If you have problems with septoria lycopersicum you need to be very carefull with the debris of diseased plants from the year past.Is not a fungi that resist without debris.Can also overwinter on solanaceous weeds like Datura Stramonium,Sonalnum Nigrum.etc.so you need to eliminate initial source of inoculum if you want to succeed.Also if you have thepossibility of crop rotation,that will be also ok.
Now ,for fungicide you have some options-you can use the classic 7 -10 day schedule with mancozeb ,benomyl,daconil , chlorothalonil etc and these are contact fungicides and also you need to correlate them with the weather and the disease cycles,mancozeb have the best action for the early blight and septoria,but not so good with Phytophtora Infestans,there chlorothalonil is much better,but mancozeb dont resist very well if is raining heavily,clorothalonil will do much better then etc.You need also to use systemic fungicid if the disease presure is high,i see above some good exemple of systemic fungicide in the strobilurine class but is very important to change frecvently the mode of action of the fungicide.A short exemple-if you use let's say Pristine who has the active ingredient pyraclostrobin(a strobilurin class)the next systemic spray will need to be done with a different mode of action class of fungicide like let's say mefenoxam-Ridomil Gold.Sorry for my english ,i am from Romania and i am pretty sure that i made some mistake.
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