The objective of this study was to determine the optimum rate of N to maximize growth of Prosopis velutina seedlings and minimize N leaching when seedlings were grown in different substrates. Mesquite seedlings were grown in sand or soilless media and were fertigated with a solution of67 % NH₄⁺: 33 % NO₃⁻ at a rate of 25, 50, 100, or 200 mg N/L. After 60 days, plants in media produced 41 % more leaves and total biomass compared to those in sand. Leaf number was greatest for plants grown at 200 mg N/L in both substrates. Root biomass of plants in media showed no response to increasing N concentrations while root biomass of seedlings in sand were similar for the three lower N concentrations and nearly doubled for the highest one. Shoot biomass of seedlings receiving 25, 50, or 100 mg N/L was similar, but more than doubled for plants fertigated with 200 mg N/L. N leachate losses were highest from seedlings growing in sand and receiving the two higher N fertigations, those in media had greatest N leachate loss when fertigated at 200 mg N/L.

The combination of Spotlight* at 1.0 pt/A plus Speedzone* at 4.0 pt/A gave 90% control of khakiweed at 14 days after treatment (DAT) and continued to offer acceptable control of 85% at 49 DAT. Acceptable control of 87 and 90% control was also observed at 14 DAT when Spotlight* was combined with Powerzone* or Speedzone*, respectively. The combinations of Spotlight* with Powerzone* or Trimec* were similar by marginally controlling khakiweed up to 21 DAT. Spotlight when combined with Turflon Ester* or Speedzone Southern* performed very similarly at all rating dates and did not offer acceptable khakiweed control.

Two or three applications of Velocity at 30 g ai/A controlled P. annua 63 to 82% in two field experiments. Multiple applications of Velocity at 17 day intervals provided a higher degree of P. annua control compared to applications made at 28 day intervals. At approximately one month after initial applications, Velocity treatments, single or sequential, demonstrated 50 to 77% control of P. annua. The activity on P. annua was minimal at two weeks after initial applications of 30 to 60 g ai/A and slight chlorosis was evident. Perennial ryegrass exhibited chlorosis at two weeks after applications and appeared to recover at one month.

Seed head production from Poa annua is problematic on winter turfs, whether they are overseeded or not. Flowering culms are unsightly, prevent a uniform surface, and insure a continuous crop of seeds for the future. A field test was conducted to evaluate the effects of PROXY and a PROXY/PRIMO PGR tank mix for seed head control. Treatments were applied on three different dates in order to evaluate the degree of response of treatments and help define treatment window applications for future programs. PROXY when applied alone at 5 ounces/product/M produced a maximum of 60% seed head control at 26 days after a single application on February 15, and 83% seed head control at 27 days after a single application on March 1. A tank mix of PROXY/PRIMO (5.0/0.25 ounces/product/M) generally produced greater seed head control than PROXY alone. The tank mix produced seed head control effects quicker, greater, and longer than PROXY alone. Seed head suppression and percent seed head control was greatest when products were applied initially on either February 15 or March 1, 2001. PROXY/PRIMO produced the darkest color turf when applied on either February 15 or March 1. At least three tank mixes seem to be needed, applied monthly to suppress/control seed heads throughout the winter/spring season.

Post emergence applications of penoxsulam herbicide were generally ineffective in weed control of Khakiweed, (Alternanthera pungens). Moderate control was achieved by the high rate of granular Penoxsulam (0.052 G, 180-lbs. acre). This treatment had 28%, 34%, and 32% Khakiweed control on September 20, September 23 and September 29, respectively. Other rates resulted in minimal or negative control. The liquid SC formulation provided minimal control, at rates tested. Penoxsulam did discolor khakiweed, but did not cause enough injury to result in stand reduction. Further aspects for investigating Penoxsulam for control of this weed is presented.

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.