Poster Presentation Science Protecting Plant Health 2017

Control of Sclerotium Rot of chillies in Australia (#343)

Len Tesoriero 1 , L Spohr 1 , A Harris 1 , J Coulombe 2 , K Montagu 3 , G Rogers 3
  1. NSW Department of Primary Industries, Ourimbah, NSW 2258, Australia
  2. Austchilli Ltd, Bundaberg, Qld 4670, Australia
  3. Applied Horticultural Research Ltd ATP, Everleigh, NSW 2015, Australia

Capsicum and chilli production in Australia is currently valued at $136M annually. Summer crops in NSW and Queensland can be affected by Sclerotium Rot caused by the basidiomycete Athelia rolfsii (asexual state = Sclerotium rolfsii). Affected plants develop a basal stem and crown rot causing them to wilt and die. Greater than 25% of plants commonly die by their harvest date. Fruit from wilting plants are unacceptable for fresh markets and only a few producers have a secondary processing market. Our aim was to develop effective controls for this disease. We conducted two field experiments in the summer of 2016-7 to evaluate chemical and biological controls for Sclerotium Rot of chillies. One trial was located on a farm in Bundaberg, Queensland that was known to be infested with S. rolfsii. The second trial was established at Somersby in NSW where a sclerotial inoculum was applied. At both sites untreated control treatments were compared with chemical (pyraclostrobin or a combined formulation of cyprodinil and fludioxoni) or biological control treatments which were drenched around the base of plants at three-weekly intervals commencing at transplanting. The trial at the Somersby site used a commercial formulation containing an isolate of Pseudomonas fluorescens while the Bundaberg site used a product of an undisclosed microbial formulation. Plots were rated for disease severity at three growth stages with a final assessment at harvest. Yield data was collected at the Bundaberg site only. Chemical treatments generally reduced Sclerotium Rot significantly at both sites. P. fluorescens also significantly reduced the disease whereas the microbial formulation at Bundaberg was ineffective. These trials demonstrate that there are potential chemical and biological control options for Sclerotium Rot of chillies. Further studies are also addressing potential cultural controls such as plant spacing and irrigation scheduling.