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John C. Majsztrik and John D. Lea-Cox

group within this committee is to inform the Chesapeake Bay modelers about how the model can be adapted to better model the inputs and practices used by greenhouse and nursery operations. In Maryland, specific water and nutrient management information is

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Robin G. Brumfield

The computer program Greenhouse Cost Accounting, available for DOS-based microcomputers and Macintosh computers, is described. The software enables the user to perform cost accounting and to determine the profitability of greenhouse crops. The information can be used by managers to analyze various production, financial, and marketing strategies. The Greenhouse Cost Accounting program uses cost information typically found on income statements and direct cost information for each crop. From these inputs, the program allocates as many costs as possible to individual crops. The remaining unallocated costs are assigned to each crop on a per square-foot-week basis. The computer output provides information on costs and returns on a per crop, per unit, and per square-foot basis. It also provides an income statement showing total costs, allocated costs, and unallocated costs. The output can aid the manager in making decisions about pricing, reducing unprofitable production, controlling costs, and increasing sales of profitable crops. The program also can be used by greenhouse management classes or for extension workshops.

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Pengpeng Duan, Ying Sun, Yuling Zhang, Qingfeng Fan, Na Yu, Xiuli Dang and Hongtao Zou

composition, MC treatment at an appropriate rate (MN2: 608 kg N/ha) was shown to be the best management strategy for greenhouse cultivation of tomato in northeast China. Literature Cited Abaas, E. Hill, P. Roberts, P. Murphy, D. Jones, D. 2012 Microbial

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Elio Jovicich, Daniel J. Cantliffe and George J. Hochmuth

84 ORAL SESSION 17 (Abstr. 502–508) Vegetable Crops: Greenhouse Management/Controlled Environmental Agriculture

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P.A. Stack, L.B. Stack and F.A. Drummond

A mail survey of greenhouse growers was conducted in 1994 and 1995 to determine the presence and importance of western flower thrips (WFT), Frankliniella occidentalis Pergande, in Maine greenhouses in growing years 1993 and 1994. Respondents were licensed growers with at least 1000 ft2 (93 m2) of greenhouse growing area. The survey objectives were to develop a grower demographic profile; determine the incidence of WFT and two WFT-vectored plant viruses, tomato spotted wilt (TSWV) and impatiens necrotic spot (INSV); and identify current WFT management strategies. The survey shows that Maine greenhouse growers are seasonal, experienced and retail oriented. Their growing area averages less than 10,000 ft2 (929 m2) and they produce a diverse crop mix and choose to import production stock as much as propagate it themselves. Both WFT and TSWV/INSV have increased in severity in Maine greenhouses over the past 10 years. Larger, year-round greenhouses are more likely to experience infestations of WFT and higher virus incidence. An integrated pest management (IPM) strategy is employed by the majority of growers surveyed. Insecticide application is the primary tactic used to control WFT. Fewer than 4% of the growers use natural enemies to control thrips. However, 63% responded that future research in pest management should focus on biological control.

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Robert T. Eddy and Clifford S. Sadof

Horticulture businesses will be encouraged to hire qualified individuals with disabilities due to the enactment of the Americans with Disabilities Act of 1990. Maintaining a safe workplace is a considerable challenge due to the use and storage of restricted-use pesticides. In a vocational training program, two persons with mental disabilities were trained to be effective Integrated Pest Management scouts using systematic teaching procedures. Trainees acquired employable skills while providing a service that enabled management to reduce use of conventional pesticides on a greenhouse poinsettia crop by up to 65%.

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John D. Lea-Cox

In 1998, the state of Maryland adopted some of the toughest nutrient management planning regulations in the Nation, requiring virtually all agricultural operations plan and implement nitrogen and phosphorus-based management plans by Dec. 2002. The nursery and greenhouse industry is faced with a far more complicated nutrient management planning process than traditional agronomic planning scenarios. Factors include a large number (>500) of plant species, various fertilization and irrigation strategies, with crop cycles ranging from 6 weeks (bedding plants) to upwards of 15 years for some tree species in field production, often with a lack of knowledge of specific nutrient uptake rates and utilization. In addition, unique infrastructural and site characteristics that contribute to water and nutrient runoff from each nursery contribute to a multitude of variables that should be considered in the planning process. The challenge was to identify a simple, effective process for nutrient management planning that would a) provide an accurate assessment of nutrient loss potential from this wide variety of production scenarios, b) identify those specific factors that contribute most to nutrient leaching and runoff, and c) provide a mechanism to economically assess the various risk management (mitigation) scenarios. This risk assessment process provides information on a number of fixed (site) and dynamic (management) variables for soils/substrates, irrigation and fertilization practices, together with any surface water management systems (e.g. containment ponds, riparian buffers). When all the risk factors for a nursery are evaluated and scored, the complete picture of risk assessment then emerges. By identifying higher risk factors and evaluating different risk management options, the grower and/or nutrient management planner can then choose economic alternatives to reduce the potential for nutrient runoff.

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Michel Carrier, André Gosselin and Laurent Gauthier

A dynamic management strategy for supplemental lighting in greenhouses was developed. It makes use of a plant growth model and of a rule-based decisionmaking protocol within the framework of a generic greenhouse climate management software system. The model, an adapted version of SUCROS87, tracks plant growth and predicts dry weight production based on measured or estimated values of light intensity, temperature, and CO2 concentration. A set of logical predicates (rules) implements the strategy's behavior. Optimization of lamp use was conducted as a function of economic criteria that enable a comparison between the additional income associated with yield increases due to supplemental lighting and incurred cost increases. Although the model is not perfectly reliable in its predictions, the system can be used to simulate the effect of changes to economic parameters on the decisions of the management strategy. The dynamic strategy described here differs from conventional supplemental lighting scenarios in the sense that it increases the length of the period of supplemental lighting when the daily solar light integral is low, and reduces or eliminates the use of supplemental lighting when the weather forecast predicts that the daily solar light integral will exceed plant requirements.

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Robert D. Berghage, Alan Michael and Mike Orzolek

Current and future plans for reductions in federal and state funding suggest that government supported programs must find ways to reduce costs while maintaining or expanding programs. The current model of extension, with an agent for each commodity in every county is not likely to survive. Furthermore, the days when university-based specialists could afford to make house calls also are probably limited. Yet, the need for extension support in the floriculture industry is as great as ever. Increased chemical costs and regulatory pressure are restricting grower options and making it increasingly important that information dissemination and technology transfer occur in timely and appropriate ways. To try to meet the needs of the floriculture industry in Pennsylvania, we have begun a program to help develop independent greenhouse crop management associations to work with milti-county and university-based extension specialists to improve program delivery to the member greenhouses. The first of these associations has been established in the Capital Region in central Pennsylvania and is providing IPM scouting and crop management services to member greenhouses. Development of associations and linkages with and the role of extension are discussed.

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Hassan Zekki, André Gosselin and Laurent Gauthier

In greenhouses, computerized climate control systems can be used to dynamically and automatically regulate climatic and environmental parameters. To support such a mode of operation, a crop growth model that was developed for greenhouse tomato plants (TOMGRO) was chosen. The model describes the phenological development and increase in dry weight of various organs from planting till maturity under variable environmental conditions. The assimilate partitioning is based on sink strength. A FORTRAN version of TOMGRO was converted to the Smalltalk object-oriented programming environment. This model was integrated into GX, a dynamic climate management software system that was developed at Laval Univ. GX defines a general architecture that may accommodate different decision-making modules based on mathematical models and rule bases. The TOMGRO model is being used to evaluate different production scenarios and will be used to calculate and predict crop growth rates, development, and yields. The model can be used to perform real-time and seasonal cost–benefit analysis and for the dynamic optimization of greenhouse climatic parameters.