Development of lawns in response to applications of imazapic alone or combined with imazapyr

ABSTRACT Successive mowings are the major maintenance cost of lawns. These costs have led to the search for alternatives to mechanical management. This study aimed to determine the effects of imazapic herbicide doses applied alone or combined with imazapyr as a growth regulator of Tifton 419 and Zoysia grasses. The experimental design was randomized blocks with four replicates, and the treatments consisted of four doses of herbicide imazapic applied alone (35; 70; 105 and 140 g a.i. ha-1) and three doses of imazapic + imazapyr mixture (7.875 + 2.625; 15.57 + 5.25 and 23.625 + 7.875 g a.i. ha-1) in two sequential applications on both grass lawns. Visible injury symptoms, canopy height, height and number of inflorescences, and total dry matter of clippings were determined. Applications of imazapic alone or combined with imazapyr effectively reduced all morphological variables of Tifton 419 grass. Imazapic applied alone or mixed with imazapyr provided adequate control of growth and quantity of dry matter of Zoysia grass clippings. Still, with some application doses of this herbicide, the number of inflorescences present in the lawns increased.

摘要：连续修剪是草坪养护的核心成本来源，该成本推动了替代机械修剪的草坪管理方案的研发探索。本研究旨在评估单施咪唑烟酸（imazapic），或其与咪唑喹啉酸（imazapyr）复配时，作为蒂夫顿419（Tifton 419）与结缕草生长调节剂的施用效果。试验采用设置4次重复的随机区组设计，处理组包含：单施咪唑烟酸的4个剂量梯度（35、70、105、140 g a.i. ha⁻¹），以及咪唑烟酸与咪唑喹啉酸复配的3个剂量梯度（7.875+2.625、15.57+5.25、23.625+7.875 g a.i. ha⁻¹），两种草坪均采用两次连续施药模式。本试验测定的指标包括可见药害症状、冠层高度、花序高度与数量，以及剪草总干重。结果显示，单施咪唑烟酸或其与咪唑喹啉酸复配，均可有效降低蒂夫顿419的全部形态学指标；单施或复配施用咪唑烟酸，均可实现对结缕草生长及剪草干物质量的有效调控，但部分施药剂量下，草坪中的花序数量会出现上升。