Abbasi P A, Lazarovits G
Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford St., London, Ontario N5V 4T3, Canada.
Plant Dis. 2006 Dec;90(12):1517-1522. doi: 10.1094/PD-90-1517.
Field trials were carried out to test the effect of phosphonate fungicide (AG3) on the severity of clubroot of bok choy (Brassica rapa var. chinensis) and cabbage (B. rapa var. perkinensis and B. oleracea var. capitata) in commercial Ontario muck fields with a clubroot history. Disease severity also was examined in the same infested soil under greenhouse and microplot conditions. In microplot trials with bok choy, AG3 phosphonate concentrations of 0.07 and 0.14% a.i. applied before or after planting consistently reduced clubroot severity (1-to-4 rating) by 0.8 to 1.6 when planted in May or June. However, only the 0.14% a.i. preplanting treatment was effective in trials in July and August. Postplanting drenches of 0.14% a.i. were consistently effective throughout the season. Fresh weight of bok choy was increased or not affected by phosphonate treatments. Under field conditions, one (0.07, 0.14, and 0.21% a.i.) or two (0.07% a.i.) postplant-ing drench applications of phosphonate significantly reduced the incidence of clubroot by 52 to 87% and severity by 1.7 to 2.5 on bok choy in 2004 but not in 2005. In the 2004 trial, two applications of 0.07% a.i. AG3 phosphonate reduced the severity of clubroot comparably to single applications at 0.14 and 0.21% a.i. rates. Fresh weight of bok choy was increased by 34 to 86% with all phosphonate drench treatments in both years. With cabbage, AG3 postplanting drench treatments consistently reduced the severity of clubroot (1-to-5 rating) by a range of 0.7 to 3.3 under greenhouse, microplot, and field conditions. In the greenhouse, a single drench application of 0.07 and 0.14% a.i. AG3 phosphonate 1 day after transplanting cabbage seedlings to the infested muck soil reduced clubroot severity by 2.6 to 3.3 and increased fresh weight of cabbage tops by 66 to 69%. Similar results were seen with cabbage trials under both microplot and field conditions at all AG3 postplanting drench concentrations.
在安大略省有根肿病发病史的商业化腐殖质土壤田块中开展了田间试验，以测试膦酸酯类杀菌剂（AG3）对小白菜（Brassica rapa var. chinensis）以及甘蓝（B. rapa var. perkinensis和B. oleracea var. capitata）根肿病严重程度的影响。同时，在温室和小区试验条件下，于相同的染病土壤中对病害严重程度进行了检测。在小白菜小区试验中，种植前或种植后施用有效成分含量为0.07%和0.14%的AG3膦酸酯，当在5月或6月种植时，根肿病严重程度（1至4级评分）持续降低0.8至1.6。然而，在7月和8月的试验中，只有有效成分含量为0.14%的种植前处理有效。整个生长季中，有效成分含量为0.14%的种植后灌根处理始终有效。膦酸酯处理对小白菜鲜重有增加作用或无影响。在田间条件下，2004年对小白菜进行一次（有效成分含量为0.07%、0.14%和0.21%）或两次（有效成分含量为0.07%）种植后膦酸酯灌根处理，根肿病发病率显著降低52%至87%，严重程度降低1.7至2.5，但2005年未出现此效果。在2004年的试验中，两次施用有效成分含量为0.07%的AG3膦酸酯，根肿病严重程度的降低效果与单次施用有效成分含量为0.14%和0.21%的处理相当。两年中，所有膦酸酯灌根处理均使小白菜鲜重增加了34%至86%。对于甘蓝，在温室、小区和田间条件下，AG3种植后灌根处理始终能使根肿病严重程度（1至5级评分）降低0.7至3.3。在温室中，将甘蓝幼苗移栽至染病腐殖质土壤1天后，单次施用有效成分含量为0.07%和0.14%的AG3膦酸酯灌根，根肿病严重程度降低2.6至3.3，甘蓝地上部分鲜重增加66%至69%。在小区和田间条件下的甘蓝试验中，所有AG3种植后灌根浓度均得到了类似结果。
