Gray Mold

[lang77]

Was wandering if this is gray mold, or some sort of blight...Temps have been extremely humid and very very hot this last week and more expected this coming week. Curious, does not seem to affect the potato leafed varieties. Heaviest on Black Cherry and Ildi.

[b54red]

It sure looks like it could be Gray mold. Don't believe it doesn't effect potato leaf plants because it does. Last year I only had it slightly on a JDs Special C Tex, Noire de Crimmee and BTDP, so I thought it was more prevalent on black tomatoes. This year it hit every type of plant but particularly my potato leaf plants. It seems to hit hardest the thickest and bushiest plants with the poorest air flow.

[Katydid]

I agree gray mold is an equal-opportunity pathogen with respect to leaf type (it first started on my Gary'O Sena PL plant) and being worse on the thickest, bushiest plants. I noticed that as well this spring in my strawberry patch - not much problem on the edges of the beds, but in the middle where plants were too dense and hence poor air circulation, it was a big problem.

[lang77]

Now that makes sense to me. It does strike on the bottom of the bushiest plants. Looks to me that there may be some trimming to do in the morning. Is it necessary that I remove all of the leaves with the margin of gray mold...and how fast does it travel upward? I have well over 60 plants all spaced two feet apart and growing vertically on a trellis network. Most are well over 6 feet tall and the leaves affected are within a foot or two of the ground.

[b54red]

Originally Posted by lang77

Now that makes sense to me. It does strike on the bottom of the bushiest plants. Looks to me that there may be some trimming to do in the morning. Is it necessary that I remove all of the leaves with the margin of gray mold...and how fast does it travel upward? I have well over 60 plants all spaced two feet apart and growing vertically on a trellis network. Most are well over 6 feet tall and the leaves affected are within a foot or two of the ground.

That was exactly how my plants were spaced this spring and the closeness caused the Gray mold to move rapidly from one to another. Cutting off the affected leaves will not stop it. I tried that early on and just as the problem was starting to get out of hand I sprayed with the bleach solution. A couple of days later I did it again. The number of leaves and plants that were affected by Gray mold became apparent as the sick parts of the plants started drying up. I only wish I had started the spraying a week or so sooner. It would have saved me a lot of damage.

[dice]

I had it in 2008 on Gary'O Sena fruit but not on the foliage (or at least
not enough foliage infection to be noticeable). My plants were pruned to
3 main stems, though, and the early summer weather was quite cool,
so the foliage was not dense.

[b54red]

I sprayed all of my plants again today as we are having thunderstorms every few days and the humidity is staying very high. An hour after I got through spraying them we got another rain. You know what else likes lots of rain and high humidity besides diseases? WEEEEDS!!!!!!

[lang77]

b54red...this a a question for you....what is the spray formula for the bleach solution? Maybe I can still save my plants. We too are having heavy rain and high humidity ....over 4 inches last night with more on the way in the next few hours. I trimmed the affected leaves and branches along with lots of unaffected leaves to provide better air flow, but the challenge remains with high humidity and more rain in the forecast. I have been spraying with Daconil as well, but I am sure with the forecast, my Daconil supply along with my budget will soon run out.

[dice]

CarolynPhillips has a nice setup for keeping the rain off:
http://www.tomatoville.com/showthread.php?t=18309
(If you scroll down aways, you can see a photo of it from the outside.)

I have seen a photo of a similar structure with some type of fine mesh
screen instead of plastic at an agricultural research facility in Vietnam
(I guess so that they can grow stuff during the rainy season without
saturating the growing media or soil).

[b54red]

Originally Posted by lang77

b54red...this a a question for you....what is the spray formula for the bleach solution? Maybe I can still save my plants. We too are having heavy rain and high humidity ....over 4 inches last night with more on the way in the next few hours. I trimmed the affected leaves and branches along with lots of unaffected leaves to provide better air flow, but the challenge remains with high humidity and more rain in the forecast. I have been spraying with Daconil as well, but I am sure with the forecast, my Daconil supply along with my budget will soon run out.

I usually spray a solution made with only the Clorox brand regular bleach because of its' consistency. I am afraid to use no name brands because of the chance of the formula being either too strong or too weak.

I pour a full gallon of water into my sprayer and then add 8 ounces of Clorox bleach and a squirt of dish washing liquid as a wetting agent. Spray late in the day and make sure to use a fine spray and hit all parts of the plant and the undersides of the leaves. You may have to spray again within a week because it is hard to get all of the Gray mold with just one spraying and if it is raining a lot it can pop up again. Usually within 3 days of the spraying the diseased leaves will shrivel up and die. If you are getting heavy rains nearly every day I would try to spray at least every 5 to 6 days until the rain lets up.

[lang77]

Thanks b54red. It is certainly worth a try.

[barkeater]

Lang,

That is not grey mold; it is early blight. For some reason the yellowing that normally occurs with EB in the beginning around the edges does not with Black Cherry. Look real close with a magnifying glass you should be able to make out the concentric circles (like a fingerprint) indicative of early blight. With grey mold, there will be an actual greyish mold on the leaf that can be rubbed off.

[b54red]

barkeater you don't always see the mold before you get that typical wet wilted rotting leaf look. The first sign of Gray mold I had this year was on my Green Giant and Spudakee plants back in May. All I was able to see was a dark wilted looking leaf in the very shady lower part of the plant on each. I had some plants later on that first showed that nice easily identifiable mold on the top of the leaves but that wasn't always the case.

Lang, I'm with you on the cost of using Daconil when it is raining constantly. We have had rain 12 of the last 14 days and that makes using Daconil just a waste of money and time. You can use the bleach spray between rains and as often as you need. The bleach spray also helps with every other foliage disease I have had to fight; but its' only preventative effect is in killing the disease that is present at the time of spraying.

[barkeater]

b54,

I agree that in the early stage it can be hard to determine exactly what disease you have. However, Lang's first picture is clearly showing Early Blight and guaranteed it is not grey mold.

[Katydid]

Originally Posted by barkeater

b54,

I agree that in the early stage it can be hard to determine exactly what disease you have. However, Lang's first picture is clearly showing Early Blight and guaranteed it is not grey mold.

Barkeater, I have early blight every year on my tomatoes. This year, in addition, a new fungus appeared that looks like just what Lang posted. I obviously can't look at his leaves with a magnifying glass, but on my plants there are clearly two different pathogens present (actually, three, because there's some septoria).

Lang, are the pictures you posted representative of what appears on the other tomato varieties, not just black cherry?

I just don't think that's early blight.