Efficacy of preplant treatments of gladiolus corms with combinations of acibenzolar-S-methyl and biological or chemical fungicides for suppression of fusarium corm rot [Fusarium oxysporumf. sp.gladioli]

Abstract

In 2003In -2005, corms of gladiolus (Gladiolus ×hortulanus) susceptible to Fusarium oxysporum f. sp. gladioli were soaked for 30 min in Actigard ® 50WP (50% in wettable powder; acibenzolar-S-methyl (ASM)), with or without biological or chemical fungicides, to determine if any treatment or combination of treatments provided season-long suppression of fusarium corm rot in the fields in Hamden, Connecticut, United States. Corms treated with ASM produced 48% more marketable flower spikes than untreated corms, and the value of the area under the disease progress curve (AUDPC) was reduced by 12%. However, this reduction was not significant. The chemical fungicides Medallion ® 50WP (fludioxonil) and Terraguard™ 50WP (triflumizole) reduced the AUDPC by 27% and 23%, respectively, and almost doubled the number of marketable flower spikes. None of the biological fungicides (Actinovate™ SP (water-soluble powder), Companion ® , MycoStop ® , and PlantShield™), nor the chemical fungicide 3336™ 50WP, were effective in reducing the AUDPC or increasing the number of spikes. No interactions were noted between ASM and the fungicides, except when ASM was combined with Heritage™ 50WP (azoxystrobin). ASM and Heritage 50WP used separately were not effective in reducing the AUDPC but, when combined, they provided season-long suppression of corm rot. Continued research on ASM may lead to an effective new strategy for reducing corm rot on gladiolus and related ornamentals. Résumé :De 2003 à 2005, des bulbes de glaïeuls (Gladiolus ×hortulanus) sensibles au Fusarium oxysporum f. sp. gladioli ont été trempés durant 30 min dans des bains contenant de l'Actigardz 50PM (50% en poudre mouillable; acibenzolar-Sméthyle (ASM)), en association ou non à des fongicides biologiques ou de synthèse, afin de déterminer quels traitements ou combinaisons de traitements procure une protection contre la pourriture fusarienne du bulbe pour toute la saison aux champs à Hamden, Connecticut, États-Unis. Les bulbes traités à l'ASM ont produit 48% plus d'épis floraux commercialisables que les bulbes non traités et avaient une valeur de surface sous la courbe de progression de la maladie (SSCPM) de 12% inférieure. Cependant, cette réduction n'était pas significative. Les fongicides de synthèse Medallionz 50PM (fludioxonile) et Terraguard{ 50PM (triflumizole) ont diminué les valeurs de la SSCPM de 27% et 23%, respectivement, et ont presque doublé le nombre d'épis floraux commercialisables. Aucun des fongicides biologiques (Actinovate{ PS (poudre soluble dans l'eau), Companionz, MycoStopz et PlantShield{), ni le fongicide chimique 3336{ 50PM, n'ont pu réduire la SSCPM ou augmenter le nombre d'épis. Il n'y a pas eu d'interactions observées entre l'ASM et les fongicides, sauf pour la combinaison ASM et Heritage{ 50PM (azoxystrobine). L'ASM et Heritage 50PM utilisés séparément ne réduisaient pas la SSCPM, mais lorsque utilisés ensemble, ils procuraient une protection contre la pourriture du bulbe pour toute la saison. De la recherche additionnelle sur l'utilisation de l'...

Genetic transformation of Fusarium oxysporum f.sp. gladioli with Agrobacterium to study pathogenesis in Gladiolus

“…Resistance against the pathogen has not been reported and tolerance is detected only in a limited number of cultivars (Löffler et al 1997;Straathof et al 1998). Very few novel chemical control methods have been tested (Elmer 2006), mostly due to insufficient knowledge of the disease process. Moreover, no efficient therapeutic treatments are available against the pathogen; hence eradication of infected bulbs is an important aspect of disease control methods.…”

Novel Elicitors Induce Defense Responses in Cut Flowers

“…In cyclamen, infection by Fusarium oxysporum f.sp. cyclaminis was reduced with increasing ASM doses (Elmer, 2006a). Additionally, the dry mass of ASM treated cyclamen plants increased with increasing ASM rates.…”

“…Chemical elicitors such as ASM have been applied in pot ornamentals such as petunia (Becktell et al, 2005), cyclamen (Elmer, 2006a) and in gladiolus corms (Elmer, 2006b), but effectiveness varied within the different experimental designs and conditions. In cyclamen, infection by Fusarium oxysporum f.sp.…”

Induction of disease resistance in ornamental geophytes

“…Similarly to the signaling molecule SA, resistance elicited with BTH was shown to be more effective against biotrophic pathogens relying on living plant tissues rather than against necrotrophs which survive on dead tissues (Gozzo, 2003;Glazebrook, 2005). This reduction however was not significant (Elmer, 2006b) ( Table 1). In Zantedeschia aethiopica, pre-treatment of detached leaves with BTH under laboratory conditions for 24 h before inoculation with P. carotovorum delayed bacterial proliferation during the first 48 h by three orders of magnitude and reduced symptoms by 50%.…”