Pathogenicity of fungi associated with wheat and barley seedling emergence and fungicide efficacy of seed treatment

Abstract

Presented study focused on the influence of Cochliobolus sativus isolates origin on pathogenicity towards wheat and barley seedlings in comparison with pathogenicity of certain Fusarium species and Microdochium nivale. The efficacy of fungicide seed treatment against C. sativus was estimated. The C. sativus isolates were collected from different locations and were isolated from wheat, barley and sunflower seeds. The pathogenicity of C. sativus, Fusarium species and M. nivale towards germinating seedlings were expressed as germination (GA) retardation and coleoptile growth rate retardation (CGR). Of wheat only, the CGR was significantly influenced by the isolate origin. The C. sativus isolates obtained from sunflower seeds were the most aggressive. Of the barley seeds, the barley isolates were the most aggressive. Barley was significantly more susceptible to damage by C. sativus isolates than wheat. The pathogenicity of tested fungal species declined in the order: F. culmorum, F. graminearum, C. sativus, F. avenaceum, M. nivale, F. poae for both barley and wheat. The results highlighted high pathogenicity potential of C. sativus equal to that of F. avenaceum and M. nivale. The symptoms of C. sativus on coleoptile and roots were very similar or the same as the symptoms caused by Fusarium species and M. nivale, except of white, pink or red colours. Of wheat sprouts, the fungicide efficacy (FE) against C. sativus declined in the order: tebuconazole + thiram, carboxin + thiram, quazatine, difenoconazole, iprodione + triticonazole (in term of GA) and carboxin + thiram, iprodione + triticonazole, tebuconazole + thiram, difenoconazole, quazatine (in term of CGR). In barley, the FE declined in the order: carboxin + thiram, iprodione + triticonazole, tebuconazole + thiram, difenoconazole, quazatine (in term of GA) and carboxin + thiram, tebuconazole + thiram, difenoconazole, iprodione + triticonazole, quazatine (in term of CGR).

Microdochium nivale and M. majus as causative agents of seedling blight in spring cereals

“…M. nivale was more common on winter barley than on winter wheat (Dawson, Bateman, 2001). In another study winter wheat was more susceptible to Fusarium species and M. nivale than winter barley (Hudec, 2007). Usually Microdochium species is present as one or both (Nicholson et al, 2002).…”

Viability of seed-borne fungi Alternaria alternata, Bipolaris sorokiniana and Drechslera teres in barley seeds in the south of Brazil

“…In the south region of Brazil, barley seeds are generally commercialized after chemical treatment. However, most of these chemical treatments have not eradicated A. alternata, B. sorokiniana and D. teres (12,13,23). In the present study, barley seeds were demonstrated to present a viable inoculum of A. alternata, B. sorokiniana and D. teres during storage, since incidence and viability of these fungi were maintained in the seeds.…”

“…Nevertheless, seed health testing has revealed that a large number of treated seeds are infected by A. alternata, B. sorokiniana and D. teres (4). Moreover, incidence of seed-borne fungi in harvested seeds is high, further compromising the treatment effectiveness (6, 13,23). Incorrect or inefficient fungicide treatment may allow the survival of necrotrophic fungi and the spread of diseases to other uninfested sites (6, 7).…”

Impact of Fungicide Timing on the Composition of the Fusarium Head Blight Disease Complex and the Presence of Deoxynivalenol (DON) in Wheat

“…Generally it is accepted that F. graminearum is more resistant to fungicides than F. poae. Using several fungicides such as diphenoconazole, tebuconazole, iprodione,… it was demonstrated that the sensitivity of F. graminearum was lower compared to F. poae (Hudec, 2007;Mullenborn et al 2008). Till now, we have no clear explanation for this discrepancy, however, possibly the isolate, the incubation temperature, the culture conditions might influence the sensitivity response in both species.…”