Knowledgebase

Tomato Leaf Damage #880645

Asked August 07, 2024, 11:57 PM EDT

Hi - I’m growing some tomato seeds that I bought from Target (no idea what kind of species). I have 4 pots with 1 plant per pot, they’re on my balcony - I’m on the 4th floor - and get 2-3 hours of morning sun and then 8 hours of artificial light from a grow light setup I created. Two of the plants have matured faster than the other two (I think I transplanted two of the seedlings too early and sent them into shock, that’s why they’re growing slower) and I’ve noticed that there are some signs of damage to the leaves of the more mature plants. They’re starting to set fruit so I want to make sure they don’t have any sort of fungal disease or anything… Please advise! None of the leaves have turned yellow yet or wilted. But it does seem like there’s something eating at the leaves or something? I’ve noticed more leaves with tears or rips. It’s also been hot and humid here lately so maybe that’s causing the damage? I also noticed that there are some gnats (?) flying around the base/soil of one of the plants especially, but I’m not confident what they are exactly. I just know they’re black and tiny and that’s it. Hopefully this was enough info to help! Thanks in advance ~

Montgomery County Maryland

Expert Response

The leaf damage pictured is not a disease or insect damage; it looks instead like simple physical damage, maybe from leaves being pinched by a cage support or some other object. It's not a concern and those leaves do not need to be removed. Chewing from caterpillars, katydids, or a few other insect types would not be unusual, however, and healthy plants can withstand some leaf chewing and not need treatment or suffer crop losses. However, expect that the plants might not bear well overall because they are not getting the ideal amount of light. Tomato plants need full sun (6-8 or more hours of direct summer sun) to grow and produce to their fullest potential. While artificial light can help to supplement low levels of natural light, it's generally not a sufficient substitute, outside of commercial greenhouse operations that use more intense artificial lighting than a home gardener would be using. (If you are using grow lights outside, be certain they are rated as waterproof as possible so they are not a fire hazard, since we are not aware of any that are intended for outdoor use.)

Fungus gnats are small and dark in color, and might be what you're seeing around the soil, since their larvae feed on fungus and other material in soil. They are usually more of a nuisance indoors than outdoors, though. Fungus gnats are a problem when potting soil is being kept too wet. Let the soil in the pots become mostly dry to the touch at least an inch or two down before watering the plants; they should not stay consistently damp or wet all the way up to the surface of the soil. If the pots drain onto a saucer or tray, make sure the collected water is emptied after draining so the pot does not soak up that water and stay too wet, rotting the lower roots in the container.

Going forward, you can use the information on the pages linked below for cultivating and troubleshooting tomatoes:
Miri

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