What's Wrong With My Tomatoes? | Solve Tomato Problems

Now that your tomatoes are settled into their beds (or pots), you can breathe a sigh of relief as you dream about the vine-ripe bounty that’s sure to come. Or is it? There may be tomato problems lurking in your future.

Don’t get too comfortable patting yourself on the back for a job well done yet. The work is just beginning. While getting your plants in the ground is a major milestone, there’s a very good chance before long that you’ll be asking yourself; what’s wrong with my tomato? The mid-season care necessary to keep your plants healthy will (or should) keep you on your toes for many of the days leading up to harvest.

To be sure, tomatoes are some of the most rewarding plants to grow in your summer garden. But the truth is, they are also the most demanding. Diseases in the soil or those blown in by the wind, or delivered by insect pests can bring you quickly back to reality overnight.

Add to that all the challenges brought on by ever-changing environmental conditions. Rain, humidity, and temperature all play a significant role in plant health, fruit production, quality and timing of the harvest.

While challenges are inevitable during any season, tomato growing mid-season care (and especially pro-active efforts ahead of that) can substantially reduce the many problems and magnitude of those that are sure to follow.

Starting with the best soil possible is one of the most important steps you can take to ensure the health and productivity of your plants. And compost is the best amendment you can add to improve it. Healthy compost can even deactivate many harmful soil borne pathogens.

Proactive measures to give your tomatoes the best chance of success from the start:

Start with the best soil possible. Healthy soil equals healthier plants and compost is the best way to ensure that. (The photo at the very top of this post shows one of the risks of starting off with bad soil. In this case, the manure added to these beds contained a persistent herbicide that caused serious damage to any tomatoes planted in them for the next several years. See the link below for detailed information about this common problem, and how to avoid it.)
Plant deep. I plant my tomatoes much deeper than the pots they were growing in. By removing the foliage up the stem to the top two or three leaf sets will allow more roots to form on the stem, and more opportunity for plants to take up water and nutrients.
Add soaker hoses or drip irrigation. By keeping water at the base of the plant, and directing it towards the roots and off the foliage (as in overhead watering), you will significantly reduce the chances of soil-borne diseases splashing onto the foliage and infecting the plants.
Add mulch. Mulch is so important for many reasons in the garden. Around tomato plants, it acts as a protective layer of insurance to prevent water reaching foliage from the soil. Mulch helps retain much-needed moisture in the soil and reduces evaporation. It also cuts down on competition for water and nutrients from weeds by suppressing their germination.

Tomato Growing Mid-Season Care

Despite your best efforts, tomato plants are likely to show signs of disease at any point in the growing cycle. Diseases can come from fungus, bacteria, and virus. While it’s nearly impossible to prevent all the problems that can arise, the best step you can take is to stay ahead of the problem and remove any infected parts at the first signs of trouble.

One of the most common diseases to plague tomatoes is Early Blight. It’s caused by a fungus that indeed strikes early, but can and often does infect a plant at any stage of growth.

Steps to proactive disease control and mid-season care include the following:

Look for any signs of change. Most often that will include spotting or yellowing on the leaves, especially starting on the lowest foliage.
Cut away infected parts of the plant, so all visible signs are removed and throw away the debris so as not to infect other plants. Do not add infected foliage to your compost!
Sterilize pruning equipment. Keep a spray bottle of alcohol or 10% bleach solution and spray cutting tools between plants or cuts.
Repeat all steps as often as possible. New problems can emerge overnight. The more often you can inspect your plants, the greater chance you have of minimizing the impact.
Consider the possibility of spraying with and organic control such as copper or Bordeaux mix (copper and sulfur), especially as a preventative or at the earliest stages. However, use sparingly. Copper can build up to adverse levels in the soil over time. Follow label instructions on how and when to apply. As an alternative to copper, consider a synthetic fungicide control.

Pest impact on tomatoes

Most diseases that plague tomatoes are caused by either fungus or bacteria. But viruses are a third and untreatable blow for tomato plants. Insect pests that use their piercing mouth part (called a proboscis) are a common vector for transmitting plant viruses when they introduce it into the plant or fruit from a previously infected plant.

Once a plant is infected, there is no chemical control. Remove the plant immediately and take the necessary steps to ensure there is no way it can be the source of future infection. Various insects including aphids, stink bugs, spider mites, leafhoppers, thrips, and nematodes are common culprits of spreading disease or causing physical damage to plants.

Perhaps the most common pest of tomato plants is the tomato hornworm. While it’s a nasty-looking devil, it’s harmless, other than it’s voracious appetite for tomato leaves and stems.

Perhaps the creepiest of all tomato-loving pests is the tomato or tobacco hornworm. The large green worms, often reaching five inches in length consume large quantities of a tomato plant’s mass practically overnight.

If you see dark round droppings at the base of the plant or on lower leaves, and the top of the plant is stripped of many leaves, it’s a sure sign of this pest. However, while you know, it’s there, finding it is another story. They blend in so well with their surroundings; it can take a surprisingly long time to locate them, despite their large size.

The most humane and effective control is simply to remove them by hand and place them outside the garden. Some gardeners even grow extra tomato plants and hand place the hornworms on these sacrificial plants to continue their lifecycle. Hornworms are what hatch from the eggs laid on tomato leaves (peppers and eggplant) by the large and attractive sphinx moth.

The other large and destructive worm commonly associated with damage to the tomato fruit is the tomato fruitworm (aka corn earworm and cotton bollworm). With tomato fruit, the damage is done when the worms bore into it. At that point, nothing can be done other than to remove the fruit.

Topping Tomatoes to Manage Size

Indeterminate tomato plants will quickly outgrow their support. Overgrown stems eventually bend and kink and encroach into the surrounding area. While there is no requirement to remove the excess, by doing so the remaining plant is given a better opportunity for light and air circulation-two conditions essential to maintaining healthy, productive plants.

Topping tomatoes is a concept that in theory makes a lot of sense. In practice, gardeners, including this one, have a hard time removing perfectly healthy foliage—especially when it’s loaded with blossoms or even fruit.

The rationale behind topping tomato plants is to limit vertical growth on indeterminate plants to create a healthier and more controlled environment for the parts left behind.

In the podcast, Craig explains how he manages his plants and when and where he makes the cuts. We will be creating a video soon on how to top tomato plants. Once it’s posted, we’ll add the link to this post as well.

Until then, or in addition to, you can watch Craig describe his tomato topping practice in the episode we filmed with him in his Raleigh, NC driveway garden in episode 803 of our PBS television series, Growing a Greener World. We’ve posted that episode link below.