One place I visited called it "Sooty Mould Exposure," but when I used the search criteria "sooty mould exposure" + geese, the only hits were back to the website that gave me that name to begin with. When I removed the quotation marks and + sign, I got hits for fungi that infect citrus and olive trees... no willow there. Replacing mould with mold didn't yield me anything better.
Again, I don't know what I think about the "mould" thing. I keep running into writings of it, but could not find any sources or instances where waterfowl were infected with and treated for this problem. I spent about 45 minutes yesterday trying to run something down. If you find something, or if due to all your willows, your geese succumb to this "willow mould" please pm me as I would be interested in putting that into my files!
Doh, maybe I should have searched for ducks, and Victoria Roberts, and plant spores... if I have time later I might do so.
Regarding wheat. I don't know how much help I can be. The wheat I buy is grown semi-locally. I talked to the farmer and know that he sprays a pre-emergent herbicide at planting, and then does nothing else. I have the name of the herbicide somewhere, but when I researched it, I wasn't too concerned. I do try my best to buy organic products, but can't always afford to do so. Occasionally I am able to pick up some organic wheat from the local organic distillery, but I knew the owners already from taking away a lot of their spent grains (mash) to supplement pigs and lambs.
Wheat seed can be treated with anti-fungals, but I do not know if they have to be labeled. Your state's wheat growing happens mostly in the coastal regions and are harvested June-July. It looks like there are a lot of organic wheat producers out there. You may want to reach out to them at some point and see if you can get any or if they sell to any smaller farms who resell it for forage systems. Summer through early fall may also be a time to look at your local craigslist to see if anyone is selling it.
Another source of wheat are breweries who make wheat beer. Not only do they have spent grains, but if they are already set up to get those spent grains to farmers, they may be willing to sell some of the fresh grain to them also - often at cost.
And I'm sure you already know this, but I'm putting this in for anyone who may come across this thread at a later date: Wheat should not be the only food stuffs available to waterfowl especially geese.
You are a wealth of info @rainplace today just to get some wheat into Babe I bought organic in the bins at the grocery store. I know they can't eat it solely I feed fermented feed so this will go into the ff. Hopefully it plus the Nutritional yeast and greens will get him back to well oiled feathers. This will give me time to find wheat that I know is food grade . I saw on the Sams Club web site they had 40lb for 38.90 little less than 1.00 a pound I'll keep looking though.