A biological control agent for Heterobasidion annosum (formerly known as Fomes annosus)
PG Suspension is manufactured in Forest Research’s Centre for Forestry and Climate Change at Alice Holt Lodge in Surrey. On average three batches are produced each year to supply Santon Downham Forest District in East Anglia.
The product is a suspension concentrate composed of live spores (oidia) and mycelium of P. gigantea. The formulation contains a mix of spores, water, sugars and colour additives.
The PG Suspension mixture is pumped into sterile plastic tubing and sealed at intervals to produce small sachets which contain 7-10ml of product. If kept refrigerated the product will retain its viability for six months as the low water activity (aw) of the formulation ensures that the growth of most bacteria and yeasts is prevented.
P. gigantea mycelium is scraped off Malt agar plates
Spores are mixed with sugar water and honey
The solution is pumped through plastic tubing
Each sachet must contain several million spores per millilitre of concentrated product in order to be successful. The concentration of viable spores is monitored before the product is dispatched to the field, and another mid-term test on viability is carried out in the laboratory to ensure the product has not deteriorated over time.