Tomato Plant Leaves Turning Black



In my greenhouse last year my tomatoes leaves went black and crispy. Now I have noticed the same is beginning to happen again. How can I stop this before I lose my plants? Would I need to disinfect the greenhouse?

A Northwood


A Northwood,

I've included some links below to some websites that may help you identify exactly what is going on with your tomatoes. From what you have described, it sounds to me like you have some type of blight problem going on. If that is the case, disinfecting your greenhouse is going to be essential to preventing further spread.

  • Repair tears in screens and seal cracks around doors and windows where airborne pathogens can enter.

  • Mulch walkways near your greenhouse to reduce weeds and help prevent the spread of soil-borne pathogens.

  • Always make sure all discarded fruit and dead plant debris is removed from your greenhouse promptly.

  • Sanitize hands, tools, pots, floors, shelves, etc., on a regular basis.

  • Wash greenhouse clothing and shoes regularly in hot water.

  • Keep houseplants out of the greenhouse during tomato production.

  • Tobacco users should be extra careful to sanitize their hands before touching tomatoes to avoid introducing tobacco mosaic virus to plants.

  • Good ventilation and proper temperature control are critical for reducing humidity and controlling airborne fungal diseases. To ensure good ventilation, allow several feet of airspace above the plants and use proper spacing between them.

  • Prune the suckers just below the first fruit set to maintain good air circulation within the plant's canopy.

Links to help with diagnosing tomato diseases:

Good luck!

About The Author: Ellen Brown is an environmental writer and photographer and the owner of Sustainable Media, an environmental media company that specializes in helping businesses and organizations promote eco-friendly products and services. Contact her on the web at http://www.sustainable-media.com


Recent AnswersAnswer this Question

By henry (Guest Post) 06/28/2008

You may have blight- caused by a fungus in the air. it likes damp warm condition and was bad last year, it is the same a potato blight and could have caught it from nearby potatoes?
Burn all the dead leaves etc. I changed my soil for this year - hope it goes OK.

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By McMillan968 (Guest Post) 07/07/2008

I lost some last year from the overly wet weather! (FLOODS) I took off ALL the leaves EXCEPT the very top and they lived.

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Here are questions related to Tomato Plant Leaves Turning Black.

Question: Tomato Plant Turning Black

I potted a tomato plant in a white bucket and filled it with soil a little over half full and put it on the porch as we live on the second floor on a busy street. I noticed the plant itself was turning a dark color. I gave it some Miracle Gro and the bottom leaves on the plant went yellow so I took those off. Now the rest of the plant has turned just about all black. There are 2 tomato's growing at the top and they are getting big. What is the plant lacking?

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I would say drainage problem and not enough soil.

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Archive: Tomato Plant Leaves Turning Black


I have a tomato plant in a large container, and it has 4 small tomatoes on it. Yesterday I noticed that the leaves were turning black as if the plant had been scorched on the edges. What could be causing this? The plant in the next container is fine.

Hardiness Zone: 6a

Peggy62 from Chillicothe



It could be a couple of things.

Normally, leaf scorch is a result of stress from drought, or caused from pesticide burn or fertilizer burn. Check these first.

It you rule these out, then what you are describing could be blight. There are two types of blight, early and late. Both are a fungal disease commonly affecting potatoes and tomatoes. Symptoms on leaves start as tiny brown spots, which develop into greenish gray or brown areas that can expand to cover the entire leaf. These spots are sometimes surrounded by a ring of yellow tissue on the upper surface of the leaves and a ring of white fungal growth on the undersides of the leaves. Affected leaves drop early, which exposes fruit to sunscald.

Treatment is straightforward: remove or destroy infected plants and get rid of all debris. In your case, it's best to relocate your plant away from the others until you figure out whether or not it's infected. Pick off all infected leaves, and avoid watering from overhead because the splash may launch the disease spores. Don't over fertilize. If you believe there is a need, get the appropriate garden fungicide for vegetable crops and apply according to directions.

If your plant ends up dying a premature death, make sure you get rid of all of the dead plant debris, then wash and sterilize the pot with a solution of 1 part bleach to 10 parts water. When replanting, look for disease-resistant cultivars. Also, preventative copper-based fungicides may sometimes help reduce the spread of early blight.


More Answers:

RE: Tomato Plant Leaves Turning Black

Sounds like mold to me. you might want to get some spray for it and spray the surrounding plants. dose it look like this? (05/23/2008)

By newlywedgal

RE: Tomato Plant Leaves Turning Black

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