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- Author or Editor: Patrick L. Byers x
Fourteen highbush blueberry cultivars are being evaluated in south central Missouri mineral soil. This soil is often not ideal for culture of highbush blueberry. The planting site was initially pH 6.3 with a 92% base saturation on the cation exchange capacity. Sulfur additions, and summer and fall cover cropping were done for 2 years prior to planting to lower soil pH (5.3) and increase organic matter content. Four replications of three plants were set in a randomized complete block in early Apr. 1998. Plant spacing is 1.2 × 3.0 m on bermed rows that are mulched with chipped hardwood. Acidified irrigation water is supplied through drip lines. Fertilizer is applied annually both as dry ammonium sulfate and soluble nitrogen through drip lines at 84 kg·ha-1 N. Cumulative yield per bush after the first five harvest seasons showed `Bluecrop', `Brigitta Blue', `Chandler', `Darrow', `Legacy', `Nelson', and `Reka' at 17 to 21 kg; `Duke', `Nui', `Ozarkblue', and `Sierra' at 14 to 15 kg; and `Collins', `Summit', and `Toro' at 9 to 10 kg. Berry weight averaged 2 g with a low of 1.4 g (`Reka') to a high of 3.3 g (`Chandler'). Plant height averaged 155 cm with a low of 117 cm (`Nui') to a high of 188 cm (`Legacy', `Nelson'). Cultivars in the two higher yield groups were recommended to Missouri growers for planting.
A moisture accounting method was used to schedule trickle irrigation on 3-year-old highbush blueberry plants (Vaccinium corymbosum L.) ‘Bluecrop’ planted in 140-liter barrels. Crop coefficients (K) of 1.00, 0.75, and 0.50 were used to relate Class “A” Weather Bureau pan evaporation to consumptive water use during three growth stages. No significant differences were found in yield, total berry number, average berry size, berry pH, titratable acidity, total soluble solids (TSS), TSS : acids ratio, and vegetative growth among the irrigation treatments. Significant differences in initiated flower buds were seen, but no trends were noted. An average water savings over the entire season of 57.0%, 67.7%, and 78.5% of the currently recommended irrigation rate of 3.8 liter·day−1 was observed when irrigation was scheduled using K values of 1.00, 0.75, and 0.50, respectively. A K value of 0.75 was considered to be the optimum crop coefficient for young highbush blueberries growing under Arkansas conditions.
American elderberry [Sambucus canadensis L.; Sambucus nigra ssp. canadensis (L.) Bolli] is being increasingly cultivated in North America for its edible fruit and flowers, yet it remains largely undeveloped as a horticultural crop. Elderberry is a shrub that produces fruit on both new and old wood, thereby offering unique pruning management opportunities and challenges. The objective of this study was to document the response of American elderberry to various pruning methods in terms of flowering, fruit yield, phenology, plant growth, and incidence of disease and arthropod pests and to consider the impact of various pruning methods on horticultural management. Four pruning treatments (annual removal of all shoots, biannual removal of all shoots, annual selective pruning, and no pruning) were studied among three cultivars at two Missouri sites over 5 years. Although significant interactions among experimental effects made interpretation challenging, several trends were evident. Annual selective pruning was an excellent way to manage elderberries with mean yields of 1086 g/plant across all experimental parameters; however, pruning to the ground annually or biannually also resulted in satisfactory yields (855 and 1085 g/plant, respectively) with a fraction of pruning labor involved. Pruning plants to the ground consistently resulted in fewer, but larger, fruiting cymes compared with selectively pruned or unpruned plants, which may be important in terms of harvest efficiency. Pruning treatment generally affected the time of flowering and fruit ripening; plants that flowered only on new stems (after removal of all shoots) ripened fruit 14 to 21 days later than plants that fruited on old wood. Although annually pruned plants generally yielded lower, the plants remained vigorous and productive, and this pruning management technique may have numerous advantages over other pruning methods.
Diurnal and seasonal measurements of leaf water potential (ψ1), leaf diffusive resistance (R1), and leaf stomatal conductance (gs) of highbush blueberry (Vaccinium corymbosum L. cv. Bluecrop) were made in 1984 and 1985. Marked diurnal variation in ψ1, R1, and gs was observed. The most negative values of ψ1 were usually reached by 1000 Central Standard Time and were maintained until late afternoon. Leaf stomatal conductance values were high in early morning, remained high throughout the day, and decreased in late evening. Stomata were absent on the adaxial leaf surface, while the abaxial surface averaged 553 stomata/mm2. Unexplained seasonal changes in ψ1 and R1 were noted in 1985. Leaf water potential and R1 were significantly correlated in one year. Leaf water potential and R1 were significantly correlated with air temperature and relative humidity, respectively, in both years.
American (Sambucus canadensis L.) elderberry genotypes were evaluated at multiple locations, whereas European (S. nigra L.) elderberry genotypes were evaluated at a single location to assess genotypic differences and, for genotypes evaluated at multiple locations, to determine genotype × environment interactions (G × E). Seventeen S. canadensis genotypes were planted in replicated trials at Missouri State University (Mountain Grove, MO) and at the University of Missouri (Mt. Vernon, MO) or at the U.S. Department of Agriculture–Agricultural Research Service in Oregon (Corvallis). ‘Johns’, ‘Netzer’, ‘Adams II’, and ‘Gordon B’ were in common at all locations. In addition, three genotypes of S. nigra, which are not winter-hardy in Missouri, were planted in Oregon. All plants were established in 2003 and evaluated in 2004, 2005, and, for some traits, in 2006. Plants were evaluated for phenology (e.g., dates of budbreak, first flowering, full flowering, and first ripening), vegetative growth (e.g., number of shoots and plant height), yield components (e.g., total yield, number of cymes, cyme weight, and berry weight), and for pest incidence (e.g., eriophyid mites). For the genotypes in common to all locations, there were significant differences resulting from genotype, location, year, and the interactions for various traits. Although the trend was for Corvallis to have the highest and Mt. Vernon the lowest yield, there was no significant location effect. The significant genotype × environment interaction appeared to be primarily the result of the differential performance of ‘Johns’, which was generally high-yielding in Corvallis and low-yielding at both Missouri locations. The significant G × E suggests that as the Missouri institutions develop new cultivars, it will be important to test them individually at other locations and not rely on their relative performance compared with standards in Missouri. For the genotypes in common to the two Missouri sites, there was significant variation for many traits. Although there were no differences among genotypes for yield across the locations, there was a significant G × E. Although there were some small changes in performance among the sites for yield, the most dramatic changes were for ‘Wyldewood 1’ that was the second highest yielding genotype at Mountain Grove and the second worst at Mt. Vernon. Plant growth in Oregon was 40% and 60% greater than at Mountain Grove and Mt. Vernon, respectively, when the plants were first measured. In Oregon, the two Sambucus species behaved differently. Phenologically, although the S. nigra genotypes flowered ≈3 weeks earlier than the S. canadensis genotypes, they ripened at the same time, thereby shortening their exposure to potential biotic and abiotic stress. ‘Johns’, ‘York’, ‘Golden’, and ‘Gordon B’ were the highest yielding S. canadensis genotypes and ‘Korsør’ the highest of the S. nigra genotypes. Although ‘Korsør’ is considered high-yielding in Denmark, it did not yield as well as the highest yielding S. canadensis cultivars.