Jessica Smith
Right at the time of year when gardeners’ mouths begin watering for ripened home grown tomatoes, many have noticed something strange happening to their tomato plants this summer.
“For the first time in thirty years, they are completely wiped out,” said Maple Crescent’s Pentti Aho. “Everything starts drying up and then they rot, even the tomatoes.”
He is certainly not the only one to experience a complete decimation of his tomato crop this year, said Atikokan Horticultural Society’s Alanna Rechlin.
“A lot of people in town have come to us and said they had this problem,” she said, adding that she has had the same experience, affecting all different types of tomato plants in her garden. Whether grown from seed or purchased as bedding plants, the results are the same: “The plants eventually die off. It produces very little fruit that is good,” she said. “The tomatoes rot and have a slimy look about them.”
It appears that another plant is also feeling some of the same effects, she added. “My potatoes are all finished; I think they’ve got the same thing.”
Rechlin’s hunch is right, according to Lakehead University’s Food Security Research Network campus garden coordinator Lee-Ann Chevrette. An LU Masters of environmental science student conducting thesis research at the garden, she observed about a month and a half ago that there was “a problem first with our potatoes, and then with our tomatoes. After doing a bit of research, we determined it was a late blight, which is a common fungal disease that affects the nightshade family [which includes tomatoes and potatoes]. First the leaves were affected, and then the stems and then it spread like wildfire right across the garden hitting the tomatoes and potatoes hard,” she said. The blight wiped out most of the potatoes and about 90% of the tomatoes.
The fungal spores spread on the wind, through contaminated water (i.e., from using a watering can that contains the spores) or contact with the diseased plants. The likely cause has been the type of weather we have experienced this summer, said Chevrette. “The blight needs warm humid weather, which we certainly had, to propagate.”
What happened after the blight hit the campus garden, which includes 120 community and 20 research plots, provided some interesting insight into what types of tomato plant were most affected, and what actions could help prevent a full-blown outbreak, she said.
Although hit by the blight, the 20 different varieties of Heritage tomatoes “seemed to have a natural resistance to blight,” she said. Heritage plants are grown from seeds that are not genetically modified and collected each year from the plant, usually preserved through many decades.
“They were still affected, but much more lightly than the commercial varieties. They are fighting it and recovering. There are some leaves and stems that are affected, but they still produced tomatoes that look healthy and taste delicious.”
Based on this year’s observation, “we will obviously be encouraging the planting of heritage tomatoes across the garden next year,” said Chevrette.
The only tomato variety completely unaffected were Tomatillos (a green tomato of the cape gooseberry family), despite having contact with diseased plants, she noted.
To protect surviving plants, she recommends gardeners remove the blighted foliage from the plants. The blight can survive over the winter, so to prevent another outbreak next year, remove all infected plants and put them in the garbage, rather than compositing them. Because the blight thrives on humidity, she also recommends improving air flow by spacing plants further apart and removing any weeds underneath the plant.
LU’s Food Security Research Network supports sustainable local food systems in northern Ontario through linkages between researchers, students, and community partners. Chevrette is completing her thesis on the role of community gardening in enhancing food security, ecological awareness and building of social supports and community well-being.
While the blight was an unexpected scourge on the campus garden, “we learned a lot and will just try again next year,” she said, adding that Atikokan gardeners also affected are certainly not alone this year. “The blight seems to be a big problem in the region right now and I suspect it was due in part to the unusually hot and humid weather.”
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