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

[ObliqueAngles]

Despite spraying fairly regularly, I've been seeing a lot of septoria and, to a lesser degree, gray mold this year. Septoria got a foothold early and it was rather difficult to tame this year for some reason. Usually it appears early in the planting season then seems to stop, but not this year.

On the other hand, haven't seen any early blight yet so I guess it's a trade-off.

The late blight epidemic that hit a couple of years ago always seemed to start somewhere in the middle of the leaves, not around the edges. If it was late blight it would show up on the stems within a day or so. If it hasn't spread to the stems (and fruits) and your plants don't look like the walking dead after two or three days, it's probably safe to assume it's not late blight. Late blight spreads and kills pretty quickly.

[b54red]

Originally Posted by 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!.

The reason for the soap is to give better coverage as a wetting agent. The bleach and water will do its' work if it is gray mold but you may have to treat several times to get it under control. You should start seeing the diseased leaves starting to die by tomorrow if it is gray mold. Some of my plants had it all the way into the new growth back in May and the bleach spray pretty much defoliated those particular plants. That is why it is best to start spraying the problem before it spreads too far and ruins the whole plant. If you can catch it early enough then you only lose a few leaves.

[Katydid]

Originally Posted by b54red

The reason for the soap is to give better coverage as a wetting agent. The bleach and water will do its' work if it is gray mold but you may have to treat several times to get it under control. You should start seeing the diseased leaves starting to die by tomorrow if it is gray mold. Some of my plants had it all the way into the new growth back in May and the bleach spray pretty much defoliated those particular plants. That is why it is best to start spraying the problem before it spreads too far and ruins the whole plant. If you can catch it early enough then you only lose a few leaves.

As you predicted, I'm seeing a lot of leaves dying back today. I'm confident it isn't the bleach killing healthy leaves, because most of the leaves on top (my plants are 7+ feet high) are still green. I suppose it could still be just the gray mold working its evil magic, but the dying leaves look more yellowish to me than what had already succumbed before spraying.

[b54red]

Glad to hear it is helping. Now keep a close eye out for new infections and don't wait if you see any indications before spraying again. The bleach spray has no preventative effects that I can tell so you might want to spray them with a fungicide to retard future infections.

[b54red]

Katydid, now that you have had a few days since you sprayed, how are your plants looking. Are there any new infections or just the old diseased leaves drying up? Is the new growth on those infected plants still looking good?

[Katydid]

Originally Posted by b54red

Katydid, now that you have had a few days since you sprayed, how are your plants looking. Are there any new infections or just the old diseased leaves drying up? Is the new growth on those infected plants still looking good?

I'm not sure. There seem to be a few infected newer leaves on the two plants most affected, but that could be because of inadequate coverage (I've got to get a new sprayer... I've attached a picture of one of the beds, and you'll see why my little hand held sprayer isn't up to the job).

I did a second spraying with bleach solution late this afternoon. I'm going to wait a couple of days, and then followup with Daconil (there's no rain in the forecast until later in the week).

Just for fun, I've also included a picture of the past two days' harvest.

[b54red]

Nice crop. I can see why you are having trouble with Gray Mold with that much foliage in that small a space. I don't see how you could get total coverage while spraying. I had the same trouble this spring with too many plants in too little space that got too big and bushy.