Written by: Declan Murphy
Edited by: Vihaan Vyas
Designed by: Eleanor Jeavons
Published by: Rayna Almas
Tomatoes are a wonderful addition to anyone’s garden. This fruit is very popular. They can easily be grown from seed, can be happy in the ground or in containers, and they aren’t the hardest plant to keep alive and productive. However, tomatoes are susceptible to a few illnesses that every gardener should be aware of.
Garden fresh tomatoes are probably some of the most popular summer treats, and most gardeners agree that grocery store purchases simply cannot beat the flavour of homegrown tomatoes. Tomatoes need ample sun and water, and warm temperatures for about 60-100 days. However, if they are happy they can reward you very well.
However, some of us have experienced the frustration of a few tomato diseases that can dash all your hopes of salads and salsa.
One of the most common problems for tomatoes is blossom end rot, so named because the fruit will be blemished, blackened or broken near the blossom end of the fruit. This is not a disease so much as it is a sign that your tomatoes have been watered irregularly and/or your soil lacks calcium, and can be prevented or managed by feeding your plants a calcium rich supplement, covering them with organic mulch, and by watering the plants evenly.
A much more serious issue falls under the term “blight,” which can not only spoil the fruit but kill the whole plant. There are two major forms of blight, “early blight” and “late blight.” Despite their names, early blight does not become late blight, and they are different diseases, caused by different species of fungus. The early and late labels refer to the time they are most likely to hit during the growing season. Both can spell doom for your tomato patch, though one is worse than the other.
Early blight is a fungal infection that affects plants early in the growing season and causes the plant’s leaves to die and drop off. Usually in July, when the humidity increases and the plant is warm and moist at night, you might start to notice black or brown spots growing on the stems of the plant. If you catch it early enough, you can remove the affected leaves, thin out the branches to encourage better air circulation, and save the plants in time. Giving the plants adequate space and staking or caging your tomatoes properly can aid better air circulation and prevent blight. If you don’t act fast, however, the blight will eventually infect the fruit, as well, causing them to become discoloured and leathery, and you will not be able to harvest any useable tomatoes that season.
Unlike early blight, late blight is almost impossible to reverse. This blight is also a fungal infection, but this one attacks the fruit. Caused by damp weather, late blight starts as a grey or black mould on the fruit that spreads quickly. Unfortunately, once your plant has late blight there isn’t a cure, especially by the time it has reached the fruit, and the best course of action is to simply remove the plant before it spreads to the others.
Because it attacks later in the season, after a lot of hard work has already gone into a garden, late blight can be heartbreaking to a gardener, so removing the plants can be hard. However, it’s the only way to save any remaining plants.
There are some ways you can prevent tomato diseases and pests. The main way to ward off tomato-specific pests and illnesses is to make sure you rotate your crops (i.e., plant your tomatoes in different plots every few years), use fresh soil (if you are growing tomatoes in containers), and to dispose of infected plants carefully to avoid harbouring the disease or pest over the winter. Cleaning up your garden after the season, in preparation for winter, is a useful habit to get into to prevent a lot of issues. If you suffer a blight contamination one season, it is recommended that you skip planting tomatoes in the same patch for two years after to avoid another blight attack.
Remember: Plants, like humans, can become infected by diseases through unclean hands and tools. So keep your materials tidy, clean your tools between uses, and, if you come into contact with suspect plants or soil, be sure to wash your hands to avoid spreading fungal spores or bacteria throughout your garden!
Hopefully, you’ll never have to deal with blight in your garden, but, if you are thinking about growing tomatoes, it’s important to know the signs!
Do you grow tomatoes? Got any tips or hacks? Please share in the comments!
Sources:
Bloomfield, C. (2023.) “Tomato Blossom End Rot Symptoms And Treatment.” Gardening Know How. https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossom-rot.htm.
Boeckman, C. (2024.) “How to Grow Tomato Plants: The Complete Guide.” Farmer’s Almanac. https://www.almanac.com/plant/tomatoes.
Ianotti, M. (2024.) “Tomato Blight: How to Identify, Prevent, and Treat.” The Spruce. https://www.thespruce.com/early-blight-on-tomato-plants-1402973.
MasterClass. (2021.) “Tomato Blight: How to Prevent and Treat Tomato Blight.” Home and Lifestyle. https://www.masterclass.com/articles/tomato-blight-guide.
RHS. (2024.) “Tomato blight.” Advice. https://www.rhs.org.uk/disease/tomato-blight.
Schuh, M. and M. Grabowski. (2024.) “Early blight in tomato and potato.” University of Minnesota Extension. https://extension.umn.edu/disease-management/early-blight-tomato-and-potato.
Seeds of Diversity. (2024.) “Preventing Late Blight in Tomatoes.” Gardening Resources. https://seeds.ca/seed-gardening-resources/gardening-resources/late-blight-tomatoes/.