... SOME THINGS NEVER CHANGE!
Head Greenkeeper KEN BARBER goes to great depths to explain the problems and solutions to excessive thatch
T
hatch accumulation is one of the most common turf related problems experienced by today’s course managers, yet this is nothing new. However, because of the ever-increasing demands placed on courses throughout the year, effective thatch management is essential. Without this, there is a point where the long term quality of greens suffers, especially if committees within a club demand that management programmes, such as hollow coring or verti-draining, are carried out early spring or late autumn, when club competitions are fewer, but unfortunately when the benefits of such operations are also minimal. The hard facts are - if thatch is not correctly managed, clubs can expect to play on temporary greens at some point during the winter, and not just because they are covered in frost, but because they retain excessive moisture. Thatch is more often the result of poor turf management than a problem that must be managed. If thatch levels are allowed to get out of control, putting surfaces can quickly deteriorate. Members then demand to know why they have to play on temporary greens most or part of the winter months. Then, at the first signs of summer, the greens develop large brown areas, usually as a result of dry-patch, and the irrigation is turned on to keep them alive. This ineffectual form of management only increases expenditure and will certainly not decrease thatch. Methods of controlling thatch will vary
from one manager to the next, and this is not just dependent on the structure of
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the greens. However, it is important to have a clear understanding of the basic components of thatch - what causes it, the effects on turf health and vigour as well as methods of control.
What is thatch?
Thatch is the accumulation of organic residuals, consisting of, and intermingled with, dead, living or partly decomposed roots, stems and shoots, which develop between the soil surface and the actively growing green vegetation. Thatch only becomes a problem when its density causes grass plants to grow on top of the thatch layer rather than on the soil surface.
What is mat?
Thatch intermingled with mineral matter, usually as a result of topdressing. Around six millimetres of mat is advantageous as it promotes weed free, drought tolerant, free draining turf, which provides a cushion against the daily wear and tear caused by golf and maintenance traffic.
What causes excessive thatch?
Thatch increases when the rate of shoot production exceeds the rate of decomposition. There are several influential factors which will contribute to, or accelerate, an increase in thatch levels and, consequently, management practices will vary from club to club depending on resources, cultural practices and ultimately, the knowledge and
experience of the manager. One or several of these factors may be linked i.e. soil characteristics, grass species, soil pH, nutrient input, irrigation practices, and microbial populations.
The characteristics of a soil will no doubt have some influence. For example, high percentage sand greens, by their very nature, have low CEC (cation exchange capacity) and, more often than not, low microbial populations, essential in thatch decomposition. However, the benefits may compensate for the negatives with this method of construction, which is favoured more and more throughout Europe. The operating costs of high percentage sand greens may be a little higher but, if built correctly and sound management practices are implemented, those costs can be redeemed through a full contented membership and maximising premium green-fee rates as the greens are free draining and playable throughout the winter months. Soil greens, or push-up greens as they
are often described, retain nutrients longer, generally have a higher CEC and microbial counts. Nonetheless, they are still vulnerable to thatch accumulation, although this is more likely as a result of compaction, reduced oxygen supplies to the root system, or excessive nutrient input.
The type of grass species and cultivar will effect the type of management regime implemented based upon the growth habit and aggressiveness of the desirable grass species. Bents, in particular the creeping bents, have a
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