Fungus?
May be... not sure. It is a bit early for "late blight" (P infestans). However, browning of stem sections is a symptom of it. With Daconil, it is NOT a curative for fungal infections... at least not some of them. It is a deterrent that must be applied prior to significant infections. After the late blight has got a foothold, it is too late for Daconil to be of much effectiveness. 'Round parts here, it WILL manifest itself if weather conditions are suitable (cool, damp). I tell folks on this very simply: "Do not wait. And keep applying every 7 days or so." Nevertheless, my words fall on apparently some deaf ears.
Reggie

Not sure, but you know how the old saying goes...."Never to thin or too rich or to early for Daconil." :-) I spray mine from early summer on.