MOWING

PART 3-FREQUENCY OF MOWING

Introduction

FREQUENCY

The mowing frequency can be as important as the cutting height in the overall physiological and development conditions of the turf grass plant. Longer intervals between mowing improves the overall turfgrass vigour and quality, assuming that the one-third rule is strictly followed.

The mowing frequency is determined by the:

a) Shoot growth rate
b) Environmental conditions
c) Cutting height
d) Purpose for which the turf is to be utilized

a) The growth rate of a turf is one of the most important factors influencing the mowing frequency. The frequency must be adjusted in relation to the shoot growth rate so that an excessive amount of leaf surface is not removed at any-one mowing. A severe shock to the physiological balance of the turfgrass plant occurs if the defoliation exceeds one-third of the leaf area. Defoliation stimulates immediate shoot growth and tillering.The shoots have priority over the roots for the available carbohydrates under these conditions. When the carbohydrate reserve is limited and defoliation is severe, all available carbohydrates may be utilized by the shoots causing death to a majority portion of the root system. Thus, shoot growth stimulation occurs at the expense of the roots

b) The vertical shoot growth rate is controlled by the environment, nutritional level, and turf grass species involved. Irrigation, increased nutritional levels, high light intensities, and optimum growth temperatures stimulate shoot growth and increase the mowing frequency. Species variability in the rate of vertical shoot growth is substantial. For example, the rate for Bermuda Grass is three times as rapid in comparison to Zoysia Grass.

c) The mowing frequency generally increases as the cutting height is lowered. A Bermuda Grass golf green maintained at 6mm, are usually mowed daily in comparison to Bermuda Grass cut at 25mm which requires a mowing interval of four to five days depending on the rate of shoot growth.

d) Mowing frequency is an important factor influencing the playability of sports turf. Bowling and putting greens require a uniform, smooth, dense, fine textured, close-cut surface. This can only be achieved through frequent mowing, usually daily.

SEED HEAD

Seed head formation influences the mowing frequency under certain conditions. Desirable turfgrass species such as Cow grass and certain Bermuda grass produce an excessive number of seed heads that disrupts the uniformity of the turf unless mowed off regularly. Frequent mowing can also be used to control the spread of weeds.

EFFECTS OF MOWING FREQUENCY

The turf can be adversely affected if the interval between mowing is too short. The following turfgrass responses are generally observed as the mowing frequency is increased:

a) Increased shoot density
b) Decreased carbohydrate reserves
c) Decreased rooting
d) Decreased rhizome development
e) Decreased shoot growth
f) Decreased chlorophyll content
g) Increased succulents

MOWING EFFECTIVENESS

The anatomy, structure, composition, and succulents of the shoot tissue can significantly influence the quality and difficulty of the mowing operation for example, most Zoysia cultivars contain a tough, fibrous vascular system that is very difficult to mow cleanly even with a sharp, properly adjusted reel mower. As a result, the Zoysia grass is quite inferior in regards to mowing quality. The silica composition of Zoysia grass leaves causes mowing difficulties and results in more rapid dulling of the mower due to the abrasive action. In contrast, the tissue structure, composition, and succulents of Bermuda grass permit a clean cut with minimal mowing difficulties.

A second consideration in mowing quality as influenced by the turfgrass species is the incidence of seed head formation. A rotary mower is preferred on lawns containing cow grass during periods of extensive seed head formation. It is difficult to remove tall seed heads with a reel type mower.

A third factor is the vigour and aggressiveness of the species. Stoloniferous, warm season turf grasses such as Zoysia grass and improved Bermuda grasses require heavier and higher-powered mowing equipment. The use of light weight, underpowered mowers on these vigorous turfgrass species results in a gradual increase in the effective mowing height and a severe thatch problem.

Media Department; The RS Group.