Late Blight Warning from UMASS

Hello!

I just received this info in an email. I'll copy and paste.....Hope it is helpful. Delcy

Late Blight on Tomato and Potatoes

Garden retailers and landscapers should be aware of Late Blight caused by Phytophthora infestans – a very destructive and very infectious disease that kills tomato and potato plants in gardens and on commercial farms in the eastern U.S.

Late blight is the same disease that caused the Irish Potato Famine in the 1840s. It has been in the US for over a century, but it has never occurred this early and this widespread. It not only threatens home gardens, but also the thousands of acres of commercial potatoes and tomatoes that are grown in Massachusetts and across New England. The disease has been diagnosed on tomato transplants throughout the Northeast. Infected plants were distributed throughout the region by several plant retailers this spring. This disease is not seed borne however, it is exceptionally contagious, and can spread to tomato plants on retail shelves not involved in the original and initial source of the inoculum.

Late blight, affects both potato and tomato crops. It produces spores very rapidly and these move very easily from one garden or field to others, because the spores are easily carried in wind currents to infect susceptible plants in even the most remote area in our region. All tomato and potato plants grown in home gardens and in commercial fields are susceptible to late blight!

What to Look For
The most common early symptoms on tomato transplants are brown lesions on stems, with white fungal growth developing under moist conditions.

Symptoms appear as large (at least nickel-sized) olive-green to brown spots on leaves with slightly fuzzy white fungal growth on the underside when conditions have been humid or wet. Sometimes the lesion border is yellow or has a water-soaked appearance. Leaf lesions begin as tiny, irregularly shaped brown spots. Brown to blackish lesions also develop on upper stems. Firm, brown spots develop on tomato fruit. Late blight can be confused with early blight and Septoria leaf spot, two common diseases found in home gardens. If the lesion has a yellow border and is occurring on the bottom of the plant, it is likely due to infection of either early blight or Septoria leaf spot.


Photo gallery of what to look for:
http://www.hort.cornell.edu/department/Facilities/lihrec/vegpath/photos/lateblight_tomato.htm
http://blogs.cornell.edu/hort/2009/06/26/late-blight-a-serious-disease-killing-tomatoes-and-potatoes-this-year/

To confirm a diagnosis contact the University of Massachusetts Plant Diagnostic Laboratory, (413) 545-3208 or see http://www.umass.edu/agland/diagnostics/index.html. There is a $50 fee for lab diagnostics.

Management
If symptoms are already appearing on plants, remove plants, place in a plastic bag, seal and discard in the trash or completely bury plants deep enough underground so plants decompose and will not re-sprout. Do not put the plants in a compost pile as spores will still spread from this debris.
.
To manage late blight with fungicides, treat before symptoms appear. Use a product that contains chlorothalonil listed as the active ingredient on the label. There are ready- to- use formulations available. Fungicides are only effective if used before the disease appears and should be reapplied every 5-7 days if wet weather persists. Chlorothalonil is a protectant fungicide, with no systemic movement in the plant, so thorough coverage is necessary. For organic farmers and gardeners, the options are very limited, since only copper fungicides can be used, and copper is not very effective on late blight.

Even with fungicide applied every week, there is no guarantee of success, especially if the rainy weather continues.

For more information, see
http://www.umassvegetable.org/index.html



UMass Extension Agriculture and Landscape Program
June 29, 2009



U.S. Department of Agriculture cooperating.
University of Massachusetts Extension offers equal opportunity in programs and employment.

Here's another link I received about it from Rutgers.

http://www.njfarmfresh.rutgers.edu/documents/Lateblightalertforgardeners.pdf

Thanks. I'm sure it's a banner year for fungus with all the rain.

$50 fee to to test a $2 plant - sounds like a government program.

This is also being discussed in the Tomato forum...and no, I am not directing you there because I started that thread (I am very humble). I mention it only because you, the Northeasterners, are the ones who would be affected and therefore might be interested.

http://davesgarden.com/community/forums/t/1008932/

Denise

This message was edited Jun 30, 2009 12:19 PM

Good Grief! Mass - keep it or I could be very sensitive (which I am not) and I could do bad things.

Late blight has been reported to be in Ohio now. This wet and cool weather seems to be the culprit.

i've had blight for the last few years - and expect to get it again this year with all the wet weather - we spray at least once a week and so far so good - ortho has a product out that has 29% of the active ingredient that slows this fungus down. last year on the t-plant forum they gave our this info so i'm sure it is there again.

actually waiting for the sun to come out to apply it again - i also started using it on hollyhocks for rust.

We also keep the leaves off the ground for at least 12" to help keep the plant away from moisture.

I'm glad to have this warning and information--thanks.
My local nursery that specializes in using organic controls sent out this message:

i have used serenade in the past and it did not do much - we may have started too late with it and it is very expensive if you apply it through the season. we have two unused containers of it if your ever in the area.

Thank you, wha, for that generous offer. Very nice of you. I've already bought some of the Serenade concentrate which I am going to apply as a spray when/if it stops raining--right now we're having a LOT of rain, thunder, lightening--the whole shebang! (Bang being the operative word.)

Now, since I started my tomatoes from seed (actually a friend in NC did) and they're up in an earthbox, I'm not worrying too too much especially since nobody near me does any growing of anything except lawn and that with much non-organic pesticide. I AM checking my tomato plants for evidence of fungus and the signs shown in that email (when it's not raining). BUT, DD#! bought a pepper plant from one of the BAD growers (Bonnie) at HD this spring when we thought we might have one (a spring, that is). Could they be a carrier? Can they get it? That pepper's not doing real well, she's frantic but I think it just wants some sun.

More:

http://news.yahoo.com/s/ap/20090703/ap_on_bi_ge/us_farm_scene_late_blight

Yeah, I saw that. I still want to know can a pepper be a carrier? Can't get to my tomatoes today - the roofers are setup in that part of the yard.

The store I got my plants from wasn't on the list(yeah) I will keep an eye out anyway.

I'm worried that my ailing Bonnie pepper could be a carrier - anyone know if that's possible?

i have seen blight on eggplant and pepper plants although they usually start showing signs after t-plants

Oh, dear. Should I dump the Bonnie pepper plant?

Carrielamont:

I have several Bonnie tomato plants in the garden and am keeping them. Here is another article on late blight, which mentions peppers: (Edited to say the link is not working for me, so maybe cut and paste if you really want to read it.)

http://plant-disease:ippc.orst.edu/disease.cfm?RecordID=1084

They use the word "occasionally" concerning peppers.

I would still like an answer to a question I posted on another thread on this subject--If you bought a Bonnie plant and has been growing awhile in your garden without symptoms, does that mean it was never infected in the first place? In other words, how long after exposure do symptoms begin?

I'm hoping the answer is "immediately," which would mean your pepper and my tomatoes are not carriers.

Denise

This message was edited Jul 5, 2009 2:46 PM

Denise, I copied and pasted, no luck, but I did read elsewhere (somewhere, another thread? another forum? another site?) that affected plants are dead within 2 weeks! Which would mean that my pepper (sickly from lack of sun but nothing like the fungus pictures) and your asymptomatic tomatoes are AOK, right? We'll all just be very wary. And I thought it was the rabbits I had to worry about!

Carrie

No expert here for sure. Here is a pic of the plant

Now a close up of the the crotch or V what ever its called. It is starting to ROT. As far as I have read and looked at pictures this is the Late Blight. Also look at the leaf, its the same as the pics I have seen. I will post it in the tomatoe forum and try to get an identification there if no one can do it here. Late Blight = death.

the one with the leaf/leaves

that does not look good sherrie - not positive though because the rest of the plant looks good - it could be from too much rain

Bill all the plants look good. But if you look at the whole picture you can see the plant is yellowing and it dont look right. I have 81 tomatoe plants I do have this posted in the tomatoe forum. Now this is the real WHAAAAA



This message was edited Jul 10, 2009 1:54 PM

pull it out then - and you may also want to trim any branches that are close to the ground - i do this to my 50 plants - since i have had blight the spores are there so i try and make it tougher for them. i will mail you later the stiff to get to spray them as i need to mix up a new batch today. works on hollyhocks too - no rust this year!!

Bill, will you post the stuff to spray? I'd like to mix some up too.