Earlier this season I purchased both Daconil and a copper fungicide to help prevent septoria leaf spot on my tomatoes. My plan was to rotate between the two every two applications.I purchased the concentrated version of both, and my husband mixed the Daconil with water in a pump sprayer for me. Well, even using the smallest measurable amount of concentrate, we still ended up with a gallon of mix, which is enough for several applications since I only have four tomato plants, so 4 or so applications later we're still on the Daconil.
My first question is, is the Daconil still effective after being mixed weeks ago, or should we have been discarding any unused portion after a certain amount of time? Unless I missed it, I didn't see anything on the label about how soon it should be used after being mixed with water.
My second question is, I sprayed yesterday evening (7 days since my last application, after 4 consecutive days of non-stop rain this week). I wasn't expecting rain last night which is why I thought it was safe to spray, but about two hours later, it rained. Should I reapply the Daconil (or maybe switch to copper) today? I don't want to cause more damage by spraying too often, but I don't know if the Daconil I sprayed last night had a chance to set before the rain came.