Tomatoes; Growing Your Own and Common Problems

William H. McCaleb Master Gardener Coordinator Program Assistant, ANR As each of us face the reality of increased cost on just about everything we buy, some find that it has been a great time to get back to the basics of vegetable gardening. When cruising the internet in late spring I started to see the trend of fewer choices of vegetable seed varieties available from nurseries and with all the calls and emails that I’ve gotten with tomato questions, it is obvious that more folks are ‘growing their own’.
Example of damage from tomato fruitworm. Be diligent in scouting for the eggs on the underside of the tomato leaves. It is easy to squash eggs and stop them from forming into larvae that damage the tomato. As we go through the summer this year, you are probably finding out that this hasn’t turned out to be a bad growing season compared to last year. Precipitation has been average, for most of us, with others getting greater amounts due to recent slow-moving thunder bumpers aka thunderstorms. Temperatures were all over the scale back in early May, but by the time June arrived, temperatures edged up and the soil warmed up. Luckily, for the past few weeks we’ve been blessed with many sunny days which has benefit the tomatoes growth. Sunlight, summer heat, warm nights is a recipe for healthy fruit. Okay, there are some things that will play havoc with the plant’s health, such as insects and other pests and pathogens. Any of you who have attended our Master Gardener garden related education events will know that we have ‘good bugs and bad bugs’ in our gardens. This year is a little different in that we have had an increase of the bad bugs compared to last year. Over the past two weeks I have dealt with an increase in calls and visits from folks with tomato and potato issues. In garden visits, I see more of the unwanted insects caught in orb spider webs and in traps that have been set out; I have also seen leaf and stem damage from flea beetles, aphids, leaf hoppers, and some other insects that I will talk about as you read on. Some of our most flavorful heritage tomatoes, Cherokee Purple, German Johnson, Mortgage Lifter and Brandywine are already showing signs of diseases and some insect damage. Unfortunately, they have low resistance to several of our normal soil borne diseases (pathogens) such as Verticillium Wilt, Fusarium Wilt, Rhizoctonia, and Pythium root rot. Preventive care and maintaining the health of the plant is the key to raising heritage varieties. Once they show signs of disease it is almost too late to stop the damage that occurs. I have seen the signs and symptoms which is about on time for these varieties. Gardeners are finding it difficult to keep their heritage crop from one soil borne fungus issue caused by the fungus Alternaria solani. This is what is commonly known as Early Blight. The solution to not having Early Blight wiping out your beautiful crop each year is to pick a variety that is ‘resistant’ to Alternaria soloni. There are quite a few varieties out there that are resistant and in early January 2023, our Master Gardeners will be putting on a program on ‘gardening on a dime’. We’ll be looking at not only disease resistance, seed availability, but also ways to improve how you garden using less chemicals, fertilizer, and still have a great looking and tasting crop. This educational opportunity will be announced in this local newspaper and if you are on my mailing list, you will also get notice via email, so stay tuned. In the meantime, I will still have people telling me they don’t want to switch from their ‘favorite’ tomato and in the conversation, I usually will hear those words of conviction “I love the taste of my heritage tomato”. It is hard to change the taste buds of a tomato aficionado. Okay, if you love the taste, then you will have to do more scouting, looking every day for signs and symptoms, as well as taking preventive measures such as making sure that you rotate your crops every year. If you don’t rotate your tomatoes to a new location each year, the frequency of early blight increases and each subsequent crop will be less vigorous and more anemic to diseases. The secret to a successful tomato crop is to keep your plants healthy all through the growing season. This fungus is in the soil and overwinters just fine. Our cold weather isn’t cold enough to affect the fungus. You also need to exercise care when in the garden. Realize that fungal spores can be spread by wind, water, insects, and even on your clothes or shoes. Especially be careful when the dew is still on the leaves/plants. And if your favorite dog followed you to the garden, that fur coat will also pick up the spores and end up being deposited elsewhere in your garden and landscape. Another pest in the garden this year is the tomato fruitworm. I’m not sure if it is because of the great early corn crop, where the same larvae is known as the corn ear worm has already had its hay day, but we are seeing an earlier fruitworm outbreak in tomatoes than normal, much worse than the past two years. This little worm, actually a larvae, isn’t limited to corn and tomatoes, but also feeds on soybeans, peppers, tobacco, beans, okra, and eggplant. This larva that gets into the tomato has an insatiable appetite and can destroy that perfectly good looking 1 pound tomato in a couple of days. When you see a yellowish colored moth with a single dark spot on its forewings, the trouble is just beginning. This adult moth will be looking around your garden at all of your tomatoes and will find a healthy leaf where it will lay singly, one egg at a time, in the crook of the veins on the underside of the leaf. In the deep south across South Carolina, Florida, Georgia, and Alabama we know they can have up to seven generations in a season. We can do the math, after I go ahead and tell you that that single female can lay an average of 35 eggs per day and she is around from 5-15 days on average. Let’s go with five days x thirty-five eggs equals to a possible 175 larvae. Or if the female does live out the 15 days, that would be 525 eggs. Because one larva will usually eat enough in a large tomato to sustain it until maturity, that would be one hundred and seventy-five or up to five hundred twenty five tomatoes that you want have for eating, canning, or to make salsa. Southern Georgia finds that they average seven generations per growing season. So, multiply seven generations x one hundred and seventy-five will give you a possible 1225 larvae doing damage during the growing season. The good news is that we generally have 3-5 generations this far north very similar to upstate South Carolina, so your tomato growing will do a wee bit better than our friends to the south. With our later season start we probably won’t see but three generations which equates to about 525 larvae. So now you know that some folks are worse off than you are when it comes to fighting the tomato fruitworm. There are a few insects and avian predators out there that like to eat young larvae, but then there are some insect eaters that not only enjoy getting the protein in a larva but then they also love to eat tomato seeds. So, now you know how a wild tomato will pop up beneath spreading shrubs or hedges elsewhere, thanks to our avian bird species that eat a balanced diet of meat and vegetables. Some birds such as Blue Jays, Grackles, and blackbirds are some birds that will eat any part of a tomato plant. And should I even mention the four-legged mammals that love to eat ‘maters’ such as deer, groundhogs, and raccoons? They all will enjoy the tomato, the seeds, stems, and leaves. As we go into the middle of the summer be sure to protect your tomatoes from the late afternoon sun if it shines directly on the fruit. This is another problem that we have seen this year, sunscald. Literally, the tomato is getting a ‘sunburn’ while it is ripening. If you see that starting, go ahead and pull the tomato and let it ripen indoors. If it is still green, you can place it in a paper bag with a banana or an apple and the ethylene gas generated will ripen the tomato quicker. Do not use a plastic bag as it does not breathe like a paper bag does. The VCE Halifax Extension Office is open from 8am – 5pm, Monday through Friday. Masks and physical distancing are required. If you have gardening questions, you can continue to reach an Extension Master Gardener or Extension staff member by sending an email to or calling the Halifax Extension Master Gardener Help Desk at (434) 830-3383. Be sure to give us your first and last name, telephone number and the nature of the call. The Help Desk phone is routinely checked, Monday - Friday. Someone will get back to you, although it may be from a different telephone number.