Munkvold G P, O'Mara J K
Department of Plant Pathology, Iowa State University, Ames 50011.
Plant Dis. 2002 Feb;86(2):143-150. doi: 10.1094/PDIS.2002.86.2.143.
The performance of seed treatment products for maize usually is evaluated in field experiments, where it is difficult to assess their effects on specific important pathogens such as fungi in the genus Fusarium. To evaluate three fungicidal seed treatments (captan, difenoconazole, and fludioxonil) against six Fusarium species that infect maize seed or seedlings, we conducted experiments in the laboratory and in growth chambers. In the laboratory experiments, treated and nontreated seeds of two maize hybrids were incubated on the surface of an agar medium colonized by each of 12 Fusarium isolates. The fungi did not reduce seed germination, but most Fusarium isolates caused decay of the seed and radicle, and arrested the development of the radicle. All three fungicides significantly reduced the colonization and decay of the seeds and radicles by Fusarium isolates and resulted in greater radicle lengths, but there were significant interactions between the effects of fungicide treatments and Fusarium isolates. Overall, difenoconazole was the most effective fungicide for the prevention of seed colonization and decay. Fludioxonil was overall the most effective fungicide in terms of increased radicle length, particularly when seed was exposed to isolates of F. graminearum, which were among the most aggressive isolates in the experiments. In the growth chamber experiments, seeds were planted in a Fusarium-infested potting medium, which resulted in lower emergence, shoot length, root length, and dry weight of seedlings compared to the noninfested control. Some isolates also caused root rot symptoms. All three fungicides significantly improved shoot and root length and root health, difenoconazole and fludioxonil significantly improved emergence, and only difeno-conazole significantly improved dry weight compared to the nontreated control. There were significant rank correlations between the results of the laboratory and growth chamber experiments in terms of relative aggressiveness of the isolates and relative efficacy of the fungicides. The laboratory experiments were more sensitive in terms of detecting differences in fungicide performance. These results indicate that all three fungicides were effective against Fusarium, but difenoconazole and fludioxonil generally were more effective than captan; the fungicides also differed in efficacy against different Fusarium species.
玉米种子处理产品的性能通常在田间试验中进行评估，而在田间试验中，很难评估它们对特定重要病原体（如镰刀菌属真菌）的影响。为了评估三种杀真菌种子处理剂（克菌丹、苯醚甲环唑和咯菌腈）对六种感染玉米种子或幼苗的镰刀菌的防治效果，我们在实验室和生长室中进行了试验。在实验室试验中，将两个玉米杂交种的处理种子和未处理种子分别接种在由12种镰刀菌分离株定殖的琼脂培养基表面。这些真菌并未降低种子发芽率，但大多数镰刀菌分离株导致种子和胚根腐烂，并抑制胚根发育。所有三种杀菌剂均显著减少了镰刀菌分离株对种子和胚根的定殖和腐烂，并使胚根长度增加，但杀菌剂处理效果与镰刀菌分离株之间存在显著交互作用。总体而言，苯醚甲环唑是预防种子定殖和腐烂最有效的杀菌剂。就增加胚根长度而言，咯菌腈总体上是最有效的杀菌剂，特别是当种子接种禾谷镰刀菌分离株时，该分离株是试验中最具侵染性的分离株之一。在生长室试验中，将种子种植在受镰刀菌侵染的盆栽基质中，与未受侵染的对照相比，这导致出苗率、苗长、根长和幼苗干重降低。一些分离株还引起根腐症状。与未处理对照相比，所有三种杀菌剂均显著改善了苗长和根长以及根系健康状况，苯醚甲环唑和咯菌腈显著提高了出苗率，只有苯醚甲环唑显著提高了干重。就分离株的相对侵染性和杀菌剂的相对防效而言，实验室试验和生长室试验的结果之间存在显著的等级相关性。在检测杀菌剂性能差异方面，实验室试验更为灵敏。这些结果表明，所有三种杀菌剂对镰刀菌均有效，但苯醚甲环唑和咯菌腈通常比克菌丹更有效；这些杀菌剂对不同镰刀菌种类的防效也有所不同。
