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Douglas A. Hopper, Troy T. Meinke, and Virginia S. Store

The computer simulation model ROSESIM is based on `Royalty' rose (Rosa hybrida L.) growth response to 15 unique treatment combinations of photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT) under constant growth chamber conditions. Environmental factors are assumed constant over an entire day, but set points may vary over the duration of the crop. Anticipated values for factors may be read from an ASCII file, allowing a variety of strategies to be modeled and compared.

A Valentine's Day crop senario compared 2 management strategies for crop development time and flower quality: [1] constant 24/17.1 DT/NT for the entire crop, or [2] 15 days warm 30/20C DT/NT to promote bud break, 10 days 20/15C DT/NT to promote stem caliper and leaf size, 10 days 25/18C DT/NT to promote bud development, and remaining time to flower 20/15C DT/NT to enhance flower size and color. PPF was increased gradually over crop time as would occur naturally for Dec. to Feb. Strategy [2] had longer stems (63 vs. 50 cm), similar stem and leaf dry weights, but less flower bud dry weight (1.0 vs. 1.6 g), while flowering 2 days earlier (41 vs. 43 days after pinch). c:\pm4\ 4

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Josiah W. Worthington, James L. Lasswell, and M.J. McFarland

A computer model was used to predict irrigation rates and numbers of emitters or microsprayers required to trickle irrigate Redskin/Nemaguard peach trees. Irrigation rates were 0, 50%, and 100% of the predicted requirement based on a crop coefficient of 50, 80, 100, 80, and 50 percent of pan evaporation for the tree's canopy area for May, June, July, August and Sept. respectively. Full irrigation (100% of predicted) was applied through 6, 8L/hr emitters or one 48L/hr microsprayer. Half the predicted rate was applied through 6, 4L/hr emitters or 1 24L/hr microsprayer. Control trees received no supplemental irrigation. Microsprayers height was adjusted to wet a surface area comparable to the 6 emitters. There was no significant difference in fruit size or yield based on emitter vs microsprayers, but fruit size and total yield was increased in direct proportion to irrigation rate. There was no treatment effect on tree pruning weights. Moisture measurements indicated that trees de-watered the soil efficiently enough that water never moved below the 30 cm level in spite of the fact that up to 260 liters per tree per day were applied in mid-summer.

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Paul R. Fisher, Royal D. Heins, Niels Ehler, Poul Karlsen, Michael Brogaard, and J. Heinrich Lieth

Commercial production of Easter lily (Lilium longiflorum Thunb.) requires precise temperature control to ensure that the crop flowers in time for Easter sales. The objective of this project was to develop and validate a greenhouse decision-support system (DSS) for producing Easter lily to predetermined height and flower date specifications. Existing developmental models were integrated with a knowledge-based system in a DSS to provide temperature recommendations optimized for Easter lily scheduling and height control. Climate data are automatically recorded in real time by linking the DSS to a greenhouse climate control computer. Set point recommendations from the DSS can be manually set or automatically implemented in real time. Potential benefits of the project include improved crop quality and the transfer, validation, and integration of research-based models. The DSS was implemented at several research and commercial locations during the 1994 Easter lily season. DSS recommendations were compared with the strategies of experienced growers. The system design, implementation, production results, quality of recommendations, and potential are discussed.

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Kay Oakley, Robert Geneve, Sharon Kester, and Patchara Wonprasaid

Standardized seed vigor tests must be developed for greenhouse-grown flower species. Current vigor tests used to evaluate large-seeded agronomic crops are generally not useful for evaluating smaller-seeded flower species. One alternative is to use radicle length in seedlings grown under controlled environments as an indicator of seed vigor. For that purpose, a seed vigor test was developed that uses digital images taken using a flat bed scanner to measure radicle length in small-seeded flower species. A novel, cellulose substrate was used for germinating seeds. It provided similar moisture-holding properties to standard germination blotters used by commercial seed analysts, but is clear. This has allowed for quick image acquisition without removing seedlings from the petri dish. Correlations were made between seedling growth (radicle length, total seedling length, and total seedling area) with other vigor tests (saturated salts accelerated aging) and greenhouse plug flat emergence. For several seed lots of impatiens that varied in initial seed quality, radicle length after 4 days showed good correlations (>R 2 = 0.79) with other measures of seed vigor for describing seed quality. This system is an improvement over other attempts to use computer-aided assessment of digital images because it provides digital images that do not vary due to external lighting; it uses software that can evaluate radicle length in a petri dish assay that does not require a slant-board for straight radicle growth; it relies on standard germination technics used by every seed lab; it uses a clear substrate to replace the opaque blotter to allow digital images to be taken within the petri dish; and accurate measurements of seedling parts is performed in under 2 min per petri dish.

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Ed Stover*, Scott Ciliento, and Gene Albrigo

Grapefruit are susceptible to melanose from initial set until fruit diam. is 6-7 cm, which can span 3 months. Common Indian River melanose-control practice has been application of Cu fungicides at petal fall, with reapplication every three wks. through the infection period. Research data were previously used to develop a computer model to estimate Cu levels on fruit and indicate when reapplication is needed to prevent potential infection. The purpose of this study was to compare melanose control using spray timings suggested by the computer model vs. standard 3 week intervals vs. non-sprayed checks and was conducted over 3 years in mature grapefruit groves near Ft. Pierce, Fla. All applications were made using airblast at 1180 L· ha-1. Melanose and melanose-like Cu injury could not be distinguished and were combined in a melanose/Cu marking (MCM) score for each fruit. Separate fruit samples from the interior and exterior of tree canopies were randomly selected from each tree. In no year was there a significant difference in interior fruit MCM from computer model vs. calendar spray timings when treated with standard rates of Cu fungicide. However, rainfall never occurred when calendar-sprayed fruit were projected to be at low Cu levels. In 2 of 3 yrs. exterior fruit in the non-sprayed checks had less MCM than those from trees treated with Cu, indicating that Cu injury predominated over melanose on exterior fruit. In these fruit, MCM increased linearly with maximum fruit Cu concentration, which was lower on trees managed using the computer model. The computer model appears to be a sound approach to managing melanose, but economic benefit over calendar-based spray timing may only become apparent when practiced over numerous groves and seasons.

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Curt R. Rom

To enhance the opportunities for students to access information and the instructors of a large, general plant science class, “Virtual Classroom” concepts using computers resources were implemented. The Virtual Classroom uses three computer resources: 1) a closed subscription LISTSERV for the extramural class discussions, 2) electronic mail for homework assignment and submission, and 3) a World Wide Web Internet homepage for the course. In a large, introductory-level class, student–teacher interaction can be limited. The size of the class and the content may inhibit questioning and discussion among the class participants. The LISTSERV allowed for questions to be posed by students at their leisure and facilitated discussion among students and the instructor outside of the confines of the class meeting. The LISTSERV also allowed instructors to to respond to the students by referring questions to “experts” on a particular subject. Using e-mail for homework assignment and submission was useful for tracking when student read assignments and submitted completed assignments. Electronic assignment grading and returning was paperless and easy for instructors to maintain. The homepage provided students with a permanent syllabus, lecture outlines, homework assignment descriptions, and study aids. Additionally, from the homepage students were able to send e-mail to instructors and search library databases and other electronic databases. Experiences from the instructors using these computer resources will be presented and discussed.

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Robert L. Geneve and Sharon T. Kester

Early seedling growth rate can be used to estimate seed vigor for small-seeded vegetable and flower seeds. However, hand measurement of small seedlings is tedious and difficult to reproduce among analysts. Computer-aided analysis digital images of seedlings should improve accuracy and reproducibility. A flat-bed scanner fitted with base and top lighting provided high resolution images of even small-seeded species like petunia [Petunia ×hybrida `Blue Picotee' (Hort) Vilm.] and lisianthus [Eustoma grandiflorum `Mariachi Pure White' (Raf.) Shinn]. Uniform lighting was provided and images were captured and analyzed in less than 2 minutes. A clear, cellulose film was used as the germination substrate in petri dish germination assays to facilitate capturing images with a flat-bed scanner. The transparent medium permitted seedlings to be imaged without removal from the petri dish and also allowed for repeated measures of the same seedlings in order to calculate growth rate. Six species evaluated in this study included cauliflower (Brassica oleracea L., var. Botrytis), tomato (Lycopersicon esculentum Mill. `New Yorker'), pepper (Capsicum annuum L. `North Star'), impatiens [Impatiens walleriana Hook. f. `Impact Lavender'], vinca [Catharanthus roseus (L.) G. Don. `Little Bright Eye'], and marigold (Tagetes patula L. `Little Devil Flame'). For germination and early seedling growth, the cellulose film compared favorably with other standard germination media (blue blotter and germination paper) for five of the six species tested. Computer analysis of seedling length was possible for all six species and was statistically similar to hand measurements averaged for three analysts.

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Christopher Lindsey, Gate Kline, and Mark Zampardo

An interactive computer-based system was designed to improve student plant identification skills and knowledge of ornamental, cultural, and usage information in a woody landscape plant materials course. The program is written for use under ToolBook, a Microsoft Windows based program, and incorporates 256-color high-resolution images and text into a single interactive computer program. Features include: a slideshow that allows students to select which genera and plant characteristics are to be viewed and in what order with the option of an interactive quiz, seeing the names immediately, or after a delay; side by side comparison of any image or text selection; and encyclopedic entries, all with a user-defined path and pace of study.

The system is being used to study how students learn the information presented to them via computer technology and which program features are most useful for improving identification skills and knowledge of other plant features. The computer tracks and logs all activity by students on the system for analysis.

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Mary Hockenberry Meyer and Warren Banks

A survey of e-mail discussion list participants found 84% rated the program as a valuable or very valuable educational tool. Most participants, 82%, thought it was equal to or more valuable than printed materials such as fact sheets or bulletins. Participants cite advantages as rapid response, unique, specific information not found in other sources, and a sense of connectedness to the Master Gardener program. Disadvantages include too much e-mail, frustration with participants who do not look up easy traditional questions, chitchat, and nonhorticultural postings. A summary of messages by subject shows tree and shrub questions are asked most often.

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James C. Sellmer, Kathleen M. Kelley, Susan Barton, and David J. Suchanic

Attendees at the 2001 Philadelphia Flower Show participated in an interactive-quiz-formatted survey on touch-screen computers to determine their knowledge and use of plant health care (PHC) and integrated pest management (IPM) practices. Participants answered 15 questions in three categories: 1) PHC practices (criteria for proper plant selection, correct planting practices, and reasons for mulching and pruning); 2) IPM practices (insect identification, plant and pest monitoring, and maintenance of records on pests found and treatments applied to their landscape plants); and 3) demographic and sociographic questions to aid in characterizing the survey population. Over half of the participants (58%) were interested in gardening and a majority (77%) were interested in protecting the environment. Most participants (66%) were between 36 and 60 years of age with a mean age of 47 years, 76% lived in and owned a single-family home, and greater than half (56%) had never purchased professional landscape services. Most recognized PHC criteria for proper site selection, although not all environmental site characteristics were recognized as being equally important. Nearly half (49%) identified the correct planting practice among the choices offered; while an equal number of participants chose among the several improper practices listed. Although reasons for mulching were properly identified by the respondents, excess mulching around trees was considered a proper planting practice by over 39% of the participants. When questioned about IPM practices, a majority reported that they identify pests prior to treating them (71%) and that they scouted their landscapes (82%). However, only 21% kept records of the pests that they had found and the treatments that they applied for those pests. Participants' responses were further examined using cluster analysis in order to characterize the participants and identify meaningful consumer knowledge segments for targeting future extension programming. Three distinct segments were identified: 1) horticulturally savvy (69% of the participants), 2) part-time gardener (25% of the participants), and 3) horticulturally challenged (6%). At least 47% of the horticulturally savvy and part-time gardeners correctly answered plant health care questions (44% of the total survey participants). These two segments included more individuals who were interested in gardening and protecting the environment and are potential targets for future PHC and IPM extension education programs. In contrast the horticulturally challenged recorded no interest in or opinion on gardening or protecting the environment. It is apparent that a majority of consumers are learning and employing PHC and IPM concepts. Proper site selection, planting practices, and mulching along with record keep- ing and pest identification proficiency remain key educational areas to be developed. Although not all gardeners are well versed in all subject matter, a basic knowledge of PHC and IPM is being demonstrated.