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S.J. Scott, M. Stevens and R.C. Gergerich

Seedlings of eight accessions of L. hirsutum and susceptible L. esculentum `VF Pink' controls were spray inoculated twice in the greenhouse with tomato spotted wilt virus (TSWV) Arkansas 85-9. Plants lacking symptoms were reinoculated, then evaluated for TSWV by enzyme-linked immunosorbent assay (ELISA). Controls were consistently infected; sixty noninfected L. hirsutum were propagated by cuttings and inoculated with TSWV isolates T2 (lettuce), G-87 (gloxinia), 87-34 (tomato) and a mixture of the four isolates. All selections became infected in at least one test, but systemic infection was often delayed. Additional wild Lycopersicon species and numbers of accessions evaluated for resistance to TSWV include L. cheesmanii (9), L. chmielewskii (17), L. hirsutum (24), L. hirsutum f. glabratum (17), L. parviflorum (4) and L. pennellii (44). No new sources of strong resistance have been identified yet. Evaluation of additional species and accessions is continuing.

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S.J. Scott, M. Stevens and R.C. Gergerich

Three methods to inoculate Lycopersicon esculentum 'VF Pink' seedlings with tomato spotted wilt virus (TSWV) were compared. Treatments were 1) two inoculations by hand (rubbing leaves with a sterile cotton swab), 2) a single inoculation using a paint sprayer at 3.56 × 105 N· m-2, and 3) two spray inoculations. All three methods were effective (>95% infection) under moderate temperatures in the spring, but hand inoculation was not effective under hot conditions in the summer. In another experiment, spray inoculation was used to compare effects of light intensity and the leaf inoculated on susceptibility of L.. hirsutum PI 127826, L. pimpinellifoliom LA 1580 and `VF Pink' to TSWV isolate 85-9. All three genotypes were susceptible under full sun and 60% shade cloth in the greenhouse. Inoculation of youngest leaves produced the highest virus titer. Background optical density for noninoculated plants differed between lower and upper leaves in the ELISA assay.

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J.R. Davenport, R.G. Stevens, E.M. Perry and N.S. Lang

The ability to monitor plant nutrient status of high value horticultural crops and to adjust seasonal nutrient supply via fertilizer application has economic and environmental benefits. Recent technological advances may enable growers and field consultants to conduct this type of monitoring nondestructively in the future. Using the perennial crop apple (Malus domestica) and the annual crop potato (Solanum tuberosum), a hand-held leaf reflectance meter was used to evaluate leaf nitrogen (N) status throughout the growing season. In potato, this meter showed good correlation with leaf blade N content. Both time of day and time of season influenced leaf meter measurement, but leaf position did not. In apple, three different leaf meters were compared: the leaf spectral reflectance meter and two leaf greenness meters. Correlation with both N rate and leaf N content were strongest for the leaf reflectance meter early in the season but nonsignificant late in the season, whereas the leaf greenness meters gave weak but significant correlations throughout the growing season. The tapering off of leaf reflectance values found with the hand-held meter is consistent with normalized difference vegetation index (NDVI) values calculated from satellite images from the same plots. Overall, the use of leaf spectral reflectance shows promise as a tool for nondestructive monitoring of plant leaf status and would enable multiple georeferenced measurements throughout a field for differential N management.

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A.K. Carter, R.S. Stevens, J.R. Hamm and N.W. Hopper

Twenty-eight seedlots of Capsicum annuum from several commercial seed companies were tested for tolerance to low temperatures. Each cultivar was tested three times at 25, 20, and 15°C in laboratory incubators. It was observed that while high germination percentages (r85%) and fast germination rates were found in several seedlots, the relationship was not strongly linked to type of chile, age of seed, or treatment temperature. Of the 28 seedlots, 14 came from companies which are in the top 10% in volume and sales. The other 14 seedlots were from smaller companies. Seventy-one percent of the seedlots with germination at r85% came from the top ten companies. Ninety-two percent of the seedlots with s85% came from small companies. To further test this finding, we randomly choose six seedlots from a small company and 6 seedlots from a small company. There was a clear delineation in germabiltiy between the small company and the large company. Our results indicate a trend that could have a negative impact on some chile seed markets. Electrical conductivity (EC) is commonly used to detect membrane leakage in seeds. Chile seed from 12 seedlots (6 from the large company and 6 from the small company) were soaked 18 hours at 25 and 5°C. There was a negative correlation (r 2 = 0.76) between the 15°C germination at 40 days and the EC. It is important to determine why membrane leakage varies in seedlots from different companies and whether the leakage is due to phenotypic or cultural factors, or due to management practices within the company.

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Elsa S. Sánchez, Thomas M. Butzler, Lee J. Stivers, Timothy E. Elkner, Steven M. Bogash, R. Eric Oesterling and Michael D. Orzolek

Butternut, acorn, and buttercup/kabocha winter squash (Cucurbita sp.) cultivars were evaluated in a conventional system in central, southeastern, and southwestern Pennsylvania in 2010–11. Results from individual locations were used to create statewide recommendations, which are also relevant for the mid-Atlantic U.S. region. Additionally, butternut and acorn cultivars were evaluated in an organic system in central Pennsylvania. In a conventional system, butternut cultivars JWS6823, Betternut 401, Quantum, and Metro are recommended based on equal or higher marketable yield than the standard Waltham Butternut. Acorn squash cultivars that performed equally to or better than the standard, Tay Belle, were Table Star, Harlequin, and Autumn Delight. In the kabocha/buttercup category, ‘Sweet Mama’ and ‘Red Kuri’ had marketable yields not different from the standard ‘Sunshine’ in central and southeastern Pennsylvania. In the organic system, butternut cultivars JWS6823, Betternut 401, and Metro all had marketable yields not different from the standard Waltham Butternut. For acorn cultivars, Celebration yield did not differ from the standard Table Queen.

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Elsa S. Sánchez, Thomas M. Butzler, Steven M. Bogash, Timothy E. Elkner, R. Eric Oesterling, Michael D. Orzolek and Lee J. Stivers

Sixteen cultivars of green bell peppers (Capsicum annuum) were evaluated on the basis of yield in three locations across Pennsylvania during the growing seasons of 2008–09. Cultivars were evaluated in comparison with the cultivar Paladin. In central Pennsylvania, all the cultivars trialed had marketable yields (based on weight) not different than ‘Paladin’ except ‘Lynx’, ‘Socrates’, and ‘Escape’. In terms of fruit number, all cultivars were not different than ‘Paladin’ except ‘Socrates’. For large-sized fruit, all the cultivars trialed are recommended. In southeastern Pennsylvania, all the cultivars trialed except SP-05–47 had marketable yields not different than ‘Paladin’. For large-sized fruit, ‘Revolution’ outperformed all other cultivars, including ‘Paladin’. In southwestern Pennsylvania, all the cultivars trialed except Lynx and SP-05–47 produced comparable marketable yields to ‘Paladin’. None of the cultivars evaluated, including Paladin, consistently outperformed Revolution in terms of large fruit. Statewide, all the cultivars, except Lynx and SP-05–47, are recommended on the basis of marketable yields. For growers looking for large-sized fruit to meet market demand the cultivar Revolution is recommended over ‘Paladin’.

Open access

Sangho Jeon, Charles S. Krasnow, Gemini D. Bhalsod, Blair R. Harlan, Mary K. Hausbeck, Steven I. Safferman and Wei Zhang

Pythium species incite crown and root rot and can be highly destructive to floriculture crops in greenhouses, especially when irrigation water is recycled. This study assessed the performance of rapid filtration of recycled irrigation water for controlling pythium root rot of poinsettia (Euphorbia pulcherrima) in greenhouses. Two greenhouse experiments investigated the effect of filter media type (sand and activated carbon), fungicide application (etridiazole), and pathogen inoculum source (infested growing media and infested irrigation water). Rapid sand filtration consistently controlled pythium root rot of poinsettia. Significant improvements in height, weight, root rot severity, and horticultural quality were observed for the plants in the sand filter treatment, compared with the inoculated control plants. However, the activated carbon filter removed essential nutrients from the irrigation water, resulting in plant nutrient deficiency and consequently leaf chlorosis, thus reducing plant weight, height, and horticultural quality. The etridiazole application did not completely prevent root infection by Pythium aphanidermatum, but plant weight, height, and horticultural quality were not negatively affected. P. aphanidermatum spread from infested growing media to healthy plants when irrigation water was recycled without filtration. Rapid sand filtration appears to have the potential to limit the spread of P. aphanidermatum that causes root rot of greenhouse floriculture crops.

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Amy Fulcher, Juang-Horng (JC) Chong, Sarah A. White, Joseph C. Neal, Jean L. Williams-Woodward, Craig R. Adkins, S. Kristine Braman, Matthew R. Chappell, Jeffrey F. Derr, Winston C. Dunwell, Steven D. Frank, Stanton A. Gill, Frank A. Hale, William E. Klingeman, Anthony V. LeBude, Karen Rane and Alan S. Windham

With increased mobile device usage, mobile applications (apps) are emerging as an extension medium, well suited to “place-less” knowledge transfer. Conceptualizing, designing, and developing an app can be a daunting process. This article summarizes the considerations and steps that must be taken to successfully develop an app and is based on the authors’ experience developing two horticulture apps, IPMPro and IPMLite. These apps provide information for major pests and plant care tasks and prompt users to take action on time-sensitive tasks with push notifications scheduled specifically for their location. Topics such as selecting between a web app and a native app, choosing the platform(s) for native apps, and designing the user interface are covered. Whether to charge to download the app or have free access, and navigating the intra- and interinstitutional agreements and programming contract are also discussed. Lastly, the nonprogramming costs such as creating, editing, and uploading content, as well as ongoing app management and updates are discussed.

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Amy Fulcher, Sarah A. White, Juang-Horng (JC) Chong, Joseph C. Neal, Jean L. Williams-Woodward, Craig R. Adkins, S. Kristine Braman, Matthew R. Chappell, Jeffrey F. Derr, Winston C. Dunwell, Steven D. Frank, Stanton A. Gill, Frank A. Hale, William E. Klingeman, Anthony V. LeBude, Karen Rane and Alan S. Windham

Mobile device applications (apps) have the potential to become a mainstream delivery method, providing services, information, and tools to extension clientele. Testing, promoting, and launching an app are key components supporting the successful development of this new technology. This article summarizes the considerations and steps that must be taken to successfully test, promote, and launch an app and is based on the authors’ experience developing two horticulture apps, IPMPro and IPMLite. These apps provide information for major pests and plant care tasks and prompt users to take action on time-sensitive tasks with push notifications scheduled specifically for their location. App testing and evaluation is a continual process. Effective tactics for app testing and evaluation include garnering focus group input throughout app development and postlaunch, in-house testing with simulators, beta testing and the advantages of services that enhance information gained during beta testing, and postlaunch evaluations. Differences in promotional and bulk purchasing options available among the two main device platforms, Android and iOS, are explored as are general preparations for marketing the launch of a new app. Finally, navigating the app submission process is discussed. Creating an app is an involved process, but one that can be rewarding and lead to a unique portal for extension clientele to access information, assistance, and tools.