Tomato blight warning
Photo courtesy of AVRDC/The World Vegetable Center
University of Maryland agriculture officials are asking vegetable gardeners in Maryland to be on the lookout for late blight, a serious fungal disease that afflicts tomatoes and potatoes.
The Plant Diagnostics Lab received a suspect sample from a Howard County garden in June and found it to be infected.
Despite the name, late blight can occur anytime plants are actively growing and is especially damaging during cool, wet weather, which we have had plenty of.
It first appears as dark, water-soaked spots on leaves. The leaves quickly shrivel and die. Dark brown spots also appear on plant stems. The disease can be slowed by hot, dry weather.
Infected tomatoes can have shiny, dark or olive-colored lesions that may cover large areas. The infection can produced a foul odor as well
This is the same blight that caused the famous potato famine in Ireland in the 1840s, and can be particularly destructive in home gardens.
It is possible that the blight, appearing this early and with such a potential to spread, might effect the quantity and price of tomatoes this season. Usually, the blight hits plants late, after most of the fruit has been harvested.
Here are a few tips for dealing with the blight, courtesy of the University of Maryland Home and Garden Information Center.
- Keep foliage dry. Avoid overhead watering. Avoid crowing plants.
- Always purchase new need potatoes that are certified "disease-free."
- Do not compost store-bought potatoes and don't store infected tubers.
- Pull out and destroy all infected plants.
- Keep developing tubers covered with soil.
- Place infected plants or fruit in a sealed bag and dispose.
- Protectant fungicides like chlorothalonii and fixed copper can help protect foliage if applied prior to infection.
Comments
Comments? What? And admit we bought some of these from the Big Box Stores! We planted tons of them at great expense! If we keep quiet, this plague might just pass us by....
GrandBob
Grandbobs Garden
Posted by: Robert | July 11, 2009 4:38 PM
If you are suffering from this blight this year, it is very late in the game to recover from. It is reported that a corn & garlic spray may be effective in helping retard the fungus. Here is how to make and apply such a spray:
Gather a handful of corn leaves leaves (any kind) and as much of the papery outer leaves of garlic as you can. Process thoroughly in a blender. Mix with sufficient water to make a thin liquid. Let sit for an hour, strain and spray on plants. Never spray in full sun. Late in the day after the plants are out of the sun is the best time to apply.
As a "tip" for next year's tomatoes - buy locally grown starters or even better yet, start your own from seed. This year's blight, especially in the East appears to have been at least partly perpetuated by plants that were mass produced and carrying the blight and then sold through several of the "big box" store chains.
Hope this helps and good luck!
Posted by: the rural independent | July 12, 2009 1:10 PM
I think you mean "affect" not "effect" in the third to last paragraph. Easy mistake.
Affect is a verb and effect is a noun.
Posted by: Jessica Gresock | July 12, 2009 7:41 PM
there is plenty said about what the blite does or looks like, i know what it goes, what i want to know is there a product on the market that i can spread on my garden over the winter to kill the fungas? i dont want it to reapere next year cause i had it in the ground.
Good question Ed, I will check into this.
Posted by: Ed Hull | September 7, 2009 7:17 PM
I know that this is late, but I wanted to reply to the question on concerning the fungus over wintering. Late blight (from what I understand) will only live in living plant tissue. The only way that it will overwinter is if you have infected potato tubers in the ground. Even then, weather conditions have to be right for it to show up again. Remove all volunteer potatoes and you should be fine.
That's what I understand, too, Shirley. --Susan
Posted by: Shirley | November 10, 2009 1:18 AM