Lalancette N, Blaus L L, Gager J D, McFarland K A
Rutgers University, Department of Plant Biology and Pathology, Rutgers Agricultural Research and Extension Center, Bridgeton, NJ 08302-5919.
Plant Dis. 2017 May;101(5):794-799. doi: 10.1094/PDIS-08-16-1169-RE. Epub 2017 Feb 10.
Four protectant fungicides applied as midseason cover sprays were quantitatively assessed for their ability to reduce brown rot caused by Monilinia fructicola during the preharvest fruit ripening periods in the 2012 through 2015 growing seasons. No fungicides were applied during bloom or during the preharvest period. Treatment programs consisted of captan, sulfur, ziram, and thiram applications beginning at early shuck-split stage and ending with the final cover spray at 23 to 26 days before harvest. The incidence of brown rot at harvest was determined by examining 41 to 91 fruit for symptoms of rot on each of four replicate trees for each treatment. The incidence of sporulating blossom blight cankers was assessed during the preharvest period at 8, 15, and 22 days after the final cover spray. An in vivo bioassay was also conducted at 7, 14, and 21 days after the final cover spray to ascertain the level of fungicide residue during the preharvest period. The bioassay uses conidia germination as a quantitative indicator of effective residue. Results of the harvest assessment showed that captan cover sprays significantly reduced brown rot incidence in all years of the study. Furthermore, results of the bioassay demonstrated that fungicide residue was the mechanism by which this control occurred. None of the other fungicide cover spray programs contributed significantly to brown rot control at harvest in any year, and bioassay results showed insufficient residue to inhibit conidial germination. Antisporulant activity against blossom blight cankers was not observed for any fungicide program, indicating that reducing inoculum production from this source was not a mechanism for brown rot control. The captan and sulfur programs provided very good control of peach scab incidence and severity, caused by Fusicladium carpophilum, while the ziram and thiram programs failed to control this disease. These findings demonstrated that captan cover sprays can contribute significantly to control of brown rot at harvest, thereby augmenting the efficacy and consistency of management by preharvest fungicide programs. Furthermore, any reduction of the M. fructicola population by the captan cover sprays should reduce selection pressure against the site-specific fungicides commonly used during the preharvest period, thereby prolonging their useful life for brown rot control.
在2012年至2015年生长季的收获前果实成熟阶段，对作为季中覆盖喷雾施用的四种保护性杀菌剂减少由褐腐病菌引起的褐腐病的能力进行了定量评估。在花期或收获前期间未施用任何杀菌剂。处理方案包括从早期脱壳开裂阶段开始施用克菌丹、硫磺、福美锌和福美双，并在收获前23至26天进行最后一次覆盖喷雾。通过检查每个处理的四棵重复树上的41至91个果实是否有腐烂症状来确定收获时褐腐病的发病率。在最后一次覆盖喷雾后的第8、15和22天的收获前期间评估产孢花腐溃疡病的发病率。在最后一次覆盖喷雾后的第7、14和21天还进行了体内生物测定，以确定收获前期间的杀菌剂残留水平。该生物测定使用分生孢子萌发作为有效残留量的定量指标。收获评估结果表明，在研究的所有年份中，克菌丹覆盖喷雾显著降低了褐腐病发病率。此外，生物测定结果表明杀菌剂残留是实现这种防治效果的机制。在任何一年中，其他杀菌剂覆盖喷雾方案对收获时的褐腐病防治均无显著贡献，生物测定结果表明残留量不足以抑制分生孢子萌发。对于任何杀菌剂方案，均未观察到对花腐溃疡病的抗产孢活性，这表明减少该来源的接种体产生不是褐腐病防治的机制。克菌丹和硫磺方案对由嗜果枝孢引起的桃疮痂病的发病率和严重程度提供了很好的防治效果，而福美锌和福美双方案未能防治该病。这些发现表明，克菌丹覆盖喷雾可对收获时的褐腐病防治做出显著贡献，从而增强收获前杀菌剂方案管理的有效性和一致性。此外，克菌丹覆盖喷雾对褐腐病菌种群的任何减少都应降低对收获前常用的位点特异性杀菌剂的选择压力，从而延长它们对褐腐病防治的使用寿命。
