First of all, let me share some words from a local farmer and long-time Ag teacher at our local school:
I really don't think it is from a herbicide. If it were, the whole plant would be twisting and wilting, and all I see are spots. This is not the time of year for aerial application of anything. That is normally done in the mid to late summer when the crops are too tall to cross with a spray rig. Farmers do not have to report to any authority when they are going to spray, but they Do Have to spray responsibly. If a farmer does the spraying himself, then his insurance will cover any damage. If he hires it done by a professional applicator (MFA or Ray Carroll Coop etc) then that business has insurance to cover the damage. I would ask around about who sprayed recently, but I still do not think it is spray drift. It is wide spread on your yard, do your neighbors have the same damage? It really is a baffling mystery. I would be curious to learn what it is.
One Facebook friend relayed a story about her relatives having had a grape crop ruined by over-spraying, and my farmer friend addressed that issue:
On the vineyard question, Grapes are terribly sensitive to broad leaf herbicides. If a grape "thinks" it smells 2,4-D or similar products, they will wilt and die. We have a small vineyard right next to one of our fields. We are terribly careful about What we spray, When we spray, and How we spray around that field. We never use 2,4-D, as just a whiff is all it takes. MFA also takes very seriously how it applies chemicals. If they have too many violations, both the company And the driver, who both hold Commercial Applicator's Licenses, can lose their certification. No license, No income, No business. They are very careful at what they do, but mistakes do happen. If they do, then a claim should be filed. They will come out and look at what the damage is, and make a settlement if they caused the problem.
He then suggested I call the University of Missouri Extension office and see if they would come and inspect the damage. I'm thinking that if they won't, I could at least send them some pictures, or even the link to my blog entries.
My young fruit trees show brown spots, rather than white ones.