Dormant bermudagrass (Cynodon dactlyon (L.) Pers. × C. transvaalensis Burtt-Davy) is overseeded with perennial ryegrass (Lolium perenne L.) to maintain green color through the fall and winter. Annual bluegrass (Poa annua L.) control is critical for overseeding success, as this weed can greatly decrease aesthetic quality and playability of turfgrass due to excessive seedhead production. Research was conducted to evaluate the infl uence of pre-seeding cultural practices (scalping, solid-tine aerifi cation, vertical mowing, and vertical mowing plus scalping) on overseeding establishment. The effect of increasing overseeding rates of perennial ryegrass (111, 222, 444, and 888 kg pure live seed·ha–1; 100, 200, 400, and 800 lb·A–1) and roughstalk bluegrass (Poa trivialis L.) (55, 111, and 222 kg pure live seed·ha–1; 50, 100, and 200 lb·A–1) on annual bluegrass populations was also investigated. Additionally, plant growth regulators (PGRs) were evaluated for annual bluegrass seedhead suppression and turf injury. Mefl uidide at 0.056 kg ae·ha–1 (0.05 lb ae·A–1), and paclobutrazol, fl urprimidol, trinexapac-ethyl, and trinexapac-ethyl plus ethephon at 0.28, 0.42, 0.382, and 0.095 plus 3.82 kg ai·ha–1 (0.25, 0.37, 0.34, 0.085 plus 3.4 lb ai·A–1), respectively, were applied twice, sequentially with a four-week interval. Contrary to previous research, pre-seeding cultural practices did not improve overseeding success. Annual bluegrass density decreased with increasing perennial ryegrass overseeding rates from 50% in the non-overseeded to 14 to 17% when overseeded with rates up to 222 kg pure live seed·ha–1, and 4 to 8% when overseeded with rates between 444 and 888 kg pure live seed·ha–1. Roughstalk bluegrass overseeded reduced annual bluegrass density from 50% in the non-overseeded, to 7 to 13% when overseeded with 55, 111, or 222 kg pure live seed·ha–1, regardless of the overseeding rate. Overseeding bermudagrass with roughstalk bluegrass or perennial ryegrass increased turfgrass green cover during winter, especially 100 days after seeding. Paclobutrazol, flurprimidol, and trinexapac-ethyl were successful at suppressing annual bluegrass seedheads and were not injurious to perennial ryegrass. Mefluidide resulted in efficient annual bluegrass seedhead suppression; however, unacceptable turfgrass injury occurred in 2012.
Cultural and Chemical Practices for Quality Improvement of Overseeded Bermudagrass [Cynodon dactlyon (L.) Pers. × C. transvaalensis Burtt-Davy] and Annual Bluegrass (Poa annua L.) Suppression
MAGNI, SIMONE;GROSSI, NICOLA;LULLI, FILIPPO;VOLTERRANI, MARCO
2015-01-01
Abstract
Dormant bermudagrass (Cynodon dactlyon (L.) Pers. × C. transvaalensis Burtt-Davy) is overseeded with perennial ryegrass (Lolium perenne L.) to maintain green color through the fall and winter. Annual bluegrass (Poa annua L.) control is critical for overseeding success, as this weed can greatly decrease aesthetic quality and playability of turfgrass due to excessive seedhead production. Research was conducted to evaluate the infl uence of pre-seeding cultural practices (scalping, solid-tine aerifi cation, vertical mowing, and vertical mowing plus scalping) on overseeding establishment. The effect of increasing overseeding rates of perennial ryegrass (111, 222, 444, and 888 kg pure live seed·ha–1; 100, 200, 400, and 800 lb·A–1) and roughstalk bluegrass (Poa trivialis L.) (55, 111, and 222 kg pure live seed·ha–1; 50, 100, and 200 lb·A–1) on annual bluegrass populations was also investigated. Additionally, plant growth regulators (PGRs) were evaluated for annual bluegrass seedhead suppression and turf injury. Mefl uidide at 0.056 kg ae·ha–1 (0.05 lb ae·A–1), and paclobutrazol, fl urprimidol, trinexapac-ethyl, and trinexapac-ethyl plus ethephon at 0.28, 0.42, 0.382, and 0.095 plus 3.82 kg ai·ha–1 (0.25, 0.37, 0.34, 0.085 plus 3.4 lb ai·A–1), respectively, were applied twice, sequentially with a four-week interval. Contrary to previous research, pre-seeding cultural practices did not improve overseeding success. Annual bluegrass density decreased with increasing perennial ryegrass overseeding rates from 50% in the non-overseeded to 14 to 17% when overseeded with rates up to 222 kg pure live seed·ha–1, and 4 to 8% when overseeded with rates between 444 and 888 kg pure live seed·ha–1. Roughstalk bluegrass overseeded reduced annual bluegrass density from 50% in the non-overseeded, to 7 to 13% when overseeded with 55, 111, or 222 kg pure live seed·ha–1, regardless of the overseeding rate. Overseeding bermudagrass with roughstalk bluegrass or perennial ryegrass increased turfgrass green cover during winter, especially 100 days after seeding. Paclobutrazol, flurprimidol, and trinexapac-ethyl were successful at suppressing annual bluegrass seedheads and were not injurious to perennial ryegrass. Mefluidide resulted in efficient annual bluegrass seedhead suppression; however, unacceptable turfgrass injury occurred in 2012.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
