Most commercial potato farmers sprayed their way through last season and ended up with a normal- enough-looking crop. But 2010 was a heartbreaking year for home gardeners, as a nasty blight worked its way across Manitoba decimating all but the most remote or chemically treated tomatoes.
First word of the blight appeared in a June 14 press release from Manitoba Agriculture. Home gardeners were advised to dispose of infected plants by removing all plant parts and burning them away from the garden or by bagging them, sealing the bags, and “cooking” them in the hot sun.
Read Also
Manitoba strawberry farms prepare for warm season
Manitoba strawberry growers and U-Pick operations are looking at spring weed control and new plantings; the 2025 berry picking season is coming fast.
As the summer progressed, many of us felt we had beaten the blight. We had planted healthy heritage plants that we knew from past years were great producers. Our market garden plants are always started in fresh soil.
I planted them into a freshly dug and organically amended virgin garden plot. Although we live in the country, our garden clearing is surrounded by thick bush. Other people across the province did their own starts from their own saved seeds, as they have always done. Although it was a damp year, by midsummer my plants were the biggest ever, taller than my head, perfectly healthy and loaded with unripe fruit.
Then one weekend, I ran into a local potato farmer.
“Do you have blight yet?” “No,” I replied smugly. “Well, you will.”
Until August 9, when the first sign of potato blight showed in a few Yukon Golds, everything was thriving beautifully on the mid-season feed of compost tea.
It showed up on some tomatoes the next day. I pruned and sprayed with hydrogen peroxide. By Aug. 12, the blight had advanced. I harvested unripe/ ripening fruit, removed the worst of the plants, sprayed with copper sulphate. On Saturday, August 14, I took the rest to the dump. Heartbreaking!
My salvaged fruit was grey and rotting. I ripped out everything, including the mulch, and hauled it to the burning pile at the municipal landfill. I pulled the Yukons and stored them in the basement, checking weekly, eventually losing about 30 per cent to blight in storage.
The reds were next to the tomatoes, so we pulled off the tops, sprayed the residue with copper sulphate, and kept them stored underground. In fall, we dug them up. In storage, we lost about 20 per cent. Interestingly, the pepper plants that shared the tomato bed were unaffected.
Some people to the east who got the blight a few weeks later actually managed to harvest and can their fruit right off the blighted vine, but one story I heard from a longtime country gardener was particularly troublesome.
Lifelong canner Liz Klotz of St. Claude had managed to preserve a lot of tomato fruit, but over Christmas, when she opened her first jar of whole tomatoes, she found a grey-white fuzzy blight mould inside the fruit. Thinking it was some kind of anomaly she opened one jar, then another. All of the beautiful red fruits were rotten from the inside out. Others who had made crushed tomatoes, or sauces, had better luck, which is useful information. It is clear that the heat of processing is not adequate to kill the blight spores, but the acid/salt mix used to preserve the tomatoes will do the trick.
IMPLICATIONS
The fact that the blighted tomato seedlings were being sold simultaneously at several unnamed retail outlets in Winnipeg and Brandon makes me think that both the greenhouse supplier and the outlets were “too big to be named” – big box-type stores. Now, more than ever, it is important to maintain food security and genetic diversity by maintaining smaller operations, and by growing and saving seed from open-pollinated heritage varieties. It is this old stock that breeders turn to when searching for traits of blight resistance.
I also can’t help but notice that the MAFRI bulletin on this issue is 100 per cent concerned with the cross-contamination of the commercial potato crop. But what were the implications for market gardeners, home gardeners, and organic farmers?
I live in sparsely populated rural Manitoba, in the bush, where the kitchen gardens are small and few and far between. It seems a far stretch that Manitoba winds became saturated with blight spores because a handful of oblivious kitchen gardeners did not notice their 1) tomatoes were blighted and 2) had reached the stage of spore creation.
In my opinion, the elimination of shelterbelts and bush pushing to enable industrial-sized potato operations were the real vectors of the blight that impacted Manitoba’s home gardeners, creating a tomato famine in the canning cupboard.
So what about this year? Longtime gardeners are approaching the season with trepidation. Old-timers say that the only chemical- free way to beat the blight is to hope for a really dry summer or two, and rest the soil from Solanaceae plants for as much as eight years.
Organic systems allow for only the occasional copper sulphate spray, and then only sparingly so that metals will not build up in the soil. Copper spray is also a preventive measure – it must be applied before the plant comes in contact with the blight spores. Hydrogen peroxide in watering water didn’t really help.
So, this year, we are starting yet another fresh plot, this time in a clearing about 100 feet away from the infected beds and the driveway, which we have decided is a vector for not only wind-borne blight, but other nasty sprays that are part of today’s standard agricultural practices.
In addition to our heritage varieties, I am trying an expensive hyrid that is touted to be blight resistant.
We will be spacing our plants further apart, and pruning and staking with more care to allow more plant isolation and circulation. If it is a really wet summer, I might not mulch to allow better drainage. And I won’t be smug until the fruit is in the pudding, so to speak. If you have any advice or guidance on how you have successfully dealt with blight, I’d love to hear from you.
Liz Clayton operates Boyne River Ridge Natural Food Farm in the Rural Municipality of South Norfolk.
———
Ialsocan’thelpbutnoticethattheMAFRIbulletin onthisissueis100percentconcernedwiththe cross-contaminationofthecommercialpotato crop.Butwhatweretheimplicationsformarket gardeners,homegardeners,andorganicfarmers?
