A Frolicsome Weed
Tomato Late Blight Reports--and an idea

Have you seen this tomato disease?

For the past few years, I, along with many other gardeners, have been losing tomato plants to a disease called tomato and potato late blight. It is the very disease that killed the Irish potato crops in the 1800s and left so many people to starve or emigrate. Fortunately, I am not dependent on my tomatoes for my very survival, but it has been distressing to lose so many tomatoes to this ugly disease.

What I want to know is who else in the San Francisco Bay Area has been having this problem. It shows up as brown lesions on stems and leaves. Often, the stem will have a brown area with green above and below, or just part of a leaf will be brown. The fruit will have a brown, shiny surface, especially near the stem, that usually starts when the fruit is still green. The plant may turn completely brown and die

My photos of this disease aren't scanned, but I can send you to a pdf file from the University of Hawaii at Manoa that shows many photos. It is at www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-45.pdf

The only tomatoes on the home garden market that are said to have any resistance to this awful disease are Legend (resistant unless there are a lot of spores around) and Juliet hybrid (tolerant of the disease, meaning it survives). Anecdotally, something called 'Matt's Red Cherry' has been called resistant, but I don't have a source for it at the moment. Probably there are some heirlooms with some resistance, though I haven't encountered them.

So please, if you will, if you have any experience with tomato late blight in the Bay Area, send me a comment. Or if you do not have the problem, I am very interested in knowing that too! Please tell me where your garden is located--city, general part of city (as in Northwest SF, or Hills of Berkeley).

I have been making test plantings of research varieties that are supposed to be late blight resistant for several years, and none have worked yet. I am hoping to get an idea of how widespread the problem is here and maybe get some attention from tomato breeders.

Thanks for any input you can offer!


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Same problem here...7 blocks from beach in Santa Monica, CA (lots of marine layer here...).

Susan Kegley

Ack! All of my tomato plants got infected with late blight just over the last week. The cherry tomatoes were hit first and hardest (Sungold and Sugar Sweetie), but it's also affecting Glacier, Red Siberian, Stupice, Black from Tulla, Green Zebra, and Roma. Less affected are Japanese Trifele Black and Black Sea Man. The tomatillos are totally fine, at least for now. The peppers in the same bed are mostly OK, but seem to have some other moldy thing going on with just the fruit. Our garden is in North Berkeley about half-way up the hill. The weather has been foggy and miserable for about a month and the tomatoes are probably too close together, which exacerbated the problem. I'm destroying all infected foliage, but it's taking a while because the plants were huge.

Pam Peirce

Yes indeed. Late blight is very bad news. I have read that Serenade, a fungicide based on the common soil bacterium Bacillis subtilis, will help control the disease, but you have to start applying it when the plants are still small, and apply it on a regular schedule as the plants grow. I don't think it will cure already diseased plants. But it is something to consider for next year.

Meantime, clean up all the fallen debris from your diseased plants--every shrivelled up fallen leaf, and get them out of your garden. Watch out for potatoes too, that come up from tubers you missed when digging. Try to keep any members of the tomato/potato plant family out of your garden from now till next April. I will post some photos of late blight soon.

Bette Kroening

Have just lost 150 plants to blight in Sebatopol, some of which were Legend (others were Chadwick, Siletz, Stupice & Perone). Very sad. Farmer friend says it's also in the Capay Valley where it's really hot, and all around.

Pam Peirce

This doesn't sound like late blight. I can't give you a definite answer, not having seen the plants, but it sounds more like a vascular rot--a fungus that is clogging the cells that transport water and food in the plant. Maybe fusarium crown rot? Try looking up Fusarium oxysporum (or you may find it as Fusarium oxysporum radicus-lycopersici) on the web to learn more about it and see pictures. That disease is indeed often transmitted by spores in the soil and takes 4 years to die once it is in the soil. If you pull out a plant with fusarium, and cut the stem lengthwise near where it enters the ground, a chocolate brown lesion will start at the soil line and continue upward for a few inches. (Maybe you can get in touch with the Sonoma County Master Gardeners and get help with a diagnosis.) If fusarium is the problem, you want to get varieties that have the letter "F" after their variety name, as these will resist the disease. There are quite a few fusarium-resistant hybrids. The heirlooms could be resistant too, but usually haven't been tested, so don't have the "F" label. I guess you will find out. Keep the labels on the plants, so you will know which is which. You can use a hole punch to make a hole in the label and twist-tie it to the stem of the plant.

Kevin McCullough

I live in Windsor - just north of Santa Rosa. Both my garden & my neighbor's garden had a similar problem - the last 2 seasons. I'm not sure it's the same blight you describe .... but our tomato plants started vigorous and healthy just until they started producing fruit. The symptoms start as a "yellowing" or "browning" of the base of the plant (stem & leaves) that works up the plant. After a few weeks of this, the only green on the plant is at the very top. I'm seaching for answers. Is the problem in the soil? Can I do anything to prevent it this season?

David Heintz

And now I'm worried that composting these plants, or overripe fruit may reinfect through the compost, which does not heat up or sterilize.

David Heintz

I'm just now starting to think this is what is messing with my tomato crop. I've seen some in the past but thought I had burned the plants with too much plant food, overwatered or something. But it's spreading and very consistent. Plant start out fine, grow big, produce good fruit, then gradually: smaller fruit, brown leaves, dead branches, uneven ripening, etc. I'm ready to pull them all out, rake up leaf debris and try next year with resistant strains if I can find them. I'm in Walnut Creek, East Bay, Mt Diablo foothills.

Steve K

Gee, been growing tomatoes in the same garden (moving location every season) never a problem. This year all of my tomatoes are dying, with heirlooms being hit the hardest. They were all large healthy plants loaded with fruit and bang.

I'm in the North Bay, Glen Ellen.

tony D

I am in Southern California in Mission Viejo and had never seen anything like this when in other areas.
We had a cool wet beginning couple of weeks in early summer and by the time the sun came out they were already on their way out.
Looks exactly like the photos but the fruits never turned brown - all of the other symptoms pics are spot on...
Tried all of the normal stuff like tobacco tea and even store bought "organic gardening" fungicide but nothing could save them.
Now I have a few green and pink,tiny tomatoes on what look like dead vines.
This year I did buy a six pack of heirloom tomatoes instead of identical hybrids.
Wiping the tears from my eyes hearing that it is not just that my green thumb has gone brown.

Warren A. Jacobs

In case you haven't heard, we are apparently experiencing the start of an unprecedented epidemic of late blight here on the east coast. My garden of approximately 80 mostly heirloom tomatoes seems to be in the process of falling victim - possibly due in part to my having brought in an infected plant from one of the growers suspected as a source of the innoculum. I hav posted my story at www.jacobstreesurgery.com ,and intend to post updates soon following lab test results. Legend is one of the varieties I'm growing. Your comments concerning genetic resistance have inspired me to track which if any varieties escape death. The first plants to become symptomatic were Rutgers Ramapos- a recently reintroduced hybrid- and I have already rogued half of them.


Hi Andy,

A plant disease expert at UC Berkeley tells me we don't have the sexual cycle of tomato late blight in California, and if that is true, then the asexual spores can't live outside of the host plant for very long. If you take out the diseased plants and pick up all of the fallen plant parts and keep them out of your garden from November through April, that should be long enough for any remaining asexual late blight spores to die. But you have to take out any other possible hosts in that period too, like volunteer potato plants, eggplant, possibly pepper, ground cherry, wild solanums.
If you do this, you should be free of last season's late blight, though more asexual spores could blow in from nearby.
Problem is that the blight strikes late, and then people lose interest in their dead tomato plants, so they, or parts of them that fell off, lie there and harbor spores for the next season.
I don't know who you consulted. Maybe they have the sexual spores, the ones that do live longer, up in Oregon, but I don't think we do here.

Andy Clason

I've experienced late season blight on my tomatoes for the last four growing seasons. I live in El Cerrito, and have tried a dozen different varieties in hopes of finding one resistant to the disease. As one of the other posters mention, the disease doesn't hit until late in the plant's development (late July/early August) so I have a chance to get a few tomatos in August. By September, it's all over for the year.

A garden expert in Oregon told me that late blight lives in the soil, and can be dormant for up to seven years. So even if you stopped planting in a diseased plot for half a decade, you still might get blight when you replanted. This guy recommended baking all of the soil in the garden to kill the disease(!). This seems completely impractical, but this year I did buy a bunch of extra soil in attempt to "bury" the old, possibly infected soil. We'll see how it goes. It's mid-June and no sign of blight yet, although there usually isn't. I'm holding my breath.

John Bowers

garden 2008
I do not live in the Bay area but have the same problem. I live on the central coast (Arroyo Grande, Ca) We are dry here in the summer but suffer from marine layer.
I didn't know what is was until I found this web site. I planted 4 different varieties and all my plants were doing very well and were mature, they were full of blossems. The blight started at one end of the row and within 2 weeks it was all the way throug every plant (15) and I lost everything.
I have never had this problem before and I am don't know if I will even plant tomatoes this year. I hope their is a blight resistant tomatoe that could save us.

chuck b.

This destroyed a half-dozen vigorous tomato plants in a community garden plot on the south side of Bernal Hill. It happened during a week of summer fog in 2006. It was very quick and totally catastrophic. Stupice and/or Early Cherry--can't remember. Never tried again.


I'm in the Mission, and planted cherry (not sure which kind), roma, black krim, siberian and I believe hierloom. All my tomatoes were fine, even the black krim and heirlooms that lasted until October/November. I did see a few browning leaves and white spores, but not what I would call mold as described in the pdf -- pretty sure it was mildew.

My mother-in-law down in Felton got hit with it badly as did most of her neighbors.

If only we could invent oxalis blight. Good god that stuff in nefarious. It is my enemy. It has punched through weed fabric and lifted up bricks I just cemented in. Ugh.


The backyard tomatoes I grew last year (in the USF area; Fulton St) were all destroyed by what seemed to me to be late blight. The worst affected plants were the SuperSteaks, which I'd rigged up a little greenhouse to try to preserve heat and light; as a result they were moist all the time, and I guess the blight loves that. The Early Girls seemed the most resistant to it, but they were also affected.


I live in a rather sunny part of Noe Valley, here in San Francisco, and my tomatoes seem to get late blight every year. But it happens very late in the season, so I get a lot of tomatoes first. But it looked exactly like the images in the PDF. I'd love to help solve this problem!

Roy Stahl

I live in El Granada, just a few miles from where you presented to our vegetable gardening group last summer.
If the brown fruit is a requirement for the disease, then no.
Browning on leaves and the mold I have seen in the past.

Last year I planted Stupice and Oregon Bush in a wine barrel that I knew had no problems.
The tomato I planted in an area that 'may' have had a problem was a 5th generation cherry tomato that sprouted out of our compost 5 years ago and it has gotten used to our garden.

Rather than rely on my aging memories, I will pay close attention this year and also see if I can gather data from other local Half Moon Bay area gardeners.


I have grown tomatoes the last two years in my Inner Richmond district garden. I have had some disease problems, but nothing consistent with late blight.

I do not know of any other vegetable gardeners in my neighborhood, I haven't grown potatoes, and prior to my garden, the yard was nothing but weeds. (We rent, and no one had used the yard much before we moved in.) I would not be surprised if there are no nearby carriers of late blight.

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