Blight On Tomatoes - Tomato Blight Treatment And Prevention


Amy Draiss
What is tomato blight? Blight on tomatoes is caused by a fungal infection and like all fungi, they are spread by spores and require damp, warm weather conditions to flourish.
What is Tomato Blight?
What is tomato blight? It's actually three different fungi that attack tomatoes in three different ways at three different times. Septoria blight, also called leaf spot, is the most common blight on tomatoes. It usually appears at the end of July with small black or brown marks on the lower leaves. While fruits may remain uninfected, the leaf loss can affect yield as well as exposing the fruit to sunscald. Overall, it is the least harmful tomato blight. Solutions to the problem include watering only at the base of plants, and avoiding the garden while foliage is wet. Early blight appears after heavy fruit set. Rings resembling targets develop first on the leaves and cankers soon grow on the stems. Black spots on the almost ripened fruit turn into large bruised spots and the fruit begins to fall. Because the crop is almost ready for picking, this may be the most disappointing tomato blight. Treatment is simple. To prevent tomato blight from invading next year's crop, burn everything the fungus may have touched including fruit and foliage. Late blight is the least common blight on tomatoes, but it is, by far, the most destructive. Pale green, water soaked spots on the leaves quickly grow into purplish-black lesions and stems turn black. It attacks in rainy weather with cool nights and quickly infects fruits. Infected fruits show brown, crusty patches and rot quickly. This is the blight that caused the Great Potato Famine of the 1840s and will quickly infect any potatoes planted nearby. All potatoes should be dug and disposed of as should all tomato plants and fruit affected by this tomato blight. Treatment is simple. Burn everything the fungus may have touched.
How to Prevent Tomato Blight
Once a blight on tomatoes takes hold, it's very hard to control. After identification, tomato blight treatment begins with fungicide treatments, although when it comes to tomato blight, solutions really lie in prevention. Use fungicides before the fungus appears and they should be applied regularly throughout the season. Fungus spores are spread by splashing water. Stay away from the garden while foliage is wet from dew or rain. Avoid watering in late afternoon or evening so that water can evaporate from the leaves and, if possible, water the ground and not the foliage. Most fungi grow best in the warm, wet dark. Rotate crops as often as possible and never turn any tomato debris back into the soil. Use healthy transplants from a reliable nursery and remove damaged lower leaves regularly since that's where most fungi attacks begin. Remove all plant debris at the end of the growing season so the spores have nowhere to over winter. What is tomato blight? It's a series of recurring fungal infections that can be curtailed with good garden housekeeping and simple fungicide treatments. Note: Any recommendations pertaining to the use of chemicals are for informational purposes only. Chemical control should only be used as a last resort, as organic approaches are safer and more environmentally friendly.
Gardening tips, videos, info and more delivered right to your inbox!
Sign up for the Gardening Know How newsletter today and receive a free copy of our e-book "How to Grow Delicious Tomatoes".

Jackie Rhoades began writing for Gardening Know How in 2010.
- Amy DraissDigital Community Manager
-
Moody Blooms For Spring: 8 Types Of Black Flowers To Add Drama To Spring Displays
From midnight burgundies to inky violets, several types of black flowers can enrich and embolden a spring display. Try these brooding bloomers for a moody garden
By Tonya Barnett
-
Can Snake Plants Live Outside? Everything You Need To Know For Snake Plants Al Fresco
Snake plants can live outside given the right conditions, but be careful that they don't take over! Learn the best way to use snake plants in your landscape.
By Mary Ellen Ellis
-
Best Tomatoes For Containers: 10 Tastiest Varieties For Plentiful Produce In Compact Areas
These are the best tomatoes for containers that prove you don't need to have a large space or elaborate garden to grow delicious produce.
By Bonnie L. Grant
-
Raised Bed Garden Layout Ideas To Maximize Your Vegetable Harvest
Curious how to maximize your vegetable garden this year? Try these raised bed layout ideas and tips to get the most out of your space.
By Teo Spengler
-
Best Herbs To Plant With Tomatoes: 6 Perfect Companions For Better Flavor & Bigger Harvests
Certain herbs make excellent neighbors to tomatoes in the vegetable garden, repelling pests, keeping down weeds, and enhancing flavor. Try these top varieties.
By Mary Ellen Ellis
-
7 Best Vegetables To Plant In February – And Start Harvesting From Early Spring
Get a head start on your garden with these delicious veggies. Plant now and you can begin enjoying home-grown harvests sooner than you think.
By Mary Ellen Ellis
-
How To Grow A Windowsill Full Of Veggies This Winter, According To A Top Gardening Expert
Award-winning journalist and climate-resilient gardening expert Kim Stoddart reveals her top plant picks and tips for a productive winter windowsill garden.
By Kim Stoddart
-
7 Perennial Herbs Perfect For Pots – Enjoy Aromatic Patio Harvests Year After Year
Discover the best perennial herbs to grow in pots. Ideal for small spaces, these low-maintenance plants offer year-round flavor and greenery on your patio.
By Bonnie L. Grant
-
Do-It-Yourself Floral Pumpkin Centerpiece
Can you believe this pretty pumpkin centerpiece was made with just $13 worth of supplies? Plus, it was quick and easy.
By Amy Draiss
-
9 Fun Things To Do With Pumpkins That Are Past Their Prime
Wondering what to do with your pumpkin after the Halloween fun is over? Learn what to do with your pumpkins when you are done decorating with them.
By Teo Spengler