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Jeffery C. Kallestad, Theodore W. Sammis, John G. Mexal, and John White

The research was supported by the Agriculture Experiment Station at New Mexico State University. This research was funded in part by the Southwest Pecan Growers, USDA ARS, and the Rio Grande Basin Initiatives. Material disclaimer: mention of a

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Michael W. Smith and Charles T. Rohla

Severe weather events frequently have devastating impacts on perennial tree crops. Pecan orchards and groves are particularly susceptible to damage from tornadoes ( Sparks and Payne, 1985 ), hurricanes ( Hagler et al., 1980 ; Kilby and Converse

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Michael W. Smith, Becky S. Cheary, and Becky L. Carroll

the Samuel Roberts Noble Foundation, the Oklahoma Center for the Advancement of Science and Technology, and the Oklahoma Pecan Growers' Association.

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Riqing Zhang, Fangde Lv, Fang He, Bixia Xie, and Lingdan Wang

Pecan [Carya illinoinensis (Wangenh.) C. Koch], a world-famous nut tree native to North America, was introduced to China in the early 1900s. However, little success had been recorded in terms of its nut production. Based on comparative studies of the geoclimate, soil conditions, and growth and performance of the pecan crop between southeastern U.S. and China, as well as in 12 other countries with successful pecan cultivation, it is feasible to grow pecan in China within the latitudes 25–35°N. In these areas, the summer temperatures range from 25–35°C with lower DIF. The annual precipitation is 500–1500 mm. Further studies using the Dendroclimate Predicative Analysis of water and heat conditions in the U.S. Pecan Belt, which is composed of seven factors, including the annual mean and extreme low temperatures, annual frost-free days, and annual precipitation, concluded that four pecan cultivation regions should be designated in China. These regions were the Favorable Region (I), the Northern and Southern Suitable Regions (IIa, IIb), the Northern and Southern Marginal Regions (IIIa, IIIb), and the Northern and Southern Undesirable Regions (IVa, IVb). The Favorable Region is along both sides of the Yangtze River in-between latitudes 25–35 °N and longitudes 100–122 °E. Some areas with microclimates, such as western Yunnan, nourish several pecan cultivars and have demonstrated a promise of pecan production. The demand for pecan is high in China, and this regionalization of pecan cultivation will ultimately enhance further collaboration on pecan production between horticulturists in China, United States, and other countries. Future research will result in the introduction of much better pecan cultivars to the different cultivated regions in China.

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Bruce W. Wood and Charles C. Reilly

The host-parasite interaction between the black pecan aphid (BPA) [Melanocallis caryaefoliae (Davis)] and pecan [Carya illinoensis (Wangenh.) K. Koch] was investigated. Three years of field observations of the ability of BPA populations to induce chlorotic blotches, or visual damage, on 32 pecan cultivars revealed considerable variation in cultivar susceptibility to BPA damage. Among the most commonly grown cultivars, `Sioux', `Cape Fear', `Farley', `Cowley', `Grabohls', and `Barton' exhibited the least damage, whereas `Choctaw', `Oconee', and `Sumner' exhibited the greatest, with `Sioux' and `Choctaw' exhibiting the greatest extremes in susceptibility. Subsequent evaluation indicated that the foliage of pecan genotypes can exhibit an antibiotic-like effect, resulting in the suppression of resident BPA populations. However, the relationship between the degree of this antibiotic effect and the degree of damage exhibited by trees, or field tolerance, was negligible (r = -0.10). For example, while `Choctaw' foliage greatly suppressed BPA population growth, this population was able to inflict relatively severe damage to leaves. An evaluation of feeding preference indicated that BPA alate viviparae (winged females) preferentially feed upon host cultivars on which they have been previously feeding. This feeding preference was eliminated by rinsing leaves with distilled water; hence, a water soluble factor(s) appears to be involved in host preference.

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Michael W. Smith and Becky S. Cheary

Pecan alternate bearing remains a major industry problem ( Smith and Weckler, 2011 ), although basic information regarding flowering regulation has expanded ( Bangerth, 2009 ; Wood, 2011 ). Current theory of angiosperm fruit tree flowering

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Bruce W. Wood

Pecan is a zinc (Zn)-sensitive species possessing a relatively high Zn requirement ( Sparks, 1987 ; Swietlik, 1999 ). Zinc deficiency is a common, and often major, problem in commercial pecan orchards, especially those established on sandy well

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M. Lenny Wells, D. Scott Carlson, and R. Philip Edwards

Pecan trees, like many fruit trees, have a tendency to bear fruit in cycles, consisting of a large crop in 1 or 2 years, followed by 1 or 2 years with little or no crop. This is termed alternate bearing, and is the most profit-limiting biological

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Chung Soo Chung, Marvin K. Harris, and J. Benton Storey

Annual variation in fruiting by pecan [Carya illinoensis (Wangenh.) K. Koch] obtained from anecdotal records and state, district, county, and orchard data from Texas indicate exceptionally high synchronous fluctuations typically occurred every 34 years with a range of 2-7 years over the 66-year data base examined. Synchrony in fruit production was inversely related to the spatial distribution of pecans reflected in coefficients of variation ranging from about 60 at the state level to about 120 for two 10-ha orchards. These characteristics show that pecan exhibits roasting and that the species warrants further examination vis a vis interactions with nut feeders.

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Randy S. Sanderlin

Pecan [ C. illinoinensis (Wangenh.) K. Koch], a tree species native to the Mississippi River floodplain of North America, is cultivated for nut production across the southeastern United States, and other states including Texas, Oklahoma, Kanas, New