Hibiscus rosa-sinensis L. plants treated three times with 850 mg·liter-1 of the growth retardant chlormequat chloride (CCC) were less susceptible to infestation with Tetranychus urticae (Koch) than water-treated control plants. The difference in mite numbers was noted within 8 days after releasing mites onto test plants. Mean number of mites per treated plant was 3.7, compared to 30 on nontreated plants. This activity was observed on all treated plants 6 months after applying CCC. Significant differences were observed on treated plants that were defoliated and allowed to produce new foliage before being evaluated. Therefore, surface chemical residues were not responsible for reducing mite infestations on CCC-treated plants.
L.S. Osborne and A.R. Chase
Carlene A. Chase, Thomas R. Sinclair, Daniel O. Chellemi, Stephen M. Olson, James P. Gilreath and Salvadore J. Locascio
Although summer soil solarization is a viable technique for the control of soilborne pests, periods of cloudy skies and high rainfall typical of the southeastern United States limit the heating of soils. This study was devised to evaluate whether polyethylene films designed for improved heat conservation could increase soil solarization temperatures under humid environmental conditions. Soil solarization was conducted in Summer 1996 at Quincy, Gainesville, and Bradenton: located in north, north central, and west central Florida, respectively. Temperatures at soil depths of 5, 10, and 25 cm were higher under clear solarization films than under black polyethylene. A clear, thermal-infrared absorbing film (TIR) was consistently more effective in increasing soil temperature than was a double-layered, clear bubble film or a 30 μm clear, low-density polyethylene film. Soil temperatures under all film types were reduced by rainfall, but remained highest under TIR film. On cloudy days with light rainfall, temperatures under TIR film exceeded 45 °C at 5 cm depth. Soil temperatures rose rapidly when rainy weather was followed by a clear day. Cumulative exposure to temperatures ≥45 and 50 °C was greater with the TIR film than with the other films, indicating that it has the greatest potential for soil solarization in humid climates.
Bryan J. Peterson, Gregory J.R. Melcher, Ailish K. Scott, Rebecca A. Tkacs and Andrew J. Chase
Sweetgale (Myrica gale), rhodora (Rhododendron canadense), and catberry (Ilex mucronata) are shrubs of eastern North America that may have potential for broader use in horticultural landscapes. Because information on their vegetative propagation is scarce, we conducted experiments over 2 years to evaluate the effects of cutting collection date, wounding, substrate composition, and the concentration of applied potassium salt of indole-3-butyric acid (K-IBA) on rooting of each species. In 2015, we collected cuttings of each species on three dates to obtain both softwood and semihardwood cuttings. Cuttings were unwounded or wounded with a razor blade, and treated by dipping into water containing K-IBA at concentrations ranging from 0 to 15,000 mg·L−1, after which they were inserted into a substrate of 3:1 perlite:peat (by volume) and placed under intermittent mist. In 2016, semihardwood cuttings of each species were all wounded, treated with K-IBA from 0 to 15,000 mg·L−1, and inserted into substrates of 100%, 75%, or 50% perlite, with the remaining volume occupied by peat. In both years, the greatest percentage of sweetgale cuttings rooted when no K-IBA was applied. K-IBA application also reduced root ratings, root dry weights, and root lengths of sweetgale. For rhodora and catberry, maximal responses for all measures of rooting occurred when 5000 to 15,000 mg·L−1 K-IBA was applied. We recommend that growers use no exogenous auxin to propagate sweetgale, and 5000 to 10,000 mg·L−1 K-IBA to propagate rhodora and catberry. Cuttings of all three species can be collected from softwood or semihardwood shoots. Finally, sweetgale can be rooted in perlite alone, whereas rhodora and catberry required the addition of peatmoss for satisfactory root development.
Jayesh B. Samtani, Curt R. Rom, Heather Friedrich, Steven A. Fennimore, Chad E. Finn, Andrew Petran, Russell W. Wallace, Marvin P. Pritts, Gina Fernandez, Carlene A. Chase, Chieri Kubota and Brad Bergefurd
Strawberry (Fragaria ×ananassa) production practices followed by growers in the United States vary by region. Understanding the challenges, needs, and opportunities in each region is essential to guide research, policy, and marketing strategies for the strawberry industry across the country, and to enable the development of general and region-specific educational and production tools. This review divided the United States into eight distinct geographic regions and an indoor controlled or protected environment production system. Current production systems, markets, cultivars, trends, and future directions for each region are discussed. A common trend across all regions is the increasing use of protected culture strawberry production with both day-neutral and short-day cultivars for season extension to meet consumer demand for year-round availability. All regions experience challenges with pests and obtaining adequate harvest labor. Increasing consumer demand for berries, climate change-induced weather variability, high pesticide use, labor and immigration policies, and land availability impact regional production, thus facilitating the adoption of new technologies such as robotics and network communications to assist with strawberry harvesting in open-field production and production under controlled-environment agriculture and protected culture.