I thought it was necessary to write a blog on the issues we are having with the greens at the moment. Hopefully it will answer some of your questions and put to bed some of the speculation that it could be (very interesting some of it). We decided to hollow core the problem greens 6th, 15th & 16th (at the time the 3rd was showing no signs of stress). After initial testing we were left scratching our heads. We took core samples from each green. Organic levels (thatch) on all greens were no different from any other green on the course. Thatch levels were 5%-10% deeper than the rest of the course but as like all the greens the organic matter was loose and free draining. By this I mean the water will percolate freely through the thatch where as if it were tight and fibrous it would act like a sponge and definitely hold the water. So that was organic matter levels ruled out. Next we tested root depth and health. This is hard to quantify this time of year as the plant is not quite growing. We should be seeing roots on the meadow grass (Poa annua) around 50mm. Most of the samples we pulled had roots of 50mm - 75mm. Roots were healthy and showing signs of new shoots. Root health ruled out. Although we did have some interesting roots on the worn areas, I will touch on that later. Next we tested the water content down to 75mm with our water probe. It was slightly high as we would expect but not high enough to worry about. Wetting agent (penetrant) had been applied at regular intervals during the winter to help facilitate water from the surface through to the sub-soil. Plant health was good at time of testing. So where do we go from here. I called our agronomist from the STRI for some advice, after explaining all the symptoms and the testing we had done we came to the conclusion the only thing it could possibly be was a perched water table. The grass plant is effectively drowning as the water is not percolating through the profile. Keeping it simple it means water is being trapped/held between two types of soil/layers. In our case I would say because our greens are over 100 years old and has no drainage by way of design. Old push up greens were designed to hold the water during the days of no automatic irrigation. As you can imagine over the last 70/80 years water has been applied damaging the sub-soil structure along with a too finer particle size top dressing previously used has caused a definitive layer (this is why we aerate so much to keep these layers free draining). Imagine a hollow tube filled with marbles, pour some water into the top of the tube and it flows pretty easily to the bottom. Now place some smaller objects into the tube like peas for instance, pour water into the tube and the water mover less freely but also catches small particles easier. This is why we dress the greens with a large size sand particle as to a very fine particle previously used. So to summarise the water is getting trapped between our dressing and a poor quality sub-soil which is causing the water to drain away very slowly. This hopefully will be confirmed by our agronomist on 19th April. See image below of perched water table (sorry about the labels)
Loss of grass coverage. There are a few reasons why we have lost grass coverage on some of the greens. We experienced this last year possibly worse. Firstly we were unable to change the holes for over 2 weeks due to the frost. When we eventually did change them some of the frost had penetrated 3-4 inches down. Footfall causes most of the damage during the frost around the hole. This is most evident on the 6th green at the back. The plant is constantly being put under stress by humans as well as environmentally. Holes not being changed for 2 weeks also causes compaction which is where we were seeing shallow rooting 15mm - 25mm. Being a busy course with a lot of footfall in a 2 week period. Even if we did change the holes during that 2 week period I think a review of our frost policies may need looking at. Temporary greens or 2 holes. A lot of the damage is also compaction caused from walk off/on areas
We have also had a chemical toxification/compatibility issue. Prior to spraying any new chemicals it is imperative you we do a jug test. Take a tablespoon of each chemical you are using and mix it in water to see if they are compatible. If they are not they will coagulate, solidify or separate. So I sprayed a chemical in with 2 other chemicals to control the moss in the greens. I did a jug test and they were compatible. My only though is the sprayer tank was contaminated which would be a surprise as we clean after every use or they reacted in a greater volume of water. This combination of chemical has scorched some of the grass and is very evident on the 3rd. Localised scorching can be seen of some of the other greens. This is a testing time of year in the cycle of the grass plant. Night time temperatures are still cool with higher than normal day time temperatures with no rain is probably the worst combination. The grass takes time to recover from the night time temperature, then losses water from the leaf (evaporation) where the temperatures are high, no rainfall to replace the water lost from the leaf and so the cycle goes putting the plant under increased stress. Add a toxic chemical to the equation and you have the loss of grass we have.
Solution, be patient. We are still in early April so i'm not panicking too much yet .Nighttime temperatures need to get a little higher, natural rain would help. We can overseed the bare areas and apply seaweed and micronutrients to encourage growth. I have no doubt these areas will recover, like I said they worse last year and they came good. We need to find why these areas are occurring and treat them accordingly. Hopefully i will have some more information after the visit from the STRI.
The picture below shows the footfall in the frost from one 4 ball.
Here is a link to our industries monthly magazine file:///C:/Users/user/Downloads/gi-april-2017.pdf
Particularly page 30 PESTICIDE WITHDRAWAL WHERE ARE WE? as we find it increasingly hard to control worms and other pests this article might help you understand the future difficulties we may have. The second article a favourite of mine Page 42 HOW DO YOU DEFINE FAST, very interesting.
Thank you for reading.
Regards Lee & Greenkeeping team.
Particularly page 30 PESTICIDE WITHDRAWAL WHERE ARE WE? as we find it increasingly hard to control worms and other pests this article might help you understand the future difficulties we may have. The second article a favourite of mine Page 42 HOW DO YOU DEFINE FAST, very interesting.
Thank you for reading.
Regards Lee & Greenkeeping team.