Gray Rot Of Tomato

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

Gray rot in some regions causes very serious damage to growing tomatoes. First of all, this disease affects plants, the stems of which were damaged during caring for them. The development of gray rot usually occurs during the fruiting stage of tomatoes, and this attack develops best when wet weather is established. If you do not provide the growing tomatoes with proper care and do not start a timely fight against gray rot, it will very actively spread throughout the greenhouse, affecting the tops of the shoots, as well as inflorescences with ripening fruits

A few words about the disease

On tomato nodules affected by destructive gray rot, the formation of grayish-brownish spots begins, gradually becoming covered with an unpleasant gray bloom. And in the nearest areas near the places of separation of the leaves, the harmful attack manifests itself in the form of brownish elongated specks. For three to five days, all the spots grow along the stems up to four to five centimeters, covering them around the perimeter. A little later, they fade in the middle to a pale straw shade, and on closer examination you can see annular blurred stripes on them. By the way, in the first six to eight days after the appearance of such spots, there are no signs of fungal sporulation on them.

Inside tomato stems, necrosis of the bark and blood vessels often develops, as a result of which, in some areas of the stems, the flow of water stops, which in turn provokes the rapid wilting of plants. The leaves located just above the necrosis turn yellow, and the formation of an impressive amount of aerial roots begins on the tomato stalks.

When affected by gray rot, the parts of plants located above the spots often wither. And after about a week and a half, an ash-gray bloom forms at the edges of the spots (and sometimes in the center). This is what conidial fungal sporulation looks like.

In the event of rainy weather, as well as high humidity, the ill-fated attack can also affect flowers with fruits. By the way, the specks formed on them are characterized by a rounded shape.

The causative agent of the ill-fated gray rot of tomato is a pathogenic fungus called B. cinerea. It is also often called a wound parasite. The spread of infection occurs mainly through the air, as well as during the care of growing crops and during harvesting. Fungal conidia can also be carried by water when irrigated. And at the end of the growing season, many tiny black sclerotia are formed on the post-harvest residues, which contribute to the long-term preservation of the pathogen in the soil.

How to fight

Despite the fact that protective measures against gray rot of tomato are well developed, they are often applied with some delay, and this, in turn, partially reduces the effectiveness of the measures taken.

The most important protective measure against the ill-fated ailment is considered to be the maintenance of a fairly low air humidity in greenhouses. In order to reduce the wound surfaces of plants and thereby prevent the successful penetration of infection, it is important to handle tomatoes as carefully as possible, not only when removing leaves and fruits, but also when forming crops. For this purpose, it is important to cut off the damaged parts of the stems and leaves only in dry weather and with an exceptionally sharp knife.

It is extremely important to remove plant residues from the greenhouses as well, as they contribute to the further infestation of tomatoes. And the spots on the affected crops are often coated with a special paste with fungicides.

Treatment of growing crops with sodium humate helps to reduce the development and further spread of the stem form of destructive gray rot of tomato by one and a half to two times.

For preventive purposes, tomato stalks are treated with a suspension of "Trichodermina". It is especially useful to carry out such treatments after removing the leaves (in order to contain the development of secondary foci of infection). And among chemical preparations in the fight against gray rot of tomato, preparations "Bayleton" and "Euparen multi" have proven themselves well.