Is anyone familiar with the grapevine disease called Flavescence Doree, which is spread by the leafhopper, Scaphoideus titanus? I have run across references to this problem in a book by Kerin O'Keefe, which I read recently, as well as some publications. What I've been able to conclude (admittedly with limited information, hence this post) is that grape growers, experiencing this disease, would prefer a more naturally occurring pesticide, such as Pyrethrins, rather than very harsh chemical pesticides. One major problem seems to be that pyrethrins are very short lived after application and, hence, suffer from low efficacy. A potential solution, which I am familiar with, is to encapsulate the pyrethrin in a polyurea shell which will allow the active ingredient to be sprayed in the field and released at a controlled rate over a period of time without suffering from UV degradation, thereby significantly increasing it's effectiveness in controlling S. titanus. I am a retired Chemical Engineer and have had experience (manufacturing engineer and product engineer) with encapsulating pyrethrins in a production facility. The end use of this product was for flea control products for cats but this application sounds like it could work. In this facility a product line of insect pheromones was also made, which were designed for spray applications in an outdoor environment.
The purpose of this post is to find out if anyone has had any experience with this grapevine disease and to let them know that a potential solution may exist. Naturally extensive testing will be needed to determine if there are any residual effects in the grapes.