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Andrew L. Thomas and Denny Schrock

Hundreds of perennial plant species native to the midwestern United States have potential as ornamentals, but information on how best to use such plants in the landscape remains scarce. Many horticulturists are looking for species that perform well under low-maintenance conditions and that also attract and benefit desirable fauna, such as butterflies and birds. While many of our native plants may fit into this category, not all such species will meet aesthetic criteria for home landscapes. Some native species respond to seasonal changes in temperature and rainfall by browning or going dormant. Others have very specific site requirements for moisture, soil, and humidity that may be difficult to meet in an urban landscape, or their size, growth habit, or other characteristics may make them aesthetically undesirable in the typical home landscape. This study evaluated the performance of 67 plant taxa native to the midwestern United States selected for their promising potential in a low-maintenance landscape situation.

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Andrew L. Thomas, Patrick L. Byers and Mark R. Ellersieck

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.

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Patrick L. Byers, Andrew L. Thomas and Margaret Millican

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Andrew L. Thomas, Jackie L. Harris, Elijah A. Bergmeier and R. Keith Striegler

An evaluation of establishment techniques and rootstocks for ‘Chambourcin’ hybrid grape (Vitis sp.) was conducted 2009–12. Our objective was to evaluate four establishment methods and their interactions with grafted and ungrafted vines in terms of vine morphology and early fruit production under southwest Missouri conditions. The study was established in May 2009, as a factorial experiment comparing four establishment methods (open-trained without protection—two shoots, grow tube protected—two shoots, paperboard carton protected—two shoots, and fan-trained without protection—six shoots) across two vine types (own-rooted and grafted to ‘Couderc 3309’ hybrid grape rootstock). All vines in four of 12 field replications were destructively harvested near the conclusion of the first growing season, with leaf area and total vine dry matter determined. In years 3 and 4, yield, fruit composition, and vegetative growth were determined from the eight remaining replications. The fan training method increased leaf area and total vine dry matter compared with the other methods, but none of the establishment techniques affected fruit yield. Trunks that were tube protected had longer internodes, smaller diameter, and less dry matter, whereas both protection devices reduced glyphosate injury. Vine type (grafted and ungrafted) did not impact total leaf area or dry weight during the establishment year, but grafted vines had increased trunk and root shank dry weights compared with own-rooted vines. Grafted vines produced greater fruit yield in 2012. The fan training method required more labor to execute; although it was successful at increasing leaf area and root dry weight, it increased susceptibility to glyphosate injury and did not promote increased precocity or early fruit yield.

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

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.

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Thomas R. Gordon, Dorothy Okamoto, Andrew J. Storer and David L. Wood

Pitch canker, caused by Fusarium subglutinans f. sp. pini, causes branch dieback and stem cankers in many species of pine. Monterey pine (Pinus radiata D. Don), one of the most widely planted pines in the world, is extremely susceptible to pitch canker. Four other pine species, which might serve as alternatives to Monterey pine in landscape settings, were found to be relatively resistant, based on the size of lesions resulting from branch inoculations under greenhouse conditions. Of these species, Japanese black pine (P. thunbergiana Franco) was the most resistant, followed by Canary Island pine (P. canariensis Sweet ex K. Spreng), Italian stone pine (P. pinea L.), and Aleppo pine (P. halepensis Mill.). Consistent with these findings, a field survey conducted in Alameda County, Calif., revealed Monterey pine to have the highest incidence of infection, with significantly lower levels in Aleppo, Canary Island, and Italian stone pines. Japanese black pine was not observed in the survey area.

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Zhen-Xiang Lu, Gregory L. Reighard, Andrew P. Nyczepir, Thomas G. Beckman and David W. Ramming

Two F1 hybrid Prunus rootstocks, K62-68 and P101-41, developed from a cross of `Lovell' [susceptible to both Meloidogyne incognita (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood] and `Nemared' (resistant to both root-knot nematode species), were selfed to produce two F2 seedling populations. Vegetative propagation by herbaceous stem cuttings was used to produce four or eight self-rooted plants of each F2 seedling for treatment replications. Eggs of M. incognita and M. javanica were inoculated into the potted media where plants were transplanted, and plants were harvested and roots examined for signs and symptoms associated with root-knot nematode infection ≈120 days later. Segregation ratios in both F2 families suggested that resistance to M. incognita in `Nemared' is controlled by two dominant genes (Mi and Mij) and that to M. javanica by a single dominant gene (Mij). Thus, Mij conveys resistance to both M. incognita and M. javanica.

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Thomas R. Gordon, Dorothy Okamoto, Andrew J. Storer and David L. Wood

Pitch canker, caused by Fusarium subglutinans f. sp. pini, causes branch die-back and stem cankers in many species of pine. Monterey pine (Pinus radiata D. Don), one of the most widely planted pines in the world, is extremely susceptible to pitch canker. Four other pine species, which might serve as alternatives to Monterey pine in landscape settings, were found to be relatively resistant, based on the size of lesions resulting from branch inoculations under greenhouse conditions. Of these species, Japanese black pine (P. thunbergiana Franco) was the most resistant, followed by Canary Island pine (P. canariensis Sweet ex K. Spreng), Italian stone pine (P. pinea L.), and Aleppo pine (P. halepensis Mill.). Consistent with these findings, a field survey conducted in Alameda County, Calif., revealed Monterey pine to have the highest incidence of infection, with significantly lower levels in Aleppo, Canary Island, and Italian stone pines. Japanese black pine was not observed in the survey area.

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Andrew M. Birmingham, Eric A. Buzby, Donte L. Davis, Eric R. Benson, James L. Glancey, Wallace G. Pill, Thomas A. Evans, Robert P. Mulrooney and Michael W. Olszewski

A mechanical planter was developed to sow seed of baby lima beans (Phaseolus lunatus) in small plots. The mechanical seeder allowed small plots to be quickly and consistently seeded at a fixed spacing. Seeds were manually spread along a 10-ft (3.0 m) base plate containing 50 holes of slightly larger diameter than the seed length and at the desired seed spacing [2.4 inches (6 cm)]. Once all the holes were filled, a slider plate below the base plate containing holes of the same diameter and spacing, but which were slightly offset, was slid horizontally so that the holes of the base and slider plates aligned and the seeds dropped to the bottom of the furrow. Compared to manual planting, the mechanical planter increased the precision of seed placement and reduced the time needed to plant 50 seeds. The planter was easy to use and transport, and was inexpensive.

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Andrew L. Thomas, Richard J. Crawford Jr., Larry J. Havermann, Wendy L. Applequist, Besa E. Schweitzer, Scott F. Woodbury and James S. Miller

Black cohosh [Actaea racemosa L., Cimicifuga racemosa L. (Nutt)] is a perennial herb commonly used for treatment of menopausal symptoms in humans. The increasing demand for this plant is leading to serious over-harvesting from the wild and presents an opportunity for potentially profitable cultivation. The plant produces a large rhizome, the principal medicinal organ, which appears to be especially sensitive to heavy soil, and prone to fungal attack if soil water drainage is not adequate. After an earlier crop failure (attributed to a PhytophthoraPythium disease complex) in an established black cohosh nursery bed, two experiments were conducted in the same soil to determine if certain horticultural approaches could help to avert fungal infection under less-than-ideal conditions. Treatments included single postplanting applications of the fungicide mefenoxam, transplantation in fall versus spring, and shallow (0.5 cm) versus deep (6.5 cm) placement of rhizomes. Shallow placement significantly improved long-term rhizome survival, but was still not able to compensate adequately for a poorly-drained soil. The horticultural approaches we studied do not appear to be reliable alternatives to proper site selection in the cultivation of black cohosh.