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Tomato Pests & Diseases

Blight prevention? Soil additives??

17 years ago

Blight is horific in my tomatoe garden...is there anything I can do, particluarly in the offseason (soil additives, etc) to prevent the onset of blight in the spring/summer?

I use Daconil to control it as much as possible, but still end up removing a significant amount of leaves on a weekly basis...and it makes the toms taste a little funny even after washing them ;)

Any help would be greatly appreciated!

gardenboy

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Comments (4)

suze9
17 years ago
gardenboy, I cannot emphasize enough how helpful and relevant it is on a gardening forum to have your state (or country) and zone information entered so that it shows up when you post. This can be added/edited on your Member page. Where do you live?

As for the blight, this tends to be used as a general term that could mean several things. Are you referring to Early Blight (Alternaria solani) or something else?

Thickly mulching (I prefer wheat straw) helps limit splashback reinfection from your soil. However, fungal disease is also airborne. In addition, the spores can multiply rapidly in hot humid climates.

Do you use the Daconil before or after you start seeing symptoms, and are you coating all surfaces of the plant when you spray?

Btw, using Daconil should not affect the taste of fruit in the slightest.
torquill
17 years ago
To my knowledge, chlorothalonil (the substance in Daconil) has no taste. I'm relying on secondhand information for that, though. :)

"Blight" is not a technical term; could you describe the symptoms you're seeing?

--Alison
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Here is something you might find interesting... My garden had plenty of early and late blight and septoria leaf spot. The following year I installed a hoop house over half of it and planted tomato plants inside and out (8 in/10 out). I sprayed/coated the outside plants several times (during wet periods) with a well known product used to control these diseases. The inside plants were treated only once (lower leaves only). Soil was the same inside and out (top quality and ammended-well with organic compost). The plants in the hoop made it all the way to freeze disease free! No blight at all inside. The outside plants, well, they were pretty much toast about 45 days earlier. The hoop house makes it sooooo much easier to garden. Never had to worry about pruning wet foliage (as it was often wet outside from the morning dew and rainstorms). The hoop house was not sealed off. It was about 50% open (no side or end walls). The plastic on top kept the direct rain off but there was some splashing along the sides. (I use leaf mulch to keep the soil from splashing up the stems). I can go on-an-on about the benefits of the hoop house but perhaps best is the reduction in plant disease. (but gardening during thunderstorms is pretty cool too!) My overall production was up more than 50%. And I suspect that with the dry and sunny conditions inside the hoop structure this winter (off-season), the bacteria and molds won't stand a chance (but I will still rotate anyway). One note, I trained my tomato plants to a rope attached to the top of the hoops. It grew vine-like plants vs. bushy plants you get on cages. It keeps the foliage drier and blight at bay. I am now less concerned about growing heirloom varieties. I hope I didn't get off topic.
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Apparently the grower of tomatoes that supplied the big box stores provided seedlings that were infected with the blight spores. The best thing you can do to prevent, or at least minimize the impact next year is to work on getting your soil into a good, healthy condition that will grow strong and healthy plants that are better able to resist plant diseases. A good, reliable soil test that tells you what your soils pH is and why it is what it is, and what the nutrient balance is would be a major aid in preparing that soil now for the next growng season. In addition these simple soil tests can be of more help, Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top. 2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drainsÂ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up. 3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart. 4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer you soil will smell. 5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.
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dstucki85
Original Author
17 years ago
Appreciate the feedback so far...I belive I'm in zone 6A. If you look at a map of Indiana and think of it as a boot, I would be really near the toe.

I'm almost positive it's early blight, per the 'Tomato Problem Solver' link posted around and seaking with others.

I think I'll try mulching next year. Actually, I'd planned to use a large plastic tarp with approx 1' diameter holes for the plants...and mulch around the bases. Don't laugh, I just don't have alot of time to till/keep weeds down.

So...maybe Daconil doesn't cause a strange taste...but I can notice a slight twang from the skin that tastes strangely like the smell of daconil. Maybe I'm mixing it too strong...or maybe it's just me.

It just seems like I can have my same varieties in a 'new' garden place and completely avoid e. blight, but when I plant in my 'normal' place, it runs rampant (spelling?). Therefore I assumed (possibly incorrectly) this frustrating stuff lays dormat in the soil.

gardenboy
torquill
17 years ago
It does lie in the soil, and gets splashed up onto the leaves by rain. Your thought about mulching is a great idea.

I've never used Daconil, but I have to wonder now whether I would taste something too -- I'm pretty sensitive to that sort of thing, much more than most people. It is pretty close to harmless in people, with an astronomical LD50 number; you'd pretty well have to chug the stuff to have a serious effect on mammals. That doesn't help with the aftertaste, though, and I wish I could suggest an alternative... chlorothalonil is simply the best antifungal we have.

It physically can't absorb past the skin; try using a mild soap to wash the tomatoes with, see whether it helps at all.

--Alison

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