Current propagation techniques for grapevine rootstocks involve rooting cuttings from dormant or actively growing canes and require relatively large amounts of propagation wood. We report an alternative method involving high-frequency, in vitro rooting of single-node cuttings that can be used when limited amounts of plant material are available. Propagation material was taken from greenhouse-grown plants of Vitis arizonica, V. treleasei, and V. treleasei interspecific hybrids (with V. acerifolia, V. arizonica, and/or V. doaniana) collected from the wild in New Mexico. Shoots were cut into one-node sections and surface sterilized in 25% commercial bleach for 10 minutes followed by three rinses in sterile water. The cuttings were placed on media containing half-strength Murashige and Skoog (MS) salts, MS vitamins, 20 g·L-1 sucrose, 2 g·L-1 phytagel, pH 5.8. The cuttings were incubated at 27 °C under a 16-hour photoperiod. Vitis vinifera `Cabernet Sauvignon' and `Chardonnay' were also rooted under similar conditions. All genotypes investigated rooted, but with varying frequency. Particular selections from the genotypes collected from the wild rooted at high frequency (>84% of cuttings rooted), while 66% of `Cabernet Sauvignon' and `Chardonnay' cuttings rooted. Plants were successfully established in the greenhouse. In vitro rooting of single-node cuttings appears to be a valid alternative for grapevine propagation.
Ashley Basinger and Richard Durham
Rose Hiskes and Richard Ashley
Posisus maculiventris, a Colorado potato beetle (CPB) predator native to Connecticut, is commercially available. This research evaluated Podisus' effectiveness against CPB at different predator-to-prey ratios. Field experiments were conducted over two summers. The first summer yields in the treatment with 100 CPB eggs and 6 predators and the control (0 CPB eggs and 0 predators) were significantly higher than treatment with 100 CPB eggs and 0 predators. The second summer yield for treatment with 100 CPB eggs and 12 predators and the control were significantly higher than the remaining treatments with 0, 3, and 6 predators. Podisus maculiventris holds promise for control of CPB on potatoes grown under rowcover. Further research, determining the effects of all native CPB predators as pesticides more favorable to them are used, is needed.
Jude Boucher, Gianna Nixon and Richard Ashley
In 1995, we compared the horticultural characteristics of one Phytophthora blight, one cucumber mosaic virus, and 12 bacterial leaf spot–resistant varieties to two popular commercial peppers in a replicated trial at the University of Connecticut. Fruit were graded for size and shape and yields were separated into early and late-season harvests. Other parameters measured were plant height, canopy width, and fruit wall thickness, length to diameter ratio, number, weight, and the percent marketable. Unreplicated demonstration plantings with three or four resistant varieties each were conducted at 12 commercial farms in 1994–95 and at the university's research farm in 1994. Several resistant varieties were judged to be equal or superior to the two popular cultivars based on a combination of characteristics, including observations on disease susceptibility at local farms. Resistant varieties recommended for New England conditions include Boynton Bell (Harris Moran), King Arthur and PSX 271092 (Petoseed), Admiral and Reinger (Roger NK).
Jason Ernest Elvin Dampier, Richard W. Harper, Ashley McElhinney and Eric Biltonen
Chinese hemlock (Tsuga chinensis) exhibits a high level of resistance to the exotic insect hemlock woolly adelgid (HWA; Adelges tsugae) relative to the native and widely planted eastern hemlock (Tsuga canadensis). Furthermore, both chinese and eastern hemlock exhibit similar autecologic and aesthetic characteristics in urban and suburban environments. This study provides a comparative 25-year economic benefit-cost analysis (BCA), tracking estimated establishment and insect control costs for the two tree species. Eastern hemlock survival requires insecticide treatments when growing within the range of HWA. Insect control scenarios used and evaluated in this study include annual horticultural oil spray, biannual horticultural oil spray, biennial imidacloprid soil drench, and no treatment. The chinese hemlock scenario did not include chemical insect control because of the species’ host plant resistance (HPR) to HWA. Benefits were estimated using the U.S. Department of Agriculture, Forest Service’s i-Tree tool, which estimates economic benefits for ecosystem services (expressed in dollars). Benefit–cost ratios (BCRs) were developed using the present value for 25-year benefit and cost streams at 2% and 4% discount rates. Payback periods were also estimated for all options that had a calculated BCR greater than one. The benefit–cost analyses for each insect control scenario were evaluated, compared, and assessed through the lens of market potential. The costs exceed the benefits for all of the eastern hemlock scenarios. The benefits exceed costs for the chinese hemlock scenario. Results suggest that chinese hemlock is a viable alternative to eastern hemlock in view of its HPR and reduced associated costs over time. If chinese hemlock becomes more widely planted, it is expected to produce greater BCRs relative to chemical control options as a result of the lack of required, ongoing insect control treatment costs.
Joseph R. Heckman, Thomas Morris, J. Thomas Sims, Joseph B. Sieczka, Uta Krogmann, Peter Nitzsche and Richard Ashley
The pre-sidedress soil nitrate test (PSNT) was evaluated in 27 fields in New Jersey, 6 in Connecticut, 5 in Delaware, and 2 on Long Island in New York for its ability to predict whether sidedress N is needed to grow fall cabbage (Brassica oleracea var. capitata) as a double crop. Soil NO3-N concentrations measured on 20 field sites on the day of transplanting and 14 days after transplanting indicated that NO3-N concentrations over this time period increased, and that residues from the previous crop were not causing immobilization of soil mineral N. The relationship between soil NO3-N concentration measured 14 days after transplanting and relative yield of marketable cabbage heads was examined using Cate-Nelson analysis to define the PSNT critical level. Soil NO3-N concentrations ≥24 mg·kg-1 were associated with relative yields >92%. The success rate for the PSNT critical concentration was 84% for predicting whether sidedress N was needed. Soil NO3-N concentrations below the PSNT critical level are useful for inversely adjusting sidedress N fertilizer recommendations. The PSNT can reliably determine whether fall cabbage needs sidedress N fertilizer and the practice of soil NO3-N testing may be extendable to other cole crops with similar N requirements.