Gray leaf spot?

[squint]

Hi, first time poster. I have learned so much from the collective knowledge here--thank you all!

I was hoping someone might be able to assist me in diagnosing these leaf spots that have plagued my plants the last couple years. They cropped up two years ago after several weeks of heavy rain, something not too common in the usually dry area of Southern California where I live (Inland Empire--zone 10, I believe). They start out as these brownish-gray blistery areas on the lower leaves, which eventually turn yellow (the leaves) then drop off. Fruit production slows or halts, though the spots don't seem to appear on any other parts of the plant. Any remaining fruit becomes sun-scalded from the increasing defoliation that spreads upward. The leaves don't appear to be deformed in any way as far as wilt or curling.



Weekly spraying with Ortho Garden Disease Control seems to keep it at bay, though this year the spots appeared earlier on this one plant (Nyagous), and impending rain has me a bit nervous

Thanks for any advice.

Suzanne











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[dice]

Does it look any of these pictures? Which one is closest? (Pay
attention to small details in the descriptions, like "halos",
"starts on the bottoms of leaves first", and so on. These can
often allow one to tell the difference between two similar
looking afflictions.)

http://aggie-horticulture.tamu.edu/p...emsolver/leaf/

[squint]

Thanks for the link.

I did look closely and believe I can see a very slight halo around the lesions on the top sides of the leaves. The description for Gray Leaf Spot seems to fit most closely, though the photo of Alternaria Canker also looks similar except that the stems and fruit don't seem to be afflicted in my plants.

Here's a couple more close-ups:


From what I've been reading, I guess the Ortho Garden Disease Control is the best route at this point to keep it under control? Maybe the earthboxes are a better way to go in the future.

Appreciate your help.

[dice]

Spores may splash up from the soil, but they can also blow
in on the wind, too. A thick mulch can keep them at bay if
they are in the soil. You probably want to remove the mulch
at the end of the season and not leave it in place over the
winter. (Or replace it with new mulch after the plants have
been pulled. A thick mulch does more than just prevent
evaporation. It also reduces soil compaction from rain and
allows soil to aggregate into larger structures than the
particle sizes in it, giving it more air space, etc.)

Gray leaf spot looks like it to me, too.

[squint]

Right after I took the first photos I did lay down some mulch around the plants, which was a good thing because now the rain is coming down pretty hard. I was going to wait until the weather was consistently warmer, but now know it probably would have been a good idea to do it as soon as I transplanted outside.

This one plant is in a somewhat isolated area away from the other tomatoes, which so far look okay, and hopefully won't contribute further to the problem. If the spots keep spreading in spite of the spraying and trimming, I'll pull it up.

Thanks for your help!

Suzanne

[dice]

We have issues up here with cold soil at the start of summer
*and* rain, so spores in the soil is a particularly annoying
problem. (A thick mulch handles the spores and prevents soil
compaction, but it slows down warming up of the soil.)

For spores blowing in on the wind from neighboring trees,
shrubs, weeds, etc, an antifungal spray is about the only
reasonable treatment.