Augusto J, Brenneman T B, Culbreath A K, Sumner P
Department of Plant Pathology.
Department of Biological and Agricultural Engineering, University of Georgia Coastal Plain Experiment Station, Tifton 31793.
Plant Dis. 2010 Jun;94(6):676-682. doi: 10.1094/PDIS-94-6-0676.
The efficacy of chemical control of stem rot (caused by Sclerotium rolfsii) of peanut (Arachis hypogaea) relies partially on increasing deposition and residual activity in the lower canopy. Tebuconazole (0.21 kg a.i./ha, four applications) and azoxystrobin (0.31 kg a.i./ha, two applications) were each applied on peanut plants in daylight or at night, when leaves were folded, in two Tifton, GA, field trials in 2007. Both timings of each fungicide provided similar control of early leaf spot (caused by Cercospora arachidicola). Night applications of azoxystrobin and tebuconazole reduced stem rot at digging and increased yield compared with day applications. Night applications of tebuconazole were also tested in Nicaragua from 2005 to 2007. Peanut plants had less stem rot, similar levels of rust (caused by Puccinia arachidis), and higher yield with night applications than with day applications. Residual activity of azoxystrobin and tebuconazole were improved on the bottom shaded leaves (on which fungicides would be better deposited with night application) compared with top, sun-exposed leaves (where most fungicide would be deposited with a day application) according to a bioassay with S. rolfsii. Increased fungicide residual activity within the bottom canopy may increase fungicide efficacy on stem rot and augment peanut yield.
花生（落花生）白绢病（由齐整小核菌引起）化学防治的效果部分取决于增加杀菌剂在植株下层冠层的沉积量和残留活性。2007年在佐治亚州蒂夫顿进行的两项田间试验中，戊唑醇（0.21千克有效成分/公顷，施药4次）和嘧菌酯（0.31千克有效成分/公顷，施药2次）分别在白天或夜间花生叶片折叠时施用于花生植株。每种杀菌剂的这两个施药时间对花生早斑病（由花生尾孢菌引起）的防治效果相似。与白天施药相比，嘧菌酯和戊唑醇在夜间施药可减少收获时的白绢病发病率并提高产量。2005年至2007年在尼加拉瓜也对戊唑醇夜间施药进行了测试。与白天施药相比，花生植株在夜间施药时白绢病发病率更低，锈病（由花生柄锈菌引起）发病程度相似，且产量更高。根据对齐整小核菌的生物测定，与顶部暴露于阳光下的叶片（白天施药时大多数杀菌剂会沉积于此）相比，嘧菌酯和戊唑醇在底部遮荫叶片上（夜间施药时杀菌剂在此处沉积效果更好）的残留活性更高。下层冠层内杀菌剂残留活性的增加可能会提高对白绢病的防治效果并增加花生产量。
