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Tomato Blight & Pumpkins

Early and late blight on tomatoes may be difficult to deal with; and advice for a first-time pumpkin grower!
by Art Drysdale
by Art Drysdale

email: art@artdrysdale.com

Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at http://www.artdrysdale.com


August 30, 2009









Above, a number of progressing photos of Septoria blight on tomatoes courtesy Dr. Meg McGrath, Cornell University College of Agriculture and Life Sciences. Below, our ‘Sun Shower’ exotic Hibiscus is doing particularly well outdoors on our seaside deck this summer!
Author photo.

On August 25th, Gene Hammond wrote to Donna Dawson from Ohio about a common problem with tomatoes in many locations, particularly including British Columbia. “I have small garden about 25 x 25 ft. I have had Septoria blight for a few years now. Nothing I do seems to get rid of it. I have several Fact Sheets about it.

“1) I have a 4 year rotation plan. 2) I pull all plants up at the end of the season and get rid of them. 3) I buy tomatoes that are supposed to be blight free. Or I start my own seeds which are blight free. 4) I mulch with newspapers to keep the water from splashing on the tomato leaves. 5) I spray with a good anti fungal spray about every 10 days from the time I put them in the ground.

“But nothing seems to work. Every year they look good till about late July. Then they start to get the specks on the leaves, turn brown and the leaves wilt, even with lots of rain. The leaves still curl up. Then the leaves turn brown and fall off. Or I hand pick them off. Eventually the stems do the same thing. I took some leaves to the County Extension Office. They sent them to Ohio State University. They said I had Septoria Blight. Is there anything you could say to help me with this problem?”

Tom Dawson, in responding to Gene, asked some additional questions: “Can you tell me where you are located, what type of soil, light and what your watering regime is like and if the plants are in raised bed, in cages, etc?”

Gene responded thus: “I live in Hubbard, Ohio. I have clay soil. Last year I had a soil test. It was neutral at about 6.5 or 6.6. Our area had just enough rain to keep everything green so I've haven't had to water very much. My tomato plants are not in raised beds, but are caged. They all are the determinant kind. Anything else I can help you to solve this problem, just ask.”

The simple answer to your question is to use a copper fungicide on your plants about every ten days. Though you mention using “a good anti-fungal spray” you didn’t tell us what. If, for example it is sulfur, that might help but will not be as effective as a copper spray. Copper sprays, by the way, are considered by most as organic.

I should also make some other comments (in addition to what I said about the spray you are using) on some of the points you mention in your notes. No tomato plants sold anywhere can be guaranteed to be free of Septoria or late blight, or even of early blight. If you check your seed catalogues you will see that many tomato cultivars are resistant to certain viruses such as tobacco mosaic, but none is able to resist either early or late blight. Your own self-started tomato plants might also not be Septoria--free simply because seed can be infected with Septoria when you obtain it! Hot water treatment of seeds is used by many to help solve the problem.

There are other possible things that could be adding to your problems. For example, the same diseases that attack tomatoes also attack other plants such as celery, potatoes and eggplants. Also, the annoying, poisonous weed, deadly nightshade (Atropa belladonna) is also subject to the two blights and having it growing somewhere nearby (another person’s garden) could be giving you problems.

When you mention that you haven’t had to water too much this year, it sounds like similar conditions experienced in southern Ontario--a great deal of rain. That happening in June would only speed up the infection of blight on tomatoes. Even having the foliage wetted by irrigation can easily cause the onset of blights. Water only the soil.

Although you say that you clean up the old plants each fall, I would want to make sure you also pick off any diseased foliage or stems as shown in the included photos.

Sorry, but I cannot offer many other suggestions. There are several other fungicides (such as chlorothalonil or maneb) but generally these are only available for agricultural uses.

A way back on August 18, I heard from Mandy Bennett in nearby Qualicum Beach: “Well hello again. I emailed you quite some time ago asking about trees and shrubs to be planted on or around my septic field in Qualicum Beach. Thank-you for your reply!

“Now, I'm asking about pumpkins. I planted eight plants (Jack-o-lantern and Connecticut field). Out of these eight seeds (planted early-mid June) only five grew, and out of these plants, there appears to be only one pumpkin which is still green and tiny; about the size of a nickel. What the heck?!!!

“Now I admit that I'm certainly a novice gardener. I am so excited and overwhelmed by everything that grows here on the West coast, (moved from Calgary last May) that I want to try everything. I have always loved plants and dreamed of having a garden and beautiful, lush yard--maybe I'm too impatient and not following proper protocol! When I put the seeds in the ground, I dumped some bought compost and bone meal into my existing sandy soil as well. So sad, please help.”

If your soil there is as sandy as ours here right on the Strait of Georgia (basically a sandbar), you likely have not pro-vided anywhere near enough nutrition for the pumpkins to grow. Sandy soil is the coarsest of all and the nutrition applied to it washes down through ever so quickly. Granular fertilizers are perhaps at least as bad as the soluble/liquid types for disappearing. (By the way, bone meal is almost useless!) One thing you should be doing is enriching your soil with organics such as peat moss, Coir and, of course, home compost. I stick generally to soluble fertilizers applied from hose-end sprayers, and I apply them just in advance of a rain, when possible. That way the plant foliage and stems can take in some of it as instant nutrition, while the rest is washed to the roots by the rain. I try to do the entire garden about every four weeks, but this year have missed an application and certain items in the garden are showing it. Keen large-pumpkin growers use a varying regimen of liquid fertilizers which you might wish to follow another year.

Nutrition is only one aspect of pumpkin growing! Generally it is necessary to hand-pollinate the female flowers (which have a tiny pumpkin just behind the flower--the male flowers do not). Do this by obtaining some of the pollen from a male flower on a Q-tip or camel’s-hair brush. Brush the pollen over the sticky stigma in the centre of the fe-male flower. When two reasonable-size pumpkins are present, remove the rest and let the two grow in size.

Good Luck!

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