Maine Extension Weighs In On Late Blight

So where did the Late Blight diseasing up Bonnie Plants in box stores throughout the Northeastern United States originate? In a press release last week, Bonnie Plants officials say Late Blight could not have originated at its facilities because the disease was confirmed at retail June 23 and not at one of Bonnie Plants’ facilities until two weeks later.

The argument is sound in that the Late Blight discovery at retail preceded the discovery at a Bonnie Plants facility in New Berlin, N.Y. But who’s to say the disease wasn’t rampant in New Berlin or elsewhere for weeks before a discovery was made at retail?

For the record, Bonnie Plants General Manager Dennis Thomas says Bonnie has yet to receive a report that says Late Blight infected Bonnie Plants tomatoes in Maine. And, Thomas adds, there have been no reports of Late Blight in Connecticut, Rhode Island, Massachusetts or New Jersey.

The verdict is not yet determined in the Bonnie Plants-Late Blight case–and an origin may indeed never be determined–but two University of Maine extension service members sounded off on our comments board last week with new information.

Maine’s Research

Dr. Dave Lambert, a plant pathologist at the University of Maine, has some input on the developing story. Lambert says the facts in the Bonnie Plants-Late Blight case from Maine are as follows:

–One week before Late Blight was discovered, tomato plants were shipped from Bonnie’s local supplier in Dresden, Maine, to stores across the state.

–Immediately after the report from New Berlin, N.Y., blight experts in Maine started checking and found 20 percent or more of the Bonnie tomatoes were diseased at every chain store visited. Tomatoes from other suppliers were clean.

–The range of symptoms indicated infections one to two weeks old, demonstrating disease had occurred in the source greenhouse.

–At this point, no Late Blight has been found anywhere else in Maine, despite widespread and intensive scouting by the Maine extension service and the potato industry.

–The Late Blight strain isolated from these plants and from subsequent secondary outbreaks in Central and Southern Maine is US14, rarely found in Maine but common this year in the Southern United States.

–Subsequent scouting around Dresden, Maine, detected the very beginnings of an outbreak in small organic and other market farms. It was evident these infections were neither old enough nor abundant enough to be the source of the greenhouse problem. The area has no recent history of Late Blight, but a number of potato and tomato crops have been lost there in the subsequent three weeks.

A Ralstonia Comparison

The bottom line, Lambert says, is Bonnie Plants is trying to put a lot of daylight between itself and the Northeastern Late Blight epidemic.

“If Bonnie was so confident of its local suppliers,” he says, “why would one of its out-of-state representatives have been quoted in a local store just after the initial outbreak saying, ‘You ought to call your Department of Agriculture and have that place (Dresden) shut down?’

Just think back to the Ralstonia outbreak a few years ago, Lambert adds, and this developing story is following right along that one’s lines.

“Circling the wagons and claiming that (Late Blight) wasn’t spread by tomato transplants may be lawyers’ advice, but it isn’t helpful to anyone in the long run,” Lambert says of Bonnie’s response to the disease’s origin. “State agencies know better, chain stores should and the tens of thousands of Alabama AFC farm families who will share in this misfortune deserve a better accounting.”

More Analysis

Steve Johnson, a crops specialist at the University of Maine, also chimed in on the Late Blight story on our comments board. Johnson says one greenhouse in Maine receives Bonnie plants and grows them for delivery to the box stores.

Johnson can’t confirm all 42 box stores Bonnie supplies in Maine were carrying infected tomatoes, but he says all box stores surveyed had infected tomato plants from Bonnie Plants. Johnson also shared some information on Late Blight’s effect on potatoes in Maine.

“July 8 was the first report of late blight on potatoes from a garden well removed form commercial potato production,” he says. “The potatoes were next to the infected tomatoes in the garden. On July 11, Late Blight was discovered in field potatoes and tomatoes. The epidemic rapidly escalated.

“This first field late blight find is about five miles from the one greenhouse in Maine that received Bonnie plants and grew them out for delivery to the big box stores. This first infected potato field is operated by [a] second generation potato farmer that has never had Late Blight on his farm before.

“In my 20 years, I have never known this area to have Late Blight.”

To read last week’s update on Late Blight in Bonnie Plants,. You can also read the latest from Bonnie Plants General Manager Dennis Thomas, who spoke August 4 with Greenhouse Grower.

Leave a Reply

17 comments on “Maine Extension Weighs In On Late Blight

  1. A few more points about late blight sources and spread. The pathogen survives the North American winter in live tissue, never in soil. Only southern Florida has active year-round blight, and in wet years this may sread north in the late winter and spring. In the North, the historic sources in the spring infection have been either large piles of dumped potatoes or infected seed. In recent years, regulatory action and seed treatment and inspection specifically for blight have reduced such sources to the point where no more than one or two are found in the entire state of Maine in any year. The reproduction time for the pathogen is a minimum of one week. Disease spread is usually very local – secondary infections typically cluster within a foot or two of the original strike. However, if conditions are right – wind, very overcast and wet conditions – blight can be spread ten miles or more IF there is a very large source of heavilly infected plants – typically tens of acres. These vast numbers of spores compensate for the near-negligable chance that a spore from an individual plant will find a target at such a distance. So, put this all together. The windborne spread of blight under the most optimum of conditions is not much more than ten miles per week. Put another way, it would take blight months to spread on the wind alone from farmed areas on eastern Long Island to upstate New York. Because there are so few sources of blight, places remote from large agricultural production areas rarely get that disease, which makes tomato gardening possible almost everywhere. However, shipment of infected plants to stores throughout populated areas and secondary movement to gardens completely short-circuits the protection afforded by slow spread. Instead of blight appearing latter in the summer in a few places, it can be everywhere early in the, with disasterous consequences. Additionally, these restrictions on windborne spread make it impossible to claim that tomato plants in stores for only a week could suffer twenty percent infection or more without hundreds if not thousands of acres of infected crops scattered in the vicinity of every affected store in the state. When blight was discovered in the chain stores, not a single lesion had been found elsewhere.

  2. As I’ve followed this story, I have wondered about seed transmission of late blight, which Dr. Lambert here affirms as one of 2 possible sources of the disease. My guess is that the presence of the disease on Bonnie Plant Farms’ product will be traced to one or more smaller seed sources, since the abundance of non-hybrid or “Heirloom” varieties in their line necessitates bringing in seed from sources other than the mainstream, “commercial standard” vegetable seed companies. I am all for small companies surviving against the corporate behemoths, but I question whether some of these smaller seed companies conduct the same level of seed testing and treatment that the larger companies do. Responsibility would therefore fall upon Bonnie Plant Farms to insure that only correctly treated seed finds its way to their regional growers, even if they have to treat it themselves, and if such seed is not available for a given variety, then that variety should not be grown as part of their line.

  3. “Seed” treatment refers to potatoes grown from cut potato pieces rather than the true seed of tomato. Supposedly, blight can be transmitted on tomato seed but this is apparently rare (not that seed sanitation is unimportant. A more likely source of blight would be the seedlings grown in a southern area already exeriencing blight, which are then shipped north. In this case, the regional growing stations start with seedlings from core greenhouses, not seed.

  4. We are home gardeners in a very isolated spot on Cape Jellison,Stockton Springs. We grow all our own tomato seedlings from seed bought either from Johnny’s Selected Seeds or FEDCO. We just removed every one of our 40 tomato plants because we identified late blight on them. It had not reached the spore stage, but our potatoes are near them and we hope we saved them by removing the tomatoes.

    We are puzzled why we would get it because of our isolation; Penobscot Bay is our front yard, woods all around, and just home gardeners, not commercial fields, to the West of us.

    We would hope the Extension Service would be mapping occurences of the disease in Maine. It is not true that the disease is just on big acres – our UPS driver told me he has it on just a few plants.

    More should be published on the spread and treatment of the disease in every major newspaper in the state.

  5. The first field find in Maine was a home gardenn in Ellsworth, late June or early July. The center of the problem is in Dresden, but given that people were taking home affected tomato plants from as many as 42 stores in the state, it could be anywhere. The Prison Farm in Warren destroyed ten acres of potatoes several weeks ago. We are just north of Bangor and have had it for three weeks. Having a large source nearby speeds things up, but isn’t essential with enough time and weather. Once things get going there are a lot small local sources that aren’t known or don’t get cleaned up. Googling The Maine Cooperative Extension Service or other sources for late blight should provide you information. Their scouting is restricted to areas with large potato acreages, but they do very well for a state that’s broke.

  6. I strongly agree with nancy, I am in waldoboro and had been spraying my tomatoes with seranade everyweek and last week they took a turn for the worst with late blight. I started my plants from seeds, from jonny’s or fedcos. I knew nothing about the large scale of the outbreak. I wish more was published in our local newspapers like the LINCOLN COUNTY NEWS. Some home gardeners might not know what is on there tomatoe plants and how to properly dispose of the material.

  7. Nancy, Anonymous – Bangor daily news has been publishing articles since late June, informing home owners on how to identify and properly dispose of infected plants. The Maine Cooperative Extension has been doing everything they can to make homeowners aware of this disease in an attempt to protect gardeners from crop failure, homeowners and commercial growers alike. http://www.mainepotatoipm.com is a website set up for commercial growers, but also may have useful information for you. If you look at overall weather and air flow patterns, such as Acadia National Park references for the smog we see in Bar Harbor – you will see that spores may have blown up here from as far south as Boston, MA, into the Penobscot Peninsula Area. With our excessive amount of rain and humidity this summer it is not too far fetched to say that the spores can travel over 40 miles from the living source. Dresden is really not that far down the coast from where you are…and it was identified there over a month ago. I would say you would be better off to rely on the Cooperative Extension website and Bangor Daily News if you want to be up-to-date on these things in the future. Best of Luck.

  8. A few more points about late blight sources and spread. The pathogen survives the North American winter in live tissue, never in soil. Only southern Florida has active year-round blight, and in wet years this may sread north in the late winter and spring. In the North, the historic sources in the spring infection have been either large piles of dumped potatoes or infected seed. In recent years, regulatory action and seed treatment and inspection specifically for blight have reduced such sources to the point where no more than one or two are found in the entire state of Maine in any year. The reproduction time for the pathogen is a minimum of one week. Disease spread is usually very local – secondary infections typically cluster within a foot or two of the original strike. However, if conditions are right – wind, very overcast and wet conditions – blight can be spread ten miles or more IF there is a very large source of heavilly infected plants – typically tens of acres. These vast numbers of spores compensate for the near-negligable chance that a spore from an individual plant will find a target at such a distance. So, put this all together. The windborne spread of blight under the most optimum of conditions is not much more than ten miles per week. Put another way, it would take blight months to spread on the wind alone from farmed areas on eastern Long Island to upstate New York. Because there are so few sources of blight, places remote from large agricultural production areas rarely get that disease, which makes tomato gardening possible almost everywhere. However, shipment of infected plants to stores throughout populated areas and secondary movement to gardens completely short-circuits the protection afforded by slow spread. Instead of blight appearing latter in the summer in a few places, it can be everywhere early in the, with disasterous consequences. Additionally, these restrictions on windborne spread make it impossible to claim that tomato plants in stores for only a week could suffer twenty percent infection or more without hundreds if not thousands of acres of infected crops scattered in the vicinity of every affected store in the state. When blight was discovered in the chain stores, not a single lesion had been found elsewhere.

  9. As I’ve followed this story, I have wondered about seed transmission of late blight, which Dr. Lambert here affirms as one of 2 possible sources of the disease. My guess is that the presence of the disease on Bonnie Plant Farms’ product will be traced to one or more smaller seed sources, since the abundance of non-hybrid or “Heirloom” varieties in their line necessitates bringing in seed from sources other than the mainstream, “commercial standard” vegetable seed companies. I am all for small companies surviving against the corporate behemoths, but I question whether some of these smaller seed companies conduct the same level of seed testing and treatment that the larger companies do. Responsibility would therefore fall upon Bonnie Plant Farms to insure that only correctly treated seed finds its way to their regional growers, even if they have to treat it themselves, and if such seed is not available for a given variety, then that variety should not be grown as part of their line.

  10. “Seed” treatment refers to potatoes grown from cut potato pieces rather than the true seed of tomato. Supposedly, blight can be transmitted on tomato seed but this is apparently rare (not that seed sanitation is unimportant. A more likely source of blight would be the seedlings grown in a southern area already exeriencing blight, which are then shipped north. In this case, the regional growing stations start with seedlings from core greenhouses, not seed.

  11. We are home gardeners in a very isolated spot on Cape Jellison,Stockton Springs. We grow all our own tomato seedlings from seed bought either from Johnny’s Selected Seeds or FEDCO. We just removed every one of our 40 tomato plants because we identified late blight on them. It had not reached the spore stage, but our potatoes are near them and we hope we saved them by removing the tomatoes.

    We are puzzled why we would get it because of our isolation; Penobscot Bay is our front yard, woods all around, and just home gardeners, not commercial fields, to the West of us.

    We would hope the Extension Service would be mapping occurences of the disease in Maine. It is not true that the disease is just on big acres – our UPS driver told me he has it on just a few plants.

    More should be published on the spread and treatment of the disease in every major newspaper in the state.

  12. The first field find in Maine was a home gardenn in Ellsworth, late June or early July. The center of the problem is in Dresden, but given that people were taking home affected tomato plants from as many as 42 stores in the state, it could be anywhere. The Prison Farm in Warren destroyed ten acres of potatoes several weeks ago. We are just north of Bangor and have had it for three weeks. Having a large source nearby speeds things up, but isn’t essential with enough time and weather. Once things get going there are a lot small local sources that aren’t known or don’t get cleaned up. Googling The Maine Cooperative Extension Service or other sources for late blight should provide you information. Their scouting is restricted to areas with large potato acreages, but they do very well for a state that’s broke.

  13. I strongly agree with nancy, I am in waldoboro and had been spraying my tomatoes with seranade everyweek and last week they took a turn for the worst with late blight. I started my plants from seeds, from jonny’s or fedcos. I knew nothing about the large scale of the outbreak. I wish more was published in our local newspapers like the LINCOLN COUNTY NEWS. Some home gardeners might not know what is on there tomatoe plants and how to properly dispose of the material.

  14. Nancy, Anonymous – Bangor daily news has been publishing articles since late June, informing home owners on how to identify and properly dispose of infected plants. The Maine Cooperative Extension has been doing everything they can to make homeowners aware of this disease in an attempt to protect gardeners from crop failure, homeowners and commercial growers alike. http://www.mainepotatoipm.com is a website set up for commercial growers, but also may have useful information for you. If you look at overall weather and air flow patterns, such as Acadia National Park references for the smog we see in Bar Harbor – you will see that spores may have blown up here from as far south as Boston, MA, into the Penobscot Peninsula Area. With our excessive amount of rain and humidity this summer it is not too far fetched to say that the spores can travel over 40 miles from the living source. Dresden is really not that far down the coast from where you are…and it was identified there over a month ago. I would say you would be better off to rely on the Cooperative Extension website and Bangor Daily News if you want to be up-to-date on these things in the future. Best of Luck.

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