Evaluation of Selected Fine-leaf Fescue Cultivars for Their Turfgrass Quality and Weed Suppressive Ability in Field Settings

A series of field studies were conducted from 1999 to 2005 in Ithaca, NY, at the Cornell Turfgrass Research Center as part of the National Turfgrass Evaluation Program (NTEP) to evaluate a collection of 78 fine-leaf fescue cultivars (Festuca spp.) for turfgrass quality, seedling vigor, and ability to inhibit the establishment of common annual and perennial weeds. Using these criteria, we evaluated the overall suitability of the cultivars for use in turfgrass settings, as well as their potential weed suppressive or allelopathic ability. The ability of fine-leaf fescue to displace weeds was visually evaluated by density-wise comparison, and several cultivars of the 78 studied consistently established well and provided good to very good suppression (greater than 70%) of common turf weeds when established at the same planting density. Other cultivars provided moderate (between 35% and 70%) to (< 30%) little weed suppression. Greater weed suppressivity is likely associated with the differential ability of fescue cultivars to establish rapidly and to form a dense canopy, as well as potential allelopathic interference. This study was conducted in conjunction with laboratory experiments that revealed that certain fine-leaf fescue cultivars produced phytotoxic root exudates that were released into the rhizosphere over time. Additional field studies conducted in Ithaca showed that cultivars Intrigue, Columbra, and Sandpiper were consistently more weed suppressive than the other fine-leaf fescues evaluated. Although our understanding of the dynamics of production and degradation of fine-leaf fescue root exudates in the rhizosphere is limited, recent field studies also suggest that allelopathic interference as well as the ability to rapidly establish influence subsequent weed infestation in fine-leaf fescue stands. From a more practical standpoint, certain fine-leaf fescue cultivars, including Intrigue, Columbra, Sandpiper, and Reliant II, could be recommended for use in low-maintenance turf settings in the northeastern United States due to their aesthetic appeal and their limited weed infestation in circumstances where herbicides are not applied.

Tolerance of Four Festuca Species to Ethofumesate and Prodiamine

Festuca species are being seeded into golf course roughs and natural or out-of-bound areas as alternative turfgrasses to replace perennial ryegrass (Lolium perenne L.) in the mid-Atlantic region. The tolerance of fine-leaf fescues to herbicides targeted for annual bluegrass (Poa annua L.) control, such as ethofumesate and prodiamine, is unknown. The objectives of this field study, therefore, were to assess the tolerance of `Rebel II' tall fescue (Festuca arundinacea Schreb.), and the fine-leaf fescue species `Reliant' hard fescue (Festuca longifolia Thuill.), `Jamestown II' Chewings fescue (Festuca rubra L. ssp. commutata Gaud.), and `MX 86' blue sheep fescue (Festuca glauca L.) to various rates, combinations, and times of application of ethofumesate and prodiamine. `Rebel II' was most tolerant of ethofumesate; however, sequential rates ≥0.84 + 0.84 kg·ha-1 reduced quality for 1 or more weeks and 2.24 + 2.24 kg·ha-1 caused unacceptable injury. Single applications of ethofumesate at rates of 0.56, 0.84, and 1.12 kg·ha-1, and sequential treatments of 0.56 + 0.56 and 0.84 + 0.84 kg·ha-1 reduced `Reliant' quality temporarily. Sequential treatments of high rates (i.e., 1.12 + 1.12 and 2.24 + 2.24 kg·ha-1), however, significantly reduced `Reliant' cover. `Jamestown II' was very sensitive to ethofumesate, but recovered from single applications of 0.56, 0.84, and 1.12 kg·ha-1; sequential applications (≥0.84 + 0.84 kg·ha-1) caused unacceptable injury, and rates ≥1.12 + 1.12 kg·ha-1 caused significant loss of cover. The cultivar MX 86 tolerated single applications of 0.56 to 2.24 kg·ha-1 of ethofumesate, but sequential treatments generally reduced quality to unacceptable levels. In one study, `Jamestown II' and `MX 86' were more severely injured when ethofumesate (1.12 or 2.24 kg·ha-1) was applied in October rather than in November. The fescues generally best tolerated a single, November application of ethofumesate at ≤1.12 kg·ha-1. Prodiamine (0.73 kg·ha-1) caused only short-term reductions in quality of `Jamestown II', but was generally noninjurious to the other fescues. Ethofumesate tank-mixed with prodiamine (0.84 + 0.36 or 1.12 + 0.73 kg·ha-1) elicited some short-term reduction in quality, but the level of injury was generally acceptable and injured fescues had recovered by spring. Chemical names used: [±]2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate (ethofumesate); N3,N3-di-n-propyl-2,4-dinitro-6-(trifluoromethyl)-m-phenylenediamine (prodiamine); S,S-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridine-dicarbothioate (dithiopyr).

604 PB 220 GROUNDCOVER MANAGEMENT SYSTEMS AND PREPLANT FERTILIZERS INFLUENCE PEACH TREE GROWTH, YIELD, MICRONUTRIENT AVAILABILITY AND UPTAKE

Growth, nutrient uptake, and yield of peach (Prunus persica) trees was evaluated in various groundcover management systems (GMSs) for three years, with and without preplant soil additions of Zn, B, and Cu. In July 1990, micronutrients (none, or 135kg Zn·ha-1+100kg Cu·ha-1+1.1kg B·ha-1) were incorporated into the upper 20 cm of a silty clay-loam soil (pH 6.7, 4% organic matter), and a fine-leaf fescue (Festuca ovina) turf was established. Trees were planted Apr. 1991, and four GMS treatments (wood-chip mulch, pre-emergence herbicide, post-emergence herbicide, and mowed turf) were superimposed upon the “+/-” micro-nutrient preplant treatments. Extractable Zn, Cu and B concentrations were greatly increased in soil of plots which had received preplant amendments. Peach leaf content of Zn, Cu and B was also greater in preplant fertilized plots in the year of planting. However, in subsequent years only leaf B (in 1992) and leaf Zn (in 1993) continued to respond positively to preplant soil treatments. No significant interactions were observed between GMS and micronutrient availability or uptake. Peach growth and yield were not affected by preplant treatments, but were substantially greater in mulch and pre-emergence herbicide plots compared with the mowed fescue turfgrass.