Guro Brodal
Seniorforsker (pensjonistavtale)
Sammendrag
Bønnebladflekk, forårsaket av soppen Ascochyta fabae (kjønna stadium Didymella fabae), er en av de viktigste sjukdommene i åkerbønne (Vicia faba). Sjukdommen er utbredt i alle områder hvor det dyrkes åkerbønne. Soppen overlever og spres først og fremst med infiserte såfrø, men kan også overleve i planterester og i spillfrø. Angrep kan starte på frøplanter kort tid etter oppspiring. Alle overjordiske plantedeler kan angripes, og infeksjonen viser seg som mørke, nekrotiske bladflekker som kan vokse og etter hvert få et lysere parti i midten. Her dannes det pyknider, som fremstår som små svarte prikker. De inneholder ukjønna sporer (konidiesporer). Sporer (smitte) spres i plantebestanden hovedsakelig via regnsprut. Det er kjent at soppen kan ha et kjønna stadium som kan utvikle ascosporer som kan spres med vind over lengre avstander, men det er ukjent hvorvidt dette har betydning for overlevelse og spredning av soppen under norske forhold. Sterke angrep kan forårsake at stenglene brekker og gi problemer med legde, eller at infiserte belger hindrer utvikling av frø. I alvorlige tilfeller kan infiserte planter dø. Dyptsittende infeksjon i belgene kan gi små, skrumpne/deformerte og misfarga frø. I fuktige sesonger kan sjukdommen forårsake store avlingstap.
Forfattere
Heidi Udnes Aamot Magne Nordang Skårn Chloé Grieu Anne-Grete Roer Hjelkrem Katherine Ann Gredvig Nielsen Silje Kvist Simonsen Nora Steinkopf Anne Kjersti Uhlen Guro BrodalSammendrag
Chocolate spot (CS) is one of the most destructive diseases affecting faba beans worldwide, leading to yield reductions of up to 90% in susceptible cultivars under conducive environmental conditions. Traditionally, the disease has been attributed to the fungal pathogens Botrytis fabae and Botrytis cinerea, however recent studies have identified three additional Botrytis species capable of causing the disease. Fungicide applications during flowering are commonly used to control the disease and limit damage to pod set, but this approach is not always effective. The reasons for this lack of control are not fully understood. To increase our understanding of the CS species complex in Norway, we used species-specific PCR to identify different Botrytis species in symptomatic leaves collected at various locations and years. Some Botrytis species are known to be high-risk pathogens for fungicide resistance development, but resistance in Norwegian Botrytis populations in faba bean have not previously been studied. Therefore, we obtained Botrytis isolates from diseased leaves and used a mycelial growth assay to assess their response to the active ingredients (boscalid and pyraclostrobin) in the fungicide commonly used for CS control in Norway. Resistance to both boscalid and pyraclostrobin was detected among B. cinerea isolates, while only resistance to boscalid was detected among B. fabae isolates. To elucidate resistance mechanisms, we analyzed target gene sequences for the presence of mutations known to confer resistance to the two active ingredients. Field experiments were conducted to test the efficacy of various spray timings and fungicides in early and late faba bean varieties. Additionally, we are developing a disease risk model for CS to better understand the conditions that lead to disease and to improve the timing of fungicide applications.
Forfattere
Magne Nordang Skårn Chloé Grieu Anne-Grete Roer Hjelkrem Katherine Ann Gredvig Nielsen Silje Kvist Simonsen Nora Steinkopf Anne Kjersti Uhlen Guro BrodalSammendrag
Chocolate spot (CS) is one of the most destructive diseases affecting faba beans worldwide, leading to yield reductions of up to 90% in susceptible cultivars under conducive environmental conditions. Traditionally, the disease has been attributed to the fungal pathogens Botrytis fabae and Botrytis cinerea, however recent studies have identified three additional Botrytis species capable of causing the disease. Fungicide applications during flowering are commonly used to control the disease and limit damage to pod set, but this approach is not always effective. The reasons for this lack of control are not fully understood. To increase our understanding of the CS species complex in Norway, we used species-specific PCR to identify different Botrytis species in symptomatic leaves collected at various locations and years. Some Botrytis species are known to be high-risk pathogens for fungicide resistance development, but resistance in Norwegian Botrytis populations in faba bean have not previously been studied. Therefore, we obtained Botrytis isolates from diseased leaves and used a mycelial growth assay to assess their response to the active ingredients (boscalid and pyraclostrobin) in the fungicide commonly used for CS control in Norway. Resistance to both boscalid and pyraclostrobin was detected among B. cinerea isolates, while only resistance to boscalid was detected among B. fabae isolates. To elucidate resistance mechanisms, we analyzed target gene sequences for the presence of mutations known to confer resistance to the two active ingredients. Field experiments were conducted to test the efficacy of various spray timings and fungicides in early and late faba bean varieties. Additionally, we are developing a disease risk model for CS to better understand the conditions that lead to disease and to improve the timing of fungicide applications.
