Tuesday, June 30, 2009

Tomato Late Blight

Hello again,

Good gardening friend David K (check out his regular garden blog @ http://gardenmaine.blogspot.com/ forwards this email from the Maine Organic Farmers and Gardeners Association (MOFGA):

"If you are growing tomatoes or potatoes, whether in your garden or on multiple acres, you need to be watching for late blight.
Tomato seedlings sold at a number of large 'big-box' retailers in Maine and the Northeast are apparently infected with the disease, and it's already started to appear around the region....
If your plants are infected, the best control is to pull the plants immediately and seal them in a bag for disposal so the blight spores don't spread further."

Check out this link http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=1084 for a pretty good description and pictures of late blight.

You can always contact us at Skillin's (check http://www.skillins.com/ for contact numbers or info@skillins.com) with any questions!

Mike Skillin
Skillin's Greenhouses
June 30, 2009


David said...

I've been following this story closely: if your garden includes potatoes, tomatoes (and even eggplant, but no others), then please watch for any sign of this blight. It's a fast-moving disease, the same one that created the great Irish potato famine in the 19th century, and could devastate commercial growers of these crops.

kcb said...

So often in my garden classes & talks (mostly at my favorite family-owned nursery)I stress the importance of purchasing plants only from locally owned nurseries and garden centers. When asked ‘why’, my answer is not so much for the plant but for the soil. The plants, shrubs and trees all may be hardy to our zone but it is what is in the soil that concerns me. As in all life, the beginnings are crucial to the health and hardiness. Often plants produced for the masses such as 'the big box stores' may not be given the same care and caution as what is found locally.
In addition to the MOFGA site is the cooperative extension site, http://www.umext.maine.edu/gardening.htm.

Thanks David K and Mike S for bringing this potential danger to our attention.

RayMc said...

Will dusting with sulfur help slow the progress of late blight? I think my plants have it, although I got them from 3 different small growers in my area of Massachusetts (Not big box stores). Small, new growth leaves are curling up, turning blackish and developing small pin holes. I try to stay as organic as possible. Thanks.

Mike Skillin, Skillin's Greenhouses said...

Ray, sulfur dusting may "slow" the blight but will not eradicate the blight if you have it. By your description the pinholes do not concern me perhaps the "blackish" spots on the leaves do. I posted a pretty good link at the post from Oregon State which illustrates late blight. If you think you have it I would pull the plants as the Cooperative Extension people suggest. Perhaps your garden center sources in your area still have plants to plant. I know we have some decent plants that will still produce!

Eric said...

I live in Portland and am dealing with late blight for the past week. All of my tomato plants are heirloom from seed, so there's no link to the Bonnie plants. So far I have pulled 5 of my 16 plants and I'm not too optimistic that I will be able to save any of them considering the continued rain. Any insight would be welcome. At this point, sympathy may be all that can be offered.

David said...


There is little that can be done, though here's some advice I found on the web:

After planting, additional precautions will reduce the chances of successful inoculations and can suppress development and reproduction of the pathogen. Using resistant cultivars will reduce the chances of infection and slow the pathogen growth rate if some infections develop. Early in the season, the lowest labeled rate of protectant fungicide will provide protection and thus prevent a rapid epidemic. Fungicide should be applied either at an appropriate regular interval for the production area or adjusted on the basis of weather. Several forecasting systems that identify favorable weather conditions are available (e.g., Blitecast, Tomcast) and can be used to adjust the intensity of scouting as well as the frequency of fungicide applications. Hilling of potatoes increases the amount of soil between tubers and the soil surface and thus helps protect tubers from sporangia that land on the soil surface.

See also link to the Cornell site that best describes the disease and any preventive measures. http://www.nysipm.cornell.edu/publications/blight/

The best thing you can do (and probably you've already done it) is to completely remove any infected plants and discard them in a plastic bag into your regular garbage bin (not into your compost). This prevents the spores from spreading to your and others' crops.

If it's any compensation, know that the blight does not over-winter here in Maine, meaning you can plant in the same soil next year without concern.

Also, be glad you're not an affected commercial grower.


Mike Skillin, Skillin's Greenhouses said...

Eric, David explained the whole situation superbly about late blight in his latest comment. I did consult the label for Seranade (www.seranadegarden.com), an all natural fungicide. The label talks about Seranade acting to suppress late blight but I would think the Seranade would have to be applied to the Late Blight in a very early stage and that might help it from spreading to other tomatoes. Not sure if this applies to your situation Eric. Seranade is sold here at Skillin's.

jennifer said...

I recently came accross your blog and have been reading along. I thought I would leave my first comment. I dont know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.



Eric said...

Here we are about two weeks after posting about my blight problem. Out of sixteen plants, I pulled five or six that were pretty severely infected. There came a point where all of my plants had some signs of blight and, according to most of the recommendations I should have done destroyed those, too. Well, I didn't. What I ended up doing instead was applying Daconil (Chlorothalonil) one time to my remaining plants and hoped they could ride out the rest of the weather. I decided to use a different product from the one you recommended only because I was watching them die and didn't hold out much hope for survival; hence, use the most potent (aka toxic, aka inorganic) product. Well, it rained for about three or four days after that, and then things have dried and warmed up. All of the plants survived the ordeal, though none of them are really thriving. I have fertilized them with Espoma and am watching them rebound quickly. Unfortunately, I lost almost all of the fruits. We'll see if there are enough days left this season to "bear fruit." ha ha

My plan for next year: plant a winter cover crop (any recommendatins?) and apply six inches of compost over my beds. I would rotate if I could, but space limitations won't allow it, so we'll see if this works. From what I've read, the blight spores do not survive the winter.

Thanks to everyone at Skillin's and others for their help. I've grown quite attached to those silly plants and am so happy that they're hanging on.

Mike Skillin, Skillin's Greenhouses said...

Eric, thanks for your latest comment and I am glad you have some survivors. It is hard to say whether you have enough time to get any fruit but days like this willl work in your favor.

Winter rye makes an excellent green manure I do know that. Anybody else have any ideas about a good green manure?

The blight does not stay in the soil but annual rejuvenations such as compost layering and green manure are excellent strategies to keep renewing the soil.

David said...


Mike is right: the blight only over-winters in southern climes.

As for green manures: I plant any leftover seeds I have from the year, especially legumes, and just turn them over in the spring a few weeks before I plant. A cheap, easy green manure.

Mike Skillin, Skillin's Greenhouses said...

David, great idea about using the unused seed for a winter green manure. I will be onto that method myself!

Mike Skillin, Skillin's Greenhouses said...

Hello all,

Just noticed on Friday my tomato plants are being attacked by blight! I am so bummed...my plants have looked so good up to now and have some nice fruit coming.

Blight is pretty fast spreading and I am afraid I should pull my plants. For the moment, I am going to pick and throw away all the infected growth I can and apply Seranade to see if I can slow the blight. I am not terribly optimistic that this method will work.

Again this blight just surfaced on Thursday or Friday and is moving fast. I spoke to a customer on the phone on Friday and she is going to do the same thing but in both our cases if the blight spreads on the plants as expected then the plants will get pulled.

I will keep you posted....