Rapid blight is a new disease of cool season turfgrasses caused by Labyrinthula terrestris. Disease often occurs on turf irrigated with high salinity water and in areas of frequent mowing. The effects of salinity of irrigation water on symptom development were studied in the laboratory using two-week-old seedlings of perennial rye "Brightstar SLT. " Irrigation water was adjusted to 0.5, 0.8, 1.4, 1.8, 2.0, 2.3, 2.8, 4.0, 6.0 and 8.0 dS/m by adding artificial seawater. Plants were inoculated with a 2x10⁵ cells/ml suspension of Labyrinthula terrestris isolated from diseased turf in Arizona. Plants were infected, but not symptomatic, when irrigated with 0.5 dS/m water. At salinities from 0.8 to 8.0 dS/m, symptom development increased as salinity increased. These findings substantiate field observations that rapid blight becomes increasingly more severe as salinity of irrigation water increases.

The U/A twenty-one clone saltgtrass accession nursery received a mowing height of 7/8" (or less) in 2003. In spring of 2003, clonal accessions C-8, A51, A53, and A138 produced the quickest green-up in early April. Accessions with good quality turf performance in spring/early summer included A138, A51, C-8, A65, A48, and A53. Starting in July, all plots were split with a rolling treatment (850 lb. roller, 2 passes, 2-3 times weekly) up until early October. The main effect of rolling caused increased positive responses for certain clonal accessions, others showed no response, while yet others showed decreased performance from the rolling treatment. Rolling increased positive turf responses among turf clones with showed good turf quality when not rolled. This occurred for nine of the twenty-one clones in this test, all when mowed 3 times weekly at 7/8". Accumulated rolling increased turf performance to enhanced and acceptable levels of quality (6.0 or greater) by the end of September. This was true for nine of the twenty-one clones as well. Accessions, which produced good quality turf (after rolling started in June) throughout the summer, included the following: A138, A65, A86, A137, A48, A51, and A40. Accessions which produced the best quality turfs when unrolled included A138. Likewise, turf density visual scores produced similar accession X rolling interactions. Eleven of the twenty-one clones produced a denser appearing turf after rolling, nine of which had mean visual density scores within the range of 6.3 - 8.7, when rolled. This enhanced response to rolling improved the overall appearance (turf quality) of select clonal accessions over their unrolled counterparts. Initial response to repeated rolling and lower mowing heights showed a favorable response among certain clonal accessions.

Pyrus calleryana are widely used in landscapes in regions where they are adapted, however there are many species of Pyrus that have not been explored for their potential use in landscapes, particularly in hot, arid climates. The Landscape Plant Development Center in Chanhassen, Minnesota has started a program to develop small statured pear trees for landscape use in different climates. This project in Arizona was initiated in conjunction with the Landscape Plant Development Center with the objective to test second generation hybrid Pyrus species for adaptation to the arid climate of the Southwest. Fifty trees were planted in Sierra Vista and 30 trees were planted in Tucson, Arizona, in March 2001. Plant growth, survival, and aesthetic characteristics were observed until fall 2004. Out of thirty trees tested at the Tucson site, one tree from the cross of Calleryana 'Chanticleer' x eleagrifolia appeared to be well adapted to the climate of the mid-elevation desert based on growth, branch structure and foliage health. Pyrus trees performed better in the cooler climate in Sierra Vista compared to Tucson. However, Texas root rot at the site decimated 40 of the 50 trees by the end of the fourth growing season. The aesthetically most pleasing tree at the Sierra Vista site was a cross between fauriei x betulifolia. This provenance was represented with 17 trees in Sierra Vista, nine of which showed good performance by October 2004. Trees from this provenance seem to be well adapted to the arid climate of the higher elevation desert and appear to have a number of desirable characteristics for urban landscapes.

Vegetative shoot growth of eleven legume tree species growing under field conditions in the Southwestern United States in Arizona were monitored over two periods of twelve months. Species included plants native to the Southwestern United States, Mexico, South America, and Australia. Based on shoot extension and branch differentiation species could be grouped into three categories. Fast growing legumes included Acacia farnesiana, A. pendula, Olneya tesota, Parkinsonia floridum, and Prosopis chilensis. Intermediate growth rates were monitored for A. jennerae, A. salicina, and A. visco. Slow growing species in this study included A. stenophylla, P. microphylla, and P. praecox. No buds, flowers, or pods were observed for P. microphylla, O. tesota, and P. chilensis during the study. Of the remaining species those native to the Americas flowered in spring and those native to Australia flowered in fall or winter.

Rhizoctonia root rot is caused by a soil borne fungus, Rhizoctonia solani and is a serious problem in bedding plants. The objective of this study was to determine the efficacy of three chemical and two biological products for controlling Rhizoctonia root rot in cool season and warm season bedding plants. Experiments were conducted with summer and winter bedding plants in a nursery production and landscape situation. The efficacy of conventional fungicides or biological products to control Rhizoctonia root rot in bedding plant production and simulated landscape growth cannot be evaluated from results of this study because of low mortality of plants.

Sales of containerized roses have increased dramatically in recent years and producing flowering plants in containers in a timely manner is important to the nursery industry. An experiment was conducted to determine whether forcing containerized roses will be faster in a retractable roof greenhouse compared to outdoors. Results suggest that forcing roses in a retractable roof greenhouse can shorten the production time and increase quality of finished plants, however, cultivar, time of harvesting, and time in cold storage also affect these parameters.

The objective of this study was to determine whether mesquite (Prosopis velutina) and jojoba (Simmondsia chinensis) seedlings have a preference for the ammonia or nitrate form of nitrogen (N) to maximize growth and minimize N leaching when seedlings were grown in sand culture. Seedlings were fertigated with different ratios of NH₄⁺:NO₃⁻ to determine effects on shoot and root growth and N leaching. Nutrient solution containing 67 % NH₄⁺: 33 % NO₃⁻ resulted in greatest biomass of mesquite seedlings after 120 days of fertigation. N tissue concentrations of mesquite seedlings were highest for plants supplied with 100% ammonium. N leachate remained stable until 12 weeks after the onset of treatment, but increased significantly by week 16. Dry weight of jojoba seedlings did not differ throughout the experiment regardless of the nutrient solution provided, however N tissue concentration in jojoba seedlings fertigated with 100% ammonium was twice as high as that of plants fertigated with 100% nitrate.

The objective of this project was to determine whether the size of planting holes and the addition of organic material in the backfill is beneficial for plant establishment and growth during the early years. Acacia farnesiana were transplanted from containers into a permanent landscape using four methods: large planting hole with or without amendments or a small planting hole with or without amendments. The study was repeated on two sites. Three years following transplanting, plant growth such as height and caliper were not affected by the planting hole size or amendments, but differed significantly between sites. Plants that received more irrigation and were planted in a less rocky soil had greater caliper and were taller than those supplied with less irrigation and planted on a more rocky soil. Visual observations one and three years after transplanting indicate that trees that were amended with compost in the backfill had the highest incidence of leaning trunks and sinking crowns (20% of trees in study or 37% of those receiving amendments) while of those trees that were not amended only one tree (3%) was leaning three years after transplanting. Hole size at transplanting had no significant effect on leaning or sinking three years after transplanting. These results confirm earlier research across the country that 33% to 50% organic amendment in backfill compared to native soil at transplanting is not beneficial for native trees, but increases the risk of leaning or sinking.

The efficacy of six ALS herbicides for controlling purple nutsedge in bermudagrass turf was demonstrated in five field experiments during the summer of 2004. The highest degree of nutsedge control at 95% at the end of the summer was observed after three monthly applications of trifloxysulfuron at 0.026 lb a.i./A.. Three monthly applications of halosulfuron at 0.062 lb a.i./A controlled nutsedge 88 to 90% at the end of September to early October. Imazaquin at 0.5 lb a.i./A plus MSMA at 3.0 lb a.i./A gave 91% control of nutsedge with three applications. The most rapid and efficacious nutsedge control was observed with flazasulfuron giving 91% control at 15 days after a single application. The highest degree of nutsedge control with a single application of sulfosulfuron was 91 to 96% control at 28 days after treatment. In general, ALS herbicides applied as a single application or multiple applications provided one month of effective control following a first application. After one month, the degree of control declined unless repeated applications at monthly intervals or as needed were applied for extended control. Penoxsulam at 0.12 lb a.i./A in one test gave only 70% control. MSMA at 3.0 lb a.i./A was applied four times and nutsedge control at the end of the season was 63 to 66%.

Higher SU herbicide rates provided more effective ryegrass removal that resulted in improved establishment of the seeded bermudagrass. In most instances in this study, the percent bermudagrass coverage increased as herbicide rates increased. Glyphosate was very effective in completely removing ryegrass non-selectively. Flazasulfuron at 0.018 lb ai/A eliminated 88% of the ryegrass. Observations also showed that foramsulfuron, rimsulfuron,and chlorsulfuron were effective in removing ryegrass. In plots where ryegrass had been eliminated, faster bermudagrass coverage in a greater area of the plot was achieved. The least amount of bermudagrass coverage occurred in the untreated plots. It appeared that most of the herbicides evaluated in this study were relatively safe on seeded Princess 77 bermudagrass since emergence and establishment occurred in all plots. The speed and degree of coverage in the plots increased due to efficacy of the herbicides in eliminating ryegrass prior to seeding.