Brown spots on tomato plants? The fruit is rotting on the stem? Are the leaves turning brown? Maybe it's tomato brown rot. Although plants from thisdisease affecteddie relatively quickly, you can still save some of your tomatoes thanks to these tips.
Recognize brown rot on tomatoes
Late blight is a disease caused by the fungusPhytophthora infestansand can affect both tomatoes and potatoes. Late blight can occur at any time during the growing season, especially when the weather is cool and humid. Longer hot dry periods can slow the spread, but not stop it. Both green and ripe tomatoes can be infected.
The pathogen not only destroys the fruits of the plants it infects, but can also spread very quickly and widely and cause devastating damage to your garden if it is not combatted in a timely and correct manner. The worst part is that late blight can overwinter, meaning it can reappear the next year even after a cold frost if the plants and soil containing the pathogen are not removed.
It is difficult to detect brown rot on tomato plants in the early stages of the disease. Many farmers do not immediately recognize that the crop is infected. If brown spots appear on the leaves, it may be associated with leaf spot disease(Alternaria tomatophila)be confused.
This is how you can recognize tomato rot:
- The leaves have large, dark brown spots with a green-gray edge that are not bordered by the main veins of the leaf.
- These spots increase in size until the entire leaf or stem turns brown and dies. Dead leaves usually remain attached to the stems.
- Dark brown, irregular spots cover large parts of the fruit. The spots can become mushy if secondary bacteria invade.
- When humidity is high, a thin, white coating of mold forms on infected leaves, fruits and stems.
It is not uncommon for tomatoes to become damaged internally as well. In this case, the disease develops without any visible signs. The buds ripen quickly and fall off. A lesion on the pulp is only discovered when the vegetable is cut open.
Brown rot – can you eat tomatoes?
After the discovery of late blight on tomatoes, gardeners are wondering whether ripening tomatoes are still edible. Opinions differ there.
“The unaffected parts are probably safe to eat. Tomato parts without disease symptoms are unlikely to pose a health risk to the consumer,” says Dr. Margaret McGrath, a plant pathologist at Cornell University and a specialist in the disease.
Barbara Ingham, food safety specialistan der University of Wisconsin-Extension, however, advises consumers to avoid the temptation to eat sick tomatoes or potatoes.
“Since eating fruits affected by late blight has not been shown to be harmful, it may be tempting to simply cut off the affected part. But the fruit then tastes bitter and may harbor other organisms that can cause foodborne illnesses.
Ingham also cautions that diseased fruit should not be preserved or frozen, even if the infected part has been removed. “Don’t be tempted to pickle or preserve infected tomatoes,” says Ingham. “The virus can alter the acidity of tomato fruits, which is crucial for the safe preservation of tomatoes. However, healthy tomatoes can be safely preserved or even frozen,” she says.
What if you have undamaged tomatoes growing on plants whose leaves, stems, or neighboring fruits show signs of infection? These are safe to eat and even preserved, says Ingham.
Why do tomatoes get brown rot?
Tomato brown rotis most often caused by the following reasons:
- Often the disease actively manifests itself with an intensive change in the weather. If one month is cool and rainy and the next is hot and dry, the disease is bound to occur.
- Bad soil. Sometimes gardeners don't even know what pH the soil on their property is. If the pH value is too high or too low, the tomatoes will rot.
- Calcium deficiency is a problem for most gardeners. The experienced gardener knows that tomatoes need to be fertilized with calcium nitrate during their growing season to avoid brown rot.
- Nitrogen fertilizer in large quantities leads to late blight.
To protect your vegetable garden from disease, you need to know how to deal with these problems and how to prevent tomato blight.
What to do if brown rot occurs on tomatoes?
So what should you do if you spot late blight in your garden? Unfortunately, you cannot “cure” this disease, but you should pull out and remove plants with late blight symptoms immediately. This will protect your neighbors' gardens and local farmers.
This is what you should do:
1. Remove the infected plants: Remove infected plants, pack the leaves and unripe tomatoes in black garbage bags and dispose of them with household waste. Do not attempt to compost infected potato or tomato plants. Most compost piles are not hot enough to kill the spores, and you risk reinfecting your plants the next season. You can find out more about thisread here.
2. Prevent spores from overwintering: Late blight can only survive on living tissue. Northern winters kill any spores that may be above the ground on trellises and tomato cages. However, late blight can overwinter in plant residues, seeds and potato tubers below the frost line. To be on the safe side, at the end of the season you should clear away any plant debris, purchase fresh seeds for next year, and remove any potato and tomato plants that sprout from the ground.
3. Make a fresh start next year: At this point, all we can do is cut our losses and hope for a better growing season next year.
Fight brown rot on tomatoes
In the fight against this disease, you can use several proven methods to prevent its spread.
Baking soda against brown rot
At the first signs of damage to the plants, it is recommended to spray the leaves with a 1-2% baking soda solution. To do this, 10 to 20 grams of baking soda are dissolved in 10 liters of warm water.
Use of wood ash
Remove all affected fruits and leaves and treat the remaining plants with a wood ash solution. The ash contains phosphorus, calcium, magnesium and boron andalso acts as a fertilizer. How to prepare wood ash decoction:
- Add 100 grams of ash to 10 liters of boiling water.
- Then let the mixture cool and then strain.
- Pour the solution into a plant sprayer and treat the fruits, leaves and roots.
Calcium chloride and calcium nitrate
External application of calcium chloride and calcium nitrate can correct calcium deficiency and stop the development of putrefactive lesions. To prepare the solution you will need:
Variant 1.
Calcium Nitrate – 5 to 10 grams
1 liter of water
Variant 2.
Calcium chloride – 30 to 40 grams
10 liters of water
First, you should moisten the soil and then spray the tomato plants with the calcium solution.
Superphosphate fertilizer strengthens plants
Phosphate-containing additives help stop the development of brown rot and prevent it from spreading to healthy bushes. Superphosphate has been proven effective. To prepare the base you will need:
3 liters of water
15 to 20 tablespoons of superphosphate
Since the fertilizer dissolves more easily at high temperatures, bring the water to the boil and pour in the granules. Stir the solution occasionally throughout the day until the granules are completely dissolved. This way you will get a mixture with a light texture.
To obtain the agent for treating tomatoes against brown rot, add 150 ml of the basic solution to 10 liters of water and add 20 g of nitrogen fertilizer as a necessary additive.
Prevent brown rot of tomatoes
The best way to combat late blight on tomatoes is primarily through preventive measures. This essentially involves:
- Select resistant tomato varieties
- disinfect the seeds before sowing
- prepare the soil before planting the plants
- pay attention to regular watering
If the tomato varieties are resistant to brown rot, this is usually indicated by the manufacturer on the packaging. The hardiest tomato varieties are:
- Philovita
- De Berao
- Resin fire
- Fantasy
- Mountain Magic (F1)
- Plum Regal (F1)
- Cocktail-Tomate Philovita (F1)
- Mountain Merit (F1)
- Tomato Fantasio (F1)
- Skystriker
- Legend
- Wapsipinicon Peach
- Lemon Drop
- Pruden’s Purple
The fight against tomato top rot begins with theDisinfection of seedsbefore sowing. If the seeds are bought from specialist retailers, this treatment is usually not necessary. If you use your own harvested seeds, you can disinfect them with potassium permanganate. The planting material is soaked in a 3% potassium permanganate solution for about half an hour, then washed under running warm water and dried.
Proper preparation of the soilBefore planting the tomato plants also helps to protect the fruit from brown rot. Experts recommend adding 2 to 3 tablespoons of fine lime or ordinary chalk to the soil.
The use ofWood ash as fertilizerPlanting tomato plants in the ground also helps to prevent late blight from affecting the fruit. To prevent the disease, add a coffee cup of ash to each planting hole.
When growing tomatoes it is important for onetimely wateringto care. Drought reduces the plant's calcium supply, which can lead to brown rot. Since calcium is better absorbed at night, it is advisable to water in the evening. A layer of mulch helps retain moisture in the soil for longer.
Tomato brown rot fungicides
Fungicides can help protect healthy, uninfected plants when sprayed regularly on all parts of the plant. A copper fungicide is less effective but is probably the best choice for organic gardeners. In all cases, you must apply the fungicide before infection for it to be effective. Always follow label directions when applying fungicides.
- Organic fungicides. Treat the plants with a copper fungicide, which you can purchase online, at a hardware store, or at a home improvement store. Follow label instructions. You can apply it once a week and after every rain until the leaves drain. Serenade® ASO also belongs to the group of biofungicides.
- Chemical fungicides. Some gardeners prefer chemical fungicides, such as Ranman and Signum, which effectively inhibit fungal development. You can also opt for crop protection products containing the active ingredient mancozeb, although these have a longer waiting period before you can safely harvest the tomatoes.
Once late blight is present and progresses, it becomes increasingly resistant to biofungicides and fungicides. Treat the plants as quickly as possible and on a specific schedule.
