Anthracnose: A Very Harmful Tomato Disease that Causes Dark Spots

There are a lot of different diseases that can inflict a tomato plant which could possibly damage a whole season of tomato crops. A lot of the diseases that can affect a tomato occur during the ripening process and can destroy every tomato in the field. One of the many different diseases that can inflict a tomato plant is called anthracnose and this is a very devastating tomato disease.

Anthracnose is a disease that causes serious harm in a tomato and is usually found in ripe and over-ripe tomatoes. Anthracnose can cause a whole crop of tomatoes to become useless because of the ability the disease has to spread. Anthracnose is most common in areas where moisture occurs and where the temperatures are very humid or hot. Anthracnose can become a problem before or after the time of year when harvesting tomatoes occurs but there are ways to spot this disease before it progresses. The tomato will often exhibit symptoms of anthracnose during the ripening process so it is important you watch your plant carefully to see if symptoms develop.

Anthracnose symptoms are usually noticeable on a ripe tomato first but it can affect the green tomato and become a problem later in harvesting season. On a ripe tomato you might notice small lesions on the leaves and stems which might not seem like a big deal. The lesions on the tomato could be indicative of where the disease has infested the tomato so it is important to visually inspect each leaf and stem for such an issue. You will also notice small sunken spots that appear round and contain black rings on the inside. Usually a tomato infected with anthracnose will have larger spots on it and the spots might darken in the hotter environments. If you live in a hot environment you also might notice a mass of gelatinous material oozing from the lesion on the tomato which is also an indication of anthracnose. The lesions could burst open and then become infected with another disease or become a host for bacteria and other germs to develop. Anthracnose is often overlooked because it is not usually a powerful pathogen.

A lot of common weeds and crops have anthracnose in them but usually it is dormant which makes it so dangerous and debilitating to a tomato. Anthracnose can be found in the soil, seeds and infected plant debris and is scattered in the fields due to rain and irrigation systems. Anthracnose is most common in warmer environments and it thrives when there is wetness on the tomato itself and the leaves. If you have a tomato plant that has another leaf disease then it will be particularly vulnerable to developing anthracnose. The best way to ensure that anthracnose does not infest your tomato plant is to manage and prevent the environment from creating the disease.

Prevention includes keeping the tomato field free of weeds and other possible debris and rotating the tomato plants once a year. You also want to use certified and disease-free tomato seeds and then treat them using hot water. Overhead irrigation is also something you want to avoid to prevent anthracnose from occurring on your tomato and you want to use mulch and soil if possible. Fungicide sprays might also be a good idea to prevent anthracnose from occurring and should be used from the beginning of the tomato season until harvest. If you have done all of these things and still have developed anthracnose on your tomato then you should use a chemical treatment to get rid of the disease.

Some chemical treatments that can get rid of anthracnose disease include Quadris, Bravo Ultrex 82 WDG, Kocide 4.5 LF, Cabrio EG and Dithane. These products require you to use them at 7 to 10 day intervals at the first sign of anthracnose disease. You also need to make sure that you read the instructions on the chemical treatments because application may vary depending on the severity of the disease. It is also important that when you are using these treatments you do not rotate the infected tomato plant with strobilurins such as Cabrio or Flint.

University of Massachusetts Amherst Staff, "Tomato Anthracnose", University of Massachusetts Amherst