uncertainty of the predictions. Year is a special case factor, because it can never be a fixed factor when the models are used in a truly forecasting manner. Therefore, year must be a random effect. Unfortunately, the number of years in the training data is
Lu Zhang, Emilio Laca, Cara J. Allan, Narges M. Mahvelati, and Louise Ferguson
Fan-Hsuan Yang, David R. Bryla, and R. Troy Peters
weather forecast program to predict the incidence of heat damage on any given day. Second, the model predicted successfully the fruit temperature patterns during evaporative cooling practices and, therefore, could be used as a useful tool for making
Michael H. Hagemann, Malte G. Roemer, Julian Kofler, Martin Hegele, and Jens N. Wünsche
cultivar, season, and treatment, and permits the evaluation of the 1) natural variation before the treatment effect during post-bloom drop; 2) treatment efficacy during midseason drop; and 3) yield forecasting at the beginning of the preharvest stage
Albert Sutherland, John Damicone, Rafal Jabrzemski, and Stdrovia Blackburn
Weather-based disease advisories have allowed vegetable producers to optimize their fungicide applications. These models typically use only past weather data to identify times of potential disease outbreak. The Oklahoma Mesonet has developed a new Spinach White Rust Advisory that improves grower disease decision support by combining forecast, current, and past weather data in calculating infection periods. The decision-support component issues initial spray advisories, based on infection hour accumulation from the first true-leaf stage or from a previous fungicide application date for subsequent sprays. The advancement in this model in relation to traditional weather-based disease advisories are: incorporation of an 84-hour forecast, hourly model recalculation, cultural practice customization, user site selection from any of 110+ statewide sites, and immediate access to detailed historical data. The model is available on the Oklahoma Mesonet AgWeather website (http://agweather.mesonet.org).
Yanqing Gao and Joseph F. Guenthner
An econometric model was developed to forecast the global demand for U.S. frozen potato products in the year 2000. Quantity-dependent demand equations were established for the U.S. retail market, the U.S. food service market, the Japanese market, and the rest of the world. It was estimated that total sales of U.S. frozen potato products will be 81.5 million cwt in 2000, a 33% increase from 1989. The domestic retail market is forecast to increase by 4%, and the food service market by 33%. Exports are expected to double 1989 volume, with a 30% increase in exports to Japan and a 264% growth in exports to the rest of the world.
Dan T. Stearns
Decisions regarding curricular direction are often made by departmental committees comprised of faculty who are most closely associated with the curriculum. While knowledgeable about current direction, these faculty may not be positioned to accurately forecast future shifts in industry focus. By including employers, potential employers, alumni, students, and representatives from similar programs in the process, alternative views and opinions critical to the visioning process are generated. Penn State's recent efforts in program assessment will be outlined.
Arlie A. Powell, Robert T. Boozer, and James A. Pitts
Phenological studies were conducted over a 3-year period beginning in Winter 1993–94 to relate flowering and fruiting stages of peach to heat accumulation [growing degree hours (GDH)]. Mature trees of `Loring' and `Redhaven' peach in the same orchard were used annually. Some variation from year to year was apparent in GDH levels related to 50% flower and other stages of development. Major sources for this variation appear to be timing and severity of pruning, tree vigor, and shoot diameter. Temperature predict models were used successfully to properly forecast GDH accumulation and and various flowering and fruiting stages once rest was satisfied.
Katharine B. Perry
Basic meteorology as it applies to frost-freeze events and a discussion of the methods of frost protection are included in this article. The presentation of basic meteorology includes descriptions of heat transfer, energy exchange, inversion, frost, freeze, microclimate, air versus crop temperature, and forecasts and warnings in the context of how each of these in involved in frost-freeze events. The second part of the paper describes the major methods of frost protection for commercial crops. The methods included are site selection, irrigation (overhead, undercanopy, man-made fog, flooding), wind machines, heaters, covers, and sprayable materials.
Bruce W. Wood
The cyclic, alternate bearing and correlative aspects of U.S. produced pecan [Carya illinoinensis (Wangenh.) K. Koch] nuts are characterized. An attempt to forecast production using stepwise autoregressive techniques identified a national level biennial cycle for cultivar (CV) and seedling (SC) class nuts and a novemennial (9 year) cycle for SG class nuts. The intensity of the biennial cycle at the national level has generally been low to moderate over the last 50 years for CV and SG class nuts with no clear time trend being expressed. During the most recent years (1979-1991), national production of CV class nuts has not exhibited pronounced bienniality, whereas that of SG class nuts exhibited a moderate bienniality. The nature of the the irregularity of cycling of U.S. and state production appears to nullify the use of univariate polynomial equations as a practical tool for accurately forecasting nut production. Nut production within individual states was also cyclic, with 2-, 3-, 5, 6-, 10-, 12-, 14-, 15-, and 16-year cycles, depending on state and nut class. The most intense contemporary biennial cycles for CV class nuts were from Oklahoma, South Carolina, and North Carolina, whereas cycling of SG class nuts was most intense in Texas and Oklahoma. Correlations of production within and among states indicated that most interrelationships are relatively weak; however, national production of CV class nuts are highly correlated (r = 0.96) with the production of CV class nuts in Georgia, whereas that of SG class nuts is most correlated with that of Louisiana.
Arlie A. Powell, Roger Getz, and Eugene H. Simpson III
An agricultural weather program has been developed in Alabama and is available on the ACENET computer network of the Alabama Cooperative Extension Service (ACES). This program involves the coordinated efforts of the National Weather Service (NWS), ACES and grower organizations. The program began in March 1987 and has been upgraded several times. Hardware now being used includes a Sun Microsystem SPARC station by NWS and a Sun Microsystems Server Model 4/280 by ACES. Existing and experimental NWS forecast products are disseminated to each of Alabama's 67 county agents offices (CEAs) and to local producers using ACES' computer network. A comprehensive selection of climate and weather related information is available to ACES staff including a widely used freeze alert program. Very detailed freeze forecasts and related information is available to users hourly, 7 days a week. A specialist prepared commentary further enhances use of information during each freeze event. Considerable cost savings have been realized by producers. A pilot program is being initiated in 1991 to incorporate data from several real time weather stations into the system.