12th Green Update

The green itself was constructed in the same method as 15, 9 & 4 with exactly the same amount of soil amendments added to the profile and we stuck to a very similar grow in method. The turf health was very good when it went down and I was expecting this green to grow in quicker than the other holes we had done due to the weather. About 4 weeks in seemed like the green had hit summer dormancy as bent grass or any cool season grass can do when temperatures exceed 32 degrees. Its very similar to what couch can do in the winter as it shuts up shop to store carbohydrates to survive. The growth on the green declined around Christmas time and we were struggling to get any real root depth and I put that down to maybe over-watering to compensate the warmer weather and the grow in of the surrounds. Granular applications of fertiliser didn’t really give the green a burst of life as we experienced on our previous greens and I was at a loss to understand what was happening.Last Friday I made a discovery when pulling out a runner of couch from the side of the green, the runner had very poor and stunted root formation that looked like it had suffered damage from a root bound insect (see photo). 2 weeks earlier we applied the insecticide Bifenthrin to target army worm that was present but army-worm tends to feed more on the crown of the plant so that wasn’t responsible for the root damage.

On the old 12th I had suspicions about nematode activity in the soil but usually with adequate moisture levels and correct nutritional inputs you can out compete nematodes. Nematodes are a microscopic parasite that is always present in the soil with over 40,000 different species identified around the world. The sting nematode is the largest nematode and can grow up to 3mm in length and feed on roots by piercing their stylets into the root and sucking out the contents from within the root cell. When the sting nematode has a high population within the soil profile they can inflict crop losses in both turf and agricultural crops throughout WA. I have been very wary of “nematode activity” as turf companies feed off this information and I have seen cases where large amounts of chemicals have been purchased and particularly in local government where ovals have needed to be replaced although the nematodes are still active in the remaining in soil.Looking into nematode activity the symptoms of having a high population within the soil is very much a like for what we have experienced, poor root growth, decline in growth, easily wilting/foot-printing. Although we removed 250mm of soil and replaced it with new sand and soil amendments the populations of nematodes must of been present in either the surrounds or deeper into the profile.

Following soil and turf analysis, plus extensive research I am confident we have made the right diagnosis. From here we will apply the prescribed insecticide to treat all greens with a follow up treatment 14 days later. As the soil temperatures drop nematode activity declines and we will schedule in further treatments in the spring to give the roots every chance to keep getting stronger and healthier.

Long term I have no concerns for the green and I expect it to bounce back and have a surface similar to 4 & 9. In the short term I’m happy to keep the green in play with some patching needing to take place on bare areas.

Dave Brennan

Course Superintendent