Penicillium expansum is common, easily recognisable but not responsible for large fruit losses commercially.
- It invades fruit through wounds, bruises or cracks anywhere on the fruit surface often as a secondary invader of other rots.
- All apple varieties are susceptible, but Bramley is especially susceptible with some infection in the core later in storage life.
- Other varieties with an open calyx are likely to be similarly affected. Penicillium expansum can grow slowly within fruit tissues without necessarily causing fruit to rot but still producing patulin as it does so.
In studies funded by the Food Standards Agency between 1998 and 2001 Penicillium expansum was detected widely within orchards, in soils, debris on the orchard floor on various parts of the apple tree including leaves, bark and fruit) and within the mature fruit core.
- This study could not establish any relationship between patulin levels in juice from processed fruit from the orchards studied and fungicide use.
- However in one case there may have been a possible connection between the use of dithianon during the blossom period in the spray programme compared with captan used in the orchard in the same period,.
- The dithianon use appeared to have some link to higher patulin levels.
- Since this work was carried out a number of new fungicides have become available to apple growers.
- One with particular activity against Penicillium is Bellis (boscalid + pyraclostrobin). Results from research in Belgium show a useful effect against Penicillium spp.