Do white spores have to be visible for it to be late blight?

[Chervena_chuska]

So now, we've just had the 96 degree heat wave that the East is suffering through now with ridiculous humidity and some of my inconsequential fungal disease is all of the sudden looking consequential indeed.

I took some samples to my county extension gardener walk in desk and the gardening expert wasn't worried about the things I thought might be trouble (bacterial problems). She did say one of my plants looked like it had phytoplasma and another of my samples looked suspiciously like late blight due to the dark green lesions. Egad!

I have sprayed a few times with copper and neem and Serenade and have been diligently pruning the low and sick looking parts of the plants, but this kicked in the panic button for me. I pruned off even more of the sick looking foliage and sprayed with Daconil. However, they are dark green lesions (mostly at the tip of the plant) which don't look like late blight to me. Some of them seem to be like marginal burn. They don't look greasy and I keep checking for white spores and find none.

Do white spores HAVE to be present to diagnose late blight? We are expecting a lot of rain now (last night) and the next few days and I checked right away this morning to see if there was any white fuzz and there was none.

Here's a couple photos from two days ago. I'll try to post another later today.

[kath]

Doesn't look like late blight to me- every one of my tomato plants went down with that inside of a week in 2009. Hope someone more knowledgeable can answer your question and help diagnose this for you.

[bcday]

No, you don't have to to be seeing white spores but it doesn't look like Late Blight to me either.

Are you seeing any irregular black blotches on the stems? For the number of affected leaves in your pics, plus whatever number you've already pruned off, I would expect to see lesions on the stems as well as the leaves.

You still need to keep an eye out for Late Blight, but I think something else is affecting the leaves in your pics. For one thing, your leaves seem to be affected mostly around the edges and at the tip. Late Blight will show irregular patches anywhere on the leaf. Here's a site that has good pics of what the black blotchy stems and leaves would look like for Late Blight: http://www.longislandhort.cornell.ed...ght_tomato.htm

[b54red]

Looks like you have a case of Gray mold. It has been bad this year in my garden. It usually shows up low or in the center of the plant first but it will quickly spread and destroy the plant and it can really mess up some of the fruit. I had been spraying with Daconil regularly but it was unable to stop the spread of this stuff in our humid conditions. It looks somewhat like late blight but it usually spreads slower and can be stopped or slowed down if you don't wait too long. It usually starts on just one or two plants but if you don't stop it in its' tracks it will start spreading very fast once it gets well established.

Take a full gallon of water and add 8 ounces of Clorox brand regular bleach along with a few drops of dish washing liquid to it. This will give you about 134 ounces of spray. If you have a lot of plants you will need more because you have to be very thorough in your spraying. Use a good pump sprayer and spray the entire plant making sure to get under the leaves, the stems, fruit, blooms, new growth, and the ground under the plant with a fine spray. DO THIS LATE IN THE AFTERNOON. Make sure to rinse your sprayer immediately and thoroughly right after you finish. Wait three days and most of the leaves and stems with lesions will be withered and dry. Cut them off and open up the center of the plant for better air flow if possible. Then check closely for any new lesions which will start as just a gray to tan looking area forming on a leaf. If you see any new lesions repeat the process. Then resume weekly Daconil spraying.

You will have to keep a constant eye out for gray mold the rest of the season. It seems that once it gets established in your garden it is hard to get rid of it completely. I don't just spray my tomatoes but everything growing in the garden to try and get rid of as much of the stuff as possible. If you wait too long it will destroy your plants. If your plants are close together Gray mold can spread very fast as I found out this spring. It also spreads much faster during times of high humidity or frequent rains.

[Chervena_chuska]

OK, the garden is finally dry and the sun is not so bright so I got some more photos.

Thanks SO MUCH for the help! I feel better already, even if it's another terrible disease. I've just been moping around with worry. (Gazpacho is SO close I can taste it...)

I have one that has small blackish/brownish patches (my Speckled Roman) on the stems, but not the ones with the dark green lesions - not anything near the late blight pics I've been researching non-stop for the last three days. The county extension woman though my Speckled Roman might have phytoplasma. The Nyagous and the Tasty Evergreen that I'm most concerned with don't have much on the stems. A few brown spots here and there but they've been suffering getting whipped about in storms this past month so I thought that might be mechanical damage.

The pics are of my Nyagous and Tasty Evergreen. The Nyagous as you can see I stripped it down across the whole bottom. There were a lot of leaves starting to get spots yesterday so I went a little hardcore on it.

Also, it occurred to me I might have burned them a bit by a 4 pm application of Copper + Serenade on Tuesday. Just a thought.

Cute dog, bcday! I have a border/lab mix and an Aussie.

[Chervena_chuska]

b54red, I was wondering if gray mold was a possibility. I looked it up and haven't seen any mold like fuzz for that either. Does that happen sometimes?

I read about your bleach spray and was thinking I might give that a shot.

[b54red]

Here are a couple of pictures of the Gray mold I had to deal with this year. Mine started in May and because I waited too long to treat it I ended up getting it on over half my tomato plants to one degree or another. The last two pictures show you how bad it can destroy the foliage on a plant. I still got some usable tomatoes off of them but only a fraction of what I should have because many of the fruits got Gray mold on the plants that were hit the hardest. The plants that I treated early enough went on to have normal production and a couple of them are still producing. I hope this helps you.

Bill

[Chervena_chuska]

Also, b54red, since it's likely to rain today and all weekend, should I continue the diluted bleach spray until it's a dry day or wait the 3 days even if it rains in between? Thanks!

[bcday]

Originally Posted by Chervena_chuska

I took some samples to my county extension gardener walk in desk and the gardening expert wasn't worried about the things I thought might be trouble (bacterial problems).

What kind of bacterial problems did you have in mind, and why did the person at the county extension think that wasn't the problem?

Has Bacterial Canker definitely been ruled out? That is a disease that thrives in warm temperatures and high humidity, and it looks like a possibility from what I see in your pics.

[Chervena_chuska]

I was wondering about bacterial canker/spot/speck which is why I took them in, mainly because of the marginal edges of the leaves were browning like a black outline almost that I was seeing early on. I didn't see any actual "cankers" or issues inside the stems, so I wasn't sure at all about the bacterial diseases. The county extension person said pretty definitively she didn't think any of the samples looked bacterial and that the marginal scorching was probably just stress related from heat, wind etc.

The only things she mentioned were to keep a close eye on possible late blight and that the plant with stem lesions might have phytoplasma. I had some with early blight lesions which I guessed and she confirmed, and she also thought there was some insect damage.

I should mention too, I did the little test where you put some diseased foliage in a sealed plastic bag over night and check for spores and I didn't see any. I can't remember if you are supposed to put a moist paper towel in with the foliage though - does anyone know?

Thanks again for the help! It's great to have knowledgeable people weighing in.

[Katydid]

I'm sadly struggling with the same thing - presumably Gray Mold - here in eastern middle Tennesse (I thought it was late blight at first). It (gray mold, not late blight) showed up on my strawberries this spring and ruined a lot of the berries. I'm also seeing more Septoria and Early Blight than last year.

I wasn't very diligent about preventative spraying earlier in the season. Lesson learned.

[b54red]

Originally Posted by Chervena_chuska

Also, b54red, since it's likely to rain today and all weekend, should I continue the diluted bleach spray until it's a dry day or wait the 3 days even if it rains in between? Thanks!

It is better if you can get the spray on the plants when they are fairly dry but it doesn't take the bleach long to do its' work. If you can get a few hours without rain prior to spraying I would still wait 3 days and see how the plants are doing. It is harder to get control of something like gray mold during frequent rainy spells. It seems to spread and multiply much faster with the dampness.

Gray mold and Late blight are somewhat similar in appearance and according to everything I have read they are frequently confused with each other. The biggest difference I noticed was the way they first show up on the plants and Late blight destroyed my plants much faster the two times I have had to deal with it. I have had 3 different outbreaks of Gray mold and they seemed to show up first in the middle or shady part of the plant first and took a while to get really bad, whereas Late blight first showed up on the upper half of the plants and spread unbelievably fast.

[Katydid]

It was as muggy as all-get-out this afternoon, followed by a brief shower, and a good chance of rain tomorrow. Fungus paradise. I decided to give that bleach spray a try.

Gray mold and early blight are really starting to get ahead of me, so I'm interested to see if this works. I hope I won't be horrified by the appearance of my plants tomorrow!

[Chervena_chuska]

Katydid,
Sorry to hear you are having such problems! I too am in the weeds when it comes to the fungus. I did try a bleach spray (plants looking fine afterwards) which I think I'm going to follow up with Actinovate which is supposed to work for gray mold (and I had luckily ordered pre-emptively a week ago or so ago but hadn't yet had a chance to apply.)

[Katydid]

Thanks. I'll report back in a few days with results (or lack thereof). The plants looked the same this morning (but I know b54red said wait about three days). I just realized I forgot to add the dishwashing soap (sticking agent?) so I've already messed up my experiment!.