If one of the wild roses has an immunity against the virus, it may be possible that grafting ornamental roses to that wild rose (used as understock) may transfer the immunity. "if silenced rootstock can efficiently transmit the silencing signal to non-transformed scions, as has already been demonstrated in herbaceous plants." This article is talking about adding genetically modified RNAi-eliciting constructs to normal rootstocks, but it should also work if a wild rose already has the proper RNAi. See the review below. Here is a link that might be useful: link to scientific article

Hi Jim: thanks for the picture of the mountains in your PA area ... that's so beautiful !! I live 1/2 hour northeast from DeKalb, IL. You are right that DeKalb is flat, mostly corn fields. I have more trees & and varied scenery here. My heavy clay is fertile too. I don't need to fertilize much, but I need to add trace elements for disease-resistance. This is my first year WITHOUT horse manure, and it's the most black spots, and disappointing year !! Horse manure NPK is low, but high in trace elements, thanks to its being a good source of bacteria. Plus zinc and copper vitamins added to the feed. Even if the soil is tested sufficient in NPK, with constant rain, and after heavy blooming .. nitrogen and potassium are leached out. Nitrogen can be re-supplied again with nitrogen-fixing bacteria, which is abundant in organic matter like composted manure. But potassium has to be supplied via fertilizer. Henry Kuska, professor of chemistry and once had a garden of over 1,000 roses, made an excellent observation that perhaps roses become depleted of potassium after a bloom cycle, esp. late fall. I agree, I gave Comte de Chambord a big-dose of potassium at the start of its 2nd flush ... it gave many petals-bloom, and the bulk of the blooms are heavier than the leaves plus the wimpy root. Now at the end of its flush, it's breaking out in B.S. To make zillion-petals bloom, a lot of potassium and calcium are needed prior to each flush. Less-petals like Knock-out are more disease-resistant, because the bulk of its roots is more than the bulk of the blooms ... the roots can easily fetch more nutrients. So for wimpy-root roses like Comte de Chambord and Jude the Obscure, immediate soluble fertilizer is needed for blooms & disease-protection. Why Mr. Lincoln is more disease-resistant for your soil than else where? Perhaps Mr. Lincoln root is most vigorous in your particular soil to fetch the nutrients needed to fight against diseases. Romanticas are clean in my alkaline soil, since their roots are very vigorous at my soil pH, with plenty of dolomitic lime for them. Your pic. shows the mountains in PA, which means less air-flow than my open Chicagoland. Plus I don't get dew, as you stated, "Here we get heavy dews outside. So around 10pm the leaves on our roses are getting wet as if it rained. They dry off early to late morning so perfect breeding grounds for BS." I find that dry & leathery leaves like Crimson Glory (prone to mildew in dry climate) tolerate wetness on its leaves. Crimson Glory is my top-clean rose, even after 1-week of constant rain. Same with shiny leaves like Pat Austin ... that one is known as a water-hog & loves the rain, but become droopy in hot & dry weather. Christopher Marlow has thick & shiny & rain-resistant leaves. It's the thin-leaves like Comte de Chambord that can't take the humidity nor wetness. I have to give that SOLUBLE calcium & potassium to make its leaves thicker. Same with Gruss an Teplitz, leaves can't take wetness, and he's the parent of Dr. Huey rootstock. Zinc and copper are the 2 strongest antifungal agents, and some soil are more deficient in those. That's why this year without horse manure, my roses are the worst ever. Calcium is a weaker antifungal agent, but it still works. That's why my Duchess de Rohan planted in my clay fixed with tons of gypsum, is 100% clean despite being a shady, perpetually wet spot where other perennials are mildewed, and other roses with BS. My clay is dolomitic lime, and I'm next to a limestone quarry, yet my soil is tested barely adequate in calcium. One hundred plus-petals bloom like Austin roses require lots of calcium and potassium, versus less-petal Knock-out. Below is a bouquet picked today, July 23, showing the many petals roses. The firm-petal one like Stephen Big Purple which lasts long in the vase, also requires an ungodly amount of calcium. It does very well next to my limestone-based patio, and doubled in growth after application of gritty lime. Pink is Sonia Rykiel, yellow is Golden Celebration, small beige Mary Magdalene, big peachy pink are Evelyn. This post was edited by Strawberryhill on Wed, Jul 23, 14 at 22:56

Question for Lynn: Is the calcium level in your soil high as well? I checked my 12 tomato plants this morning. The ones in the front (flat ground) with gypsum, plus bagged cow-manure are perfect, zero yellow lower leaves, but the ones in the backyard (without gypsum for this year) ... all have yellowish lower leaves, despite the advantage of on a tall raised bed. Will post pics. later. Below are some pics. from the internet of calcium deficiency in tomato. I see blackspots on Carding Mill, which I DID NOT put gypsum in the planting hole, only alfalfa pellets. But the other roses with gypsum & cracked corn in the planting hole are 100% clean, despite another all-night rain last night. This is our wettest year !! Calcium has anti-fungal properties. http://thumbs.dreamstime.com/z/calcium-deficiency-tomato-fruit-19943968.jpg For those who don't have access to red-lava-rock to buffer rain-water against black-spots, rock-dust is equally good in re-mineralization of plants (good defense against fungal disease). Below is a link that sells rock-dust at 5 lbs. for $16 (includes shipping). "Agrowinn-Minerals Rock Dust (CDFA Registered) is the best rock dust on the market (also known as rock powder or stonemeal) - and can be used successfully on all varieties of plants, trees, and vegetables. This Volcanic Rock Dust is environmentally friendly and will not leach into your ground water." http://www.fertilizeronline.com/rockdust.php Agrowinn Minerals provide natural Phosphoric Acid, Soluble Potash, Calcium, Magnesium, Iron, and numerous other trace minerals with this guaranteed analysis: Guaranteed Analysis: Available Phosphoric Acid (P205).....................................0.13% Soluble Potash (K2O)..........................................................0.11% Calcium (Ca)........................................................................ 1.23% Magnesium (Mg)...................................................................1.74% Iron (Fe)................................................................................ 0.8465% Sodium (Na) ......................................................................... 1.20% More info. on rock dust: "Locally, I have granite dust available from the gravel pits, which is okay to use but not best. The mixed gravel dust from the local stream beds is better. A better yet rock dust comes from glacial gravel or volcanic rock like basalt. Another is montmorillonite. Montmorillonite is a very soft phyllosilicate mineral that typically forms in microscopic crystals, forming a clay. It is the main constituent of the volcanic ash weathering product, bentonite. [6] Read more: http://davesgarden.com/guides/articles/view/727/#ixzz3e5UQAn00

For me, what little result I saw was strictly on annual weeds that sprout from SEED, and like Ann said, only on the warm weather ones. Some of my worst weeds are Winter and Spring weeds, most of them mat-forming, and by the time the weather warms enough for the gluten to be effective, they're going to seed AGAIN. I suspect if your oxalis is perennial that you would see next to no control, since gluten meal doesn’t inhibit weeds that already have root systems. It works by preventing root growth in seedlings that have just sprouted, sooooo if there's a perennial root/crown/bulb it does nothing but fertilize them (corn gluten is full of nitrogen). Oh...P.S. I haven't heard anything about gluten being anti-fungal. That would be interesting.