As some of you have noticed, we are dealing with a minor issue in the low areas (#4 right side, #7 front right, etc.) and on #8 green. The following paragraphs will detail the current problem, what we've done and are doing to combat the issue, as well as future measures and expected recovery.
What We Are Seeing: The algae you are seeing is cyanobacteria (not actually algae), which we found from the results of a diagnostics test we sent off from #8 green on 4/18/16. So the darker slimy areas that you have seen as well as the surrounding yellowing areas are all a result of cyanobacteria. The formation of cyanobacteria in the low areas or high traffic areas is there this time of year for several reasons. The most prevalent of these is poor drainage and wet conditions (surface moisture). The mechanical stress and foot traffic compaction also aids the growth of cyanobacteria. With the heavy rainfall we received throughout April, along with days with inadequate sunlight, combined with ridiculously poorly constructed drainage systems are all contributions to these results. As we check moisture 2-3 days a week for hot spots, we also check our low areas. A majority of those areas maintain 40-50% moisture, and the acceptable moisture range for our greens is typically between 18-24%. During the growing season, they dry faster and are easier to maintain with higher evapotranspiration rates. However, throughout the winter and up to this time of year, the ET rates are lower and we have to mechanically open up pore space with solid aerification tines. What we are seeing is a winter's worth of wet conditions and traffic stress, and this spring hasn't been kind on us with consistent, periodic rain and shade from cloud cover. What is visible now is something that happens this time every year, but to a lesser degree.
The Underlying Problem: We found on that Monday (4/18/16) that the daylight to #8 green's drainage was submerged due to the recent rain, which basically suffocated the green and caused it to react as it did. we've since found out that the pipe has a sink in it 30 feet from the edge of the native, so there is a pocket in the pipe that holds water. This normally would not be an issue as long as the daylight is completely void of water, but I didn't discover the sink in the pipe until that week. In addition, the drainage system to the pipe is 3-4 feet deeper than a normal USGA spec system, and this is the case for all of the greens where we have exposed the drainage pipe (#9, #6, #4, #13, etc.) to add 4-ways and knife valves.
The Attack Plan: The following paragraph details what we've consistently done for 3+ years, as well as how we are addressing the problem with what we've seen this spring. On 4/18/16 we cleaned the daylight of #8 green, sent off a sample for diagnostics, and injected air into #8 with our air2g2 machine. In addition, we sprayed Oxyflor (hydrogen peroxide aqueous solution) and Pervade (soil penetrant/surface tension reducer) to #8, #9, #3, #4, and #5. On that Tuesday we finished cleaning out any other daylights that had potential for submersion, as well as re-trenched all the drainage trenches. We also aerified all of the low areas and areas showing cyanobacteria or anaerobic areas with a 1/4" pencil tine, and all of the greens were sprayed with two fungicides (chlorothalinil and a phosphite fungicide) for the cyanobacteria. That Thursday we blew air into all of the greens that we have installed 4-ways and knife valves on (#1, 2, 4, 5, 6, 7, 9, 11, and 13). We also hand spiked and topdressed those areas last week and again this week to mechanically remove the wet/slimy soil and replace it with sand. On Monday (5/2/16) we pencil tine aerified all of the greens, and our next round of fungicides specified for the cyanobacteria was sprayed on Saturday morning (5/7/16). We are in the process of adding a 4-way and knife valve to #8 this week, and in order to find the pipe we rented a camera snake for a week. The vent from the 4-way alone should help #8 in the long run, and the overall goal would be to have them installed on all 20 greens at Cowan Creek. Supposedly there are blowouts (pipes on the high ends of greens where gases can escape), but we've looked for years using a deep-tine aerifier and probes all to no avail. We confronted the construction superintendent, and he couldn't help in that regard, nor could he point us in the direction of any as-built drainage maps. We've utilized the time with the camera snake discovering other challenges to overcome with our greens' drainage elswhere. Feel free to read a report written on the blog in 2013 about the implementation of sub-surface airflow on how we manage greens with poorly constructed drainage: http://sctxgcmaint.blogspot.com/2013/01/attacking-our-problems-from-top-to.html