Identification and Biological Characteristics of Ryegrass (Loliumspp.) Accessions in Arkansas

Abstract

Italian ryegrass is a major weed problem in wheat production worldwide. Field studies were conducted at Fayetteville, AR, to assess morphological characteristics of ryegrass accessions from Arkansas and differences among otherLoliumspp.: Italian, rigid, poison, and perennial ryegrass. Plant height, plant growth habit, plant stem color, and node color were recorded every 2 wk until maturity. The number of tillers per plant, spikes per plant, and seeds per plant were recorded at maturity. All ryegrass accessions from Arkansas were identified as Italian ryegrass, which had erect to prostrate growth habit, green to red stem color, green to red nodes, glume (10 mm) shorter than spikelet (19 mm), and medium seed size (5 to 7 mm) with 1 to 3 mm awns. However, significant variability in morphological characteristics was found among Arkansas ryegrass accessions. WhenLoliumspecies at the seedling stage (1- to 2-wk-old plants) were compared, poison ryegrass was characterized as having a large main-stem diameter and wide droopy leaves, whereas perennial ryegrass exhibited a short and a very narrow leaf blade. These two can be distinguished from Italian and rigid ryegrass, which have leaf blades wider than perennial ryegrass but narrower than poison ryegrass. Italian and rigid ryegrass are difficult to distinguish at the seedling stage but are distinct at the reproductive stage. At maturity, Italian ryegrass and poison ryegrass seeds are awned, but perennial and rigid ryegrass seeds are awnless. Poison ryegrass awns were at least 4-fold longer than Italian ryegrass awns. Perennial ryegrass flowered 3 wk later than the other species. Poison ryegrass glumes were longer than the spikelets, whereas Italian ryegrass glumes were shorter than the spikelets. Morphological traits indicate that some Italian ryegrass populations are potentially more competitive and more fecund than others.

Multiple herbicide–resistant Lolium spp. is prevalent in wheat production in Texas Blacklands

“…In fall 2017, ryegrass populations were planted in pots (15-cm diameter) filled with commercial potting-soil mix (LC1 Potting Mix; Sungro Horticulture Inc., Agawam, MA) and maintained in a greenhouse at a day/night temperature regimen of 26/22 C, with a 12-h photoperiod. The populations were classified as Italian or perennial ryegrass on the basis of morphological and taxonomic indicators (Bararpour et al 2017), with reference to samples obtained from the Germplasm Resources Information Network of the U.S. Department of Agriculture.…”

Glyphosate-Resistant Italian Ryegrass (Lolium perenne L. spp. Multiflorum) Control and Seed Suppression in Mississippi

“…With populations evolving resistance to one or multiple herbicide chemistries, the ability for Italian ryegrass to mature and return seed back to the soil seedbank is becoming more prominent. In Arkansas, Bararpour, Norsworthy, Burgos, Korres, and Gbur [3] reported populations of Italian ryegrass plants producing 20,000 to 45,000 seed plant −1 . Natural infestations of Italian ryegrass of Arkansas were ±323 plants m −2 ; furthermore, with interference due to densities of this magnitude wheat yield reductions were reported to be as high as 72% over 6 years [18].…”

“…These studies emphasize the importance of achieving 100% control of Italian ryegrass and ways to prevent seed returns to the soil seedbank. The high capacity of seed production will lead to increased seed deposition into the soil seedbank and may increase the evolution of herbicide-resistant populations of Italian ryegrass [3]. Combining these factors will ultimately lead to herbicide failure and cause technologies that are available to producers to collapse.…”

“…Husnot) is among the top ten most abundant and problematic weeds for wheat production in the mid-southern United States [1,2]. Ryegrass weed spp., has a high capacity for evolving complex herbicide resistance patterns, making them one of the most troublesome weeds to control [3]. Hybrids of cultivated Italian ryegrass species and Italian ryegrass have been reported to escape along roadsides which have become problematic to control.…”

Effective Preemergence Herbicides for Rigid Ryegrass (Lolium rigidum Gaud.) Control in Irrigated Bread Wheat (Triticum aestivum L.)

“…Rigid ryegrass has many features that contribute to the evolution of resistance, including i) a very well adapted species to the Mediterranean climate, ii) a propensity to occur in large densities, iii) the high genetic diversity within populations, iv) a self-incompatibility and cross-pollinated species, v) the potential to set a large amount of seed, allowing any resistant survivors to significantly increase the resistance status of a population, vi) the short-lived innate dormancy, which results in a large amount of the seedbank germinating in the next season, vii) the short soil seedbank life, and viii) the ability to rapidly evolve resistance to herbicides (Castellanos-Frias et al, 2016;Bararpour et al, 2017).…”