A few members have recently asked questions about the odd yellow to brown footprints noticeable on a few greens. They were very good questions indeed, and to be completely honest, they are a bit of a mystery to us. We’ve considered various possible reasons and analyzed the conditions leading up to these blemishes, but there are still several unexplainable facts.
In our ongoing quest to provide you with high quality putting surfaces, we apply plant protectants to the greens on a weekly basis. As mentioned in an earlier 'Pest Management' blog (available here), plant protectants include many items such as nutrients, micronutrients, fungicides, plant growth regulators, and biostimulants, to name a few. These weekly applications are usually made on Friday’s so that if high stress conditions, (high heat & humidity - which can induce certain fungal activity leading to disease and turf loss) were to occur on a busy weekend, we would not interfere with play by conducting emergency spray applications.
Two weeks ago we made a routine plant protectant application which included nutrients, biostimulants (sea-weed extract, plant hormones, vitamins), and plant growth regulators. We’ve used all of these products in the past, but this time we added half rates of two different plant growth regulators instead of the full rate of just one. This is the only difference from past applications. We’ve applied this mixture many times before on fairways but not on the greens. However, these same products and mixtures have been, and continue to be, used at other courses in our area and even at much higher rates than we typically use. We wanted to be very cautious and use very low rates initially, as these are very active compounds (1 ounce per acre). In time, we would then increase rates to normal recommended levels.
You may ask, “Why do we need a mixture of growth regulators”? I could write a multi-page blog on this topic alone, but basically, the varying types are used to provide two modes of action and two different responses. One type slows the vertical growth causing the turf plants to grow more compact (more consistent green speed by slowing the growth from morning into the evening), while the other type helps lateral growth, aiding in recovery from ball marks and wear.
Two days later we noticed these peculiar, off-colored footprints appearing and upon a thorough inspection of all greens, it appeared as though 7 greens had these mysterious footprints. We of course, became concerned and began to speculate. Was it happening that day? Was it something from a previous day? Was it caused by a golfer (it looked like the prints were going to and from a previous hole location)? Was it something that we recently sprayed and then walked over to replace the flagstick after making the application? The questions really started to flow.
Perhaps it was this “new to the greens” growth regulator mixture that was a little phytotoxic (damaging to plants) when traffic was present immediately after application? However, the same mixture was used on all greens, so why was it not more wide spread and only on 7 greens? Four tank mixtures are needed to treat all the greens. As we reviewed our records and recalled the process, there was no clear indication that any one tank mixture was the problem. Footprints occurred on greens from 3 different tank mixtures, but not all of the greens treated with these tanks were affected. Very puzzling indeed!
We contacted suppliers of products and reviewed our tank mixtures and were reassured that these problems had not occurred with our same tank mix recipe at anywhere in the past. And, as I mentioned before we have applied these same products to fairways and in fact, the same week applied 4 times the rate (still well below maximum rates) of these same products to our fairways, with no signs of traffic or mystery footprint damage!
We thought about other possibilities as to the cause and considered that perhaps it was something on the applicators shoes, maybe a spill in the mix area that picked up on his shoes and he unknowingly tracked it onto the greens. This would explain multiple tanks being involved but why not all the tanks, and also, there was no obvious spill during the mixing process! And, if something were perhaps, on the floor board (carried by the shoes of the applicator) of the sprayer, why then would there be 2 sets of footprints on one of the greens, coming from persons from 2 different vehicles. Any CSI’s out there?
It’s usually at about this point in a mystery story where a clue finally surfaces that allows the mystery to become unraveled and solved. Problem is… we think we have thought through all possible scenarios, and we don’t have any other clues!
So, as we continue to scratch our heads and ponder the cause of these mysterious footprints, fortunately we can take a little comfort knowing that, at least, the damaged areas were limited and they do appear to be recovering.