Here at Pukekohe Golf Club we are currently in the process of a grass species conversion within our greens. Our aim is to convert the existing Poa. annua greens to brown-top.
Why brown-top?
The reasoning is simple. Brown-top provides a world class putting surface and requires less inputs than poa does, It requires less fertiliser, less water, less agri-chemicals and has a good year round quality.
So how do we convert to brown-top?
Nutrient Inputs:
Brown-top requires less nitrogen than poa does, this means we apply less nitrogen which gives the brown-top a distinct advantage over than poa, this is relatively obvious in the summer months and the poa can appear yellow and starved (this will not effect putting green smoothness and trueness but will affect the colour uniformity). Acidifying the putting green surface with certain fertilisers such as Ammonium Sulphate also plays a part in encouraging the the brown-top to dominate as it prefers a lower pH than poa.
Water Management:
Brown-top requires significantly less water than poa. Here at Pukekohe GC, we have introduced an extensive moisture reading programme through the summer months and our target moisture levels are now 20% or under. Whilst we still have a large poa percentage within the greens we must be sure not to run them to dry as this will cause the poa to wilt and die.
Over-seeding and chemical controls:
At our annual March renovation we will over-seed with Arrowtown brown-top to introduce some new brown-top. Our over-seeding earlier this year was a huge success and many seedlings germinated very quickly. As for chemical controls, we are not at levels where this is currently possible, but once our brown-top percentages are upwards of 90% we may consider using selective herbicides to eradicate the poa.
There are many other factors to influence the brown-top grass but those are the main three.
Regards
Pukekohe Golf Club Maintenance Division.