When is Scalping a Good Thing?

When is scalping a good thing? When it teaches us something useful. In parks and commercial landscapes in Southeast Asia, the normal maintenance for broadleaf carpetgrass (Axonopus compressus) or manilagrass (Zoysia matrella) involves infrequent mowing at low mowing heights. Grass may be allowed to grow to a height of 30 to 50 mm (1.25 to 2 inches) or higher and then it will be scalped down with a string trimmer nearly to ground level, to something less than 12 mm (0.5 inch). See the video below from a resort at Pai in northern Thailand. I was here recently for some belletristic work.

This scalping would seem like rather poor maintenance, but I suggest that the scalping is a good thing in that it teaches us something about these grass species and their adaptation to low light conditions. Broadleaf carpetgrass and manilagrass tolerate (or even thrive with) this regular scalping, while seashore paspalum and bermudagrass do not. Sure, the average turf quality would be better if the grass was mowed frequently rather than scalped, but this removal of 70 to 90% of the leaf area at one mowing produces a good turf for many resorts and parks and lawns and roadsides in this part of the world.

I like to think about scalping as applying artificial shade to the grass. Shade reduces the amount of light available for photosynthesis. And so does scalping, by removing nearly all the leaves. The grasses that can tolerate scalping in Southeast Asia are also those that are well-adapted to this growing environment. And these are also the grasses that have minimal disease problems and thrive on golf courses. Golf courses planted to bermudagrass or seashore paspalum generally have more disease pressure, whether that be bermudagrass decline or dollar spot or an assortment of leaf spots and other maladies.

Now consider broadleaf carpetgrass (above, on a fairway mowed at 8 mm [0.3 inch] in Hong Kong) and manilagrass, by comparison. These grasses can be scalped. And they are relatively disease-free. Other than fairy ring, I have never seen any disease on broadleaf carpetgrass anywhere in tropical Southeast Asia. In sub-tropical Asia it may suffer from large patch during the short winters. That’s all. The only diseases I have seen on manilagrass in tropical Southeast Asia are fairy ring and curvularia leaf blight. Just those two. Ever. The curvularia leaf blight (see below) only occurs during the rainy season and is relatively easy to control.