September Tomato Problems: Solutions for Late Blight and Cracking

Whether you call them fruits or vegetables, tomatoes are iconic crops in the summer garden. Cherry varieties grow bushels full of small tomatoes, while slicers and heirlooms offer giant, juicy tomatoes full of flavor. 

The last thing you want is your tomato plants croaking at the end of the growing season. Cool temperatures, ample rainfall, and frosty conditions threaten your ripening tomatoes before you can harvest them. Knowing what’s to come can help you prepare for the worst. 

Some of these September tomato problems are diseases, while the majority are physiological issues that tomato plants encounter. Don’t give up if you notice them on your tomato crop! Learn to prevent, manage, and treat the problems for a successful end-of-season harvest.

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Late Blight

Late blight (Phytophthora infestans) is a condition that causes rapid tomato death in late summer, fall, and early winter. As its name suggests, it shows up late in the growing season. Rainfall, cool weather, and soggy soil lead to its occurrence and spread. It’s caused by oomycetes, which are fungus-like organisms that attack plants. 

Symptoms and Signs

This September tomato problem doesn’t just harm tomato crops. It affects other solanaceous species, like potatoes, petunias, and nightshades. It has symptoms and signs; symptoms are the plant’s responses to the disease, while signs are structures the disease creates. 

At first, tomato plants will have brown-gray, water-soaked lesions on the tops and undersides of their leaves. Eventually, white powder forms on the spots, and the leaves shrivel and brown. The pathogen spreads when the wind picks up the white powder and spreads it to nearby crops.

Tomato fruits will begin to show symptoms and signs of the pathogen in extreme infections. Small, mushy brown spots form in the fruits. They enlarge and produce the white powder over time.

Prevention 

This blight spreads most rapidly under cloudy, moist conditions at the end of the season. You can escape its clutches by planting earlier in the growing season. An earlier planting ensures the tomatoes ripen before the disease becomes prevalent. 

Avoid wet leaves by watering the soil, and not the tops of the plants. Overhead sprinklers are easy to use, but they lead to wet foliage that harbors blight. Use drip irrigation, hand watering, or olla pots to water the soil and not the leaves. 

Some tomato varieties are resistant to late blight. Consider planting them if the disease reoccurs in your region in the fall. Try ‘Mountain Merit!’ It’s a determinate slicer tomato that you can succession plant for repeat harvests. 

When you see symptoms of these September tomato problems, remove any infected leaves and tomatoes while the spots are still small. If a plant has symptoms of the disease all over itself, consider removing it to control the pathogen’s spread. 

Treatment

It’s difficult to treat this blight once it infects a tomato plant. Fungicides may work, though they cause a litany of other issues in the soil. It’s best to plant resistant varieties early in the season to avoid blight altogether.

If you do choose to use a fungicide, opt for an organic one that contains copper. Weekly sprays are necessary to prevent the spread. Note that the spray won’t kill the pathogen; it merely prevents it from spreading to other tomatoes.

Cracking and Splitting

Cracking, or splitting, is an incredibly common September tomato problem! It’s not from a disease. It’s caused by fluctuating water levels. Not enough or too much water leads to a swollen tomato with split skin.

Causes

Tomatoes crack when their insides grow quicker than their skin. The skin can’t keep up with the rapid swelling, and it splits instead of staying whole. This occurs when the garden is dry and suddenly receives an influx of water, like when rains return at the end of the growing season. 

Two types of cracks appear on tomatoes: concentric and vertical. Concentric cracks are common on heirloom tomatoes that swell to impressive sizes. As each chamber of the fruit develops, it forms a ridge at the top that’s susceptible to splitting. Simply harvest the tomato, cut off the top part, and eat the rest. 

Vertical splitting is a bit different. It occurs along the sides of the tomato, leading to mushiness and rotting symptoms as the fruit ripens. This type is the one that commonly occurs because of infrequent or irregular watering. 

Prevention

A few easy tricks prevent these September tomato problems. You want to keep the soil as consistently moist as possible. Water regularly; if you struggle to remember, try hooking your system up to a timer. Automatic timers turn the water on when you program them to, so you’ll never miss a watering session!

Other tricks preserve moisture in the soil so the tomato roots don’t dry out. Mulching is one such trick. Organic mulches feed, protect, and nourish the soil. They prevent water loss through evaporation, and they foster beneficial soil organisms like bacteria, fungi, and worms.

The best mulch to use in the garden is compost. It’s easy to make at home, and it’s a great way to recycle waste and save it from the landfill. All you need is a space, a good ratio of plant scraps, and a pitchfork! Create a pile, turn it daily, and keep it moist. You’ll have ready compost in three weeks or longer. 

Treatment

There are some quick cures for healing tomatoes that are cracking. Start by mulching the soil with an organic mulch. Then, begin watering regularly to keep the soil moist, but not soggy. Regular moisture will prevent cracks from occurring in the future.

If rains occur at the end of the season and the soil is already moist, it’s a good idea to protect the ground. Set up a tarp or umbrella over your plants, and secure it with stakes or supports. Then, when sunshine returns, remove the covering and let the light hit your tomatoes.

Alternatively, extreme heat can scald and burn the tomato skin, and the burns may lead to cracking over time. Ensure the site stays moist during heat waves, and cover the tomatoes with shade if temperatures stay high for prolonged periods. 

Tomatoes Aren’t Ripening

Late-season tomatoes may not ripen properly, as cool temperatures and a lack of sunlight make it difficult for the plants to photosynthesize. Green tomatoes may hang on the vines for weeks in the fall. Don’t worry—there are a few tricks to get them to ripen after picking. 

Causes

This September tomato problem occurs because of improper growing conditions. The crops struggle to create energy, and they cannot turn their green fruits ripe red. The green tomato fruits remain on the plants until frosty weather turns them mushy, after which they fall to the ground. 

This may occur in the summertime because of a lack of nutrients. In autumn, it’s most likely due to the changing weather. Green tomatoes are common in regions with wet and cool fall seasons, like the East Coast and the Pacific Northwest. 

Treatment

Treatment varies depending on whether the tomato fruits are picked or still sitting on the vine. If they’re on the vine, you’re in luck! Start by removing all extra flowers and small tomatoes that won’t ripen in time. Then, chop the stems above the last tomato cluster. 

This pruning removes excess growth, allowing the plants to redirect their energy towards ripening the remaining tomatoes. If temperatures are cold at night, add greenhouse plastic over the tomato bed. Secure it to metal U-posts or wooden stakes. The plastic traps heat, allowing your plants to stay warm despite frosty weather.

If you already picked the tomatoes, try ripening them with the power of ethylene. Ethylene is a naturally occurring gas that apples, bananas, and most other fruits emit. It induces ripening. This is why chefs say not to store apples in the fridge with other produce. Apples produce lots of ethylene gas, and they cause other fruits to ripen and spoil.

This is good news if you need to ripen a green tomato. Simply place a ripe apple in a paper bag with your unripe tomatoes. Set the bag on your kitchen counter, and check it daily. Each green tomato should slowly turn red (or yellow) over time. When a tomato is fully ripe, store it in the fridge until you’re ready to use it. 

Mushy Tomatoes

Mushy tomatoes are bad news and one of the most common September tomato problems. Not only are they mushy, but they also taste terrible. If parts are mushy, you may cut them out and eat the healthy portions. Often, after an extreme frost, all of the remaining tomatoes in the garden will turn mushy and rotten. 

Causes

Mushiness at the end of the season stems from early frosts. A tomato cannot withstand freezing temperatures; its cell walls burst, and the tomato loses its structure and rigidity. It may still look green the day after the frost, but within a few days it’ll turn mushy and discolored.

Early mushiness may stem from a myriad of diseases and physiological problems. If your tomato crop is mushy in spring and summer, inspect the garden for signs of diseases and pests. Wormy larvae, fungi, and bacteria are all possible causes.

Prevention

There’s no way to make a mushy tomato not mushy. It’s best to prevent these September tomato problems by harvesting regularly. If a light frost is in the forecast, pick any remaining green tomatoes and ripen them indoors. Use ethylene, or set them on your kitchen counter if they’re halfway ripe already.

If the frost is only for a few hours at night, use greenhouse plastic to conserve heat throughout the tomato bed. Open the plastic covering during warm days, and close it at night to protect your frost-tender plants. 

Mushy tomatoes are unsightly, but you can use them anyway. Chop off the mushy parts and sauté the green tomatoes. Or, try making fried green tomatoes. If a tomato is red, remove the mushy flesh and eat the rest, or mix it in a sauce with other ingredients.