Handling, mixing and using PG Suspension

Operator sampling PG Suspension at the harvester headA biological control agent for Heterobasidion annosum (formerly known as Fomes annosus)

Instructions on the safe handling of the product are clearly displayed on the product label and leaflet. Those that appear as statutory conditions are legal requirements and must be complied with.


As PG Suspension is made up of live fungal spores special care is needed in its storage and handling to maintain its efficacy. Sachets must be kept refrigerated at 4oC before use, and exposure to high temperatures will kill the spores. The chilled product has a shelf life of around six months and the expiry date is clearly displayed on the label.

Sachet of PG Suspension


Once the spores have been mixed with water they germinate, and their shelf life is reduced to 24 hours. Therefore new working solutions must be made up every day. Any solution remaining in the tank at the end of the day must be emptied onto a stump, so do not make up more solution than you need. Make up the solutions with clean water in clean containers free from residues. If tanks are not cleaned on a regular basis bacteria can build up on the sides, and this may affect the viability of the solutions, and in extreme conditions create a health hazard.


Apply PG Suspension as soon after felling as is possible, and within 30 minutes. Stumps need to be completely covered to ensure adequate levels of control, and to aid treatment a dye can be added to the solution to provide a marker on the stump. Note that this dye must be compatible with the living product, and not present a health hazard to operator or environment.

Where PG Suspension is being applied mechanically through harvesting machinery operators perform periodic checks on spore viability by sampling the solution in the storage tank of the harvester and also from the hoses near the harvester head. Operators should also take random samples from stumps in thinnings or clear fell sites which have been treated within PG Suspension, and examine them for any signs of colonisation by H. annosum.

Operator taking sample of PG Suspension from harvester head Conidiophores - characteristic fruiting structures produced by H. annosum growing on wood

These tests will highlight any viability problems which could arise if the solution passes through hot spots, or areas of high pressure along the hoses leading down to the harvester head.


What's of interest

PG Suspension statutory information note
PG Suspension product label containing statutory conditions
Product label (PDF-1237K)

PG Suspension for the control of Fomes Root Rot of pine
Forestry Commission Information Note 18 (PDF-1514K)

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