MOWING

Mowing n most basic of all turfgrass cultural practices. A periodic removal of a portion of the turfgrass shoot. Is detrimental to the turfgrass plant. First turf mowers were animals.

Advantages n Controls top growth n Provides a uniform surface n Controls weeds n Reduces fire hazard n Shoot growth is greater under mowed than unmowed turfs.

Disadvantages n Dec. food production n Dec. root growth n Dec. carbohydrate reserves n Creates entry ports for pathogens n Inc. water loss n COST!

Costs of Mowing in NC n Airport - 83% n Parks - 60% n Athletic fields - 75% n Roadsides - 72% n Golf courses - 43% n Schools - 66% n Home lawns - 75%

Types of mowers Rotary Reel Flail - two types of cut: shearing (scissors) vs. impact

Reel Mowers n Reel - Rotating reel with blades and a stationary bedknife. Quality of cut depends on 1) blade sharpness, 2) proper adjustment of blades to the bedknife across the entire width of the bedknife. Also affected by the relationship of the mowing height (MH) to the clip of the reel (CR).

Triplex Greens Mower

Walk Behind Greens Mower

Low Budget Reel Mower

Clip of the Reel n CR - forward distance traveled between successive clips. Ideal cut occurs when the MH=CR. Controlled by three factors: n 1) forward speed of mower. n 2) # blades on reel. n 3) rotational velocity of reel. n Mowing quality decreases when speed is too high, or the height of turf is too high. n Marcelling - rippling effect.

Rotary Mowers n Rotary - horizontal rotation. Usually > 1" cutting height. Impact cut. Blade must be very sharp and well balanced. Need fairly high rotational velocity to give best cut. u Objects - damage blade, engine shaft. u Injury - very dangerous. u Versatile units - simple maintenance, less costly.

Riding Rotary Mower

Walk-behind Rotary Mower

Flail Mower n Flail - Numerous knives, vertically mounted which are free swinging. An impact cut. Also recuts a lot of the leaf tissue. u Objects - less likely to throw objects. Utility use, low maintenance areas. Lower quality cut.

Large Flail Mower

Mowing Height and Mowers n Mowing height with a reel mower is equal to 1/2 the diameter of the reel. n Highest mowing quality is with reel mowers. However, there are problems: u Objects - can cause a biting or dipping action to occur which disrupts the uniformity of cut. u Turns - tendency to cause the outside edge of the cutting unit to dip and scalp the turf. n Use of reel mowers is a necessity for closely mowed turfs. Limitation on use where seed stalks are a problem.

Decreasing the Mowing Height: 1) Dec. carbohydrate synthesis and storage 2) Inc. shoot growth/unit area 3) Inc. shoot density 4) Dec. leaf width 5) Inc. succulence of shoot tissue 6) Inc. chhorophyll/unit area

Decreasing the Mowing Height: 7) Dec. root growth rate and mass 8) Dec. rhizome growth 9) Dec. environ. stress tolerance (heat,drought, wear) 10) Dec. temperature insulation 11) Need to inc. turf manager's expertise

Mowing Heights n very close " bentgrass, bermuda n close " colonial bent, bermuda, zoysia n medium " red fescue, cent., KBG, Per. rye n high " bahia, tall fescue, St. Aug. n Excessively short mowing increases weed invasion. High mowing can increase thatch, scalping, puffiness.

Scalping n removal of an excess quantity of green leaves. u irregular contours u excess thatch u infrequent mowing interval

Mowing threshold n Defoliation effects are minimal when <40% of leaf removed at any one time. Root loss risk if otherwise.

Factors affecting frequency: n 1) shoot growth rate n 2) environmental conditions n 3) cutting height n 4) turf use n 5) irrigation n 6) fertilization n 7) irradiance n 8) temperature n 9) seedhead development

Mowing Frequency n Mowing frequency increases with decreased cutting height. A major factor in management and playability of sports turfs.

Frequency Depends on Vertical Extension Rate (growth) n Ex: St.Augustinegrass - vertical leaf extension rate of 0.25 in/day. n Mowing height = 3 inches, remove 40%, mow at 5.0" Frequency = 8 days n Mowing height = 2 inches, remove 40%, mow at 3.5' Frequency = 5 days n Mowing height = 1 inch, remove 40%, mow at 1.75" Frequency = 3 days

Mowing schedule n HeightFrequency n 1/4daily n 1/22-3 days n 14-5 days n days n days

Remove Clippings When: n interferes with use of turf (ball roll) n excessively heavy, long n enhance disease development (Fusarium only at high N rates). n - Minimal contribution to thatch development.

Clippings are Free Fertilizer n Clippings provide nutrients 3-6% N, 2-3% K,.5-1% P. n Trash load to community % material sent to landfills is lawn debris.

Grain n Tendency of leaves and stems to grow horizontally in one direction. u - need to shift mowing pattern u - brush or comb prior to mowing (groomer attachments)

Mowing Pattern n alternate directions, overlap u 1) reduce grain u 2) enhance appearance u 3) differential compaction (ruts), clean-up pass n disease/weed movement - schedule problem areas last. Wash mower afterward.