Tomatoes are the most common plant for gardeners of all types and skillsets.  It is an easy plant to grow and is extremely forgiving to most kinds of weather.  Who can resist the taste of a ripe tomato from a garden?  They are so much better than any that you can buy from the grocery stores. Yet even as easy as tomatoes are to grow, they come with a whole host of problems. Fortunately, tomato problems are easy to diagnose. Today, I’m walking through the kinds of tomato problems I’ve encountered in my years of gardening.

Tomato Leaf Problems

Tomato leaf problems can appear anytime during the plant’s lifecycle, from seedling until well after the plant has produced fruit. Leaf problems on tomato plants may be an easy fix, or signs of a much deeper problem. Some issues noted on the leaves can spread to the fruit if left untreated. Here’s a few common tomato leaf problems.

Leaf Curl

Leaf curl on tomato plants can be a sign of greater disease. However, more commonly, it’s just a sign that your tomato plant is stressed. The most common causes for tomato leaf curl (professionally called physiological leaf roll) is high heat and low watering. To conserve water during hot summer days, tomato plants curl their leaves to maintain what moisture they have. The stomata (pores on the tops of leaves) close up to prevent evaporation and this causes the leaves to curl up.

Tomato plants that are stressed for water will recover very quickly once you water them. After the heat of the day has passed, give your tomato plants a good soaking at the soil level and see if that improves your tomato plants’ fortunes. They should uncurl their leaves within an hour (often as little as 30 minutes).

If your tomatoes don’t uncurl their leaves after watering, or you notice other problems in the leaves (such as yellow or purple discoloration of the leaf veins), you may have a disease like the Tomato Leaf Curl Virus or the Curly Top Virus. Unfortunately, most plants with these sorts of viruses generally don’t survive once symptoms present themselves. In these cases, you must remove the plant from the tomato bed to avoid infecting nearby plants.

Leaf Spot

Leaf spot is typically a sign of a fungal infection on the surface of the leaves. It mainly affects older leaves that grow at the bottom of the plant. If left untreated, the fungus will migrate upward throughout the plant over time. Leaf spot is typically found when the weather is particularly humid, or water has splashed on the leaves from above. Splashing water spreads the fungus to neighboring leaves.

Two of the main perpetrators of tomato leaf spot are Septoria leaf spot and early blight. It can be difficult to differentiate between these two. However, if you look closely at the affected leaves, you will be able to tell the difference. You can identify Septoria leaf spot by a collection of dark brown structures in the centers of the tan centers of the spot. Meanwhile, early blight will have concentric circles around the dead spot in the center.

Tomato leaf spot is a problem that can travel to the fruit where it produces similar spots or rings as on the leaves. To contain leaf spot, remove any infected leaves up to 1/3 of the entire plant if necessary. If the plant’s leaves are more than 1/3 affected, remove the plant from the tomato bed to avoid contaminating others. A fungal spray diluted in water can have an optimal effect of killing the fungus and saving your plants.

Purple Leaves

Purple leaves on tomato plants is a problem that occurs with a phosphorous deficiency. Tomato plants also can’t absorb phosphorus if the soil is too cold. Tomatoes like soil that stays greater than 60 degrees Fahrenheit (about 15 degrees Celsius).

A purple leaf problem on tomato plants isn’t permanent. Plants will repair themselves once the soil needs are met. Apply a fertilizer with added phosphorous and make sure the soil temperature is warm enough and purple leaves should regain a healthy green again.

Tomato Fruit Problems

Leaves are only one indication of a tomato plant problem. Unfortunately, some tomato problems don’t appear until after the fruit has set. In these cases, the fruit is largely inedible, but that doesn’t mean that all is lost. In many cases, if you take action soon enough, you can help the fruit that forming now, even if you can’t help the already affected tomatoes. Younger batches of tomatoes can still form well even if the first batch was a loss.

Blossom End Rot

I have previously written about how important it is to prepare your soil bed properly when transferring seedlings outside. This means giving them the proper nutrients right off the bat so they’ll have what they need in the soil waiting for them throughout the season.

Blossom End Rot (BER) occurs at the end of a tomato where the flower used to be when the tomato was small. It can affect any soft fruit that forms at the end of a blossom including tomatoes, squash, peppers, and melons. Fruit that is affected is usually about halfway grown when blossom rot appears.

There are a few possible causes for blossom end rot, but the main problem is your tomato plants are not getting enough calcium from their soil. Make sure the soil has enough calcium by watering with water that has had eggshells in it. Or mix some powdered milk into a watering can before you water your tomatoes next.

Fruit affected by blossom end rot are edible, but only after the affected portion has been cut away. In most cases, blossom end rot affects a full third to half of the fruit making it worthless to only save the remaining unaffected portions. The affected fruit cannot heal itself. But once your tomatoes have enough calcium in the soil, the next round of tomatoes your plants produce should yield better results.

Splitting Tomatoes

Inconsistent watering practice can cause problems, cracking or even splitting the tomato skin and flesh. When a tomato is green, the skin is thicker and more capable of stretching to accommodate new growth. But just before harvest, as the skin of the tomato turns red with the influx of Lycopene, the skin thins out. At this point, the skin can’t take on as many nutrients. As a result, the tomato skin cracks and, if a new influx of water comes after a significant dry spell, the tomato flesh will split.

Unfortunately, once you discover tomato cracks or splits, there’s nothing you can do about it.  Those tomatoes can’t heal themselves. Remove the cracked tomatoes from the vine (they’re still edible as long as the fruit under the skin isn’t too cracked). Then fertilize your tomatoes and help out the next crop still maturing behind the fruit that cracked. Start watering regularly and make sure the tomato plants have plenty of water when you do. You can also place some mulch around your tomato plants to make sure that evaporation doesn’t steal the water you’re trying to give to your precious plants. It will help keep some of the moisture in place.

Uneven Ripening

It’s the strangest thing to see a whole tomato hanging out on the vine with one side so perfectly ripe and the other side stubbornly refusing to turn. This becomes a problem when there is a lack of potassium in your tomatoes’ soil.

Potassium is key for the transportation of sugars and production of proteins in the plant.  It also helps the plant to produce any lycopene at all.  Lycopene is a red pigment composed of hydrogen and carbon (technically referred to as a hydrocarbon).  Without lycopene, it is impossible for a tomato to turn red.

The easiest way to add potassium to your soil once you recognize there is a deficiency is to add potash to the soil.  If potash is unavailable, then you can find a commercially available fertilizer with added potassium to do the trick. Once you add potassium to the soil, your tomatoes should start to ripen on their own.

Tomato Pest Problems

While the old adage states, “It’s what’s inside that counts,” sometimes a problem comes from without. There are a lot of pests in nature that find your tomato plants as tasty as you do. Sometimes, a little garden warfare is in order to take back what’s yours. These are the most common pests attracted to tomatoes that you need to watch out for.

Aphids

A classic killer of a host of garden plant is the dreaded aphid. These pests are like tiny vampires and suck the sap from your tomato plants’ vascular systems and drain it dry.

There are a lot of different ways to combat aphids. I’ve previously listed methods to defeat aphids naturally. The key is to check your plants often for signs of aphids. If you catch them early, your chances of mitigating the damage and saving your tomatoes from problems is much higher.

Tomato Hornworms

Although they look so cute in the children’s picture book, The Very Hungry Caterpillar (affiliate link), most caterpillars that you find in your garden are not the friendly sort. The tomato hornworm is just such a culprit and is a huge problem in the garden.

Tomato hornworms are strange looking creatures who look like they’re both coming and going. Their tail stands up as if it is their head and many have spots that look like eyes. Their anatomy and coloration confuse and scare off predators. And, for the large part, it does a pretty good job. Some tomato hornworm predators see through this camouflage, such as certain varieties of parasitic wasps. Yet, in general, the tomato hornworm is largely unrivaled if it finds its way to your tomato plants.

These wriggly insects will strip your tomato plants bare of leaves, stems, and fruit in scant days if allowed to continue. They are severe pests in almost every tomato garden. Happily, if you check your plants regularly and know what you’re looking for, they’re also very easy to spot and pick off by hand. Squash or crush them and throw them away, and your plants will be the safer for it.

White Flies

Often found in conjunction with aphids and other such pests, white flies perform much the same function and cause problems when they suck the juice out of your tomato plants’ veins. They can be difficult to control since they often arrive in sheer numbers. They make their homes on the undersides of leaves and lay eggs that hatch in only a little more than a week (7-10 days). Once white flies have made a home in your plants, it can be very difficult to eradicate them.

Methods of controlling white flies involve many of the same steps as controlling aphids. They are soft bodied and susceptible to neem oil, soap, or alcohol solutions in water. Just make sure to spray the undersides of the leaves, since that’s where they hang out.

Combat Your Tomato Problems

With these warnings in hand, you’re ready to combat the most common problems that your tomato patch is likely to encounter during the hot and humid summer months. I hope you never encounter any of these problems, but that if you do, you feel better armed to handle them! Good luck out there, gardener!