USDA-ARS-SEFNTRL, Byron, GA 31008.
University of Georgia, Tifton, GA 31793.
Plant Dis. 2020 Jul;104(7):2014-2022. doi: 10.1094/PDIS-10-19-2225-RE. Epub 2020 Jun 2.
Peach scab, caused by , is a damaging disease of peach in the southeastern United States. Thus, fungicides are applied to reduce peach scab. Tractor speed was investigated as a variable affecting spray deposition and disease control in relation to volume applied. In experiments in 2015 and 2016, trees were sprayed with fungicide to control scab at petal fall to 1% shuck split and at shuck split to 10% shuck off. Speeds were 3.2, 4.8, and 6.4 kph resulting in 1,403, 935, and 701 liters/ha, respectively, with the dose of active ingredient (a.i.) per ha kept constant. Deposition declined for all speeds with later spray dates. There was a negative linear relationship between tractor speed and spray coverage on three of four dates the experiment was repeated. Tractor speed (different volumes, equal doses) affected peach scab. In 2015 and 2016, mean incidence at 3.2, 4.8, and 6.4 kph was 68.6, 59.2, and 38.3%, and 64.2, 53.0, and 40.4% of fruit scabbed, respectively. Effect of speed on lesion number per fruit depended on year: in 2015, lesions per fruit were reduced at 6.4 kph compared with 3.2 and 4.8 kph but were not different in 2016. Control trees had fewer lesions per fruit high in the canopy, but there was little effect of sample height in fungicide-treated trees. Concentration of a.i. in lower volumes applied at higher speed may provide some benefit in reducing incidence of peach scab, but there appeared to be less effect on severity.
李痘病，又称细菌性穿孔病，是美国东南部桃树上一种破坏性疾病。因此，常使用杀菌剂来减少李痘病的发生。本研究调查了拖拉机速度这一变量对喷雾沉积和与施用量有关的疾病控制的影响。在 2015 年和 2016 年的实验中，桃树在花瓣脱落至 1%的核壳分裂期和核壳分裂至 10%的核壳脱落期施药防治李痘病。速度分别为 3.2、4.8 和 6.4 公里/小时，相应的施用量为 1403、935 和 701 升/公顷，公顷有效成分（AI）施用量保持不变。随着施药时间的推迟，所有速度下的沉积量都有所下降。在四次重复实验中，有三次拖拉机速度与喷雾覆盖率呈负线性关系。拖拉机速度（不同的体积，等量的剂量）影响李痘病的发生。在 2015 年和 2016 年，以 3.2、4.8 和 6.4 公里/小时的平均发病率分别为 68.6%、59.2%和 38.3%和 64.2%、53.0%和 40.4%，果实感病率分别为 68.6%、59.2%和 38.3%和 64.2%、53.0%和 40.4%。速度对每果病斑数的影响取决于年份：在 2015 年，与 3.2 和 4.8 公里/小时相比，6.4 公里/小时下的果实病斑数减少，但在 2016 年没有差异。树冠高处的对照树每果病斑数较少，但在施药处理的树木中，采样高度的影响很小。在较高的速度下应用较低体积的 AI 浓度可能有助于减少李痘病的发病率，但对严重程度的影响似乎较小。
