- Pre-harvest fungicide sprays such as cyprodinil + fludioxonil (Switch) and pyraclostrobin + boscalid (Bellis) used for control of other storage rots may give some control of Penicillium rot.
- Treatment of water with chlorine (calcium hypochlorite) has been used in the USA and South Africa, either alone or as a pre-wash prior to fungicide application, to reduce inoculum levels of Penicillium spores and other wound pathogens, present on the fruit surface and in water in flotation tanks and hydro-coolers.
- Trials at East Malling confirmed that active chlorine (100 ppm at pH 7.5) killed fungal spores, bacteria, yeast cells present in the drench tank, with consequent reduction in rotting.
- However, such treatment is ineffective against fungal rots which are already present in the fruit as latent infections.
- Specialist application equipment is needed to ensure that the effective concentration is maintained as chlorine is quickly mopped up from solution by any organic debris such as leaves.
- Chlorine is also corrosive to metal surfaces.
Avoiding fungicide resistance
- The resistance status of P. expansum to cyprodinil + fludioxonil (Switch) and pyraclostrobin + boscalid (Bellis) is not known. The most effective strategy is to ensure cultural measures are used effectively and not rely on fungicides for control.