I'm attaching a few pictures. I noticed the spots about six weeks ago on one plant and it's now spread to every plant in both raised gardens. I'm sure this has been covered, but, please replay with any ideas to treat plants.
Thanks for the link gixxerific. Looks like I'll need to pickup some fungicide to battle this. I'll also have a little more work to do this fall as I can't rotate crops in raised gardens. I've not had this issue in the past and really hate to hear that it will stay in the soil over the winter. This has spread faster than you could believe...
This has been a really good year so far. I've already harvested a few celebrities and romas and ate my first tomato May 31st.
I wouldn't worry too much about rotating crops. I've had Septoria hit just as bad in new plots as in plots that grew tomatoes for 20 years. End of season clean up and mulching keep things in check. Weather conditions are responsible for year to year differences, and some varieties are more susceptible than others (but you don't know which ones until you grow them). Lush growth from high nitrogen also may make it worse. It usually hits my plants early-mid season, causing me to prune-defoliate the bottom of the plants. Then I may not have to do anything else and I just live with low level infection, or if the weather is bad I may end up spraying.
Some people have better luck with potatoleaf varieties resisting foliage diseases like Early Blight and Septoria.
I just got back from visiting the Farmer's Co-Op. They recommended and sold me Liquid Copper Fungicide to use on the infected plants, which in my case, is every tomato plant.
I about to sit down a read through the instructions/risks of applying this to my plants. Does anyone have any experience or recommendations concerning using this fungicide? If I prune all the infected areas it's really going to result in losing the bottom third of most of my plants.
Septoria is often due to soil splashing up on leaves, so some mulching around plants will help that. Also, if you prune off the lower leaves, you will have better air circulation.
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Yep, sometimes you end up removing the leaves on the lower half of the plant. Its not pretty, but the upper foliage is less likely to get hit with spores, and it dries out faster.
Copper fungicides are barely "Organic". They are listed as synthetics only to be used as a last resort because of the danger. This is a case where chemicals such as Daconil (Chlorthalonil) may be as safe or safer, but because of their manufacture/chemical makeup won't be considered for Organic certification.
https://www.extension.org/article/18351
https://extoxnet.orst.edu/pips/chloroth.htm
You can probably get away with occasional spraying of one fungicide for Septoria and Early Blight [Alternaria], but it is best to alternate fungicides with more than one mode of activity when facing a dangerous fungal threat like Late Blight, but you can't do that if you are Organic since copper is your only option.