Checking my irises today while pulling weeds and grass from around them, I found NO leaf spot. We have had one of the wettest springs ever. In the past years, the iris leaves were so damaged by leaf spotting by now that I just cut them at almost ground level and sent them off with yard waste. Sometimes, they would again become spotted by early fall. This year, I applied an anti-fungal spray early in the spring when the leaves were about 6 to 8 inches tall and followed with a couple more applications about 2 weeks apart. Used a brand called Hi-Yield which has the same active ingredient as Daconil. CHLOROTHALONIL. Used an ounce or so of concentrated dish detergent as a binder along with an extra heavy mix of the anti-fungal ingredient, possibly 4 ounces in a 2 gallon sprayer. Sprayed the leaves heavily enough to have a good runoff on and around the rhizomes. Have enough left to apply again after the beds are clean.
The chlorothalonil has different concentrations from brand to brand. My Hi-Yield was 12.5% but Daconil is usually much lower.
This treatment will not work after the leaves are spotted. You should begin the treatment early in the spring.
Good to know=) I don't normally have any spots till fall but if spraying early will help head that off, I'm all for it. I know people say dish detergent but does it matter which one? I tend to think old school like Ivory, Palmolive green or original blue Dawn but I usually only have one of the frufru scented antibacterial stuff--would that be OK too:lol:
Name: Dee Stewart Willamette Valley OR Snowpeak Iris
Yes, you are correct that it must be kept out of any waterways...or ponds on your place. We have a seasonal stream on our place and lucky it is almost at the far side of our place and during late spring and summer it is not running, but we make sure it does not get near it.
I would never spray anything near my ponds or stream, ever. Too chancy, in fact that's why I don't plant much there. Just planters around the pond. And I don't even have fish, just wouldn't want to hurt the little snakes and froggies.
Dee Do you still have 'Dark Aura'? Some people have like the look of Gerald Darby wo are looking for that type of cross. I have posted to look for DA at your garden. also warned about possible loopy stems because of the virginica side. the person showing pictures of GD didn't seem to have them. Our pure virginicas are fading now. Everything seems late this yr.
Spent about 4 days on and off my old knees pulling weeds and grass. Really had the potential for serious leaf problems. Some places, the grass was as high as the irises. As a point in preventive treatment, some pics of a plot at different times. There have been 3 treatments of fungicide and, so far, spots are rare. Some dying in the tips of mature leaves which is normal for me this time of the year.
Same bed 7-02
Different plot with irises and new peonies. I have read where the appearance of wetness on the leaves was a sign of diseases but that hasn't turned out that way for me.