Moss
There are several different types of moss that can cause problems in amenity turf, but they generally colonise a weak sward. These are usually scalped, worn, nutrient deficient, drought stressed or wet turfgrass areas.
Mosses belong to a group of plants called Bryophytes which like most plants contain chlorophyll and photosynthesise to facilitate their growth and development. However they do not have typical roots but possess so-called rhizoids that help to anchor them to the ground and take up water directly through their leafy surface.
Moss plants don’t produce seed but release microscopic spores that can easily be spread across the turf and enter the profile to depth. The vegetative parts of the moss plants can also serve to increase its composition in an infected sward.
Moss can be a problem in turf all year round but its presence in the sward will be more apparent if turf becomes weak.
The silver thread moss Bryum argenteum is a common problem on weak or worn turf areas and once in the sward, it can rapidly become established and very difficult to remove. This moss in particular can have a significant and detrimental effect on the visual and playing quality of a close-mown, fine turfgrass surface. Other moss species have a more open growth habit than that of B. argenteum, but all moss invasions will change the quality of the playing surface and should be targeted for removal as soon as they are seen.
Effective and long-term control of moss in turf relies heavily on producing a strong sward that will out-compete the moss plants.
It is often said that ‘moss invades a problem and then becomes a problem’. Products aimed at weakening the moss plants should be applied when the rootzone is moist and when the moss is actively growing. One to two weeks after application, the moss plants should become darker in colour or show reduced vigour.
These weakened plants can be removed by scarification and the sward encouraged to fill
in through the thinned areas, thus reducing the conditions favourable for re-establishment of the moss. Since moss rhizoids can typically colonise the upper 20-30mm of the rootzone, deeper scarification will be necessary to remove the moss fragments and reduce its impact on the sward.
The upright and compact nature of B. argenteum in particular makes this a challenging moss to remove because applied products are not likely to wet / penetrate the plants but be dispersed across their surface.