China and are one of the vegetables with low environmental requirements. Tomato Fusarium wilt is a disease that very easily occurs during its growth process. Below, let us take a look at the key technical points for its prevention and control.

I. Symptoms of tomato Fusarium wilt

Tomato Fusarium wilt has a long disease course. Infection begins at transplanting, mostly starting from the root tip, and symptoms do not begin to appear until around flowering. After symptoms appear, the plant can still survive for a long time, generally 15-30 days before withering and dying. In the early stage of the disease, the lower leaves first turn yellow and wither, and a large number of them drop off. The cortex of the stem base in contact with the ground surface becomes water-soaked and rots, and the stems and leaves above ground rapidly wilt; sometimes the diseased part develops only on one side of the stem, forming a longitudinal strip-shaped necrotic area, causing the leaves on one side to turn yellow and then brown and die; in some cases half a leaf sequence or half a leaf turns yellow. When the underground root system of a diseased plant is dissected, it also shows water-soaked soft rot, the cortex peels off very easily, and the xylem turns dark brown to sooty black. Under high humidity conditions, the diseased part produces a pink mold layer, namely the pathogen's conidiophores and conidia. After tomatoes set fruit, plant vigor weakens, nutrient consumption is great, and the plants are severely depleted, so Fusarium wilt symptoms begin to appear.

II. Causes of tomato Fusarium wilt

The pathogen causing tomato Fusarium wilt is Fusarium oxysporum f. sp. lycopersici, which belongs to the Fungi kingdom, Deuteromycetes. Diseased stems carry the pathogen 100%, and the pathogen passes through the vessels from the diseased stem through the fruit stalk to the fruit, and then spreads to the seeds as the fruit rots, causing seed contamination. It can also overwinter in the soil as mycelium or chlamydospores with diseased plant residues. The pathogen generally invades the host from young roots or wounds, enters the vascular bundles, blocks the vessels, and produces fusaric acid, causing the leaves of diseased plants to turn yellow, wither, and die. The pathogen can spread through water flow or irrigation water. The specific causes of the disease are as follows:

1. Continuous cropping land, fields with heavy clay soil, acidic soil, and large amounts of Fusarium wilt pathogen accumulated in the soil,

2. When there is a certain amount of nematodes and other underground pests in the soil, the pathogen invades the roots through wounds caused by the pests,

3. Contaminated seeds, contaminated nutrient soil used for raising seedlings; or contaminated organic fertilizer, or organic fertilizer that is not fully decomposed, with manure maggots damaging the roots, allowing the pathogen to invade through the wounds and cause damage.

4. Fields with excessive nitrogen fertilizer application and insufficient phosphorus and potassium,

5. After continuous rainy days or after heavy rain, when it suddenly clears up and the temperature rises rapidly; or alternating sunny and rainy weather, or hot and stuffy weather.

III. Key technical points for preventing and controlling tomato Fusarium wilt

1. Agricultural control measures: First, plant grafted seedlings. Enhancing disease resistance is the best measure and first choice for preventing Fusarium wilt. Second, implement rational crop rotation. Carry out rotation with crops not of the same family for more than 3 years, or adopt paddy-upland rotation. Third, promote the application of bio-organic fertilizer as a base fertilizer. Use bacteria to kill bacteria.

2. Root irrigation with medicinal solution for disease prevention: the timing is controlled so that root irrigation is done once as a preventive measure on the day after transplanting and once at the early flowering stage. The agents can be 150-fold Chongchaling solution or 20% zinc thiazole suspension concentrate at 500-fold, applying 250 milliliters of medicinal solution per plant each time.