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Brent Rowell, Terry Jones and J.C. Snyder

We conducted trials of vine-ripened, staked tomato cultivars in 1998 and 1999 to identify a variety suitable for marketing as a premium “Kentucky Tomato.” Essential qualities of our ideal Kentucky tomato were determined in conversations with marketing specialists at the Kentucky Dept. of Agriculture and merchandising managers from the state's largest supermarket chain. A carefully selected group of 14 varieties (including 10 from the 1998 trial) was evaluated at two locations for yields, returns per acre, appearance, and quality in 1999. New varieties were compared with commercial standards `Mountain Spring' and `Mountain Fresh'. Yields of different sizes and grades of marketable fruit were multiplied by appropriate market prices for a given harvest date and summarized in a single “income per acre” variable for each variety. Although many varieties were in the highest 1999 income group (`Fabulous', `Mountain Spring', `Emperador', `Florida 47', `Sunleaper', `Floralina', `Mountain Fresh', `SunGem', NC 98274, `Enterprise'), not all were acceptable in terms of fruit quality and firmness. `Fabulous' and `Emperador' had higher percentages of fruits with radial cracks at one location in 1999 than in 1998. Consumer taste tests were conducted in 1998 and `Mountain Fresh' and `Floralina' were considered the best tasting among the six varieties tested. `Sunleaper', `Floralina', `SunGem', NC 98274, and `Fabulous' (for local markets) together with `Mountain Fresh' were considered prime `Kentucky Tomato' candidates and were recommended for further testing in farmers' fields in 2000.

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Andreas Westphal, Nicole L. Snyder, Lijuan Xing and James J. Camberato

Watermelon, Citrullus lanatus (Thunb.) Matsum. & Nakai, crops are continuously exposed to soilborne diseases. In many areas of the United States, greenhouse-raised watermelon seedlings are transplanted to the field to allow for early crop establishment and early fruit production. This practice can result in weakened root systems, which potentially make the plant prone to premature senescence and reduce crop productivity. Mycorrhizal fungi have been reported to improve plant growth in many crops through enhanced root growth and function. We hypothesized that amending potting mixes with commercial inocula of mycorrhizal fungi during seeding of watermelon in a greenhouse would improve watermelon production when seedlings were transplanted to the field. Colonization of watermelon roots with mycorrhizal fungi from three commercial formulations was compared with the colonization of onion roots to confirm the efficacy of the mycorrhizae. Two inocula of mycorrhizal fungi that resulted in colonization of watermelon roots were tested in the field and glasshouse for their potential to improve watermelon production. MycoApply improved early plant growth in two tests, one under Meloidogyne incognita-infested conditions in loamy sand and another at two phosphorus fertilizer levels (0 or 22 kg·ha−1 P) in a loam soil. Mycor Vam Mini plug improved early fruit yield in soil infested with M. incognita. Application of Myconate (formononetin), a potential enhancer of colonization with mycorrhizae, increased early fruit yield in M. incognita-infested soil. Myconate had positive effects when potting mixes were not amended with inoculum of mycorrhizal fungi, but reduced watermelon growth when mycorrhizal fungi were supplied in the potting mix. In glasshouse tests, inoculation with mycorrhizal fungi did not suppress disease. Mycorrhizal fungi inoculations improved early plant establishment and increased the most valuable early fruit yield under some environmental stress conditions but did not increase total fruit yields.

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J. Strang, J. Hartman, R. Bessin, T. Jones, G. Brown, T. Barnes, T. Yankey and J. Snyder

Four different netting types were evaluated in the field for excluding Japanese beetles and green June beetles from `Dirksen' thornless blackberry plants. These nets were bird net, crop net, rack mesh, and Agryl P17. Observations were made in an unreplicated trial on `Reliance' grapes using OV3018 and OV7100 nets in addition to those listed. Plants were not sprayed with insecticides or fungicides after net application. Rack mesh appears to be the best net of those evaluated during a dry season for excluding Japanese beetles and green June beetles on thornless blackberries and grapes. Plants covered with rack mesh had minimal fruit and foliage damage due to insects and fruit rot. The use of rack mesh eliminated the need for insecticide sprays for 53 days on thornless blackberries and 41 days on grapes. Light intensity was reduced by the netting, but did not reduce (hornless blackberry yield or soluble solids; however it did unacceptably reduce `Reliance' grape fruit coloration.

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André Snyder, Matthew J. Morra, Jodi Johnson-Maynard and Donald C. Thill

Brassicaceae seed meals (BSMs) average 6% nitrogen (N) by weight and contain glucosinolates (GLSs) that produce biologically active compounds. A two-season field study was initiated to determine how Brassica juncea L., Brassica napus L., and Sinapis alba L. seed meals, each with different glucosinolate profiles, alter carrot (Daucus carota L. subsp. sativus) growth, microbial biomass N (MBN), and soil N mineralization. BSM applications of 1 and 2 t·ha−1 36 days before planting did not influence carrot emergence, whereas carrot emergence decreased up to 40% in S. alba treatments seeded 15 days after BSM application. Crop quality was unaffected by BSM treatments and total fresh market yields were equal to or higher than the unamended controls in both years. At 4 and 8 days after seed meal application, MBN in the high-GLS B. juncea and S. alba treatments was 48% to 67% lower than in the low-GLS B. napus treatment. Seasonal apparent net N mineralized expressed as a percentage of the total N applied in the seed meals was unaffected by glucosinolate concentration and ranged from 30% to 81% across both years. BSMs can be used to increase soil inorganic N and carrot yields, but crop phytotoxicity is possible depending on the meal and its respective glucosinolate content. GLS degradation products inhibit microbial N uptake in the short term, but longer-term N availability is not compromised.

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Richard G. Snyder, A. Brent Rowell, Thomas J. Koske and R. Allen Straw

The protocol for agent training has always been for extension specialists to train agents within the same state in each aspect of agriculture. However, with ubiquitous cutbacks among universities, and extension in particular, it is no longer feasible for every state to provide expertise in each field. Consequently, agents cannot receive training in some specialized fields. With a partnership agreement from the USDA Risk Management Agency, the Greenhouse Tomato Short Course in Jackson, Miss., provided training for five to seven agents from each state in the region: Louisiana, Tennessee, Kentucky, and Mississippi. Funding was made available to cover travel expenses, registration, and a resource notebook for 25 agents. As a result, these agents took part in 3 days of intensive training seminars, as well as a 1-day tour of greenhouses. Invited speakers from around the United States spoke to these agents, as well as current and prospective commercial growers from all over the United States. Topics included basics of producing a commercial crop of hydroponic greenhouse tomatoes, budget for establishing and operating a greenhouse business, marketing and promotion, principles of risk management, pest and disease identification and management, grower's point of view, heating, cooling, and ventilation of greenhouses, new technologies, diagnostics, recent research in greenhouse production, and alternative crops (lettuce, peppers, mini-cucumbers, galia melons, baby squash) for the greenhouse. With this training, agents from throughout the south-central region returned to their offices with the skills to assist growers in their counties to succeed in the hydroponic greenhouse tomato business. Complete information on the short course can be found at www.greenhousetomatosc.com.

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Mayuki Tanaka, Robert Snyder, John K. Boateng, William J. Lamont, Michael D. Orzolek, Kathleen M. Brown and Jonathan P. Lynch

The utility of alumina-buffered phosphorus (Al-P) fertilizers for supplying phosphorus (P) to bell pepper (Capsicum annuum L.) in soils with low-P availability was evaluated. Plants were grown at low-P fertility (about 100 kg·ha–1, low-P control; LPC), with conventional P fertilization (205-300 kg·ha–1 annually, fertilizer control; FC), or with one of two Al-P sources (Martenswerke or Alcoa) in 2001–03. The two Al-P fertilizers were applied in 2001; no additional material was applied in 2002-03. Plants grown with Martenswerke Al-P had similar shoot dry weight, root dry weight, root length, leaf P concentration, and fruit yield compared with plants grown with conventional P fertilizer in both 2002 and 2003 seasons. Bell pepper grown with Alcoa Al-P had similar shoot dry weight, root dry weight, root length, leaf P concentration, and fruit yield compared with plants grown without P fertilizer in both seasons. Alcoa Al-P continuously released bioavailable P for 2 years between 2001 and 2002, while Martenswerke Al-P continuously released bioavailable P at least 3 years between 2001 and 2003. These results indicate that some formulations of Al-P can serve as long-term P sources for field vegetable production.

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Kim S. Lewers, Patricia R. Castro, John M. Enns, Stan C. Hokanson, Gene J. Galletta, David T. Handley, Andrew R. Jamieson, Michael J. Newell, Jayesh B. Samtani, Roy D. Flanagan, Barbara J. Smith, John C. Snyder, John G. Strang, Shawn R. Wright and Courtney A. Weber

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Kenneth A. Shackel, H. Ahmadi, W. Biasi, R. Buchner, D. Goldhamer, S. Gurusinghe, J. Hasey, D. Kester, B. Krueger, B. Lampinen, G. McGourty, W. Micke, E. Mitcham, B. Olson, K. Pelletrau, H. Philips, D. Ramos, L. Schwankl, S. Sibbett, R. Snyder, S. Southwick, M. Stevenson, M. Thorpe, S. Weinbaum and J. Yeager

To be useful for indicating plant water needs, any measure of plant stress should be closely related to some of the known short- and medium-term plant stress responses, such as stomatal closure and reduced rates of expansive growth. Midday stem water potential has proven to be a useful index of stress in a number of fruit tree species. Day-to-day fluctuations in stem water potential under well-irrigated conditions are well correlated with midday vapor-pressure deficit, and, hence, a nonstressed baseline can be predicted. Measuring stem water potential helped explain the results of a 3-year deficit irrigation study in mature prunes, which showed that deficit irrigation could have either positive or negative impacts on tree productivity, depending on soil conditions. Mild to moderate water stress was economically beneficial. In almond, stem water potential was closely related to overall tree growth as measured by increases in trunk cross-sectional area. In cherry, stem water potential was correlated with leaf stomatal conductance and rates of shoot growth, with shoot growth essentially stopping once stem water potential dropped to between −1.5 to −1.7 MPa. In pear, fruit size and other fruit quality attributes (soluble solids, color) were all closely associated with stem water potential. In many of these field studies, systematic tree-to-tree differences in water status were large enough to obscure irrigation treatment effects. Hence, in the absence of a plant-based measure of water stress, it may be difficult to determine whether the lack of an irrigation treatment effect indicates the lack of a physiological response to plant water status, or rather is due to treatment ineffectiveness in influencing plant water status. These data indicate that stem water potential can be used to quantify stress reliably and guide irrigation decisions on a site-specific basis.