Common Tomato Diseases

Written by April Reinhardt (last updated May 27, 2020)


Whether you consider the tomato a fruit or a vegetable, you must agree that it is a versatile food. You can cook them into a mash to use in salsa, or you can chop them for a stew or chili. You can slice them fresh out of the garden to top a hamburger, or you can chill them and fill them with tuna salad. They preserve extremely well, whether you freeze them, can them, or dry them. While you can buy them from the grocery store, there's nothing like growing your own tomatoes and using them fresh from the vine. While it is relatively easy to grow tomatoes, they can contract certain diseases. Here are some common tomato diseases and their symptoms:

  • If you see dark spots on the leaves of new plants, then your plants have early blight. Some leaves may turn yellow and die. Always make sure that your planting area is clean from the previous fall, and avoid over watering.
  • Later in the growing season, tomato leaves may develop greasy spots, eventually turning papery gray and dry. The same spots develop on the fruit of the plant, with a surrounding ring of mold. A sure sign of late blight, it spreads rapidly throughout your entire garden if you don't stop it as soon as you discover it.
  • Only affecting the leaves of tomatoes, and not the fruit, gray leaf spot creates small, dark spots on both sides of the leaf, and eventually inhibit growth of the fruit.
  • A virulent fungus that causes tomatoes to rot, anthracnose manifests itself as round, sunken spots on the fruit. The spots increase in size and darken, merging with adjoining spots, rendering the fruit entirely inedible.
  • Located at the blossom of the plant, blossom end rot has dark brown and black spots that cause the entire tomato to rot.
  • More a ripening problem than a fungus, gray wall makes green fruit look gray, and may even cause gray spots to appear. Fully ripened tomatoes will have gray wall on the inside of the fruit, showing as green or brown areas.

In all instances, tomato diseases can be avoided by controlling moisture levels and applying fungicides when warranted. Always make sure that your garden bed is free of standing water before planting, and never allow tomato vines to trail into water. If your area experiences high humidity, apply fungicides, leave plenty of space between your tomato plants to improve air circulation, and ensure leaf health to provide an adequate canopy to protect fruit from sun scald.

Author Bio

April Reinhardt

An admin­istrator for a mutual fund man­age­ment firm, April deals with the writ­ten word daily. She loves to write and plans to author a memoir in the near future. April attend­ed More­head State Uni­ver­sity to pursue a BA degree in Ele­men­tary Edu­ca­tion. ...


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What is two less than 3?

2015-12-27 01:15:25

Lindsay Evans

Hi April,
This year being very hot early in the season, Blossom end rot seems to be very common.
I live in Northern Victoria which has been very hot for early tomatoes.
although in the past I have grown Tomatoes commercially, I have never had this Blossom end rot any where near the extent to what I have now on just a few backyard tomatoes. It seems very hard to control and have lost 80% of tomatoes as they get anywhere near ripe.
Because it has been so hot, it has been hard to adjust the watering when the plant tips start to drop usually means they require more water but unfortunately the more water I give them the more end rot develops.
I am trying to restrict the water at present to control this without letting the plants suffer to much.
The soil is well drained and sandy with mulch to try and keep soil moisture present.
Any other suggestions would be appreciated as other friends are having the same problems as well


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