Poa annua or annual bluegrass is a cosmopolitan winter annual weed in turfgrass systems. A field test was conducted to evaluate the effects of sulfentrazone herbicide, both with and without the fall overseeding practice on bermudagrass in the desert. Sulfentrazone was applied three days before overseeding at 0.125, 0.187, 0.25, 0.375, 0.5 and 0.625 lbs.AI/A. Percent Poa infestation levels were dramatically less on overseeded (perennial ryegrass added) turf throughout the entire test period than non-overseeded (dormant bermudagrass) turf. For non-overseeded turf, sulfentrazone provided a maximum of 74% weed control at November 1997, 68% in December, and 25% by March 1998 at the highest application rate of 0.625 lbs./A. For overseeded (perennial ryegrass) turf, the highest level of weed control was achieved for sulfentrazone at the 0.625 lbs./A rate, which was 68% in April. The practices of overseeding and sulfentrazone applications provided the greatest weed control, however, different rate/timing regimes should be investigated to increase efficiency.

Sulfentrazone was applied to a highly infested purple nutsedge groundcover as either single or double combination (split) applications for initial evaluation for weed control during the summer of 1996. One time single applications at 0.125 lb. AI/A resulted in 15% or less control, from 10 to 64 days after treatment (DAT). Nutsedge control from 0.25 lb. and 0.38 lb. AI/A treatments were not significantly different from each other (ranging in 10% difference or less) but was greater than the low rate 0.125 lb. AI/A. Single applications of imazaquin and halsulfuron (at known label rates) had better control than sulfentrazone at the rates tested here when tested as single applications. Single applications at 0.50 lb. AI/A appear warranted for sulfentrazone. Split (multiple) applications greatly enhanced the activity of Sulfentrazone at the two higher split rate treatments, both which resulted in a total application of 0.50 lb. AI/A total. The 0.375/0.125 split application had slightly better control than the 0.250/0.250 split treatments. Split applications of imazaquin or halsulfuron at known label rates resulted in slightly higher control. All plots experienced re-growth. Based on these results, sulfentrazone does have activity against purple nutsedge. Additional treatments in a new and different rate structure appear warranted to increase initial control and longevity of effect.

Sulfentrazone herbicide was applied to a SR1020 creeping bentgrass putting green (5/32") on October 15, 1996 and again on March 4, 1997 at the rates of 0.125, 0.250 and 0.375 lb. AI/A. Betasan was included at the standard rate of 5.6 ounces of product/1000 ft2. Turf response to sulfentrazone was mostly linear with application rate, with higher application rates causing more damage to the turf. Responses occurred quicker in the fall (by 3 DAT) compared to late winter (7DAT). Magnitude of injury was also somewhat less in the late winter than in the fall, although rank responses were still rate dependent for sulfentrazone treated creeping bentgrass turf. Applied rates of 0.250 and 0.375 lb. AI/A were deleterious and not acceptable for putting green quality turf. A marginal (acceptable) response occurred overall at the 0.125 lb. rate. Betasan applied at 5.6 ounces product/1000 ft², caused no visible damage to the turf in the fall and was similar in response to sulfentrazone in the spring at the 0.125 lb. AI/A (repeat) application rate.

Saltgrass (Distichlis spicata), clonal accession WA-12, collected from Wilcox, Arizona was studied in a greenhouse to evaluate its growth responses in terms of shoot and root lengths, shoot fresh weight, and shoot and root dry weights under control and salt (sodium chloride) stress conditions. Plants were grown under control (no salt) and three levels of salt stress (100, 200, and 400mM NaCl equivalent to 6250, 12500, and 25,000 g Lᴮ¹ sodium chloride, respectively), using Hoagland solution in a hydroponics system. Plant shoots (clippings) were harvested weekly, oven dried at 60 °C, and dry weights recorded. At each harvest, both shoot and root lengths were measured and recorded. At the last harvest, plant roots were also harvested, oven dried, and dry weights were determined and recorded. The results show that the shoot and root lengths decreased with increasing the salinity levels, however, both shoot fresh and dry weights significantly increased at 200mM NaCl salinity compared with the control or the 400mM NaCl level. Root dry weights at both 200mM and 400mM NaCl salinity levels were significantly higher than the control.

A field test was conducted to evaluate the turf performance of improved hybrid ryegrass (sometimes called intermediate ryegrass) Lolium hybridum versus that of perennial ryegrass germplasm (Lolium perenne) for winter overseeding purposes. "Gulf" annual ryegrass was also evaluated for comparison purposes. On all evaluation dates, the treatment effect was significant for all visual response variables measured (quality, color, texture, density, etc.). The mixture of LHRT hybrid ryegrass/Poa trivialis established quicker than other treatments during the first month (November). Perennial ryegrass entries provided the darkest color turf. Among hybrid ryegrasses, Pick A-97 was slightly darker in turf color when compared to LHRT. LHRT alone was darker in color than when mixed with Poa trivialis. In terms of overall turf quality, Pick A-97 and LHRT hybrid ryegrasses were essentially equal in performance. The spring decline was greater among hybrid ryegrasses than that of perennial ryegrass. Both hybrid ryegrasses (A-97 and LHRT) were superior to annual ryegrasses in all aspects of turf performance. By mid-June of 1999, Pick A-97 had more bermudagrass present (52%) than LHRT (28%). LHRT had more straw-colored (dead transition grass) than A-97 as well. By early July, A-97 and LHRT had 72% and 62% bermudagrass, respectively, and essentially the same amount of overseed present (20-23%). LHRT had 15% plot straw at this time, while A-97 had 8%. Among perennial ryegrasses, Sunshine had the slowest transition (42%), followed by Jiffie (50%) and Future 2500 (71%) by early July. The addition of Poa trivialis to LHRT hybrid ryegrass increased overall quality of the LHRT alone, but slowed transition slightly, most likely due to increased canopy densities achieved by the addition of Poa trivialis. This test demonstrated that the hybrid ryegrass germplasm tested here provided adequate fairway turf performance, and that transition among and between Lolium germplasm is variable, and genetically dependant.

Twenty-one clonal (genotype) accessions of Distichlis are being continually evaluated for field performance as replicated mowed turf plots under desert conditions. The genotype ("treatment") affect was significant for most field variables measured, or assigned to plots using visual rating scales customary for turf evaluations. Genotype differences occurred for percent plot composition color, quality, texture, uniformity and leaf width. Visual stress (prolonged hot weather without irrigation) and leaf hair presence were not significant responses between accessions. Long term mowing stress shows divergent performance amount Distichlis germplasm for growth characters and turf persistence under mowed conditions.

Fifty-one overseed entries were evaluated in 1997-1998 for turfgrass performance. New experimental accessions of perennial ryegrass were darker in color than most of the commercially available germplasm included in this test. Ryegrass germplasm had better turfgrass quality after April, than did mixtures of perennial ryegrass with Poa trivialis, which performed well in December, January and March. General appearance for total plot leaf texture was best generally among the Poa trivialis containing mixtures. Hybrid (or intermediate) ryegrasses (L. which are crosses between perennial X annual ryegrass, are generally closer to annual ryegrass in performance. There was a vast improvement in L. hybridum (Pick YNC) when compared to annual ryegrass alone for turf performance. Intermediate and annual ryegrasses did show signs of decline in June (more so than ryegrass or Poa trivialis blends), which was desirable from a transition standpoint.

Clonal accessions (genotype selections) of Distichlis continue to show divergent responses for turf-type growth habit and general turf-type adaptation under field mowing stress. The treatment (clonal accession) affect was significant for all field response variables from mid July to mid August (data collections for Report #4, except for "percent plot straw" on October 12. In July 2000, mean percent plot green cover ranged from 47% to 96% among clonal accessions. Turfgrass quality in July was best among the entries A138, A86, A137, A48, A51, and A40. These entries had the greatest percent plot cover, moderately fine leaf texture, and high shoot density, compared to other entries. In the calendar year 2000, (includes weather conditions in Report #3), the test site was exposed to atmospheric conditions which included a reference ET. of 3.59" (January); 4.42" (February); 6.23" (March); 8.96" (April); 11.32" (May); 9.08" (June); 9.31" (July); 7.53" (August); 7.37" (September); 3.55" (October). The test was subjected to severe drought conditions throughout the test, starting April 2000. Rainfall from January too, and including April was 1.28 inches. There was no rain from May 1 to June 15. Four rains from July 17 to July 30 added 2.94 inches of rainfall, with two thirds of this occurring from one storm on July 29. No irrigation was added from July 1, until September 15. During that time period, 3.26 inches of rain fell in July. In August, 2.47" of rainfall occurred. From June 1 to September 15, the accumulated reference ET. was 29.68 inches. Total rainfall was 5.81" (no irrigation practiced). Most (but not all) Distichlis accessions maintained adequate turf color and percent plot green, up to late August. Visual stress ratings in early August showed differences in visual stress ratings and leaf canopy temperatures measured with a hand held IRT device. Entries A48, A51, A40, A138, A61, and C10 exhibited the least amount of visible drought stress in early August. Accessions that had the highest overall quality ratings in July were A138, A86, A137, A48, A51, and A40. Accessions that exhibited acceptable (highest) turf quality prior to and during the drought period included A138, A40, and A51. Drought induced dormancy finally occurred at the beginning of September, as most accessions drastically decreased the amount of green plot foliage after a prolonged period without irrigation. After flood irrigation and fertilizer applications on September 15 and September 29, plots recovered by mid October. The recovery was not full, as the greatest amount of green percent plot cover ranged from 23% to 83% among entries. Entries with the greatest amount of green cover after the post dormancy period included, A65, A138, A137, A77, and A72. All entries did exhibit reduced quality in comparison to July ratings. Based on these results, Distichlis should be irrigated once/month in a desert condition to avoid drought induced dormancy. During the calendar year 2000, accessions which had notable performance included: Early Spring Green Up: C8, A77, A138, A86; Early Summer Quality (non-water stress in May, and water stressed in June): A55, A86, A51, and A40, A138; Mid Summer Quality: A48, A86, A137, A51, A138; During Drought Quality: A138, A40, A51; Post Dormancy Quality: A65, A138, A137, A77, A72.

Perennial ryegrass germplasm was quicker to establish plot cover on a "Tifgreen" bermudagrass green than that of Poa trivialis when used alone. Poa trivialis alone produced lighter color turfs when compared to perennial ryegrass. Turfgrass color was generally uniform in appearance, however, within each entry. Therefore, color as a selection criteria is a matter of choice by the user. The turfgrass mixture "Catalina/Winterplay" (80% perennial ryegrass/20% Poa trivialis) was intermediate in turfgrass color. "Brightstar II" PR generally produced a dark turf throughout the growing season. For overall turfgrass quality, the perennial ryegrasses generally out performed the Poa trivialis germplasm. The mixture of "Catalina/Winterplay" produced a very dense turf, followed closely by "Turfstar Plus" PR, "95-1" PR and "PT-4" PT. ASnowbird@ PT had the least amount of living ground cover by May 31, which is desirable from a transition standpoint.

Twenty-three overseed entries (and a non-overseed check) were evaluated from November 1996 to June 1997 for turf performance over Tifgreen (328) bermudagrass. Entries varied for turfgrass establishment, color, quality, density, texture and uniformity on all evaluation dates. One annual ryegrass and three intermediate ryegrass Lolium hybridium entries were included. The intermediate type 'Hybrid X-NC' had better performance than 'Froghair' or 'Hybredium' intermediate hybrids in most cases, except for early transition. Entries which consistently had the darkest green genetic color included 'Citation III', 'LPQ-N3', 'EP-20', 'Charger II', '84-91', 'WX-140', and 'Roadrunner'. Entries which consistently ranked high in overall turfgrass performance included 'Citation III', '2-DLM', '84-91', 'Roadrunner', 'Charger II', 'WX-140', '93-7', and 'LPQ-N3'.