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R.M. Crassweller and G.M. Greene

Apple scab is the primary disease that drives commercial pesticide recommendations; therefore, the use of cultivars that are resistant to this disease would help in reducing chemical inputs in apple production. To date, there has been only limited information on the performance of the scab-resistant apple cultivars. In 1990 and 1991, apple cultivars that are resistant to apple scab were planted at two sites in Pennsylvania, one site was the Fruit Research and Extension Center (FREC) in south-central Pennsylvania, and the other was the Horticulture Research Farm (HRF) in central Pennsylvania. Horticultural characteristics measured were trunk cross-sectional area (TCSA), flowering characteristics, yields, and fruit maturity. Trees at the FREC produced fruit 1 year earlier than those at HRF. `Enterprise'/M.26 has been the most-productive cultivar at FREC, as measured by average total weight of fruit per tree. At HRF, `CO-OP 26'/M.26 had been the most-productive cultivar. At the end of the 1994 growing season, `CO-OP 26' and `Williams Pride', both on M.26, are the largest trees as measured by TCSA at HRF. At the FREC, `Enterprise' was the largest cultivar.

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R.M. Crassweller and D.E. Smith

A peach and nectarine cultivar and training trial was planted in 1989. Training methods were open center (OC) and central leader (CL). The orchard was divided into three sections for early, mid-, and late season peaches with 10 individual-tree replications. The following characteristics were measured from 1989 to 1994: trunk cross sectional area, fruit yield, number of fruit, and fruit color. Early season peaches, those ripening with and before `Salem' in the OC system had significantly greater TCSA at the end of the fifth growing season. At the end of the sixth growing season, however, there was a significant training cultivar interaction. There were no differences between the mid- or late season cultivars. Measurable yields were obtained in 1991 through 1993. In all years, greater yields per tree were observed from trees in the CL system, although not significantly different for the late season cultivars. `Redhaven' and `Newhaven' had the highest yields for the early season cultivars, `Glohaven' for the mid-season cultivars, and `Cresthaven' and Biscoe for the late season cultivars. Trees in the CL system tended to have higher tree efficiency than trees in the OC system. Fruit color at harvest varied by year and training system.

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R.M. Crassweller and S.J. Wallner

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D.E. Smith and R.M. Crassweller

Water-sorbing polymers have been used in greenhouses and in arid and semiarid regions to improve soil water properties. Laboratory and field studies were conducted to investigate the effects of a cross-linked polyacrylamide polymer when incorporated into a silt loam. The soil treatments consisted of 0%, 0.06%, 0.12%, and 0.25% polymer by weight. The laboratory study consisted of four soil columns each containing a treatment. Water was added at a rate of 6.1 mm to the columns every 2 days. Soil moisture and volume was measured daily. The field experiment contained apple trees planted into soil amended with the different rates of polymer and covered with a polypropylene weed barrier. Tree growth and fruit yield were recorded from 1996-1998. The volume and bulk density of the soil-polymer matrix were dependent on the moisture content due to the swelling properties of the polymer. Bulk density was highest when no polymer was added and lowest for soil containing 0.25% polymer. Soil moisture measured by time delay reflectometry showed multiple wetting fronts in the soil columns after water was added. During the 1996 growing season, soil moisture was higher for field plots containing the weed barrier and amended with polymer; however, this trend was reversed in 1997. Tree growth was not effected in any of the years data was taken. Fruit yields did not differ between treatments in 1997. Fruit set and yield in 1998 was greater for trees planted without the weed barrier and polymer. The addition of polymer was not found to benefit apple tree growth or yields.

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R.M. Crassweller, V. Esh and J.W. Travis

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R. M. Crassweller, J. W. Travis, P. H. Heinemann and E. G. Rajotte

Apple orchards are highly diversified and complex ecological and economic systems. Production is affected by a wide range of insects, diseases, weeds, and mammalian pests. The incidence of these pests is often dependant upon climatological effects; and the microclimate within orchards. An expert system, a form of artificial intelligence, has been developed and commercially released to apple growers that utilizes weather data to make recommendations regarding production decisions. Users of the system are instructed on how to establish a weather station, and to collect, and input weather data from the farm. The information is utilized to calculate disease infection periods and pesticide residues to arrive at a control recommendation. Other weather dependant modules include the scheduling of trickle irrigation as well as water application rates during a frost. An interactive demonstration of the system will be presented to the group.

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R.M. Crassweller, J.W. Travis, P.H. Heinemann and E.G. Rajotte

Decreasing resources and increasing complexity of horticultural crop production necessitate that new technologies be developed to transfer information to commercial producers. Expert systems (ES) have been cited as potential tools that can facilitate knowledge transfer. The definitions of an expert system, however, technically only indicates a computer program that simulates the thought processes of a human expert and, as such, does not supply all the facets necessary to assist commercial producers. The combination of databases, graphic capabilities, and textual information into a comprehensive program would provide a more complete package. To differentiate the two, we use the term decision support systems (DSS). The development, testing, and release of DSS, however, require greater commitment and interdisciplinary cooperation. Developing DSS fosters interstate, interregional, and international cooperation among researchers and extension personnel. Using systems developed in fruit production as examples, we outline the value of DSS to promote cooperation, the resources necessary to develop these systems; and the attitudinal change necessary to build the systems.

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S.S. Miller, R.W. McNew, B.H. Barritt, L. Berkett, S.K. Brown, J.A. Cline, J.M. Clements, W.P. Cowgill, R.M. Crassweller, M.E. Garcia, D.W. Greene, G.M. Greene, C.R. Hampson, I. Merwin, D.D. Miller, R.E. Moran, C.R. Rom, T.R. Roper, J.R. Schupp and E. Stover

Cultivar and planting site are two factors that often receive minimal attention, but can have a significant impact on the quality of apple (Malus ×domestica) produced. A regional project, NE-183 The Multidisciplinary Evaluation of New Apple Cultivars, was initiated in 1995 to systematically evaluate 20 newer apple cultivars on Malling.9 (M.9) rootstock across 19 sites in North America. This paper describes the effect of cultivar and site on fruit quality and sensory attributes at a number of the planting sites for the 1998 through 2000 growing seasons. Fruit quality attributes measured included fruit weight, length: diameter ratio, soluble solids concentration (SSC), titratable acidity (TA), flesh firmness, red overcolor, and russet. Fruit sensory characteristics rated included crispness, sweetness, and juiciness, based on a unipolar intensity scale (where 1 = least and 5 = most), and acidity, flavor, attractiveness, and desirability based on a bipolar hedonic scale (where 1 = dislike and 5 = like extremely). All fruit quality and sensory variables measured were affected by cultivar. The two-way interaction of cultivar and planting site was significant for all response variables except SSC, TA, russet, crispness, and sweetness ratings. The SSC: TA ratio was strongly correlated with sweetness and acidity sensory rating, but was weakly correlated with flavor rating. The results demonstrate that no one cultivar is ideally suited for all planting sites and no planting site is ideal for maximizing the quality of all apple cultivars.

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Emily E. Hoover, Richard P. Marini, Emily Tepe, Wesley R. Autio, Alan R. Biggs, Jon M. Clements, Robert M. Crassweller, Daniel D. Foster, Melanie J. Foster, Peter M. Hirst, Diane Doud Miller, Michael L. Parker, Gregory M. Peck, Jozsef Racsko, Terence L. Robinson and Michele R. Warmund

Researchers have collected a considerable amount of data relating to apple (Malus ×domestica) cultivars and rootstocks over the past 30 years, but much of this information is not easily accessible. The long-term goal of our working group is to increase access to this information using online technology available through eXtension. In eXtension, researchers and extension personnel are developing a community of practice (CoP) to increase the quality and amount of online information for individuals interested in our work [referred to as a community of interest (CoI)]. For this project, our CoI is broadly defined as commercial apple producers, nursery professionals, county extension educators, Extension Master Gardeners, home gardeners, and consumers. Our CoP is developing diverse educational tools, with the goals of increasing productivity, profitability, and sustainability for commercial apple production. Additionally, we will provide other members of our CoI access to research-based, reliable information on the culture of apples. We chose to begin our focus on cultivars and rootstocks adapted to the eastern United States and will add other U.S. regions as our resources and interest in our project grows.