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PG Suspension – Handling, mixing and using

ha_pg_headsamp.jpgA 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.


Because 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 about six months and the expiry date is clearly displayed on the label.



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. Bacteria can build up on the sides if tanks are not cleaned regularly, and this might 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 the operator or the environment.

Where PG Suspension is being applied mechanically through harvesting machinery, operators should 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 on thinning or clear-fell sites which have been treated with PG Suspension, and examine them for any signs of colonisation by H. annosum.

ha_pg_head_sampling.jpg ha_pg_hannosum.jpg

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.




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