This finding confirms the merit of the increasingly common practice of applying a suitable fungicide during bloom.
The work was carried out by Dr Xiangming Xu, who described it at an EMR Association tree fruit members' day on 24 November. It was deemed necessary due to a lack of information about the development of Nectria rots in relation to the fruit's age and wet periods during the fruit's development, said Xu.
One or more of several apple varieties, including Bramley, Cox and Gala, were artificially inoculated with the fungus at various times up to 18 weeks after full bloom. The fruit was subsequently subjected to as many as five wet periods.
However, Xu pointed out that these procedures were not an accurate reflection of what happens in practice, although the conclusions are valid. On average, the experiments showed that the earlier the inoculation was done, the higher the incidence of eye and storage rots. Furthermore, the longer the wetness duration, the worse the rotting of the fruit inoculated first. That effect was not repeated with the fruit inoculated on the latest date, though.
"The three cultivars didn't differ significantly in their susceptibility to Nectria," added Xu. "These are the first studies to confirm that eye and storage rots come from early infection."