Brown rot of tomatoes can affect almost all parts of the plant, including the leaves, stems and fruits. Although the plants do not die, they are weakened and produce fewer tomatoes than normal. Stressed plants or plants in poor health are particularly vulnerable. The fungal infection can kill a plant within a week. That's why it's important to look out for telltale signs and act quickly as soon as you spot them.
Brown rot is a common tomato disease caused by the fungus Alternaria solani. The fungus can come from many sources. It can be in the ground or already on purchased seeds or seedlings. It can even overwinter in the diseased residue of your plants and persist in the soil or residue for at least a year. Brown rot can occur in any weather, but it prefers moist conditions, such as frequent rain or even heavy dew.
Symptoms of fungal disease
In the early stages of brown rot tomatoes, black rings first appear on the lower leaves. This causes the leaves to turn pale green to a musty yellow. The leaves eventually become so infected that they fall off.
On Older Plants: Dark spots with concentric rings form first on older leaves. The surrounding leaf area may turn yellow. Infected leaves may die prematurely, exposing the fruit to sunburn. The dark lesions on the stems are initially small and slightly sunken. As they grow larger, they expand and you can see concentric markings like the spots on the leaves.
On tomato fruit: When brown rot spreads to the fruit, the spots begin at the stem end and form a dark, leathery, sunken area with concentric rings. Both green and ripe ones can be usedTomatoes affectedbe.
On seedlings: Infected seedlings have dark spots on leaves and stems. You can even get sick from the cotyledons. The stems often become garland-shaped.
Prevention measures
Brown rot on tomatoes cannot be completely prevented - but you can take steps to reduce the likelihood of infection. You can take the following measures to get the problem under control:
- Certified Seeds: Buy seeds and seedlings from reputable sources and check all plants before putting them in your garden.
- Air circulation: Provide enough space for the plants. Good air circulation helps keep plants dry. If you are growing tomatoes in a greenhouse or polytunnel, you should ensure that they do not become too humid by keeping them well ventilated. Also choose a well-ventilated place for theGrowing tomatoesoutdoors. To keep plants dry, it is important to prune leaves and side shoots to maximize air movement and ensure evaporation of surface moisture. Remove the lower leaves as the fruit develops. This prevents the leaves from lying on the damp soil. Air circulation is promoted and the ripening of the fruits is accelerated because they receive as much sun as possible.
- Garden hygiene: Since brown rot can overwinter on plant residues and in the soil, thorough cleaning of the garden is essential.
- Crop rotation: If the fungal infection breaks out in your area, consider planting your plants elsewhere next year, even if they are in containers.
- Tying or staking the plants: Support shrub plants with a stake to keep their leaves off the ground, or tie cordon tomatoes regularly with soft twine to improve air circulation. Vine tomatoes grown in pots can be partially supported with a bamboo cane.
- Water the plants in the morning. This will prevent them from staying damp all night long. Try to only water the soil and keep the leaves dry.
- Never plant tomatoes in soil or compost that previously contained diseased plants. Tomato disease spores can remain in the soil for 3 to 4 years.
- Proper composting of plant waste is of paramount importance and gardens and allotments must be free of “plant waste” to reduce contamination.
Grow varieties that are resistant
Many modern varieties have the cultivation of tomatoesthrough earlier maturityand improved disease resistance made easier. There are a number of varieties that have been bred with resistance to brown rot.
- 'Merrygold'. This is the world's first mold-resistant variety with orange fruits. This plant is very productive and produces lots of bright orange tomatoes.
- 'Cocktail Crush'. This variety is highly resistant to brown rot and is ideal for outdoor cultivation.
- 'Crimson Blush'. This mold-resistant type of beefsteak is sweeter than other types of beefsteak.
- 'Tommy Toes' are red, tiny heirloom tomatoes that have a bold flavor and are very juicy.
- 'Legend' is a red beefsteak variety and a favorite of most commercial growers.
- 'Juliet' is a small red hybrid variety
- 'Manyel' is a yellow tomato that is also low in acid.
Fight brown rot on tomatoes
What to do about brown rot on tomatoes? If the worst happens and you notice signs of the infection on some of your plants, the best treatment is to remove those infected plants immediately to prevent it from spreading to other plants. Check plants regularly during the growing season, especially when conditions are warm and humid. If possible, burn infected plants or compost the foliage and fruit if you have a good composting system, as composting kills the spores.
It is important that you do not plant your tomatoes next to potatoes, which can also be affected by brown rot, but that you plant themChoose companion plants carefully.
Brown rot tomatoes spray: baking powder
Baking soda can be used as a treatment for the infection. You can make the following solution:
Add to 4 liters of water:
- a heaped tablespoon of baking powder;
- a teaspoon of vegetable oil;
- a small amount of a mild soap.
Spray plants with this solution and apply regularly to maintain its effectiveness.
Are brown rot tomatoes edible?
If you have an infected plant, you should not eat fruit that is obviously affected by the fungal infection, but ripe fruit that shows no signs of brown rot is still perfectly edible. However, if you leave the fruits on an infected plant, they will not ripen. You cangreen tomatoes, which show no signs of brown rot, are harvested and processed into green tomato chutney.
