The vast majority of growers will have had no problem with this bacterium contaminating their produce. However a few unlucky ones have lost one or more crops. The question arises who bears this loss? It certainly should not be the grower. I would have liked to see government compensate, although I can't see this happening. To me the situation appears not dissimilar in principle to the various recent disease disasters in agriculture with which we are only too familiar. If only a compost levy had accumulated sufficient funds! Either to make a case or pay out to the unlucky ones. Another avenue is third party liability.
It was only a rapid reaction by casing manufacturers, imposing a restriction on supplying sugar beet lime (SBL) that prevented more widespread losses. Without SBL some growers have reported poorer quality mushrooms. However it is not certain that the absence of SBL is the cause of this quality fall. Ambient temperatures have also risen rapidly during this period and in some cases compost quality may have fallen into one of its regular troughs as opposed to rising to one of its peaks. Care in not over watering the casing will improve mushroom quality. Reduced watering is important because of higher ambient temperatures and higher relative humidities and therefore less evaporation. Nevertheless, SBL is reported to increase casing density and also reduce mushroom numbers. Fewer mushrooms aids quality. Furthermore SBL may well reduce the ease with which mushrooms take up water from the casing. This would have the effect of increasing their dry matter, making them harder and thus less easily bruised. In any case SBL should now not prove to be a problem if it is obtained from a supplier who can give a guarantee that it is not contaminated by either S. kedougou or E. coli. The casing manufacturer would also have to check this by regular sampling.
At the moment all the casing manufacturers in Northern Ireland have made a big effort to spring clean, dump all old stock of raw materials and as a consequence have had a long succession of negative tests. They are thus anxious to resume business as usual and bring in fresh supplies of SBL from England.
There have been two other consequences of the outbreak. In some cases case run has been extremely slow. It appears likely in such cases that part of the mycelium from the compost, or more likely, most of that from the casing inoculum has been killed by some treatment that the casing is receiving now, that it was not previously. It must be stressed that casing should not be overdosed, either with formaldehyde by the casing manufacturer or by Red Label (hypochlorite) by the grower. A healthy bacterial flora in the casing is also essential for pin formation.
The other consequence is that all concerned have been forced to accept that casing will have to be treated with much greater hygiene care than would have been thought reasonable previously. The principle that has emerged is that mushrooms are a high risk food (like any other vegetable that may on occasions be eaten raw). Because casing comes into intimate contact with growing mushrooms it also has to be free of any organism that could be injurious to human health. In other words, casing itself should for all intents be treated as a food! With this main principle in view, a very detailed code of practice is being drawn up as a cooperative effort North and South. It will also include a thorough risk assessment of every aspect of production. A substantial outlay will be required to update facilities, consequently casing prices may be forced to rise somewhat.
