Leaf Clippings Research Articles

Effects of Clipping Disposal, Nitrogen, and Growth Retardants on Thatch and Tiller Density in Zoysiagrass

Accumulation of thatch is a cultural problem affecting managers of ‘Meyer’ zoysiagrass (Zoysia japonica Steud.). Research was undertaken to investigate the effects of clipping disposal, N fertilization, and growth retardants on thatch accumulation and resistance of plant tissue to decomposition. In a 2‐yr field study, clipping disposal (removed or left on plots); N fertilization (98.0 kg ha−1 yr−1); and the growth retardants mefluidide (N‐[2,4‐dimethyl‐5‐[[(trifluromethyl)‐sulfonyl]amino]phenyl]acetamide) applied twice each year at 0.4 and 0.8 kg a.i. ha 1, and flurprimidol (α‐(1‐methylethyl)‐α(4‐trifluromethoxy)phenyl)‐5‐pyrimidine‐methanol) applied at 1.7, and 2.2 kg a.i. ha−1 twice in each year were examined for their effects on thatch, tiller density, verdure, and stolon weight. Relative degradation of leaves and stolons was compared by in vitro digestion in a prepared cellulase solution. Returned clippings increased thatch by only 3.4% and decreased tiller density by 12% when N was applied. Nitrogen increased thatch and tiller density. Growth retardants did not affect thatch. Degradation of leaves (64%) by the cellulase solution exceeded that of stolons (60%). The reduction in tiller density associated with returned clippings may be due to shading from clippings in the turf canopy resulting in leaf etiolation and reduced tiller bud development. Leaf clippings contributed slightly to thatch accumulation, most likely due to their physical accumulation rather than indirect effects of N recycling. Both stolons and, to a lesser degree, leaves appear to contribute to thatch accumulation in Meyer zoysiagrass. Decreased use of N in the culture of Meyer zoysiagrass, within limits required for acceptable appearance, might help reduce thatch accumulation. Removal of clippings is not recommended for thatch control considering their small contribution to thatch cover and due to the benefit of recycled nutrients.

Comparison of iron analyses and iron chlorosis in Kentucky bluegrass cultivars

Abstract Iron chlorosis is a common problem for Kentucky bluegrass (Poa pratensis L.) grown on calcareous soils. Iron concentrations are commonly used to assess cultivar differences to chlorosis. Iron concentrations in leaf clippings determined by x‐ray, O‐phenanthroline, and ferrozine were used to evaluate visual Fe chlorosis ratings of 12 Kentucky bluegrass cultivars over two years. Cultivar differences for Fe concentration were greater for total Fe (x‐ray and o‐phenanthroline) than for ferrous Fe (ferrozine). Total Fe concentrations determined by o‐phenanthroline were higher than by x‐ray; ferrous Fe concentrations were relatively low. Leaf Fe concentrations determined by each method did not correlate with cultivar leaf Fe chlorosis ratings. From visual chlorosis ratings, the cultivars Sydsport, Victa, and Glade were fairly tolerant and Park, Wabash, and Delta were fairly susceptible to Fe chlorosis when grown on a calcareous soil in the field.