Preventing, not reacting to, leaf disease

[ScottinAtlanta]

Folks, I had the following two problems (pictured) last year in my tomatoes. The leaf miners I understand. The other problem - the yellowing and then withering of the leaves - eventually got 80% of my plants. I want to prevent it this year - I have read Mischka's excellent post on Forewarned is Forearmed, and I understand that I might need to start spraying with chlorothalonil (Daconil) at this point.

I have mulched with wheat straw to prevent splashing.

My question is this: Can anyone identify more clearly the foliar disease pictured below? Should I be doing anything at this point to prevent it?

[clkeiper]

This looks like septoria fungus. We spray the tomatoes regularly with a couple different fungicides throughout the growing season. Daconil and copper are the two we most frequently use. Spray them when you set them out and keep it up, especially if you live where it rains frequently. Wet foliage is the biggest contributor to disease on the plants. I have also heard of spraying wilt proof (or equivalent) on the plants to help prohibit the fungus from actually coming in contact with the actual leaf surface, I would think you would need to spray the new growth weekly with this product also. Since this makes a physical barrier on the leaf the fungus cannot grow. I like to stay as organic as I can, but that is not always possible.

[Kazfam]

Our local garden center (Piedmont Farm & Garden) has a nice link with soil prep and planting advice. This last little diddy on that page sounds like good prevention:

Final Wrap
When tomatoes have begun to grow and have some height to them, break off every branch from the ground level up to about 14-16” high on the plant. We have discovered that this action significantly increases air circulation, and cuts down on the incidence of water splashing on foliage of the plant.

Lack of air circ. and water splashing are a causes of disease spread, yes?

Here is the link: Growing Tips and Culture

[kath]

Originally Posted by Kazfam

Lack of air circ. and water splashing are a causes of disease spread, yes?

Here is the link: Growing Tips and Culture

Yes, keeping the leaves dry as much as possible will cut down on leaf disease- air circulation helps of course, and some plant diseases are soil-born.

Helpful link- thanks for posting it.