late blight continues to kill tomatoes

Pests & Pathogens, Tomatoes

On yesterday’s visit to my community plot I found late blight on all of my remaining tomato plants. My next chore will be to remove them all. Bag and dispose in the trash. I was hoping a few of my plants would have survived, but all have succumbed. 16 plants – 11 varieties that I babied since March.

I also had a sad note from the New Hampshire Farm that I distribute CSA shares for. Its a long but very interesting note so I’m posting most of it here. Very sad to think of all the lost crops for local farmers.

I’m nervously watching my little patch of 8 tomato plants tucked in next to my house. But, with fingers crossed, they look fine so far. I make sure not to go near it after being at the community garden. Looks like another day or two til the big tomatoes ripen.

Late Blight appeared on our farm last week. Thursday, in the cherry tomatoes, enough small lesions that we took out the entire planting immediately, with the hope of preventing spread to our main tomato and potato fields. With several advisors from UHN Agricultural Extension, we examined our main season tomatoes and potatoes, and found no sign of Late Blight on Thursday. But by this morning, I found blight lesions in various places in the tomato field, including on one ripening tomato.

The quick summary for you again: Late Blight is a fungus endemic to the southern U.S. that, in wet years, makes its way north to New England. This is usually in September or later, and affects a few potato and tomato fields after the main harvest is concluded. It is not harmful to humans, except in terms of crop loss. It’s not normally (never before this season) a big deal for most NE farms. This year, it seems that a single nursery from the south distributed infected tomato seedlings to Wal Mart and Home Depot, among others, who sold those plants to home gardeners across the Northeast. Once these plants were planted outside, the fungus began spreading across our region, some three months ahead of the typical schedule and in time to do serious damage to the harvest of both gardeners and farmers alike. Weather conditions suited the Blight perfectly – cool and wet – and we haven’t yet seen the long stretch of hot and dry that might put the Late Blight in check. This week may be the dry and warm we’ve all been hoping for, though it’s probably too late for the tomatoes on our farm.

There is no organic control for this fungus once it appears, and conventional sprays have limited effectiveness as well. The organic copper fungicides that we have used over the past 6 weeks may have some preventative effect, but because they are washed off in every rain, this has been a challenge. With the blight on our farm, the only options are to burn, bury, or discard affected plants to try to slow the spread through our farm and to other growers.

So right now, we are facing limited choices and a mountain of work. The sunny weather will be on our side as we proceed. In the tomatoes, the cherries are already untrellised and tilled in. Because the main season crop looks beautiful and is just beginning to ripen, we’re going to try pulling out infected plants one by one, as well as using our hand-held flame weeder to burn infected leaves. Honestly, we’re not hopeful, particularly because other farmers who are further along with the blight aren’t reporting great success with these “pruning” strategies. We’ll try this approach for a few days. Of course, we have a whole farm to care for, so cannot let everything else go for a potential fool’s errand in one crop (even one of the favorites).

Potatoes, we are thanking our lucky stars that we already have a reasonable crop underground – blight notwithstanding, it’s been a great potato growing season. However, the Late Blight spores can quickly travel through the vines and rot the potatoes underground. We’ve decided to kill the potato vines, and enjoy the harvest that is already sized up. Up and down our valley, farmers are doing the same. Conventional farmers use an herbicide for vine kill, and it is certainly disconcerting to see dead potato fields all over in early August. As organic growers, we have a harder road to hoe, as we attempt to mechanically kill all of the vines without damaging the potato hills underneath. First, we’ve been mowing the field. Later today we’ll go through with weedwackers (yes, that’s 8 miles of weedwacking!). When that’s all done, we’ll sweep through with the crew and loppers, knocking back the last remaining living stubs. We’re learning that there’s no such thing as “overkill” when it come to late blight. We’ll see a smaller yield, as some spuds would have continued to size up over the rest of the summer. And we’re uncertain if we’ll lose some storability with such early vine kill – the potatoes have to store underground for at least two weeks after the vines are dead, to set the skins for storage. We’ll see. But plenty of mashed potatoes remain in our future this season!

Of course, we’re disappointed about (likely) losing the tomatoes, as we know you are as well (why couldn’t it be the turnip blight?!). The epidemic proportions beyond our farm, as well as the connections to large-scale, industrial agriculture, make the blow a bit harder to swallow (or not swallow, as the case will be). We are so deeply sad for many other farmers who are seeing serious financial losses due to the blight. We hope you understand that there is abolutely nothing that we can do to have this crop for you this season. I really, really, really wish we did (can you hear me stomping my feet now?). Of course, everyone knows, not just farmers, that hard work doesn’t always lead linearly to good results. We are affirmed in our commitment to growing for you, through Community Supported Agriculture. We are grateful for your support and understanding.

Jenny and Bruce, Picadilly Farm LLC, Winchester, NH

And another quote added Wednesday, August 5. This from a CSA farmer in White River Junction VT, after blight landed on his farm last week:

“All this reminds me that while climate change is the big cloud hanging over the land, it’s actually transportation that has done the serious damage to our ecosystems so far. (Both problems being manifestations of fossil fuel use.) We humans love to travel, and we love to move stuff all over the place for fun or profit or by necessity. This brings new species into contact with one another, often to the detriment of one or both. Most of the damage in VT/NH has been to our forests so far – chestnut, elm, butternut, and beech essentially gone, with ash, hemlock, and possible sugar maple in imminent peril. Agriculture is in less danger, primarily because everything we grow is not native to here anyway. Hopefully in this case, a nice cold winter will wipe out the blight and bring us a fresh start next year.”

14 Comments. Leave new

  • My heart is breaking for you and your local farms all the way in Hawaii. :o( I'm sending sunshine your way!

  • Thanks for posting the above letter. It really is a sad season for many farmers.

  • Thanks TANYA! That's so nice of you.

    Our weather is actually OK now. Alternating wet and dry. And its getting nice and hot. Its just that when it does rain, about every three days, we get several inches. More is due tomorrow evening.

    In July, Boston had 6.9 inches of rain and our normal July average is 3.06 inches. In Providence they shattered records for the wettest and coldest July ever (Boston Globe article).

  • It's been quite a year for gardening – and not in a good way. Can't believe this is the year I BEGAN gardening – it's been an uphill challenge for sure. But, not blight yet, though we have vigilant watchers at our community garden! And if it comes, into a plastic bag my toms will go.

  • nice job

  • I am devastated- found late blight on all my lovingly tended tomatoes in my home garden today. They were so big and beautiful and just about to ripen. I am crushed. Is it possible to save the green fruit and let it ripen alone, or do they need to go too? What a waste…

  • Katie,

    If you've just found it and it isn't too bad, I would spray with copper spray. I used Concern a copper soap. It will give you at least 2 more weeks. Also remove all infected growth and dispose of it. If the fruit have no fungus spots, definitely pick them once they show a little color, wash them well, and ripen them inside.

    Sorry to hear about that.

  • KatieF,

    You can also make piccalilli from green tomatoes.

    I haven't yet actually preserved anything, for fear of poisoning all my relatives, but my Mom's piccalilli recipe keeps a very long time in the frig. I usually make enough to carry over to the next year and store it in the fridge. It store well because it's acidic, I am just guessing.

  • Kathy
    Does it effect the tomatoes? If you have only a few infected leaves can you cut them out and save the plant? It looks a lot like septoria.How to tell the difference. New gardener and really confused!

  • If you don't have any rotting brown areas on the stems, its not Late Blight.

    Late blight will cause rotting brown areas on the stems of the tomato plant as well as brown nickle sized spots in the leaves. In wet conditions, there will be white fuzzy fungus on the underside of the brown patches. Its aggressive and will progress til it kills the plant.

    Late blight will also cause the tomatoes to rot. You can't miss this. Its messy.

    The sooner you remove late blight affected plants, the more you reduce the spores that will be around next year. But most people (myself included) spray the plants and remove affected plant matter and try to get some tomatoes. You may get some unaffected tomatoes, and you can cut off affected areas of a tomatoes and eat the rest of it. (Late blight doesn't affect people.)

    Two other common fungal diseases, early blight and septoria leaf spot, don't kill the plant, but cause defoliation and reduce yeild.

    Septoria leaf spot fungus causes numerous small brown spots and yellowing of the leaves moving from the bottom upwards. (I don't think leaf spot hits the tomato fruits much, but the fruits don't grow well because of defoliation. This was what happened to my plants last year.)

    Another common fungal disease of tomatoes is early blight, which results in irregular brown leaf lesions or spots up to 2 inches in diameter. Often the lesions coalesce causing the leaf to turn yellow, dry up, and fall off the plant.

    Even without any fungus the leaves at the base of a tomato plant will yellow since they are blocked from getting enough sunlight by the upper leaves as the plant grows. Its always recommended that you remove the yellowing lower leaves, especially in wet weather to increase airflow and reduce dying growth susceptible to fungal attack.

    For an organic approved control for any of these fungi, use a copper spray (every 7-10 days and reapply after heavy rains) and remove and destroy affected plant matter. (I've also heard that the non-organic fungicide Mancozeb as a routine application starting early in the season works well.)

    Good sanitation reduces spores. In the fall, till plants into the soil or remove from the garden. Don't plant tomatoes in the same place more than once in 3 years. Purchase clean seed or healthy transplants. Stake or cage plants to allow for air movement. Place straw or plastic mulch around the base of each plant to reduce splashing. Avoid overhead irrigation of plants.

  • blight is so brutal. I've lost all 46 of my tomato plants. It set in while I was away and after a whole week of rain was too advanced by the time I got back. I thought I'd managed to salvage at least a few trusses of green toms for chutney making but after a couple of days the tell tale brown spots appeared. A few days after I'd binned them I noticed the two house plants nearby where infected as well!

  • Two Toad Farm in Lebanon Maine lost 5,000 lbs of Certified Organic (mostly heirloom) tomatoes for its Summer CSA as well as local markets. Thank you, Bonnie and Home Depot, KMart, Lowes, et. al.

  • It really is a terrible shame. All that hard work and investment at small farms has gone down the tubes. And we all wonder about next year.

  • Blight did much damage to our garden here in Carver,Ma. My wife and I make and can our own salsa and we were lucky to get a little less than half what we harvested last year. I fought blight last year toward the end of the growing season, but it was nothing like this year!
    As to the farmer's note in White river junction at the end of your post I have to say that many of us who concern themselves with the environment sometimes take the whole Global warming theory too far, blaming it for every negative we experience. But they not only blame global warming, which is a natural occuring cycle in weather patterns on the face of the Earth more to do with heavy sun spot activity than with man's very existance, in cooling periods like we are experiencing now there has been an extreme lack of solar activity as was the case for the little ice age's from 1150 to 1460 and again from 1560 to 1850. In both cases man's industrial pollution and burning of fossil fuels were almost non existant except for maybe 30 years in the 1800's and even then it would not have been heavy enough to alter global temps. Now the same author of that note is blaming man's transportation of goods and himself?? Why don't we all just kill ourselves to satisfy the extreme environmentalists? Sometimes things just happen in nature and we can't control it. Species die off. new ones are found and the cycle continues. Yes, do whatever you can to prevent pollution and treat the Earth and animals with respect, but sometimes things are out of our hands. The human race isn't always to blame for every ill that comes upon the Earth. Hell, one volcanic eruption puts more caustic gases and carbon in the atmosphere than we have in 200 years I imagine. Good blog by the way.


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