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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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R. Terry Jones and David C. Ditsch

In Kentucky, fresh-market tomato production is a 3-million-dollar crop involving 405 to 486 ha. During the 1980s, on-farm demonstrations showed yields and grower returns increased when intensive production practices were followed. Fertigation recommendations were based on a 1 N: 2 K ratio with a total of 225 kg N/ha. Symptoms of Mg deficiency and blossom-end rot sometimes were seen, and we were concerned about potentially high fertilizer concentrations in the plant root zone. Farm fertility trials (1992 to 1994) showed no yield response to applied N rates between 101 and 393 kg·ha–1. In 1993, a presidedress N test (PSNT) (NO3 + NH4-N) indicated 131 kg N/ha was available in the top 31 cm of soil. At the final tomato harvest, 343, 529, and 647 kg NO3 + NH4-N was measured in the top 46 cm of soil for the three N rates tested (191, 298, and 391 kg N/ha). In 1994, the PSNT showed 86 kg NO3 + NH4-N/ha was present in the top 31 cm of soil. At final harvest 58, 124, and 157 kg NO3 + NH4-N/ha was measured in the top 91 cm of soil for the 140, 225, and 309 kg N/ha applied. Tomato phenology vs. petiole NO3-N concentration showed that all three N levels gave similar values, with no clear distinction between petiole NO3-N and the N rates tested. Future tests need to include a zero applied N rate to determine if a predictable relationship exists between a PSNT or petiole NO3-N levels and a yield response to fertilizer N.

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Brent Rowell, R. Terry Jones and William Nesmith

Bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vesicatoria is the scourge that has devastated and continues to limit expansion of both fresh-market and processing pepper production in Kentucky. Fourteen new BLS-resistant varieties and breeding lines were evaluated together with two standard (susceptible) varieties in 1995 at two locations. Twenty advanced lines and commercial varieties were tested at the same locations in 1996. All entries were exposed to an induced BLS epidemic at one location, but were kept disease-free at the second location. Epidemic development was slow and field resistance to four races of BLS was high for all but one of the lines tested, which claimed resistance to races 1, 2, and 3 in 1995. Six entries performed well both under BLS epidemic conditions and in the disease-free environment in 1995. Cultivars with resistance to only race 2 or races 1 and 2 of the pathogen were no different from susceptible checks in terms of yields and disease resistance and were not tested in 1996; combined results form 1995 and 1996 are discussed.

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R. Terry Jones and David C. Ditsch

Tomato fertility trials (1992–94) showed no yield response to fertigation N rates between 101–393 kg·ha–1. In 1995, soil Cardy NO3-N readings taken just prior to fertigation showed 53 kg NO3-N/ha in the top 30 cm. Laboratory test on the same sample showed 72.4 kg/ha (NO3 + NH4-N). Forty percent of the available nitrogen was NH4-N, which is not detected by Cardy meters. Soil mineral N levels were measured at fourth injection, second harvest, and 9 days after last harvest. On these dates the 0 kg N/ha treatment had 28, 24, and 8 mg N/kg available in the top 15 cm of soil, similar to the N fertigation treatments. As the growing season progressed, soil mineral N levels decreased, and 9 days after the last harvest residual soil N levels were close to those seen initially. Tomato petiole sap Cardy NO3-N readingsshowed a significant difference between the 0 kg·ha–1 treatment and those (84, 168, and 252 kg·ha–1) receiving N (512 ppm vs. 915, 1028, and 955 ppm NO3-N, respectively). Treatments receiving fertigation N gave petiole sap NO3-N readings higher than those listed by Hochmuth as sufficient for tomatoes. While the data showed a clear separation between the three N treatments and 0 N rate, no significant difference in yield of US #1 or US #2 large fruit occurred. This suggests that adequate N fertility was provided from O.M. mineralization. The highest N rate also had significantly more US #1 small and cull tomatoes than the other treatments. Some Kentucky soils have adequate residual N capable of producing commercial fresh-market tomato crops with little or no additional N. In addition to potential ground water pollution, overfertilization of tomatoes may decrease fruit size and reduce fruit quality by causing NH4-K + ion competition, as well as increase the risk of certain fungal and bacterial diseases.

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Brent Rowell, Terry Jones and William Nesmith

Kentucky growers currently produce about 1300 acres of bell peppers worth $2 million for both fresh market and processing. Bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vesicatoria has been the scourge which continues to limit expansion of pepper production in the state. Fourteen new BLS-resistant varieties and experimental lines were evaluated together with two standard (susceptible) varieties in 1995 at two locations. All entries were exposed to an induced BLS epidemic at one location but were kept disease-free at the second location. Field resistance to four races of BLS was high for all but one of the lines tested, which claimed resistance to races 1, 2, and 3. Cultivars with resistance to only race 2 or races 1 and 2 of the pathogen were no different from susceptible checks in terms of yields and disease resistance. Six entries performed well at both locations; these will be included in further trials in 1996.

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Brent Rowell, Terry Jones, John Snyder and William Nesmith

We began trials of vine-ripened, staked tomato cultivars in 1998 to identify a variety suitable for marketing as a premium “Kentucky Tomato”. In conversations with marketing specialists at the Kentucky Dept. of Agriculture and merchandising managers at the Kroger Company's regional distribution center, we identified essential qualities of our ideal Kentucky tomato. A carefully selected group of 16 varieties was evaluated at two locations for yields, appearance, quality, disease tolerance, and taste. New varieties were compared with commercial standards like `Mountain Spring'. Yields of different sizes and grades of marketable fruit were multiplied by appropriate real-market prices for a given harvest date and summarized in a single income-per-acre variable for each variety. Some of the highest yielding varieties in eastern Kentucky (`Fabulous' `Sunbeam') appeared to have some tolerance to early blight; other varieties in this highest-yielding group included `Emperador', `Enterprise', `Sunleaper', and `Sunbrite'. All of these had fruit quality we considered acceptable for commercial markets with the exception of `Sunbrite'. `Fabulous', `Emperador', `Sunleaper', `SunGem', and `Sunpride' were the highest yielding varieties in central Kentucky. `Sunleaper' and `Sunpride' appeared somewhat tolerant to tomato mosaic virus (ToMV), which occurred at this location. Preliminary taste tests identified six varieties that were evaluated further by consumers at a local farmers' market. `Mountain Fresh' and `Floralina' were considered the best tasting varieties overall. The search continues in 1999.

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Brent Rowell, R. Terry Jones, William Nesmith and John C. Snyder

Bacterial spot epidemics, caused by Xanthomonas campestris pv. vesicatoria (Doidge) Dye, continue to plague bell pepper (Capsicum annuum L.) growers in a number of southern and midwestern states. A 3-year study designed to compare cultivars and breeding lines under induced bacterial spot epidemic and bacterial spot-free conditions began soon after the first release of cultivars having the Bs2 gene for resistance to races 1 to 3 of the pathogen. Bacterial spot epidemics were created by transplanting `Merlin' plants (inoculated with races 1 to 3) into plots of each test cultivar at an isolated location in eastern Kentucky. Plots of the same trial entries at a second location were kept free of bacterial spot for 2 of the 3 years of trials; however, a moderate natural epidemic occurred at this location in 1996. Bacterial spot resistance had the greatest impact on yields and returns per acre in the inoculated trials. Cultivars with only Bs1 or a combination of Bs1 and Bs3 were highly susceptible in the inoculated trials. There were statistically significant and economically important differences in resistance among cultivars and breeding lines having the Bs2 gene; some were nearly as susceptible as susceptible checks. Although many Bs2-gene cultivars showed satisfactory levels of resistance, only a few were highly resistant, horticulturally acceptable, and comparable in yields to the best susceptible hybrids in a bacterial spot-free environment.

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C.R Roberts, Dean E. Knavel, John Snyder, Terry Jones and Dave Spalding

Internal brown spot (IBS) was found consistently in the `Atlantic' cultivar at Lexington in 1967, 1968 and 1989, and at Owensboro and Quicksand, KY in 1987, Treatments of foliar and soil applied CaSO4 in 1987, soil-applied CaSO4 in 1988, and straw mulching in 1989 did not reduce IBS. Irrigation increased IBS because of larger tubers and increased Ca content of plants as compared with non-irrigated plants. Tubers showing IBS had higher Ca content in affected tissue than in non-affected tissue. Both IBS and Ca content of leaves increased as the plants aged.

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Brent Rowell, R. Terry Jones, William Nesmith, April Satanek and John C. Snyder

Bacterial spot epidemics, caused by Xanthomonas campestris pv. vesicatoria (Xcv), are still considered serious risks for commercial pepper (Capsicum annuum) growers in a number of eastern, southern and midwestern states. Newly released bell pepper cultivars with the Bs2 gene for resistance to Xcv races 1, 2, and 3 were compared in 2000 under bacterial spot-free and severe (natural) bacterial spot epidemic conditions in central and eastern Kentucky where similar trials had been conducted from 1995 to 1997. In addition to the replicated bell pepper trials, 49 hot and specialty pepper cultivars were grown for observation in single plots at the same two locations. As in previous trials, there were economically important differences in resistance and marketable yields among bell pepper cultivars having the Bs2 gene; some resistant cultivars were as susceptible as susceptible checks. Others were highly resistant in spite of the presence of Xcv races 3 and 6 in the eastern Kentucky trial. Only a few were highly resistant with excellent fruit quality. With a few notable exceptions, most of the hot and specialty cultivars were very susceptible to bacterial spot. Two of the three new jalapeño cultivars carrying Bs2 were highly resistant to bacterial spot and high yielding under severe epidemic conditions.