Cornell's Late Blight resource page:
http://www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm

Scroll down for many great photos.

[How can photos of Late Blight be "great"? *rolls eyes*]

Helpful photos would be a better choice of words. I have not experienced the blight as of yet but my farmer friend tells me you WILL know when you have it cuz your plants WILL be dead.

Not like some of the discolored pix I have seen where people ask "is this blight". He said they turn black and mushy.

There's the black-and-mushy-in-less-than-48-hours kind of Late Blight, yes. Gee, they were fine yesterday: how can they look so bad today? BTDT in 2007.

But there's also a more gradual kind, the 2009 vintage (did I mention yet that I had my appendix out that April? *lol*). It kinda went like this:

Oh, there are spots on my Variety G. Hm. Don't like the look of that.

AAAGH! the Late Blight photos look like the spots on Variety G. Wasn't it Late Blight that killed the volunteer grapes two years ago?

*furious comparison and re-comparison of photos and leaves*

Well, I don't want to pull up Variety G. I'll just pull off the leaves with the spots and spray everything.

*much running to the store for Daconil and spraying. (finish the bottle of Daconil before the end of the row, repeat from *)

Next day, pull more leaves off Variety G. Exhaustive inspection of the rest of the row shows no more spots.

Next day, additional spots on Variety G lead to pulling up Variety G. Spots are discovered on Variety F and Variety V.

*much cursing and removing of leaves from Varieties F and V*

And it all went downhill from there. And they all died (though with variations) -- even the ones in pots on the edge of the carport (200' away) and the volunteer grapes in the compost. And I actually got to eat fruit from about six varieties. But the mysterious NAR with the wrong leaves was a goner, so I'll never know if it was any good.

Agri Fos can be used as a treatment for late blight. While I generally don't recomment chemical treatments, it gets a passing score because it readily degrades into normal chemicals like phosphorus which plants absorb from the soil.

Once an infection is established, Daconil is ineffective. Agri Fos by comparison will both prevent and treat even after infection is established.

DarJones

Darrel, I didn't it, never saw it recommended so Googled it and it's not only a systemic, which concerns me a bit, but also the company has been in violation of the EPA as one of the links shows. Nothing to do directly with sale of it , though.

Directions talk about large scale tank mixing, so I wonder if it's used primarily by large scale commercial farmers.

I also wonder if it's avaialable without a pesticide license in many states. I know NYS requires those licencees for almost anything systemic but didn't take the time to check that out just for my own state.

Also says you can tank mix both Agri-Fos and Daconil together, but beware of any copper spraying that's been done.

And yes, the link above posted by missing was noted by many at different message sites and all I can say is here we go again b'c I was in NYS pretty much at the center of that Late BLight event in 2009 and fields of tomatoes went down near me, but my tomatoes out back didn't get it.

And right now my tomatoes out back look worse and worse every day. Freda got them out late, the woodchucks feasted, now this prolonged drought and heat an humidity and right now I can't get anyone to go out there and water for me.

Been absent here and there b'c both my phone and DSL lines went bad, the guy got here at 5 PM yesterday, it was some protector module where the line comes into the house that went bad, as he said they eventually do.

Somehow I didn't feel quite right asking this Verizon man to go out and water my tomatoes. LOL

The concern is that I'm dependent on the phone for my medi-alert system associated with the hospital.

Carolyn

Here is a link that might be useful: Agri-Fos; Google search

Carolyn,
To what do you attribute your avoidance of late blight? Is daconil effective for late blight if used early? I though it was effective only for early blight.
John A

My tomatoes look OK (well, some light spots - I'll try to take a pic) but I just went out and watered 3000sf by hand (only 50 gal - we are expecting rain tomorrow) since it was 95 yesterday and will be today. I'm pretty sure I've got late blight on the potatoes - just as they're starting to blossom. Picked off the leaves - I also would like to know if there is a fungicide (pref. organic) that will control this long enough to harvest new potatoes and keep it from spreading to tomatoes in row 10ft away (peppers in between potatoes and tomatoes)?

Here are pix of the potato leaves (sorry, a bit worse for wear being crammed into the front pocket of my jeans)

Sorry, Carolyn, just can't make the trip to water your garden ;-)

John. Daconil is effective at helping prevent both Early Blight ( A. solani) and Late Blight ( P. infestans). My commercial friends who have pesticide licenses have access to more effective stuff to use but we hobby gardeners, at least me and quite a few others, have only Daconil.

And knowing of the early reports of LB here I had Freda spraying a LOT of the Bonide Fung-O nil on them.

It also has to do with the windpatters and wind direction as well, and I live off the valley floor on the NY/VT border and it was mainly those on the valley floor near me who were wiped out.

The prevailing winds here are from the West, and they are to the West of me but the wind might well sweep up the "hollow" on which I live and my Home will also inhibit direct windflow from the West and even more so the hill above my home causes an upsweep of W wind over my house and acreage.

Carolyn

This is puzzling to me. the weather has not had the conditions to be condusive to this happening. wonder if it was a contaminated plant from a big box store?

This is puzzling to me. the weather has not had the conditions to be condusive to this happening. wonder if it was a contaminated plant from a big box store?

Exactly how I think it was originally spread. Those who started their own plants were not affected unless they were in the wind path mentioned.

The initial suspicion about the start of the 2009 LB outbreak was centereed on plants that were sold at one big box store in the NE, I'd have to go fetch all the data, but I think it was Cheff Jeff's plants that were involved.

But that not was true.

For those of us in New England and adjacent areas, we went through many weeks this Spring of COLD RAINY weather, which is conducive to LB infection. Same situation back in 2009.

And where from? Lots of data to indicate from potato cull piles where, if they were infected the LB is still Ok since LB cannot survive except in living tissue of either tomatoes or potatoes and the potatoes in cull piles are still viable.

Carolyn

agri-fos is available from garden supply stores here in small bottles for home use. No idea if it is similarly available in NY.

"Biorational Agri-Fos was approved by the Biopesticide Division of E.P.A. as a biorational fungicide. It has minimal impact on the environment. There is little concern for public exposure to surface residues because active ingredients readily disappear into plant tissues. Even though low risk, normal precautions should be followed by the applicator since the product is high in soluble phosphite salts. Do not spray bodies of water or where runoff may occur. See label for precautions. "

Do your own due diligence. It is ranked in the same category as daconil.

DarJones

Hi Carolyn,

I'm glad you're back online. You must have felt completely cut off from the larger world. :-)

As you may recall, I'm down in southwestern Albany County. I have spotted some suspicious lesions on the leaves of my container grown potatoes. I don't grow potatoes in the ground, but i have 2 25-gallon containers. Grew them last year for the first time with no problems.

The lesions look very much like the late blight on the tomato leaves back in 2009. They are blackish, oily-looking, with a "water-soaked" halo around the lesions. They do look like they have grown spores. I found them yesterday afternoon and, as of today, I could swear that even more leaves have become affected.

Anyhow they are going up to Cornell Cooperative Extension tomorrow morning. I'll drive them there myself, since the extension is only a few miles away. I'll let you know what happens.

So far, the other potato container looks fine, and my handful of tomato plants are clean. But we all know it's probably just a matter of time, assuming this turns out to be what I think it could be.

Here we go. Fingers crossed.

lionheart - I know my pix were bad since the leaves were crumpled in my pocket, but do they look like yours? My potatoes have these only on the top leaves, I had noticed some purple tips more than a week ago, but not all the brown lesions are on the tips. They are dark brown and look like they are a bit fuzzy, hard to tell if white spores but don't really look like drought stress even though the lesions (not the whole leaf) are dry and crunchy.

Good luck - let us know what they say. I have market today (unless strong T-storm comes through - I'm not sure how much lettuce I should cut this AM), so will have to wait til Monday to run samples into my test station, if I see any more lesions. I picked up some Bonide copper dust just in case.

I'm on the border of Litchfield/Hartford counties (actually, the potatoes are in Hartford). Didn't have any problems with tomatoes in 2009 - but 2011 was wet and the plants that survived Irene got every fungal diseases known to man (and tomato)!

Hi Ajsmama,

They are very similar. I really suck at making judgments from photos, but it looks very much alike.

Is it spreading fast to other leaves? Are spores forming? I remember Carolyn once saying to take a few of the leaves, seal them in a plastic bag with a damp (not soaking wet) paper towel, and look at the leaves the following day or so to see if the spores are obvious.

To me it seems that the disease cycles so quickly that it's hard to catch photos at various stages of infection. A leaf with a lesion looks very different on the 2nd day than it does on the 1st day.

In another hour I'll be heading to the Cooperative Extension. They don't open until 9:00 am.

Correction - they're more leathery, didn't crumble til they were in my pocket. I just went out again, picked a lot more leaves off the partial row (15 plants, Red Pontiac). Looks like it's spreading fast since I swear I got them all yesterday. Full row to the east was still wet with dew so I didn't start pulling those, will have to go out later. It *is* mostly on the tips, but not always. Didn't see any stem lesions, and it still is the upper leaves, not lower ones where I surrounded with hay after DH hilled up with soil the 1st time (these things are getting huge!).

I picked a gallon-sized bag full off just those 15 plants, broke a few branches off where multiple leaves were affected, but it's mostly single leaves. stuck a dry paper towel in and put it in the fridge - looks like I might be headed to CAES this AM anyway, once the kids are up and rush hour into Hartford is over. I'll take pix of the fresh leaves and let you know what they say (even though this is tomato forum and not potato!).

Tomatoes still look good - though now I've lost 1 Speckled Roman and 1 Krim to something that chewed halfway through the stems above the TP roll collar.

Lion, you must be very near to Vorheesville, where last I knew the Cornell Coop Ext was located. I haven't been down that way in many years.

The only other disease I know of that can mimic Late Blight is Gray Mold and that one has often been confused with LB, and I plead guilty on that one as well.

My farmer friend Charlie, who helped me so much with my field prep in Loudonville and in whose greenhouses I eventually raised all my plants had someone from Cornell visiting for some purpose I've now forgotten what.

And I asked Charlie if the fellow could look at some of my plants, and at the time I had some planted not at Charlie's place, but at his brother's place, The Shaker Shed, which is up by the Albany airport.

I sighed relief when he told me that it was Gray Mold and not LB and that there was no evidence of LB in Albany Co at the time.

So let us know what they say and lets hope you don't get one of the newbie Master Gardener folks who are doing their stint at volunteering.

Carolyn

Hi Carolyn,

Yes, I'm right outside of Voorheesville, in the town of New Scotland. I'm also very familiar with Loudonville and spent a good-sized portion of my life working at Siena College.

I've never seen Gray Mold, unless it is related to botrytis that occurs mostly on petunias and occasionally on the roses when it has been cool and wet. I am rooting for Gray Mold now because it's the way lesser of two evils. :-)

My only concern is the rate at which it as spreading among the leaves in this one container. More leaves are getting this crud every day, despite the fact that they haven't been watered since the last rainfall and the soil-less mix is pretty dry.

The plants are still a few inches from the top of the container, so hopefully the container is containing (pun intended) whatever it is that's causing the problem.

The samples have been dropped off at CCE and they are going to have someone look at them under a microscope and let me know what they find. It sounds like it will be looked at today. Let's hope so.

Yeah, I got a Master Gardner who was buffaloed and didn't know that they actually look for and track Late Blight outbreaks. So I was insistent and persistent, explained that this is somewhat important in case it is LB, paid my $3.00 and will follow up if I don't hear anything.

In the meantime, I'll post back one way or the other later today. Patience is not one of my virtues. :-)

I got a PhD to look under a microscope, he says it's hard to ID in tissue so is going to try to get it to sporulate - will TRY to get back to me today b4 it rains (and definitely b4 Monday???). But it doesn't look good. He said not much else causes this type of lesion (I didn't ask about Gray Mold).

Patience is not one of my virtues either, but I really don't want to pull 60 plants (my whole crop) 2 weeks or less before harvest if there's a chance it's something else. Then again, I don't want to jeopardize my 75 or so tomato plants (or my cousin's a mile away, or the farmer's 4 miles away) either. So I hope I hear today.

I could have sworn these leaves looked OK yesterday:

This is how it starts:

Hmm, I thought the purpling tips might have been drought stress when I first saw them, since I've never watered these potatoes - just saw this page on Cornell website. What do you think, is there hope (esp. if CAES can't get the samples to sporulate)?

Here is a link that might be useful: LB imitators

I'm pretty sure mine was not drought stress. It doesn't really look like the photos, and there was some fuzziness (looked like spores) and an ugly blackish color, surrounded initially by a lighter green "watermark". Within hours the watermark was gone and replaced by an oily blackish-olive color.

I'll keep my fingers crossed for you too.

I heard back from the local CCE and their response was "We just don't know what it is". They told me to bring in another sample on Monday and to watch the stems. Seriously? Okay.

I wish I had taken pictures of them, but I'm terrible at even the so-called idiot-proof cameras. :-)

I took about a dozen leaves from Thursday evening that I put in a ziploc bag and brought inside. Then I picked 4 more this morning, put them in a separate ziploc and went directly there. So they did get lots of samples.

So far the stems look clean, although it's hard to tell because I buried them in another 5 or 6 inches of grower's mix on on Wednesday evening (which is when those lesions jumped out at me). Anyhow, the little bit of exposed stems look clean.

I'll keep an eye on them. For now I'll assume it's Gray Mold, unless the problem escalates. I see one more suspicious looking leaf since this morning. No other containers of potatoes and tomatoes show any signs of problems right now.

Let us know how it goes with you.

Dr. called this afternoon said he hadn't gotten it to sporulate yet but it's still early, when it's dry out it's hard to get it to happen (but I don't know why he doesn't mist them down or something and put in a sealed bag. Says Gray Mold sporulates rapidly so that's not it, assume it's LB. BUT he said you can arrest it if it's dry weather. So advised me to top off the plants (he said must have been airborne since top leaves are affected, and potatoes have twice as many leaves as they need, also my stems aren't affected), dust/spray with copper (the tomatoes too! Which I was planning on) and I may be able to get a couple of weeks til harvest.

Of course it poured tonight - don't know how bad it was at home, but at market my canopy collapsed barely an hour in (and before any customers - there were half a dozen people wandering around from 3-4pm, things don't pick up til after 5).

My digital camera did not get good closeups (maybe b/c I would get too close rather than using zoom?) but the iPad takes really good pictures and the Photobucket app is easy too.

Gumby - how did you get that alert? Are you on a mailing list from UCONN? USA Blight? I signed up for alerts, also checked the map and USA Blight isn't showing any more cases in CT. I haven't heard back this week whether my samples sporulated, I don't know if CAES is updating anything to say I've got it, but don't see anything on UCONN (ladybug) link above. I emailed CAES this morning to ask about my samples and haven't heard back.

lionheart - what about you?

I've been cutting and pulling leaves all (rainy) weekend, and sprayed today, starting with the tomatoes that haven't been affected yet (ran out of fungicide so will finish the potatoes in the AM). But I noticed my uncle's potatoes showing the same brown withered spots, he thought it was drought stress but I told my cousin it might be LB and wouldn't hurt to spray.

Yes I am on a UConn mailing list. Sorry for the delay, I haven't been coming here much lately.