only what the site recommends. sorry i couldn't be more help.you might try and dig them up and cut them back discard or burn what you cut off wash them off real good maybe soke them in a bucket with a small amount of dishwashing liquid in it for abought 2 or 3 hours rinse them off and replant them in a new area of your yard.also spray the old area with a fungaside let it dry good them till the area up then respray with the fungaside then retill up again then just let it dry out dont use it again untill next year.if you keep all the weeds
cleaned out of your flower
beds they will be dryer this should help prevent the fungis from starting again.only water them at ground level but dont over water them.if you do all this they should be ok.the spors thrive in wet areas the other plants
that where there with them was holding in to much moister for your iris.hope this helps your friend in gardening DIGGER
heres a couple of photos of my iris this year.