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K.G. Weis, S.M. Southwick, J.T. Yeager, W.W. Coates, and Michael E. Rupert

The years 1995 and 1996 were low chill years in California with respect to stone fruit dormancy. Advancing reproductive budbreak and flowering was accomplished in `Bing' cherry (Prunus avium) by single-spray treatments of a surfactant {a polymeric alkoxylated fatty amine [N,N-bis 2-(omega-hydroxypolyoxyethylene/polyoxypropylene) ethyl alkylamine]} and potassium nitrate in combination when applied at “tightbud,” ≈ 42 days (1 Feb. 1995) before full bloom and with surfactant and potassium nitrate in combination when 10% green calyx was apparent, 33 days before full bloom. Applying 2% surfactant (v/v) + 6% potassium nitrate (w/v) was most effective in advancing bloom, speeding progression through bloom, and advancing fruit maturity when applied at tightbud stage. Surfactant (2% or 4%) applied with 25% or 35% calcium nitrate (w/v) on 2 Feb. 1996 significantly advanced full bloom compared to nontreated controls. Fruit maturity (1995) was somewhat advanced by surfactant–nitrate treatments, but fruit set and final fruit weight were equivalent among treatments. No phytotoxicity was noted in foliage or fruit. In California, marginal and insufficient winter chilling often causes irregular, extended, or delayed bloom periods, resulting in poor bloom-overlap with pollenizers. As a result, flower and fruit development may be so variable as to have small, green and ripe fruit on the same tree, making harvest more time consuming and costly. Data indicate that this surfactant, in combination with a nitrogenous compound, has potential to advance reproductive budbreak and advance maturity in sweet cherry without reducing fruit set or fruit size. Advancing the ripening time of sweet cherry even 2 to 3 days can increase the price received per 8.2-kg box by $10 to $20.

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Agustín Rumayor-Rodríguez

The annual yield variation in a Japanese plum (Prunus salicina Lindl.) germplasm collection [with 32 cultivars (cv)] was used to generate regression models to describe fruit yields in terms of climate. A Geographic Information System (GIS) combined with generated regression models was used for a regional analysis of potential areas for growing plums in Zacatecas, Mexico. Three distinct cv groups were obtained by principal component analysis and were included in the study: a) `Frontier'–`Santa Rosa', b) `Ozark Premier'–`Burbank', and c) `Shiro'. The amount of winter chilling and temperatures during bloom time were the climatic conditions most related to yield. `Frontier'–'Santa Rosa' had relatively low chilling requirements (700 chill units) compared to `Ozark Premier'–`Burbank', which required the most chilling (900 chill units). `Shiro' yields were more consistent than those of the other two groups, suggesting that it has less strict requirements and received sufficient chilling every year. High temperatures at bloom reduced fruit yield in all cultivars; however, the dependence of yield on temperatures during bloom in `Shiro' was modified by summer temperatures the previous year, suggesting that temperatures at the floral induction and formation stages affect flower primordia development. Using GIS, three potential areas for growing plums in the region were defined on maps, and the differences in potential yield between the cultivar groups were determined. `Frontier'–`Santa Rosa' may be good choices as plum cultivars for the region because they were the cultivars with the highest potential yield in the largest area; however, the flexibility of the method used allows the user to get a regional gradient of the expected yields with several plum cultivars. Using experimental information and a GIS can extend the applicability of germplasm collection data to regional planning in the establishment of orchards and new fruit industries.

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Hsin-Shan Lin and Jia-Shing Lin

Taiwan, located in subtropic regions, naturally is not an ideal region for temperate-zone fruit trees' production due to the supra-optimum temperature, heavy rainfall, and higher relative humidity in summer and insufficient chilling in winter. Higher relative humidity and temperature in summer and autumn months cause excessive vegetative growth, resulting in poor flowerbud initiation and formation. Typhoon invasions result in the severe damage of twigs as well as the loss of quality and yield of fruits. In order to overcome these natural barriers, Hengshan (Pyrus serotina Rehd.) pear has been selected as a major cultivar for lowlands in Taiwan. It has low-chilling requirement and higher temperature tolerance. Branches of Hengshan are pulled and tied to a horizontal wire net to adapt to the environmental status. This trellis system enhances flowerbud initiation through the retardation of vegetative growth. It also induces numerous water shoots. Scions from high-chilling cultivars grown at a high altitude on mountains are grafted onto water shoots of Hengshan pear trees. The system has been successful in the production of both high-chilling pears in June and the Hengshan pears in August, and has made production of both pears an important industry in Taiwan. Heavy load and trellis systems, however, result in hastening the senescence of Hengshan trees. Vitality of trees could be restored by grafting scions from a vigorous cultivar, P. koehnei, onto the terminal position of the branches. The practice resulted in several advantages including: 1) uniform growth of branches, 2) redistribution of water shoots, 3) inducing formation of calluses on old damaged trunks, 4) quick recovery of mealybug-damaged branches, 5) rejuvenation of branches, and 6) termination of dormancy.

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Aroldo Isudro Rumayor Flores*, Jose Antonio Vázquez Ramos, Martínez Cano Andres, and Borrego Escalante Fernando

In hybrids of apple (Malus × domestica Bork.) subjected to study phenological in Aguanueva, Coahuila, Mexico, their requirements of chill hours (CH), heat units (HU), bud breaking flower and vegetative % (BB) for good adaptation to warm milder climate, bloom period (BP), and vegetative period (VP), were determined using the Methodology of Identification of New Cultivars of Fruit Breeding (Ploudiv 1983). They were material with requirements of cold from 200 up to 650 (CH) when they underwent a test of controlled conditions of (CH). These materials are; AR-109 (200 CH), AR-106 (300 CH), AR-108 (300 CH), AR-147 (300 CH), AR-144 (550 CH), and AR-a60 (650 CH), while the control Mutant Aguanueva II (500 CH). Under winter conditions of the year 2000 with so slone 168.76 (CH), some materials showed a bud break superior to the control. The bud break dates understand between 30 days before the witness Aguanueva II, as the hybrid AR-147 and 34 days later in the case of the hybrid AR-151, location this way to the materials as: Early with regard to the control; AR-16-S (24 days), AR-130 (14 days) and AR-147 (30 days). Similar to the control; AR-144, AR-103 and AR-127. Later than the control; AR-111 and AR-103-B. since they don't require spray bud breaking res compounds for their bud break and they have bloom period (BP) of 8 to 21 days. And when presenting low chill requirements they will be set fruit in a microclimate frost-free and growing and have their cultivation in a mild winter climate.

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Stephen M. Southwick, Kitren G. Weis, James T. Yeager, Michael E. Rupert, and Janine K. Hasey

In 1994, we established that a surfactant, Armothin (AR), reduced fruit set when applied as 3% and 5% AR at 100 gal/acre with a Stihl mistblower to `Loadel' clingstone peach [Prunus persica (L.) Batsch]. In 1995 we compared 3% AR at volumes of 100 and 200 gal/acre (935 and 1870 L.ha-1, the volumes most commonly used by tree fruit growers in California) applied with commercial airblast sprayer; overthinning resulted with the latter. In 1996, we applied 3% AR at 100 gal/acre and 1% AR at 200 gal/acre. In 1995, differential applications of 3% AR at 100 gal/acre (two-thirds of the material applied to either the upper or lower canopy) reduced fruit set in the upper canopy in proportion to the amount of chemical applied (twice as much fruit set reduction with twice as much chemical); fruit set in the lower canopy was reduced by an equal amount regardless of amount of chemical used. Salable yields, equivalent to those obtained by hand thinning, and improved fruit size were achieved with all treatments of 3% AR at 100 gal/acre in 1995 with a 76% reduction in hand thinning. Following a low-chill winter (1995-96) with a protracted bloom, flower bud density (return bloom) was significantly greater in 1995 AR-treated trees. In 1996, treatment with AR did not result in fruit set reduction due to the protracted bloom and poor weather conditions before and after bloom. Nonetheless, 1% AR at 200 gal/acre applied in 1996 increased salable yield and increased final fruit mass. Return bloom in 1997 was equal among 1996 treatments.

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Craig E. Kallsen and Dan E. Parfitt

overlap the female receptivity of ‘Kerman’ in years with low chilling hour accumulation, such as 2014–15. Some growers have grafted ‘Randy’, an early flowering male, into ‘Kerman’ orchards, to help cover the pollination period of ‘Kerman’. However, during

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Jose Martínez-Calvo and María L. Badenes

Iglesias, 2002 ). ‘Precocinho’ with 150 chill units (C.U.) contributed to the low chilling requirement ( Topp et al., 2008 ) and early ripening ( Romeu et al., 2015 ). Description ‘Presivac-1’ has low-to-medium chilling requirements (350–450 C.U.). Trees

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Jessica Scalzo

There is an increased interest in late-ripening blueberry cultivars in New Zealand and other aspects the growers are looking for in a new cultivar are late flowering to overcome early spring frost, high yield, and adaptability to medium- to low-chill

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Gerard W. Krewer, Thomas G. Beckman, Jose X. Chaparro, and Wayne B. Sherman

Statistical procedures for agricultural research Wiley New York, NY Richards, G.D. Porter, G.W. Rodriquez, J. Sherman, W.B. 1994 Incidence of blind nodes in low-chill peach and nectarine germplasm Fruit Var

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Craig E. Kallsen and Dan E. Parfitt

full bloom flowering dates for male and female cultivars are shown for 5 years in Table 1 . ‘Tejon’ flowering dates were coincident with the early blooming female ‘Gumdrop’ ( Kallsen and Parfitt, 2017a ) in 2016–18. During the low chill years of 2014