For those of you that do reel mow and sand your lawn and are seeing an abundance of poa, there is a reason! If you are going to reel mow there are certain maintenance practices you must employ. Do Not Use 100% sand topdressings (see “Sanding Woes” below.)
You must aerate at least once per year to manage your compaction (aeration cannot completely eliminate compaction). On some lawns multiple aerations are needed to manage compaction. Heavy reel mower types can cause increased compaction simply because of their weight. Reel mowing keeps the turf so short you lose the cushioning effect of thicker turf.
As you move into August allow the turf to grow higher and recover from the reel mowing. The shorter the turf, the shallower the root system. Raising the mowing height to 3″ by October allows the turf to prepare for winter.
Compacted turf, especially with sand layers, also greatly reduces the efficacy and longevity of the pre-emergence in the soil. This fact, along with what may be resistance development in the poa to the herbicides available for pre-emergence treatment results in even more poa than should be expected (there will always be some sneaking through).
Simply stated, high compaction levels prevent the pre-emergent weed control, nutrients, water and oxygen from moving into the root zone causing poor turf quality, thinner turf, low vigor and excessive stress. These turf conditions allow the poa to germinate more vigorously.
Additionally, during the growing season you will have more Dollar Spot disease and more overwinter disease due to the stressed turf. Because of the compaction layers that form from topdressing with sand you also can see “hotspots” develop during hot, dry weather because the rain or irrigation cannot move down through the soil and the water just runs off.
Sanding Woes
One of the major factors contributing to compaction in reeled mowed turf is using sand instead of soil for topdressing. We are seeing a renewed interest in sanding yards. As we always preach, sanding is a golf course practice best kept on the golf course.
When golf courses are built much of the soil is removed and replaced with a specialized mix. When the courses topdress they use the same mix to spread over the top. IT IS NOT SAND!
For any lawn when you spread sand over a clay base (most home soils) you produce compaction layers. The first is usually just at the surface with another developing where the clay particles interface with the clay subsoil. These layers are in essence growth barriers directly reducing water penetration, pre-emergent efficacy and root growth depth which leads to TURF PROBLEMS.
Poor turf growth and potential for winter kill is one of the problems that develop. Uncontrollable poa outbreaks is another. As we mentioned the poa outbreaks are also the result of resistance development to the pre-emergence weed control. This is something over which we have no control.
There is nothing wrong with a reel mowed lawn. They look great and usually can make you the envy of the neighborhood IF you do all the things you need to do to reduce the accompanying problems. Unfortunately, these turfs usually also require additional treatments, (such as additional poa control, fungal control and humate/penetrant applications, which we can add to your program) above and beyond the basic program.
The bottom line is that reeled mowed and sanded home turf requires more of everything. If you are willing to make the commitment to the expanded program SOME of the problems are manageable.
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