Cultural strategies to improve zoysiagrass acceptability and performance in the transition zone

Abstract

Zoysiagrass (Zoysia spp.) is more heat and drought resistant and requires fewer cultural inputs than cool-season (C3) turfgrasses; however, its widespread use may be limited by an extended period of winter dormancy, the disease Rhizoctonia large patch (Rhizoctonia solani Kühn AG-2-2 LP), and lack of cold hardiness. Objectives of these 2012-2014 field studies were to evaluate: 1) turfgrass colorants and overseeding for color enhancement; 2) three colorant application volumes on color persistence; 3) colorants applied at two volumes, once or sequentially, on buffalograss (Buchloë dactyloides) and zoysiagrass; 4) the impact of nitrogen source and application timing on large patch severity; and 5) winter hardiness and turf quality of new experimental lines. The colorants Ultradwarf Super and Green Lawnger provided acceptable lawn-height ‘Chisholm’ zoysiagrass color for 7 to 9 and 19 to 24 weeks after treatment (WAT), respectively. Chisholm receiving a sequential application of either product in mid-winter (14 WAT) maintained an acceptable color level after that point until mid-May (28 WAT). Overseeding with annual ryegrass did not provide acceptable color for more than 4 weeks. Evaluation of the colorants Green Lawnger, Endurant, and Wintergreen Plus showed that acceptable Chisholm color at lawn-height occurred for 8 to 14 WAT at 80 gallons per acre (GPA) and 16 to 26 WAT at 240 GPA. Buffalograss at lawn-height receiving a single autumn colorant application had acceptable color for 8 to 12 WAT at 100 GPA or 8 to 14 WAT at 160 GPA. ‘Meyer’ zoysiagrass maintained at a 0.5 inch height receiving a single autumn colorant application had acceptable color for 8 to 18 WAT at 100 GPA or 14 to 18 WAT at 160 GPA. No differences in large patch occurred between spring and fall applications of ammonium sulfate and calcium nitrate, nor between those treatments and summer-applied urea. Applying fertilizer in spring when soils reached 21 ºC increased green cover on some rating dates compared to applications in fall when soil temperatures fell to 21 ºC but differences were minimal. Out of 985 experimental zoysiagrass lines planted in the field, about 25 were identified for further evaluation for cold hardiness, large patch resistance, and turf quality.