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Joanne Logan, Marcella A. Mueller, and Michael J. Searcy

Peach [Prunus persica (L.) Batsch.] production in the southeastern United States. has suffered a decline in the past several decades due to late and severe spring freezes. Much of the peach production in Tennessee is located on topographically diverse sites. Peach producers do not have adequate information about the effects of microclimates within their orchards on peach bud development and subsequent freeze risk. Such information may help them select the best adapted cultivars based on microclimate. The objectives of this study were to use a `Redhaven' peach bud development model to compare and contrast the phenology and freeze risks at five sites within the orchard, and to study the freeze characteristics (advective vs. radiative) of these same sites. Automated weather stations were located in topoclimatically different areas of a peach orchard in Dandridge, Tenn., from October 1990 to April 1992. Hourly weather data included average air temperature, chill units (CUs), growing degree hours (GDHs), and wind speed. The data show that the microclimatic factors that affect peach bud development and freeze risk, such as CUs, GDHs, and minimum temperatures, can vary in a topographically diverse orchard, but the effects are not as straightforward as previously reported. For instance, peach buds at a site at a lower elevation may break dormancy later due to slower accumulation of CUs, which could be beneficial to the grower. Then the buds may develop more slowly due to cold air drainage to the lower elevations, which would also be desirable. However, the lower temperatures due to cold air drainage could be damaging to the bud and cause more problems with injuries. Over the two seasons, there were more radiative freezes than advective freezes, but the advective freezes were more severe. Small differences in wind speed can account for surprisingly different freeze conditions during radiative situations. Any improvement in cold air drainage should help decrease the duration and severity of radiative freezes.

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Anna K. Kirk and Rufus Isaacs

after anthesis would be useful for growers of crops dependent on insect-mediated pollination. If a crop requires cross-pollination, as is the case for many fruit crops ( McGregor, 1976 ), it is also important to know the phenology of each participant

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James A. Schrader, Diana R. Cochran, Paul A. Domoto, and Gail R. Nonnecke

cultivars in colder regions depend on their overall cold tolerance, their annual phenology (timing of annual development and dormancy), and how well these traits match with area climate. Even if there is little risk of winter damage to trunks or canes, cold

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John M. Capik and Thomas J. Molnar

winter temperatures affect flowering phenology of hazelnut in the eastern United States. For example, over a 10-d period from 22 Dec. 2008 to 1 Jan. 2009, winter temperatures in New Brunswick, NJ, varied from −11.1 to 18.9 °C, then back to −8.3 °C

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Shengrui Yao

studies regarding pollen amount and pollen germination from China ( Guo and Shan, 2010 ; Han et al., 2008 ; Liu and Peng, 1992 ), but no such studies in the United States. Phenology provides basic information about a fruit species introduction and is

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Samuel Salazar-García, Luis E. Cossio-Vargas, Isidro J.L. González-Durán, and Carol J. Lovatt

ProCa applied at different stages in the phenology of ‘Hass’ avocado trees to influence inflorescence development, date of anthesis, fruit maturation, and time of harvest. In addition, the effect of each treatment on yield and fruit size was quantified

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Krista Shellie, Jacob Cragin, and Marcelo Serpe

southwestern Idaho. The trial site was located within a commercial vineyard and was planted in 2008. Vine phenology was characterized by recording the day of year when 50% of buds or clusters on a vine had reached stage 4 (budbreak), 23 (bloom), and 35

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Chad E. Finn, Andrew L. Thomas, Patrick L. Byers, and Sedat Serçe

plants remained healthy and vigorous at all three locations during this study; however, there were differences in arthropod/disease pressure, phenology, and fruit yield traits in the various groups of plants across the three locations. The first ANOVA

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Sylvie Jenni and Gaetan Bourgeois

. Materials and methods Quantifying phenology. The crisphead lettuce variety Ithaca (Coop Uniforce, Sherrington, Quebec, Canada) was direct seeded in nine fields on three commercial farm sites ( Table 1 ). Plots consisted of double-row beds, 6 inches high and

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Joanne Logan and Michael J. Searcy

Peach production in Tennessee has suffered a decline in the past decade due to late and severe spring freezes. East Tennessee is an area of diverse topography. It may be possible to use topoclimate exposure to ameliorate the low temperatures in spring and therefore lessen the damage to peach buds. Exposure also may also influence the accumulation of chill units and growing degrees, therefore affecting the stage of peach bud development when the freeze occurs. Five automated weather stations were located in topoclimatically different areas of a peach orchard in Dandridge, Tennessee, from September, 1990 to May, 1991. Hourly chill units (base 6.1 °C) and growing degrees (base4.4 °C) were calculated. Twigs from peach trees close to each weather station were forced every three days to determine the date of completion of rest. Hourly freeze data were collected from each weather station. Preliminary results on the effects of topoclimate on spring freeze characteristics, accumulation of chill units and growing degrees, and peach phenology will be presented.