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  • Author or Editor: A.A. Powell x
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A journal of the type proposed as HortTechnology is long overdue. Extension and other applied horticulturists thought Hortscience, when introduced several years ago, would become their primary repository for reporting professional accomplishments, etc. However, this 2nd Journal quickly became the house organ for short term research. The format for HortTechnology looks good if implemented as proposed. An overview committee consisting of a majority of Extension Horticulturists should be established to monitor progress and development of this publication (in addition to present development committee). Extension specialists and others involved in applied horticulture must avail themselves of the opportunity to publish in one or more of the peer reviewed as well as other sections of the publication. To make this journal a success Extension workers must support this effort through submitting papers on a regular basis. This referred journal could and probably will become the most popular and widely used of ASHS publications.

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A very successful project at N. C. State University began in 1983, with the first N. C. Landscape and Turfgrass Field Day. The Field Day is co-sponsored with the N. C. Landscape Contractors Association and the Turfgrass Council of North Carolina. The Field Day is an excellent opportunity for industry to visit with faculty and observe research projects and extension demonstrations. Over the years the attendance has grown to over 1200 paid attendees. The Field Day is actually divided into four separate functions: 1) Educational Field Day, 2) Product and Equipment Field Day, 3) Turf Workshops, and 4) Construction Workshops. The Extension and Research projects benefit financially from this endeavor. Any projects from the Field Day are given back to the University. This typically is about $4000.00. The Field Day is held the third Wednesday in May, rain or shine.

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Abstract

Self-pollination, emasculation and gibberellic acid (GA) were used to study translocation patterns of l4C-metabolites during flowering and fruiting in calamondin (Citrus madurensis Lour.). Radioautographs showed similar translocation patterns with self-pollination and GA. GA and self-pollination resulted in a considerably stronger mobilization of 14C-metabolites to young ovaries and developing fruits than when flowers were emasculated and no further stimulus provided. The movement of l4C-metabolites to fruits, especially in the 3-week period after anthesis, appeared essential for fruit set and development.

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The utilization of imidacloprid in controlling silverleaf whitefly (SLWF) (Bemisia argentifolii Bellows and Perrin) and its associated disorder tomato (Lycopersicon esculentum Mill.) irregular ripening (TIR) was investigated under field conditions. Tomato seedlings were transplanted into the field and drenched with 0.0, 14.5, 24.0, or 43.5 mg a.i./plant of imidacloprid during Fall 1995 and Spring 1996. Adult SLWF populations were reduced in plots drenched with imidacloprid as compared with the untreated control plots during both growing seasons. In the fall, the low, medium, and high rates of imidacloprid reduced the percentage of tomato fruit with external tomato irregular ripening symptoms from 33.4 in the untreated control to 1.4, 0.3, and 0.7, respectively. The percentage of fruit with internal symptoms was reduced from 83.8 in the untreated control plot to 14.2, 4.0, and 6.1 for the low, medium, and high rates of imidacloprid, respectively. In the spring experiment, the incidence of external TIR symptoms in all plots was minimal (<1%), but the higher rates of imidacloprid reduced the incidence of internal symptoms relative to the untreated control. Chemical name used: 1-[(6-chloro-3-pyridinyl) methyl]-N-nitro-2-imidazolidinimine (imidacloprid).

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It is always challenging to develop innovative Extension programs delivery methods. The development of a winter chilling model (Modified 45) for Alabama, the evaluation of a growth regulator (Dormex—hydrogen cyanamide) to replace lack of chilling in peaches and the establishment of a computerized weather program allowed us to create a superior expert program for grower application. Access through a personal computer is all that is required to monitor chilling accumulation and determine the most ideal time for application of Dormex (which is very critical). This information (formerly available from NWS) is now accessible through a private weather firm. The development of a chilling hour/heat unit (growing degree hour) for peaches is showing promise of providing growers still another useful product (via their PCs) in improving orchard management via better timing of practices.

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The distribution pattern of citrus tristeza virus (CTV) T-36 isolate in leaves of infected mexican lime [Citrus aurantifolia (Christm.) Swingle] plants was visualized using a whole-leaf-blot immunoassay (WLBIA) procedure in combination with a computer scanning imaging technique and CTV-specific monoclonal antibody 17G11 (CTV MAb 17G11). The distribution pattern of CTV T-36 in leaves varied with the age of the leaves and shoots of infected plants. In the young leaves, especially the about 5-day-old leaves and the completed expanded leaves, CTV T-36 was easily detected in most of the leaf veins, the main veins and the large and small primary veins. In the old leaves, CTV T-36 only was detected in the main veins, sometimes in a few of the large primary veins with weak signals, and seldom in the small primary veins. The distribution density and immunoassay reaction signals of CTV T-36 reacted to CTV MAb 17G11 in leaves from new shoots were much higher than that in leaves from old shoots. ELISA test results using leaves with different ages from different shoots of the same mexican lime plants infected with CTV T-36 supported the visualized-test results obtained by the WLBIA in combination with computer scanning imaging technique. This is the first reported visual analysis of the distribution pattern of CTV in leaves of infected citrus plants. The results indicate that the WLBIA in combination with computer scanning imaging technique is a useful tool for studying the distribution of plant viruses in leaves of virus-infected plants.

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One hundred single brown citrus aphid (BCA) (Toxoptera citricida Kirkaldy) transmission attempts were made from each of 16 different citrus trees [8 grapefruit (Citrus paradisi Macf.) and 8 sweet orange (C. sinensis (L.) Osbeck)] previously inoculated with decline-inducing (T36-CTV), non-decline-inducing (T30-CTV), a mixture of the two Citrus tristeza virus isolate types, or no CTV. Successful CTV transmission occurred in 1.5% of attempts from grapefruit trees that had been bark-chip-inoculated with T36-CTV, 3% of attempts from orange trees inoculated with T36-CTV, 3% of attempts from grapefruit trees inoculated with both T36- and T30-CTV, 4% of attempts from orange trees inoculated with both T36- and T30-CTV, 1.5% of attempts from grapefruit trees inoculated with T30-CTV, and 3.5% of attempts from orange trees inoculated with T30-CTV. Single BCA were able to recover T30-like-CTV from trees believed to be inoculated only with T36-CTV, and T36-like-CTV from trees believed to be inoculated only with T30-CTV, suggesting that these inoculum sources were also mixtures of T36-CTV and T30-CTV. The T36-CTV was not immunologically detectable in some of the trees from which it was transmitted indicating that single BrCA can recover T36-CTV from a T36-CTV/T30-CTV mixture in which the T36-CTV is an undetectable, minority component.

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Sixty-eight percent of the `Pineapple', 52% of the `Navel', 46% of the `Valencia', 38% of the `Hamlin', and 0% of the `Ambersweet' orange [Citrus sinensis (L.) Osh.] trees in five Florida citrus nurseries were infected with severe strains of citrus tristeza virus (CTV), as demonstrated by reaction with a monoclinal antibody specific for severe strains of the virus. Severe strains of CTV infected 4%, 46%, 76%, 30%, and 48% of the trees at each of the five nurseries, respectively, indicating a considerable difference in severe strain prevalence among the nurseries. Thirty-five percent of the trees in the scion blocks (budwood source) of the nurseries also contained severe strains of CTV.

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Mature-green and mature-red tomato (Lycopersicon esculentum Mill.) fruit were harvested from spring- and fall-grown plants infested with sweet potato whitefly (SPWF; Bemisia tabaci Gennadins). The mature-green fruit were either ripened at 20 to 22C or cold-stored at 10 to 13C for 3 weeks and then were allowed to ripen at 20 to 22C. There was no significant difference in the appearance of either external or internal tomato irregular ripening (TIR) symptoms between the two storage–ripening regimes or in the appearance of internal TIR symptoms among the two storage regimes and vine-ripened tomatoes. Thus, removing the tomatoes from the SPWF during ripening does not reduce TIR symptoms. About half of the mature-green tomatoes, ripened with or without cold storage (10 to 13C), developed no external TIR symptoms, but about half of these tomatoes had internal TIR symptoms. About one-third of the tomatoes developed external symptoms during ripening, but these symptoms disappeared after ripening was complete. A high percentage (71%) of these tomatoes with external symptoms also had internal symptoms. The remaining tomatoes developed external TIR that did not disappear, and almost all of these tomatoes had internal symptoms. These data suggest that culling tomatoes that develop external TIR during ripening will reduce but not eliminate tomatoes with internal TIR from the fresh-fruit market.

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This multifaceted study was conducted over the past 6 years in Alabama to determine the efficacy of using hydrogen cyanamide to replace lack of chilling in peaches and to develop a working chilling model to allow proper timing of application. Several timings (0%, 25%, 50%, and 75% chilling accumulation) for each chilling level and rates (0%, 0.5%, 1.0%, and 2.0% v/v of 50% hydrogen cyanamide) were evaluated in commercial orchards using replicated studies. It was determined that for Dormex to be effective, 60% to 65% of chilling for the cultivar involved must be accumulated, accompanied by no bud activity beyond bud swell. Rates of 0.5% and 1% v/v of 50% work well with the latter preferred. A computer chilling model was developed to assist growers with proper timing of application.

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