Fruit infection occurs on the tree through the calyx, lenticel or stalk end and takes place between blossom and harvest.
- Recent inoculation experiments have shown that fruit is most susceptible to infection at blossom and petal fall.
- Fruit susceptibility then declines in summer with a small increase in susceptibility before harvest.
- Fruit infection that occurs in late bloom may develop into visible eye rot in the orchard or remain latent and develop in cold store.
- The factors that determine whether infection develops into eye rot or remains latent are not clear.
- Infected apples in the orchard rot and mummify. These mummies can then act as a source of inoculum.
- The resistance of young Bramley apples to Neonectria is thought to be related to the presence of benzoic acid in apples, the toxicity of which decreases as the fruit matures.
- Controlled atmosphere storage also influences the development of Neonectria rot in store.
- In Bramley, concentrations of CO2>5% v/v in the fruit store atmosphere progressively inhibit the production of benzoic acid and hence increase rotting due to Neonectria.
- Storage under ultra low oxygen regimes also increases the incidence of Neonectria rot.
- Hence storage regimes for Bramley of 5% CO2 and 1% O2, used as an alternative method to post-harvest treatment with DPA for control of superficial scald, will increase the incidence of rotting due to Neonectria in stored fruit from cankered orchards.
- Rot development in fruit stored at 1-2oC (e.g. Gala) is reduced compared to that in fruit stored at 3.5-4oC (e.g. Cox and Bramley).