Distance Late Blight Airborne Spores Can Travel?

13 years ago

""Most other diseases, we can live with," McGrath said. "With late blight, you lose everything, and it's very contagious, with spores carried on the wind.

Late blight is caused by a fungus-like organism called an oomycete that's spread by airborne spores. It flourishes in cool, wet conditions and can survive during the winter in living tissue, such as potatoes buried underground."

Ok, my question if anyone knows...How far can these spores travel? For instance, is a garden planted 220 feet away from a LB infected garden safe?

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Comments (11)

spiced_ham
13 years ago
I think it is something like 30 miles per day.
platys
13 years ago
I caught late blight from a garden about 3 blocks away from me - you could watch it invade from the infected garden, to mine, and then down the street to all the hanging tomatoes everyone had last year.

I'm so spraying this year. :)
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Here is something you might find interesting... My garden had plenty of early and late blight and septoria leaf spot. The following year I installed a hoop house over half of it and planted tomato plants inside and out (8 in/10 out). I sprayed/coated the outside plants several times (during wet periods) with a well known product used to control these diseases. The inside plants were treated only once (lower leaves only). Soil was the same inside and out (top quality and ammended-well with organic compost). The plants in the hoop made it all the way to freeze disease free! No blight at all inside. The outside plants, well, they were pretty much toast about 45 days earlier. The hoop house makes it sooooo much easier to garden. Never had to worry about pruning wet foliage (as it was often wet outside from the morning dew and rainstorms). The hoop house was not sealed off. It was about 50% open (no side or end walls). The plastic on top kept the direct rain off but there was some splashing along the sides. (I use leaf mulch to keep the soil from splashing up the stems). I can go on-an-on about the benefits of the hoop house but perhaps best is the reduction in plant disease. (but gardening during thunderstorms is pretty cool too!) My overall production was up more than 50%. And I suspect that with the dry and sunny conditions inside the hoop structure this winter (off-season), the bacteria and molds won't stand a chance (but I will still rotate anyway). One note, I trained my tomato plants to a rope attached to the top of the hoops. It grew vine-like plants vs. bushy plants you get on cages. It keeps the foliage drier and blight at bay. I am now less concerned about growing heirloom varieties. I hope I didn't get off topic.
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The issue is survivability of the fungal spores from plant through composting and then in the tea. There are so many variables, coupled with an unidentified pathogen, and uncertainty of whether the composted leaves were even infected, that I don't believe anyone can suggest with any certainty what the probability of spore survival in your situation will be. So, it's a crapshoot. Reports of fungal spore destruction during composting of tomato vines infected with either late blight fungus (Phytophthora infestans) or early blight fungus (Alternaria solani) are varied. Spores of both can survive a year or more on infected plant tissue and in soil. Most reports indicate that spores associated with early blight is destroyed in hot thermophilic composting followed by adequate maturation. Spores associated with late blight, however, have been reported to survive composting. As for a compost extract or tea, I've not seen anything that indicates what impact the brewing process may have on spore survival for either. If the composted leaves were disease and spore free, the risk would be probably non-existant. There have been a lot of tomato plant residues composted by many gardeners without problems following. The concern arise if there were spores present, either on the plant material or in any attendant soil that came with that material. If the plant materials that you composted were infected, there is a clear risk. But, I don't think with what you've provided anyone can gauge whether the risk is high or medium or low.
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mulio
13 years ago
no

when they say carried on the wind they mean miles. all that depends on topography, vegetation, structures and air currents.
catman529
13 years ago
I read once that they don't last very long in the air, or at least if it's sunny or otherwise not cool and wet. Also they could be lessened if rain is falling from the rain catching the spores and bringing them down (hopefully not on any tomatoes). OK I'm no expert though, but I really hope I don't see any LB this year considering how bad it was last year.
digdirt2
13 years ago
Agree with mulio - miles and miles. Path plots done on the NE spread last year provided an excellent picture of how topography and air currents affected it radiating out from central cores - 2 miles here, 26 miles there, dead stop here, etc.

The current Gulf oil spill drift pattern is a good comparison although it has no sheltering valleys nor high blocking hills to interfere but it rides the water currents just as fungus ride the air currents.

Dave
carolyn137
13 years ago
The potato cull piles in Western NY state have often been the source of Late Blight as carried by wind and rain across the state to the eastern part of NYS, where I live. I didn't look up the distance but that would be maybe around 500 miles from West to East across the state b'c our prevailing winds and storms are almost always from West to East, excepting nor'easters and the like.

Carolyn
bigdaddyj
Original Author
13 years ago
OH man, now I'm worried. Last year my neighbor definitely had LB in late August I think it was. Her plants all croaked in days. For like the tenth straight year she asked me for the same advice and once again I gave her the same advice but it's obvious she'll never use it. They are VERY nice people BTW. BUT, she buys her plants at HD, crowds them in cheek to jowl, overhead waters almost every evening, shoots MG at them as soon as they start to yellow, sprays the bejeebers out of them with bug killer, all things I DON'T do! Last year I must have been lucky...NO LB from her garden. I start all my plants from seed and so far this year they are doing great despite two nights of 34F, three days of 50MPH winds and a hailstorm! I sure hope this local HD doesn't have any LB infected plants for sale this year and my luck changes. She doesn't grow tomatoes but she does grow millions of beets. Please don't tell me LB can over winter in Beets!???
bigdaddyj
Original Author
13 years ago
Last two lines should read:

She doesn't grow POTATOES but she does grow millions of beets. Please don't tell me LB can over winter in Beets!???
spiced_ham
13 years ago
My row of tomatoes planted next to the house under the eaves (protected from most rain), stayed LB free for a month after the rest of the garden was hit. LB is a water mold and needs the water to infect the leaves so it would be possible to tarp over top of a small tomato patch on rainy days.
gardningscomplicated
13 years ago
bigdaddy - Which way does the wind usually blow? If she's typically downwind, maybe you'll get lucky.
bigdaddyj
Original Author
13 years ago
Out of the northwest, seldom out of the southeast! Hadn't thought of that. Thanx! Her garden is definitely down wind from mine...:-)

Distance Late Blight Airborne Spores Can Travel?

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