Did you notice that on your tomato bushes with fruits, the tops began to fade? In this case, the leaves were covered with ugly chlorotic spots?
Most likely, you have to save the tomatoes from Fusarium wilting. This sore is a real scourge of greenhouse tomatoes!
Fusarium wilting of tomatoes: what is it, signs
The reason for the spread of the disease in a covered ground is most often the failure to observe cultural turnover and the absence of an annual change (or steaming) of the land. It can occur at different stages of the growing season. However, the pathogen exhibits maximum activity during the period of fruit formation, when the plant immunity is greatly weakened.
The following symptoms are characteristic of fusarium wilting of tomatoes:
- The leaves in the lower tiers of the bushes turn yellow, the veins acquire a lighter color, and the edges begin to curl into a tube.
- The upper branches wither and die.
- In the last phases of development, the disease affects the roots, which leads to the irreversible death of the entire plant.
How does the causative agent of fusarium? First of all, it penetrates the young roots of seedlings. Most often this occurs at the sites of lateral branching or through microtrauma. The infection continues to develop along with the tomato bush.
Subsequently, the mycelium is carried with the plant’s juice to all above-ground parts – leaves, stems, petioles, stalks, and the fruits themselves. And in advanced cases, it even penetrates the seeds. A diseased tomato dies rapidly since a mushroom mycelium clogs the vessels of all tissues and releases a lot of toxic substances.
The disease spreads particularly quickly through the greenhouse during hot periods.
The development of fusarium wilting is favored by factors:
- Sudden changes in temperature and humidity in the greenhouse. Extremely dangerous drop in temperature below +14 degrees in the first weeks after planting of seedlings and heating of the air in the room to +27 … 28 during the fruiting period.
- Low light.
- Mechanical damage (especially during herding), which facilitate the penetration of infection into tomato tissue.
Under such conditions, the pathogen begins to intensively produce toxic substances. This provokes sharp dehydration of tissues, the fall of their turgor, and causes the withering of the whole plant as a whole.
The roots of diseased tomato bushes rot and quickly turn into dust. The infection is transmitted through the soil, with irrigation water and garden tools. Sources are also seed material, greenhouse, and garden soil.
How to treat fusarium wilting tomato
In most cases, growing tomatoes in a greenhouse are carried out in a monoculture, that is, without replacing or disinfecting the greenhouse soil. Therefore, preventive measures to prevent fusarium wilt include:
- A thorough examination of plants even in the seedling stage for the presence of symptoms of a formidable disease;
- Mandatory disinfection of the root layer of the soil in the greenhouse by steaming – heating at a temperature of +96 to +100 degrees for an hour.
- Removing thickening leaves and stepsons only with a special tool, followed by disinfection of the wounds and the tool itself. This is convenient to do with alcohol or a 5% solution of potassium permanganate.
- Sowing seeds only in warm soil.
- Fertilizing fruit-bearing tomatoes mainly with potash fertilizers with a parallel decrease in the number of nitrogen fertilizers.
- Maintaining in the greenhouse the conditions most conducive to the development of crop plants. It is optimal if at night in a greenhouse the temperature fluctuates in the range from +16 to 18 degrees and humidity from 60 to 65%. For daylight hours, these indicators should be respectively +22 … 24 and 75-80%. In sunny periods, the glass parts of the greenhouse should be whitened and the plants should be given the correct irrigation regime. That is, by principle rarely, but plentifully.
Of the chemicals used to combat Fusarium wilting of tomatoes, Previkur 607 SL gives a good effect. The drug is introduced into seedlings and watered with seedlings with an interval of 3-4 weeks – from 2 to 4 liters of 0.15% working solution per square meter.
But the use of radical measures is advisable only with a severe infectious background. In other cases, it is quite realistic to restrain the development of the disease using the measures described above.