S.M. Hoyte, P.A.G. Elmer, F.J. Parry, J.T. Taylor, R.S. Marsden
Sclerotinia sclerotiorum attacks petals and stamens of 'Hayward' kiwifruit leading to blighted flowers, scarring and field rot on developing fruit. The cost of direct crop loss to the New Zealand industry is estimated to be $5–11 M p.a. International market demands for fungicide residue-free fruit has stimulated interest in biological suppression of Sclerotinia as an alternative disease control strategy. A single flowering application of two biological control agents (BCAs), Epicoccum nigrum (HRE) and Ulocladium oudemansii (BOTRY-Zen®, BZ) significantly reduced the incidence of S. sclerotiorum in petals during 2004–2005. HRE and BZ reduced fruit scarring and BZ was equivalent to the fungicide (iprodione). Laboratory assays on necrotic kiwifruit petals assessed a wide range of BCAs and natural products for suppression of Sclerotinia. The developmental BCA (HRE), BZ and two other commercial products, based on Coniothryrium minitans and Trichoderma sp., reduced Sclerotinia petal infection by 100%, 83%, 91% and 82% respectively, when averaged over four petal bioassays. Unfortunately, the C. minitans product is currently not available for field use in New Zealand. Field evaluation of the other three BCAs, alone and combined at half field rates, was carried out in 2005–2006. All BCAs applied alone significantly reduced petal infection and flower blight incidence, but only HRE and BZ significantly reduced fruit scarring. Results using a combination of BCAs (BZ+HRE) at half field rates were equivalent to the BCAs applied alone at full field rates. BCA efficacy for all treatments ranged from 55–73% for petal infection; 24–70% for flower blight and 0–63% for fruit scarring, and was generally less than the fungicide, iprodione (78–96% efficacy).
Hoyte, S.M., Elmer, P.A.G., Parry, F.J., Taylor, J.T. and Marsden, R.S. (2007). BIOLOGICAL SUPPRESSION OF SCLEROTINIA SCLEROTIORUM IN KIWIFRUIT. Acta Hortic. 753, 661-668
DOI: 10.17660/ActaHortic.2007.753.87
Actinidia, disease control, efficacy, BOTRY-Zen®, Epicoccum nigrum, Trichoderma spp.

Acta Horticulturae