Since it's peak tomato growing season in most areas of the northern hemisphere, I thought it would be a good time to revisit an old episode about tomato plant diseases! This is not a comprehensive list, but a discussion of eight of the most prevalent diseases. As always, be sure to check with your local university extension to find out which diseases are most prevalent in your area. This will save you some stress. Let's dig in!
Episode Resources:
Ep. 99 - Eight Common Tomato Diseases: Identification, Prevention, and Treatment
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Welcome back my gardening friends to another focal point
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Friday episode. Let's spend just a few minutes
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together, reviewing a snippet of information, from a previous
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episode, highlighting a new topic or quickly focusing on a
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current event in the food and agriculture world.
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Let's get down and dirty. So as we move into June, the
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majority of us have gotten our tomato plants in the ground.
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If you are in the southern part of the northern hemisphere, you
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are probably well on your way to your first harvest.
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If you're a little bit further north of me than you are
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probably. We just now getting your tomato
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plants into the ground or you are anticipating being able to
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do that soon. And those of us here in West
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Central, Missouri are probably already starting to battle
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tomato diseases at based on our humidity and our rain patterns.
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So I thought today would be a good time to revisit something
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about tomato plant diseases. I covered the top eight of these
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in episode 99, so we are going to revisit that one today,
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enjoy. Now, I'm not going to hit all of
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the possible diseases that you could get on your Tomatoes.
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I'm just going to hit the eight, most common ones.
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There are honestly, so many diseases that could hit your
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tomato plants, depending on where you live.
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This would be a three-hour episode if I covered them all.
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So these are going to be the ones that I have seen and read
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are the most prevalent. Now, I've not had Direct
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experience with all of them, thankfully, but I have a lot of
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resources for my college classes and All my Growers guide, so
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I'll do my best to relay the info on the ones that I'm not
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familiar with. So you can at least get an idea
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of what to look out for and how to prevent or contain diseases
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in your Tomatoes. I would always recommend doing a
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search on your local University, extension service or plant Lab
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website for diseases that are most common in your area.
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So you're not freaking out about something that just isn't very
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common in your climate. So without further Ado, let's
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dig into the eight most common tomato plant diseases.
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First up, bacterial Wilt, bacterial Wilt.
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It's also called Southern bacterial.
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Blight is a serious disease caused by Ralph's.
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Tonyia soul in this area. Now, that last name their soul
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in a cerium tells you, this is a disease of the solanaceae is,
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right? Or tomatoes or peppers, are
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potatoes, that sort of thing. This bacteria survives in the
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soil for Periods. And it enters the roots through
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wounds made by transplanting cultivation.
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Insect feeding damage, what have you?
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This is different from the bacterial Wilt that we see in
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cucumbers and other qubits that bacterial Wilt is spread by
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insects specifically, cucumber beetles.
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This bacterial Wilt is specific to tomatoes and their other
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solanaceae cousins and rely resides in the soil.
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Now, high temperatures and high moisture.
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Speed the growth of this disease, the bacteria multiply
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rapidly inside the water conducting tissues of the
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plants. That's the xylem filling it with
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slime. So this causes a really fast
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wilting of the plant. While the leaves still stay
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green. And if an infected stem is cut
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crosswise, it's going to look Brown and you're going to have
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these tiny droplets of a yellowish ooze coming out of it.
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Yum. Control of bacterial Wilt.
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When you have infected soil, is really, really difficult.
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Rotation with non susceptible, plants like your corn, beans
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cabbage, for at least three years between planting other,
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solanaceae will provide some control.
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You do not want to use Peppers or eggplant, or potatoes,
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sunflowers or Kosmos in that rotation.
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You do want to remove all infected plant material.
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If you discover that your plants are infected.
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It though, unfortunately, there is no chemical control for this
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disease. So you might consider growing
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all of your susceptible solanaceous plants in a separate
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newly prepared Garden site. If you discover that you have
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bacterial Wilt, you want to be completely separate from your
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original garden. And then you also want to make
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sure that you thoroughly hose off all the soil from any of
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your tools that you used in the original infested beds and
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thorough way. Sterilize them before you use
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them in your new Garden site. Next on our list is early blight
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early, blight also known as alternaria leaf, spot is one
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that I am very familiar with this disease, is caused by the
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fungus, alternaria land area, and it first pops up as these
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small brown lesions mainly on the older foliage of your
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tomato, plants the spots, then get bigger and they form these
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concentric rings in a bull's eye.
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Pattern usually smack dab in the center of the disease area.
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And then the to the tissue surrounding the spots is going
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to start turning yellow, a sickly color.
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Now, here's what usually causes the biggest problem.
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If you get both high temperatures and high humidity,
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at this stage of the disease, a lot of the foliage on your plant
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is just going to be killed off plants with early.
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Blight may also get lesions on the stems that look, very
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similar to the ones on the leaves and it's sometimes Just
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causes caller rot, which is where the lesions will girdle.
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The plant right at the soil line.
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If all of this doesn't kill the plant off and it does manage to
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produce fruit, the fruit will often have really large lesions
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usually covering most of the entire fruit with those
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concentric rings. And then the infected for
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usually just drops right off the plant.
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Now this fungus survives on Infected, debris in the soil, it
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survives on seeds, it will show up on volunteer.
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Tomato plants and other solanaceous plants.
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Like potatoes and eggplants plus black Nightshade which is a very
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common weed and it is also in that same family.
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That's generally what we think is the alternate host in our
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area that holds onto the fungus until it's time to spread it.
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I'll happily to Our tomato plants that black knight shape.
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So to prevent the disease you want to use resistant or
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tolerant tomato varieties if you can and don't save seeds from
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open pollinated plants. Were infected the year before.
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Use a good crop rotation. Keep your weeds in your
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volunteer tomato, plants at Bay and use proper plant spacing to
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keep them from touching each other.
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You want that airflow mulch your plants to keep the soil from
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splashing up on onto the, the leaves and try to avoid overhead
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watering especially during very warm and human times in the
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season. Now, if you see signs of the
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disease, trim off and dispose of all of the infected lower
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branches, and And the leaves. This is one reason why I
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generally will prune my tomatoes so that the leaves and branches
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that are closest to the ground are completely removed even
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before I see signs because it's pretty inevitable.
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That we're going to get it here. If you do, end up with more
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signs of the disease, make sure you trim up and remove all of
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those affected leaves and then treat with an appropriate
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fungicide for your garden practices for me, that means a
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copper fungicide. I'm getting ready to apply my
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first round of it this week and I'll put a link in the show
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notes for what I Be using. I am very confident.
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I'll be able to nip it in the bud because, yes, I am already
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seeing signs of it on my lower leaves.
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And I am thankful this week is predicted to be a little bit
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lower in humidity, so I can trim up the plants and give them a
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good spray of that copper. So, usually, what follows
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immediately? After early blight in my garden
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is next on my list, which is sub Toria leaf spot, but it
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absolutely can be its own Standalone disease in your area.
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The reason it follows early blight so, well, is because
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Because the fungus that causes it septoria like a person.
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Key is most active when temperatures range between 68
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and 77 degrees Fahrenheit. And the humidity is high and
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there has been some rainfall or some overhead irrigation wedding
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the plants that is usually the conditions that follow our hot
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humid weather where the early blight comes in.
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In fact, we're getting that now with overnight lows in that
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temperature range, but we're in a dry spell right now.
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So the humidity isn't quite as And but I have no doubt it's
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coming back soon and therefore septoria will probably rear its
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ugly head. Now Satori leaf spot damages the
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Tomato, foliage the petioles and the stems.
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But unlike early blight the fruit is not infected no
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infection usually occurs on the lower leaves near the ground.
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After the plants begin to set fruit, you'll get numerous small
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circular spots with dark borders.
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Surrounding a beige colored Center on once again.
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The older leaves. These are the ones that are
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usually closest to the ground. And then the center of those
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spots. You'll see these tiny black
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specks and those are the spore producing bodies.
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Severely spotted leaves will turn yellow.
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They'll die. They'll fall off the plant and
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then this defoliation is going to weaken the plant.
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It's going to reduce the size and the quality of the fruit and
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it's going to expose any fruit that does develop two sons
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called. Now, this fungus is not soil
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born but it can overwinter On crop residue from previous crops
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decaying vegetation. And on some of those weeds
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related to Tomato like that black Nightshade that we talked
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about. So prevention includes crop
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rotation as always and cleaning up.
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All the garden debris at the end of the season, keeping those
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related weeds in check and not using overhead irrigation.
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Now once you see the disease remove the infected leaves,
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prune them to ensure good airflow.
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And then that same copper spray that I'll be using Using for the
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early blight can also be used for Satori leaf spot.
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In my case, using it multiple times in the early part of the
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Season controls, both of them and I'm usually good to go after
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that. So the next is, he's on our list
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is bacterial spot. Now, this disease is caused by
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several species of the bacterium xanthomonas, which infect Green
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Tomatoes but not red tomatoes. So the disease is more prevalent
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during wet Seasons. Damage to the plants, includes
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leaf and fruit spots, which result in reduced yields
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defoliation. And so once again, Sun scalded
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fruit, the symptoms consists of numerous Angular 2 irregular
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water soap spots on the leaves and then slightly raised to
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scabby looking spots on the fruits that look like black
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dots. The leaf spots have a yellow
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Halo and the centers of the spots will start to dry out and
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they may cause the leaf to actually tear in the center.
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Now the bacteria survive the winter on volunteer tomato
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plants and on Infected plant debris, seeing a pattern here.
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Moist weather can also lead to disease development another
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pattern. Most outbreaks of the disease
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can be traced back to heavy. Rain, storms, that occurred in
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your area, infection of the leaves, occurs through natural
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openings, but infection of fruits must occur through insect
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punctures or other mechanical injuries.
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So, if you see the beginnings of this disease, you ought to make
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sure that you are clearing out as many of the insect pests as
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you can. And be careful not to puncture
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the fruit while you're working with it now.
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Bacterial spot is difficult to control once it appears in your
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garden. Any water movement from one leaf
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or plant to another like splashing, raindrops that
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overhead irrigation or touching and handling the plants while
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they're wet after it's been rained on that can spread the
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bacteria from the diseased. Plants to the healthy plants.
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So prevention is really important here.
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Only use disease, free seeds and plants crop rotation is key.
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And again, avoiding overhead. Ed, watering remove and dispose
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of all the disease in the plant material.
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If you see any and then prune your plants to promote air
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circulation. Once again, a copper fungicide
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will give fairly good control of this disease and get you all the
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way through to your Harvest. Now, the next disease on our
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list of dastardly tomato, diseases is anthracnose
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anthracnose on tomatoes is caused by a group of fungi
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within the genus Cola to track, mmm, and these species.
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These are primarily pathogens specifically of the tomato
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fruit. Now, as the fruit are ripening,
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the symptoms first become noticeable as small circular
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indented areas and then that indented area later gets this
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really dark Center to it. Those disease spots are going to
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continue to get bigger and bigger with time because the
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infection is continuing to spread deeper into the fruit
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then if you combine this with warm moist and humid weather,
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You'll see these pinkish colored spores that are standing up from
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the black fungal material, that's in the center of the
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spots and then those spores are spread by splashing water.
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Like you guessed, it rain or overhead irrigation.
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Now, the fungus that causes anthracnose can be transmitted
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within the seed. So if your seeds aren't
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certified as being free of this specific fungus, you can take
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matters into your own hands by treating them, by soaking them
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in. 82, °F water for 25 minutes, to destroy the fungus prior to
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planting. And there are some varieties of
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tomatoes that have built-in resistance to anthracnose.
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Once again, do not over head, irrigate your Tomatoes splashing
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water AIDS in the spread of those fungal spores, how many
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times are we going to say that in this episode plant?
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The garden in a sunny site and steak or cage?
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Your tomato plants to provide better air movement and better
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leaf. Drying conditions, you want your
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leaves dry, keep your garden weed free the presence of weeds,
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May raise humidity levels around the plants and that's going to
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slow the drying conditions. And of course you very well may
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have other weeds in the solanaceae family that are
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there. That can also Harbor this
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disease now because this disease does affect other plants.
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In the solanaceae family, you really want to be sure that
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you're rotating your crops. Preferably nothing in that
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family in the same space for 3 years, Like I said some weeds
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that infest the garden are also in the same family which is
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another reason to keep your garden as free of weeds as
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possible and I know easier said than done.
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The fungal spores can remain in the soil to inflict plants the
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following year. So mulching, your garden is
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going to help create a barrier between that soil surface and
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the fruit to reduce infections Harvest, your tomato, fruit
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daily, and then, remove and destroy the crop debris.
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As soon as the crop has finished bearing, do Do not add this
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debris to your compost. You want to burn it or
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otherwise, remove it from your property.
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Now, fungicide sprays can help reduce anthracnose disease
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specifically, the copper ones there are chemical based
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products that can be sprayed weekly to reduce infection.
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It's entirely up to you if you choose to use those just please
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follow the label directions. Remember the label is the law,
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for instance, there is a five-day waiting period between
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spraying Picking, if you're using a spray that contains
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mancozeb so be cognizant of what you're using and how you're
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using it. Our next disease is fusarium
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Wilt. This is a warm weather disease,
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caused by the fungus fusarium oxus Purim.
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Now, this is particularly common in the southern us, but it can
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occur anywhere, really the first indication of disease.
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Usually happens early in small plants where the lower leaves
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will droop and Wilt and then the Yves begin to turn yellow and
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then finally the entire plant just Wilt over and dies.
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Now, often leaves only on one side of the stem will turn
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yellow at first and the outside of the stem of these wilted
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plants won't show any signs of Decay, but when you cut it
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lengthwise, the lower stem will have a dark brown, discoloration
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of the xylem, which is that vascular system that
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distributes, the water throughout the plant.
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So the fungus is soil, born and Passes upward from The Roots
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into the vascular system of the stem.
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And it blocks the water conducting vessels in the plant
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and that causes the plant to wilt and die.
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There is no chemical control for fusarium Wilt.
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Once it's in your soil. It's there for the Long Haul.
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Once you see signs of this in your garden area, you'll need to
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stop growing anything that is susceptible to the fungus.
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There are some cultivars that are resistant to through cerium
00:17:08
welt, if you must continue planting NG and crop rotation is
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going to be absolutely important here, but you may end up needing
00:17:15
just to create raised beds, that contain no native soil.
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In order to prevent the pathogen from taking hold of your plants.
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Next up, Southern blight, this one is caused by the fungus
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ethelia. Rolf CI, the first symptom just
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like other wilts is the drooping of the leaves.
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Now, on the stems, there will be a brown.
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Dry rot that develops? Right?
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Near the soil line. And then there's a white fungal
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growth with these brown little. I don't know.
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Bumps that look like mustard seeds.
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That will develop over top of that dry rot area.
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The stem lesion is going to develop really really rapidly
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and it's going to grow the stem and result in a sudden and
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permanent Wilt of all of the above ground parts of your
00:18:03
tomato plant, the fungus can also attack fruits where they
00:18:06
touch the soil. So it's important to stake your
00:18:08
plants this. Is can survive for years in the
00:18:12
soil and the plant debris. And it is favored most by
00:18:16
moisture conditions and high temperatures.
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So crop rotation is essential to preventing Southern blight, do
00:18:23
not plant tomatoes after beans or Pepper or eggplants, it may
00:18:27
also help to plant small grains. After any of your solanaceae is
00:18:31
to help with the control and removal of plant debris,
00:18:34
immediately after harvest, will also help to control the disease
00:18:38
and Finally on our list of these tomato plagues is tomato.
00:18:44
Yellow Leaf curl. Now this is a virus that is
00:18:48
transmitted by whiteflies. We talked about this one a
00:18:50
little bit. A few episodes ago in our
00:18:52
question of the week this disease is extremely damaging to
00:18:57
fruit yield in your Tomatoes whiteflies bring the disease
00:19:01
into the garden from infected weeds nearby specifically, those
00:19:05
black night shades and Jimson weed after infection your tomato
00:19:09
plants. I have no symptoms for as long
00:19:12
as two to three weeks. And then suddenly, you'll begin
00:19:15
to see the upward curling of the leaves yellowing of the leaf
00:19:19
surface between the veins. We call this chlorosis, you'll
00:19:22
have smaller leaves than normal on the plant.
00:19:25
The plant will be stunted and then it'll start dropping its
00:19:28
flowers. If tomato plants are infected
00:19:30
early in their growth, there may be no fruit formed at all and
00:19:35
this infection Maybe random throughout the garden.
00:19:37
Some plants may get it and others may not.
00:19:40
Not removal of plants that have those initial symptoms may slow
00:19:45
the spread of the disease. And any infected plants that you
00:19:48
remove should immediately be bagged up to prevent the spread
00:19:52
of the whiteflies feeding on those plants and then bringing
00:19:55
them back into your garden to infect your uninfected plants.
00:19:59
Keep your weeds controlled in and around the garden site
00:20:02
because again those weeds maybe alternate hosts for the
00:20:05
whiteflies and also for the disease.
00:20:08
Now, if you see white flies appear, you can use a neem oil
00:20:12
spray to help keep them away or a horticultural oil spray.
00:20:15
If you had any infected plants at all or solid infestation of
00:20:19
whitefly at the end of the season, remove all susceptible
00:20:23
plants and burn them or dispose of them elsewhere.
00:20:27
You don't want the whitefly feeding on them or
00:20:29
overwintering. If this has been a problem in
00:20:31
your garden in the past, there are also tomato cultivars that
00:20:35
are resistant to Tomato Yellow Leaf curl.
00:20:38
Virus. Thanks for joining me on this
00:20:41
focal point Friday. I'll be back again on Tuesday
00:20:43
for another regular episode of the just grow something podcast.
00:20:46
So, until next time my gardening friends, keep on cultivating
00:20:49
that dream garden and we'll talk again soon.
00:20:38
Virus. Thanks for joining me on this
00:20:41
focal point Friday. I'll be back again on Tuesday
00:20:43
for another regular episode of the just grow something podcast.
00:20:46
So, until next time my gardening friends, keep on cultivating
00:20:49
that dream garden and we'll talk again soon.