What can you tell me about crown gall control, especially resistant varieties?
Answer: Here is an interesting item from Canada about crown gall, which includes some information on crown gall resistant rootstocks: www.agf.gov.bc.ca/cropprot/grapeipm/crowngall.htm. This will be helpful if you know how to graft or if you could get them custom grafted for you. Note that towards the end of the article, the authors state that not much could be done once crown gall is established, but they do give some advice. One of the things they mention is the biological control Agrobacterium tumefaciens radiobacter.Cornell researchers say Agrobacterium tumefaciens radiobacter is effective on most plants but not grapes. An alternative biological control bacterium, A. vitis strain F2/5 shows promising disease control and is under further investigation. Strain F2/5 is nontumorigenic and is effective in experiments when applied to grape wounds before they are inoculated with tumor-causing bacteria. F2/5 is not yet commercially available, and research is being done to determine its efficacy in field trials.An excellent article from Oklahoma State http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-4926/EPP-7669web.pdf includes a list of varieties with varying levels of susceptibility. The least susceptible are Cynthiana (Vitis aestivalis, pure American), Marechal Foch (French X American hybrid), and Concord (Vitis labrusca, pure American). All pure European wine grapes, Vitis vinifera, are very susceptible. So, while there is not a simple answer, I hope this information provides you with some guidelines and some hope. At the very least, it looks best to stick with pure American species and to avoid European wine grapes.