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Fungicide Suggestions for the Year

As we are at bud break, keep in mind the need to start sprays of mancozeb and sulfur as soon as green stem tissue shows to protect against Phomopsis and powdery/downy mildews.  All require control on young tissues, but especially Phomopsis. A little bit of Phomopsis, downy mildew, or powdery mildew is never good, as early-season disease sets up the epidemic conditions for the remainder of the season. Early control is critical.

I am attaching a document that might be helpful to you, so use it if you can.  At recent workshops, several of the newer producers have asked for something like this to help them develop their fungicide programs.  There is a lot of redundancy in it, but I hope it keeps you from having to search for the critical information. If you do not understand something or if you see something with which you disagree, please let me know.  Keep in mind that this is developed for vinifera grapes and those hybrids that are susceptible to the diseases listed.  I am making mancozeb, captan, and sulfur the backbone products for the program, as they do not develop resistance.  We then add Botrytis active fungicides (at critical points) and more efficacious materials as needed for powdery and downy mildews when rainfall is prevalent.  Anyway, I hope it is of value, but I am open to suggestions.  You need to control the diseases listed in the efficacy chart, so each tank mix applied needs to have something in it for all these diseases — a daunting task.

For sour (vinegar) rot, we have discussed the connection between insect management (drosophila fruit flies) and control of bad yeasts and bacteria.  Therefore, at or shortly before veraison, add insecticides and Oxidate for help with this disease complex.  It is not in the attached chart, as insecticides are the heavy hitters for managing this disease.  Also, don’t forget about the insecticides needed to manage mealy bugs (leaf roll virus) and sharpshooters (Pierce’s disease) as needed.  Brett Blaauw has discussed this at meetings, but I want to remind you as we are talking diseases.

Also, utilize the spray guides that you find on the web, such as ours at www.smallfruits.org, to further help you as you develop your programs this year.  Make sure to check Reentry Intervals (REI) and Preharvest Intervals (PHI) for all the fungicides and other chemicals you utilize.  Check the Personal Protective Equipment (PPE) guidelines carefully as well.  Follow all label directions, and if any of our information is in conflict with the label, please let us know, but follow the label.

 

 

Suggested Spray Program 2019

Posted in Bunch Grapes, Pest management Guidelines, Uncategorized. Bookmark the permalink.

About pbrannen

Phil Brannen is a Professor in the Plant Pathology Department at the University of Georgia. He attended the University of Georgia for his undergraduate degree in Plant Protection and Pest Management, where he also received an M.S. in Plant Pathology, followed by a Ph.D. in Plant Pathology from Auburn University. He has extensive experience with disease management programs in numerous cropping systems. He serves as the extension fruit pathologist for Georgia – conducting research and technology transfer for multiple fruit commodities. His efforts are directed towards developing IPM practices to solve disease issues and technology transfer of disease-management methods to commercial fruit producers. He also teaches the graduate level Field Pathology Course, the History of Plant Diseases and their Impact on Human Societies Course, team-teaches the IPM Course, coordinates the Viticulture and Enology in the Mediterranean Region Course (Cortona, Italy), and guest lectures in numerous other courses throughout the year.