Late blight now confirmed on tomato and potato in Mifflin Co., PA

[b54red]

Originally Posted by carolyn137

I'm going to type out the sequence of development for LB that appears in my Seminis tomato pathology book b'c Seminis is the world's best place/lab, for tomato diseases and it's their photos that you see at TAMU and some other places.

So here we go.

****

The first symptom of the disease is the bending down of the petioles of infected leaves.Leaf and stem lesions are large, irregular, greenish, water soaked patches. These patches enlarge and turn brown and paper-like. During wet weather the underside of the leaves may have a white sporulating fungal growth. A rapid blighting of the foliage may occur during warm, moist periods. Entire fields can have extensive foliar and fruit damage.. Fruit lesions are firm, large, irregular, brownish- green blotches. The surface of the fruit has a greasy rough appearance.)

The next section is titled Conditions for Disease Development and the last section is titled Control.

The pictures shown are:

Burnt foliar appearanace in the Field
Fluffy White Sporulation on the Leaf
Large Necrotic Stem Lesions
Necrotic Expanding Leaf Lesions
Rough Brown Fruit Lesions

....... and please remember that Gray Mold disease looks almost like LB and is often confused with LB.

Hope that helps.

Carolyn one thing I have noticed with Gray Mold is that it usually starts deep in the plant in the shady more protected areas while LB seems to show up first on more outer portions and nearer the top of the plants. They look similar but LB is much more virulent and fast acting in my experience.

[carolyn137]

Originally Posted by b54red

Carolyn one thing I have noticed with Gray Mold is that it usually starts deep in the plant in the shady more protected areas while LB seems to show up first on more outer portions and nearer the top of the plants. They look similar but LB is much more virulent and fast acting in my experience.

For sure LB is more fast acting and lethal, but if you look at the Cornell link on LB you'll see that they prominently note that Gray Mold can mimic LB/

To date I have not had LB on any plants either here since 1999 or prior to that where I grew plants at Charlies farm, or prior to that when I grew them at the old famil farm starting in 1983.

But quite a few years ago when I was growing plants at Charlie's brother's farm as well, there was a huge outbreak of LB in W NYS, the source was potato cull piles, and the prevailing winds are W to East and we'd had quite a bit or rain. And there was a LB alert out for the whole Capital District of NYS. All of a sudden I saw these symptoms on my plants at Dave's place, Charlie's brother, and I panicked b'c they looked just like the symptoms I'd seen by Googling LB.

The leaf lesions didn't start on the inside portion of the plant at all.

And what happened was that Charlie's pesticide agent took a look at them and said no, not LB, it's Gray Mold. So Carolyn could breathe again.

[b54red]

Carolyn,I had only seen Late Blight one time before I started growing tomatoes from spring through the late fall. Most growers down here are through with their tomatoes by late June or early July and don't grow a fall crop. I have seen it twice in the last five years, once in late August and once in the fall but can't remember whether it was October or November. Ten or so years ago it hit in mid June and wiped every plant out really fast just as they were peaking in production and I had never seen anything like it before. I tried all the fungicides on the shelf to no avail.

I had never seen Gray Mold until I started growing mostly heirlooms. The first time I ever saw it was on a JDs Special C Tex and since then nearly every variety of black tomato I have grown has been affected by it at one time or another. Not every plant but a sampling of all the blacks except Gary O' Sena has been hit by it. I have gotten it on other varieties also but not to the degree it hits the blacks. It is much worse when there is frequent rain and very high humidity which we have had this year. We almost always have the humidity but rain can be sketchy at times and that actually helps with most of the foliage diseases; but it sure makes the spider mites worse.

[RayR]

http://lateblight.nysipm.cornell.edu...aga-county-ny/

http://www.usablight.org/

[RandyG]

The image in the post by Tania (#42) appears to be the stem lesion phase of early blight and not late blight.

[Farmette]

For those of us who are in the drought, would you say we are much less likely to have to worry about late blight this year? While we have had some days and nights with higher humidity, it has been VERY hot during the days with only a drop of rain here or there for weeks. My tomatoes seem to be overall much less affected by any disease so far this year.

[bcday]

Dry hot weather isn't favorable for LB spores to germinate but as long as there is dew in the morning and humidity in the air, LB is possible. LB is an infection of the aboveground parts of the plant and is not at all affected by how dry the soil is. Morning dew, fog, or a few warm humid days/nights are enough to get an infection started if there are spores around. Be vigilant.

[Farmette]

Thanks for the advice...better to be a little safer.

[pooklette]

Originally Posted by Farmette

My tomatoes seem to be overall much less affected by any disease so far this year.

Mine too. I'm usually fighting all kinds of spots, splotches, and yellowed leaves by this point in the season. I definitely think the dry conditions are helping to keep disease at bay.

[Tania]

Originally Posted by RandyG

The image in the post by Tania (#42) appears to be the stem lesion phase of early blight and not late blight.

Randy, I never seen early blight starting on stems, producing white fuzzy growth and quickly spreading and killing a plant in a matter 2-4 days. I believe the early blight produced grayish fungal growth, and it starts on lower leaves, manifesting itself in grayish concentric spots which eventually leads to yellowing leaves.

I wish I had early blight, and not late blight, that's all I can say! Well, actually I wish I never have either, now or in the future! .

I actually never seen early blight lesions on my tomato leaves since we moved here (perhaps it is just too cold here for its rapid development most of the summer). They are very different from late blight lesions.

[RandyG]

Originally Posted by Tania

Randy, I never seen early blight starting on stems, producing white fuzzy growth and quickly spreading and killing a plant in a matter 2-4 days. I believe the early blight produced grayish fungal growth, and it starts on lower leaves, manifesting itself in grayish concentric spots which eventually leads to yellowing leaves.

I wish I had early blight, and not late blight, that's all I can say! Well, actually I wish I never have either, now or in the future! .

I actually never seen early blight lesions on my tomato leaves since we moved here (perhaps it is just too cold here for its rapid development most of the summer). They are very different from late blight lesions.

Your original post with the picture said you removed the plant and that the late blight disease did not spread. That is one of the reasons I said it was early blight. If it was late blight, there would have already been latent infection when the disease showed up on the stem, and you would have seen more late blight on nearby plants.You did not indicate in the original post for this to be the case. Also, early blight often does infect stems even before it shows the leaf spotting. this is called the stem lesion or collar rot phase of early blight. If you search on the internet, you can find images of the stem lesion phase of early that look like what your picture showed. The image you presented does not look typical of late blight development on the stem. Also, stem lesions from late blight usually show up after leaf symptoms.

[barkeater]

Late blight now confirmed in Syracuse and Duchess County, NY, said to have been blown in on strong winds.

[Tania]

We have lots of LB damage in my area by now.

My GH tomatoes are still OK though, and I hope they'll stay that way until I get to sample some right tomatoes. But I lost half of my potato beds, luckily foliage only, the tubers were still OK.

I hope the hot and dry spell we are finally having now will make the late blight go dormant. Please no rain in the next 2 weeks and no more heavy dews!!!!

[barkeater]

It's HERE! Late Blight was confirmed this weekend in Clinton County, NY, where I have my one garden and in Hyde Park, VT, 20 miles southwest and Derby, VT, 20 miles north of my VT garden. It has been hot and dry for weeks, especially NY, but nothing has stopped the progression of late blight to our area. The late blight map shows it all over VT now.

I'm getting worried but am spraying diligently and hoping to avoid it as I did in 2009. Besides the Bloody Butchers and now my Red Siberian plant in NY, none of the other 16 plants are near ripening but are loaded with tomatoes.

[Tania]

barkeater, I hope your garden will be OK. I am keeping my fingers crossed for all of NYers and VTers.