Cultural Practices. Maintaining Quality Turf

Transcription

1 Cultural Practices Maintaining Quality Turf

2 Cultural Practices The management of turfgrass involves what are known as cultural practices, that is, those things we do to try and maintain quality turf Cultural practices are divided into two classes, primary and supplementary Primary cultural practices consist of Mowing Fertilization Irrigation

3 Cultural Practices Supplementary cultural practices include Coring and other cultivation methods Rolling Topdressing Matting Wetting Agents Turf colorants Plant growth regulators

4 Mowing

5 Mowing Objectives Mowing- periodic removal of a portion of turfgrass shoot growth Some Reasons for Mowing Maintain top (aerial shoot) growth within specific limits Control undesirable vegetation that is intolerant of mowing Sustain the desired quality of a specific type of turf Produce a true putting surface on golf greens Develop sod crop in preparation for harvesting

6 Mowing Equipment The first mowing device was a hand scythe Considerable labor and great skill were required to produce a uniform appearing turf by scything The first mower was developed in 1830 by textile engineer Edwin Budding It was an adaptation of the rotary shear used to cut the nap on carpets

7 Mowing Equipment (cont.) Until the development of gasoline powered equipment mowers were pushed or pulled by hand or by horses or powered by steam

8 Principal Types of Mowers Reel Use a stationary bedknife and a rotating reel cylinder with 3 to 10 or more blades Produces the highest quality cut Rotary Uses a flat blade spinning on a vertical shaft at high speed parallel to the ground Flail Uses a series of swinging blades attached to a central horizontal cylinder

9 Reel Mowers Reel knives guide the grass leaves toward the bedknife where they are cut by a scissors like action Quality of cut is influenced by the sharpness of the cutting edges and the adjustment of the bedknife against the reel blades If adjusted too tightly all cutting surfaces experience accelerated wear, heat buildup and increased power requirement for mowing

10 Rotary Mowers A flat rotating blade spins at high speed parallel to the ground Quality of cut is influenced by both the sharpness of the blade and the balance of the blade (less wobble) Used for utility turf and lawns Versatile Inexpensive Low maintenance

11 Flail Mowers Used primarily for utility turf in areas likely to have hidden obstacles It cuts and re-cuts debris until it is small enough to clear the housing resulting in fine mulch Expensive Low quality of cut

12 Mower Comparison Reel Rotary Flail Quality High Medium Poor Expense High Low High Maintenance High Low High Versatility Low High Low-Med

13 Other Mowing Considerations Area Determines the size and sophistication of the mowing equipment required Landscape Obstacles Abrupt changes in topography Ornamental plantings Buildings and structures Where possible, landscape obstacles should be modified to facilitate mowing operations

14 Mowing Quality Influenced by the relationship between mowing height (MH) and the clip of the reel (CR) which is defined as the forward distance traveled between successive clips Also called uniformity of cut

15 Clip of the Reel CR is determined by- The number of blades on the reel Each additional blade reduces the distance between cuts The rotational velocity of the reel blades With faster rotational velocity CR is reduced The forward operating speed of the mower As forward speed increases the distance between cuts increases

16 Uniformity of Cut The most uniform cut occurs when CR=MH When CR>MH turf takes on a wavy appearance called marcelling When CR<MH the efficiency with which reel blades direct the leaves to the bedknife is reduced and cut is ragged The inverse of CR is frequency of clip or FC FC is the number of clips per unit distance traveled An FC of 2 per inch = a CR of.5

17 Marcelling Explained With clipping turfgrass leaves are drawn together to form an isosceles triangle Afterwards the shoots return to an upright orientation resulting in a marcelled surface with measurable peaks and valleys The height difference between the peaks and valleys is called the restitution height (R)

18 Computing Marcelling When CR and MH are known R can be computed by determining the hypotenuse formed by the shoots rooted farthest from the position where clipping occurs If we substitute MH for a and CR for b/2 in a right triangle R=SqRt(MH 2 +CR/2 2 )-MH Percent variation (V) = R/MH Where CR=MH %V=12 which is acceptable and doesn t result in observable marcelling

19 Mower Operation Care must be exercised to achieve an acceptable cut Acceptable cut is extremely variable depending on the purpose of the turf (golf green vs. highway median)

20 Striking Objects Mowers tend to dip and dig into the turf Damage to blades or shafts may occur Replacing reel blades, entire reels or bedknives may be required (expensive) Extensive regrinding of bedknives (time consuming, expensive) may be needed

21 Turning Issues Mower is depressed on the outside of turn Scalping can occur Common on the rim of golf greens The solution is to reduce forward speed Or redesign the green to ease tightness of turns

22 Metal to Metal Wear Lubrication is required at the cutting edges, this cools the blades When cutting this is accomplished by the juices from turf When transporting across long non-vegetative surfaces reels must be disengaged to prevent heat expansion of metal causing severe wear or failure

23 Mower Maintenance Grinding Reel blades and bedknives should be ground when nicks appear or when cutting edges become worn Lapping Periodic lapping with emery powder slurry (oil or water with detergent) with reels rotating backward helps to maintain sharp cutting edges between grindings Operation manuals have directions for frequency

24 Reel Mowers

25 Pull-Type Gang Reel

26 Push Reel Mower

27 Reel Mower Blade Grinding

28 Reel Mower Bedknife Grinding

29 Reel Mower Bedknife

30 Flail Mowers

31 Flail Mower Shaft and Blade

32 Rotary Mowers

33 Rotary Gang Mower Working

34 Rotary Push Mower Parts

35 Rotary Blade Sharpening

36 Mowing Variables Mowing height Mowing frequency Mowing pattern Clippings

37 Mowing Height Effective mowing height is the height of aerial shoots immediately following mowing Bench setting is the mechanically set mowing height Bench setting and effective height should be similar but aren t likely to be exactly the same Above ground shoots (verdure, elasticity and rigidity) raise effective height Thatch and other compressible components of growth medium lower effective height

38 Mowing-tolerance Range Each turfgrass genotype has its mowing-tolerance range within which it can be expected to provide a satisfactory turf Below this range the turfgrass stand would become thin and weedy Above this range it might become puffy or decumbent or just fail to make satisfactory turf

39 Scalping The excessive removal of green shoot tissue resulting in the exposure of unsightly shoot stubble or bare earth Caused by Too low a mowing height Terrain too uneven for type of mower Excess speed during turns

40 Effect of Mowing Heights Within the mowing tolerance range reduced mowing heights result in- Stimulated aerial shoot growth Increased shoot density Smaller shoot size Decreased root and rhizome growth Decreased photosynthesis and storage of carbohydrates Increased plant succulence

41 Lower Mowing Heights With decreased mowing height the turf is More aesthetically pleasing Less tolerant of environmental stresses More disease prone More dependent on a carefully implemented cultural program

42 Mowing Height Adjustment The lower limit of the mowing tolerance range depends on the magnitude of environmental stress Turf managers have tended to raise mowing heights on coolseason grasses during summer and of warm-season grasses during early and late portions of the growing season

43 Mowing Frequency The number of mowings per unit time This is the mowing interval or the number of days between successive mowings This can vary from daily mowing of greens to a few mowings during the season of utility turf Frequency is adjusted so that no more than 1/3 of shoot growth is removed per mowing Cutting more than 1/3 can cause retarded growth and a more open, less competitive turf stand Too frequent mowing results in same issues as cutting too low

44 Mowing Pattern Mowing tends to orient aerial shoots toward the direction of travel Causes difference in light reflection resulting in alternating light and dark bands Double cutting at right angles results in a checkerboard pattern Mowing direction should be varied to encourage upright shoot growth and avoid differential soil compaction

45 Clippings Clippings may be removed or returned with mowing Except for greens clippings may be returned without serious adverse affect in most cases Clippings are rich in plant nutrients and return substantial quantities of nutrients Clipping removal necessitates increased fertilization to make up for nutrient loss