Pollen is a dye contained within a lipid, first the lipid or fat part of the stain must be treated with a gel to prevent the dye element from running into surrounding fibres, then the dye part of the stain can be treated. This is the most difficult part and can have limited results if the fibres are woolen and have taken on the dye. Call a trained professional for best results. Matt Carpet Cleaning Trafford 07855 114 660