Mueller D S, Jeffers S N, Buck J W
Department of Plant Pathology, University of Georgia, Georgia Station, Griffin 30223.
Department of Entomology, Soils, and Plant Sciences, Clemson University, Clemson, SC 29634.
Plant Dis. 2005 Mar;89(3):255-261. doi: 10.1094/PD-89-0255.
The recent introduction and rapid spread of rust on daylilies, caused by Puccinia hemerocallidis, suggested a need for fungicide treatments that reduce urediniospore viability on plant surfaces. Twelve fungicides in seven chemical classes were evaluated in vitro for toxicity to urediniospores of rust fungi that occur on daylily (P. hemerocallidis), geranium P. pelargonii-zonalis), iris (P. iridis), oxalis (P. oxalis), mint (P. menthae), and Florida azalea (Pucciniastrum vaccinii). Germination of urediniospores of all six rust fungi on potato dextrose agar in the absence of fungicides ranged from 54 to 88%. Germination of urediniospores of all rust species during and after exposure to azoxystrobin, chlorothalonil, copper sulfate pentahydrate, mancozeb, and trifloxystrobin was less than or near 1%. Germination during exposure to fenhexamid, iprodione, myclobutanil, propiconazole, thiophanate-methyl, triadimefon, and triflumizole ranged from 0 to 60% and usually was greater (0 to 75%) after fungicide residues had been removed. Germination of urediniospores of P. pelargonii-zonalis decreased when exposed to azoxystrobin, copper sulfate pentahydrate, and mancozeb for 1 min and was nearly eliminated after a 30-min exposure, while exposure to trifloxystrobin and chlorothalonil eliminated germination after 4 and 8 h, respectively. Urediniospores that had been allowed to imbibe water for 4 h had no further germination or germ tube growth after a 24-h exposure to azoxystrobin, chlorothalonil, copper sulfate pentahydrate, mancozeb, and trifloxystrobin. Less than one lesion per plant developed on seedlings inoculated with urediniospores of P. pelargonii-zonalis that had been sprayed with azoxystrobin, chlorothalonil, copper sulfate pentahydrate, and mancozeb, whereas seedlings inoculated with spores not exposed to fungicides developed 148 lesions per plant. The strobilurin (azoxystrobin and trifloxystrobin), broad-spectrum protectant (chlorothalonil and mancozeb), and inorganic copper (copper sulfate pentahydrate) fungicides were fungicidal to urediniospores of the six rust fungi. However, the benzimidazole (thiophanate-methyl), dicarboximide (iprodione), hydroxyanilide (fenhexamid), and demethylation-inhibiting (myclobutanil, propiconazole, triadimefon, and triflumizole) fungicides were only fungistatic to rust urediniospores.
由萱草柄锈菌（Puccinia hemerocallidis）引起的锈病最近在萱草上出现并迅速传播，这表明需要进行杀菌剂处理，以降低植物表面夏孢子的活力。对七类化学物质中的12种杀菌剂进行了体外评估，以测定其对发生在萱草（P. hemerocallidis）、天竺葵（P. pelargonii-zonalis）、鸢尾（P. iridis）、酢浆草（P. oxalis）、薄荷（P. menthae）和佛罗里达杜鹃（Pucciniastrum vaccinii）上的锈菌夏孢子的毒性。在没有杀菌剂的情况下，所有六种锈菌的夏孢子在马铃薯葡萄糖琼脂上的萌发率为54%至88%。暴露于嘧菌酯、百菌清、五水硫酸铜、代森锰锌和肟菌酯期间及之后，所有锈菌种类的夏孢子萌发率均低于或接近1%。暴露于咯菌腈、异菌脲、腈菌唑、丙环唑、甲基硫菌灵、三唑酮和氟菌唑期间，夏孢子萌发率为0%至60%，去除杀菌剂残留后，萌发率通常更高（0%至75%）。天竺葵柄锈菌（P. pelargonii-zonalis）的夏孢子暴露于嘧菌酯、五水硫酸铜和代森锰锌1分钟后，萌发率降低，暴露30分钟后几乎完全不萌发，而暴露于肟菌酯和百菌清后，分别在4小时和8小时后萌发完全被抑制。已吸水4小时的夏孢子在暴露于嘧菌酯、百菌清、五水硫酸铜、代森锰锌和肟菌酯24小时后，不再进一步萌发或产生芽管生长。用嘧菌酯、百菌清、五水硫酸铜和代森锰锌处理过的天竺葵柄锈菌夏孢子接种的幼苗，每株植物上形成的病斑少于1个，而用未接触杀菌剂的孢子接种的幼苗，每株植物上形成148个病斑。甲氧基丙烯酸酯类（嘧菌酯和肟菌酯）、广谱保护剂（百菌清和代森锰锌）和无机铜（五水硫酸铜）杀菌剂对六种锈菌的夏孢子具有杀菌作用。然而，苯并咪唑类（甲基硫菌灵）、二甲酰亚胺类（异菌脲）、羟基苯胺类（咯菌腈）和脱甲基抑制剂类（腈菌唑、丙环唑、三唑酮和氟菌唑）杀菌剂对锈菌夏孢子仅具有抑菌作用。
