Hi-Yield Captan 50W Fungicide is considered rainfast after having dried completely. This normally takes at least 2 hours.
Unfortunately, Hi-Yield Captan 50W is not labeled to be used on tomatoes. You can use something like Ferti-Lome Triple Action instead. It is labeled to treat a variety of diseases and can be used on a variety of fruits and vegetables, including tomatoes. You will use 1 oz per gallon of water.
Hi-Yield Captan 50W Fungicide is not labeled for use on any vegetables including mustard greens. It is only labeled for use on fruits and ornamental plants.
Unfortunately, Hi-Yield Captan 50W Fungicide is not labeled to treat Bearded Iris Rhizome nor any type of rotting.
We recommend getting in touch with your local extension office to get a positive identification and what the source may be for it.