By Clint Thompson
It’s that time of year when Georgia pecan producers need to start protecting their trees against fungal diseases, including scab. According to the University of Georgia Extension pecan blog, sprays vary among the different cultivars and their specific level of resistance.
Low Input Cultivars
Those that are considered low input cultivars include Avalon, Elliot, Excel, Kanza, Lakota and McMillan. These require a minimum of three sprays which help manage minor diseases like powdery mildew, anthracnose and downy spot, while also maintaining scab resistance. UGA Extension recommends growers apply a phosphite in mid-to-late April; another in mid-to-late May; and an 11+3 mix in early-to-mid June.
Medium Input Cultivars
Those medium input cultivars include Creek, Kiowa, Oconee, Sumner, Zinner, Ellis and Gloria Grande. These require fungicides to manage scab, which can be controlled without an intensive spray program.
Scab should be controlled with seven sprays. UGA Extension recommends growers apply a phosphite in mid-to-late April; a phosphite or 11+3 in mid-May; Miravis Top in early-to-mid June; Elast+Tin or phosphite in mid-to-late June; Miravis Top in early-to-mid July; Tin or Elast+Tin in mid-to-late July; and Miravis Top in early-to-mid August.
High Input Cultivars
Those high input cultivars include Byrd, Cunard, Desirable, Morrill, Pawnee and Treadwell. These must be sprayed intensively if growers expect to produce a crop. They require at least 10 sprays and likely more in some locations. If you need more than 10, continue rotating Miravis Top and Elast+Tin.
UGA Extension recommends growers apply a phosphite; another phosphite; 11+3 mix; Miravis Top+phosphite; Elast+Tin; Miravis Top; Elast+Tin; Miravis Top; Elast+Tin; and Miravis Top.
Those medium-high cultivars include Caddo, Cape Fear, Huffman, Schley, Stuart, Tanner, Tom and Whiddon. These could fall into either of the other two categories.
Group 3 and Group 11 fungicides contain both a Triazole and Strobilurin fungicide chemistry.
Fungicide sprays should continue through shell hardening.