Late blight?

[maf]

I discovered what looked like a textbook case of late blight a couple of days ago. Pulled the plant (brought about 12 healthy looking full size tomatoes inside to ripen) and sprayed the other outdoors ones with copper oxychloride. I think Daconil is banned over here, so copper is about the only preventative available.

Luckily the plant (Marmande) is in a group of 3 well away from any others. Had to trim a couple of leaves from the other 2 in the group, and one of them has a couple of stem lesions similar to the pictures of the pulled plant below. I know I should remove this other plant also, but I am having doubts as to whether it even is late blight any more as the plant seems quite healthy apart from the stem patches.

Anything else it could be apart from late blight? Or should I just dispose of the other plant asap?
bl1.jpg bl2.jpg bl3.jpg

Thanks in advance.

[b54red]

I don't know if that is Late Blight or not but I had the same thing on about a half dozen of my tomato plants. I sprayed them with the dilute Clorox spray and it seems to have stopped it. I'll just wait and see. I sprayed again this afternoon. I have only seen this stuff late in the summer. If it is Late Blight and the Clorox spray works that would be nice. Those stem lesions like in your photo were really bad on one of my plants. I just thought it had something to do with the heat and was spraying for Early Blight and whatever mischief high heat and humidity bring.

[Marko]

Sorry maf, but there's no cure for late blight when you see stem lesions. The plant will become black mess in few days.

[French-Connection]

Yes that is well advanced blight, I have some quite good pictures on my site of early signs.

http://mr-tomato-king.blogspot.com/search/label/Blight

[carolyn137]

I agree that it's Late Blight, which can occur both early and late in the season, and also agree that there is no treatment that can help once the infection becomes advanced since it's not a foliage diseaase but a systemic disease.

If affected leaves are removed ASAP after noting them then sometimes the plant can be saved, And I also agree that most plants that are infected will be a stinking mass of black tissue within a few weeks. So when I read someone saying that their plants have new growth and have seen the pictures they show, I know it isn't Late Blight.

There are several diseases that can show such affected stems and fruits, some common, some not so common.

maf, when interacting with folks from England I was told that you don't have what here we call Cooperative Extensions where help in diagnosis is possible. So you have no way of really knowing what diseases are in your area. And that having any tomato material be checked for a diagnosis is terribly expensive and usually not worth it, so you're pretty much on your own re diagnosis.

perhaps it might be helpful if I once again link to the excellent FAQ about Late Blight from Cornell, who have taken a lead on LB.

http://www.hort.cornell.edu/departme...path/lbfaq.pdf


And here's a second link that is helpful to many and the reson I posted it is also for the several links you'll find on the right had side in terms of possible control, and more.

http://blogs.cornell.edu/lateblight/

[maf]

Thanks all.

I thought I was clutching at straws hoping it wasn't blight!

I will remove the other plant with some stem lesions right away, and keep a close eye on the one other that was situated between the two pulled plants. Luckily it is near the end of the season here, and the tomatoes on these plants are mostly full sized and can be ripened indoors, so the loss is not great.

Mostly the affected areas are very low down on the plants while the tomatoes are higher up, so last night's rain will not have washed the spores onto the fruit (hopefully).

[Stepheninky]

Looks like late blight as well. Usually late blight will decimate a plant in about 12 days . As Carolyn said though you should not be seeing new growth from growing tips. Usually late blight will stunt the plant from the stress as it does its work. I have seen several post from you guys across the pond where you are suddenly having tomato disease issues of late. So I did some digging on the net. Did not find much to be honest but did find a possible link.

http://www.independent.co.uk/life-st...ps-872401.html

[maf]

I removed both the remaining plants in that group just now, and brought the undamaged fruit in to ripen. I only had to throw away one suspect tomato. The plant I was thinking about leaving did not have any lesions on the main stem, but I noticed some on the stems of the fruit trusses so I yanked it anyway. It started raining again as soon as I finished - couldn't have timed it better! I now have about 50 tomatoes harvested from the three Marmande plants and they are in a room by themselves to ripen in quarantine.

I haven't seen any symptoms on the other plants in this garden, which luckily are at least 15 yards away and around the corner of a building, not in a direct "line of sight" with the infected plants. A couple of days ago they were given a protective spray with Bayer's copper oxychloride product which seems to have replaced Bayer's Dithane on the market recently in the UK. As far as I can tell the Mancozeb/Dithane is now banned for the amateur gardener in the UK, although I believe forms of it are still available for commercial farmers. French-Connection, not sure if this is an EU-wide issue that will affect you also in France, although I suspect you have the contacts to obtain some from commercial sources.

Carolyn and Stephen, it was hard to tell if there was any new growth on the plants as I had removed the growing tips a few weeks ago, but I did find one 9 inch long sideshoot that I had missed, and which seemed to still be growing in a healthy fashion. Of course I wasn't about to leave the plant in to find out if it carried on growing!

Also, thanks for the link to the Goji article. There are goji berry bushes in this garden which I believe came from a mail order source 2 or 3 years ago. Further digging around on the web seems to show that the area of concern is a species of Asian mite that also affects capsicums, rather than any blight type diseases, but for sure something I should be aware of. See this factsheet for anyone interested: fera goji gall mite pdf

I know late blight is typically far and away the number one most destructive tomato disease in the UK, so shouldn't really be surprised to get it here. It is just that up until recently we had been having a much drier than normal summer in the eastern half of the country, and I see very few reported cases on the potato council website which tracks UK outbreaks.

Thanks again for all the advice.

[Marko]

Originally Posted by Stepheninky

I have seen several post from you guys across the pond where you are suddenly having tomato disease issues of late.

I live in a country that is known as a potato country. It's not a question if you'll get late blight but WHEN you'll get it. This season was short, LB hit in mid august, I pulled out my plants two weeks ago.

[French-Connection]

Maf

Remove any leaves with all signs of blight. Any plants with lesions on the stem should be removed. The friut with no damage can be saved, but keep an eye on it and any that later show signs dump. Wash your hands and all equipment used.

Spraying can protect further infections on uneffected plants.
You can use Mancozeb Fungicide Dithane instead of Bordeaux mix.

[French-Connection]

Years ago when I grew commercially we used to make a thicker mix of what we sprayed with and painted it on the black stem lesions. This would control the spread of blight a little and kept the plants going until we picked most of the fruit. The idea is to stop the spores spreading through the rest of the crop.
Most things that are used to prevent the spread will stunt the growth a little it seems. But the new growth is fine, which has happened to my plants. Luckily the weather got dryer so helped stop the spread.

It is very important to burn any affected plant material, and beware of potatoes crops close by, which seem to get it first.
Air circulation arond the base of the plant is also important, so that plants dry out if you water with a hose, or condensation from the soil. Splashes from spores on the soil could also spread onto lower leaves.
But I am sure most of you who have had it have Googled as there is to know about.

[RinTinTin]

If the mites on the goji come from (illegally) imported plants, why not just grow from seed?

[maf]

If the mites on the goji come from (illegally) imported plants, why not just grow from seed?

If I ever need any more goji plants I will do just that.

The illegally imported goji plants came in to the country around 2007/2008, which is about the time these ones (a gift) were planted. They may be from that batch, they may not. I can't see any signs of mites on them, luckily, and testing done at the time did not show any other major pathogens in the imported batch of plants, AFAIK. (There is no evidence that late blight can affect goji plants.)

In fact, I would not have realised goji was related to tomato if it had not been mentioned here. Glad to say I can still learn something new every day.

[Stepheninky]

The mites were the primary threat, but as I read it the goji can be a carrier of the tomato diseases, Though I guess any related plant ex. peppers and potatoes could also be carriers. That was the link I was referring to. By introduction of live plants from other countries new diseases or new strains could be introduced. Not saying they were or anything else just pointing out that their is the possibility. That is part of the reasoning behind them being illegally imported.

[maf]

I agree with you totally. They could potentially carry a virus or viroid that could make the jump to tomato, or indeed other pathogens. I believe they were brought in in the dormant season, without leaves, so chances of spreading foliage diseases is low.

The sad thing is that the goji plants were not even imported direct to the UK. They were mistakenly approved in the Netherlands, and then made their way to us from there, as there are no restrictions on live plant movement within the EU.