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Background and Objectives: Koa (Acacia koa A. Gray) is an economically, ecologically, and culturally valuable tree species endemic to Hawaii. A vascular wilt disease caused by the fungal pathogen Fusarium oxysporum f. sp. koae Gardner (FOXY) induces high rates of mortality in plantings and threatens native koa forests as well. Landowners are reluctant to consider koa for reforestation purposes in many areas due to the risk of mortality caused by FOXY. Producing seeds with genetic resistance to FOXY is vital to successful koa reforestation and restoration. The Hawaii Agriculture Research Center (HARC), with both public and private partners, operates a tree improvement program to develop wilt-resistant koa populations in Hawaii. The population genetics of koa is poorly understood and seed zones are evolving. Thus, HARC uses provisional seed zones based on genetic and biogeographic variables and has selected wilt-resistant koa populations that are locally found in Kokee, Kauai (eco-regions) of Hawaii. Materials and Methods: To make these selections, virulent FOXY isolates were used in previous seedling inoculation trials to evaluate resistance levels among koa families in greenhouse experiments, and the most resistant families were used in the field trial reported here. Results: In this trial, survival rates two years after planting varied by family, and ranged from 45% to 95%, but all resistant families had greater survival rates than the susceptible control (25%). The trial has been converted to a seed orchard. Conclusions: The higher survival rates of the families are encouraging and seeds coming from the orchard will improve the success of future restoration and reforestation efforts. Within these resistant families it was also possible to make some selections based on height, growth, diameter, and stem form. Thus, the establishment of a wilt-resistant seed orchard results in locally adapted, eco-region specific, disease-resistant koa seed that will allow for the restoration of this iconic species and provide plant material for commercial reforestation opportunities at the landscape level.
Nicklos Dudley; Tyler Jones; Kaitlin Gerber; Amy L. Ross-Davis; Richard A. Sniezko; Phil Cannon; John Dobbs. Establishment of a Genetically Diverse, Disease-Resistant Acacia koa A. Gray Seed Orchard in Kokee, Kauai: Early Growth, Form, and Survival. Forests 2020, 11, 1276 .
AMA StyleNicklos Dudley, Tyler Jones, Kaitlin Gerber, Amy L. Ross-Davis, Richard A. Sniezko, Phil Cannon, John Dobbs. Establishment of a Genetically Diverse, Disease-Resistant Acacia koa A. Gray Seed Orchard in Kokee, Kauai: Early Growth, Form, and Survival. Forests. 2020; 11 (12):1276.
Chicago/Turabian StyleNicklos Dudley; Tyler Jones; Kaitlin Gerber; Amy L. Ross-Davis; Richard A. Sniezko; Phil Cannon; John Dobbs. 2020. "Establishment of a Genetically Diverse, Disease-Resistant Acacia koa A. Gray Seed Orchard in Kokee, Kauai: Early Growth, Form, and Survival." Forests 11, no. 12: 1276.
Subirrigation (SI), where water is provided to container seedlings from below and rises through the growing media via capillary action, is regarded as an environmentally-responsible method of delivering water and fertilizer to nursery-grown plants, resulting in more uniform crops and improved production efficiency. While a concern around adopting this method is that a potential higher salt concentration in the upper layers of growing media under SI may inhibit root growth and result in decreased plant quality, few studies have focused on how root morphology is altered by SI. Therefore, a balanced two-factor factorial design with three rates of fertilization (50, 100, and 150 mg N seedling−1) and two irrigation methods (SI or overhead irrigation (OI)) was used to examine the growth response of Prince Rupprecht’s larch (Larix principis-rupprechtii Mayr) seedlings for one nursery season. Associated changes between rhizosphere electrical conductivity (EC) and root morphology of different root size classes were analyzed. Results show that (1) height, root-collar diameter, and root volume were similar between seedlings grown under SI and OI. However, (2) compared to seedlings receiving OI, SI-seedlings had less root mass, length, and surface area but greater average root diameter (ARD). (3) Morphological differences were evident primarily in root diameter size classes I–III (D ≤ 1.0 mm). (4) Fertilizer rate influenced root length and surface area up to 130 days after sowing but affected ARD throughout the growing season such that seedlings treated with 50 mg N had smaller ARD than seedlings treated with 100 mg N. (5) As the growing season progressed, SI-media had significantly higher EC compared to OI-media and EC increased with increasing fertilizer rate under SI but not under OI. These results indicate that SI can produce larch seedlings of similar height and root collar diameter (RCD) compared to OI, but root systems are smaller overall with fewer small-diameter roots, which may be related to high EC levels in SI-media, which is exacerbated by the use of high rates of fertilizer. Therefore, the EC in the media should be monitored and adjusted by reducing fertilizer rates under SI.
Fangfang Wan; Amy L. Ross-Davis; Wenhui Shi; Christopher Weston; Xiehai Song; Xiaochao Chang; Anthony S. Davis; Yong Liu; Fei Teng. Subirrigation Effects on Larch Seedling Growth, Root Morphology, and Media Chemistry. Forests 2019, 10, 38 .
AMA StyleFangfang Wan, Amy L. Ross-Davis, Wenhui Shi, Christopher Weston, Xiehai Song, Xiaochao Chang, Anthony S. Davis, Yong Liu, Fei Teng. Subirrigation Effects on Larch Seedling Growth, Root Morphology, and Media Chemistry. Forests. 2019; 10 (1):38.
Chicago/Turabian StyleFangfang Wan; Amy L. Ross-Davis; Wenhui Shi; Christopher Weston; Xiehai Song; Xiaochao Chang; Anthony S. Davis; Yong Liu; Fei Teng. 2019. "Subirrigation Effects on Larch Seedling Growth, Root Morphology, and Media Chemistry." Forests 10, no. 1: 38.
Despite advances in restoration of degraded lands around the world, native plants are still underused. Selection of appropriate plant materials is a critical factor in determining plant establishment and persistence. To inform decision‐making, we examined cold hardiness dynamics, flowering phenology, and survival among five geographically distinct sulphur‐flower buckwheat (Polygonaceae: Eriogonum umbellatum Torr.) populations in a common garden. LT50 (a measure of freezing injury) was determined every 6 weeks across a complete year; one population was also evaluated at the source. Cold hardiness dynamics were similar across populations, with annual fluctuations in mean LT50 exceeding 40°C. Rate of deacclimation (i.e., loss of cold tolerance) in spring varied across populations and was not related to the elevation from which a population came. Plants were less cold‐hardy in October 2014 compared to October 2013, likely reflecting a response to colder local conditions in 2013. Although the range of LT50 was similar for a single comparison of common garden versus wild‐grown plants, wild‐grown plants acclimated and deacclimated earlier than common garden‐grown plants. Plants derived from a low‐elevation population showed delayed flowering phenology, while high‐elevation populations showed earliest flowering phenology, with one high‐elevation population having the lowest survival rate in the common garden. These results suggest that, despite considerable plasticity in seasonal cold hardiness dynamics, population variability in deacclimation and flowering phenology have implications for selection and movement of sulphur‐flower buckwheat for ecological restoration. This article is protected by copyright. All rights reserved.
Matthew R. Fisk; Kent G. Apostol; Amy L. Ross‐Davis; Dexter O. Cahoy; Anthony S. Davis. Informing native plant sourcing for ecological restoration: cold‐hardiness dynamics, flowering phenology, and survival ofEriogonum umbellatum. Restoration Ecology 2018, 27, 616 -625.
AMA StyleMatthew R. Fisk, Kent G. Apostol, Amy L. Ross‐Davis, Dexter O. Cahoy, Anthony S. Davis. Informing native plant sourcing for ecological restoration: cold‐hardiness dynamics, flowering phenology, and survival ofEriogonum umbellatum. Restoration Ecology. 2018; 27 (3):616-625.
Chicago/Turabian StyleMatthew R. Fisk; Kent G. Apostol; Amy L. Ross‐Davis; Dexter O. Cahoy; Anthony S. Davis. 2018. "Informing native plant sourcing for ecological restoration: cold‐hardiness dynamics, flowering phenology, and survival ofEriogonum umbellatum." Restoration Ecology 27, no. 3: 616-625.
Haiti has suffered great losses from deforestation, with little forest cover remaining today. Current reforestation efforts focus on seedling quantity rather than quality. This study examined limitations to the production of high-quality seedlings of the endemic Hispaniolan pine (Pinus occidentalis Swartz). Recognizing the importance of applying sustainable development principles to pine forest restoration, the effects of growing media and container types on seedling growth were evaluated with the goal of developing a propagation protocol to produce high-quality seedlings using economically feasible nursery practices. With regard to growing media, seedlings grew best in compost-based media amended with sand. Topsoil, widely used in nurseries throughout Haiti, produced the smallest seedlings overall. Despite a low water holding capacity and limited manganese, compost-based media provided adequate levels of essential mineral nutrients (particularly nitrogen), which allowed for sufficient seedling nutrition. Seedling shoot and root growth, as well as the ratio of shoot biomass to root biomass, were greater in polybags relative to D40s. Results indicate that economically feasible improvements to existing nursery practices in Haiti can improve the early growth rates of P. occidentalis seedlings.
Kyrstan L. Hubbel; Amy L. Ross-Davis; Jeremiah R. Pinto; Owen T. Burney; Anthony S. Davis. Toward Sustainable Cultivation of Pinus occidentalis Swartz in Haiti: Effects of Alternative Growing Media and Containers on Seedling Growth and Foliar Chemistry. Forests 2018, 9, 422 .
AMA StyleKyrstan L. Hubbel, Amy L. Ross-Davis, Jeremiah R. Pinto, Owen T. Burney, Anthony S. Davis. Toward Sustainable Cultivation of Pinus occidentalis Swartz in Haiti: Effects of Alternative Growing Media and Containers on Seedling Growth and Foliar Chemistry. Forests. 2018; 9 (7):422.
Chicago/Turabian StyleKyrstan L. Hubbel; Amy L. Ross-Davis; Jeremiah R. Pinto; Owen T. Burney; Anthony S. Davis. 2018. "Toward Sustainable Cultivation of Pinus occidentalis Swartz in Haiti: Effects of Alternative Growing Media and Containers on Seedling Growth and Foliar Chemistry." Forests 9, no. 7: 422.
Armillaria mexicana (Agaricales, Physalacriaceae) is described as a new species based on morphology, DNA sequence data, and phylogenetic analyses. It clearly differs from previously reported Armillaria species in North, Central, and South America. It is characterized by the absence of fibulae in the basidioma, abundant cheilocystidia, and ellipsoidal, hyaline basidiospores that are apparently smooth under light microscope, but slightly to moderately rugulose under scanning electron microscope. It is differentiated from other Armillaria species by macromorphological characters, including annulus structure, pileus and stipe coloration, and other structures. DNA sequence data (nuc rDNA internal transcribed spacers [ITS1-5.8S-ITS2 = ITS], 28S D-domain, 3′ end of 28S intergenic spacer 1, and translation elongation factor 1-α [TEF1]) show that A. mexicana sequences are quite distinct from sequences of analogous Armillaria species in GenBank. In addition, sequences of ITS of the A. mexicana ex-type culture reveal an ITS1 of 1299 bp and an ITS2 of 582 bp, the longest ITS regions reported thus far in fungi. Phylogenetic analysis based on TEF1 sequences place A. mexicana in a well-separated, monophyletic clade basal to the polyphyletic A. mellea complex.
Rubén Damián Elías-Román; Rosario Medel-Ortiz; Dionicio Alvarado-Rosales; John W. Hanna; Amy L. Ross-Davis; Mee-Sook Kim; Ned B. Klopfenstein. Armillaria mexicana, a newly described species from Mexico. Mycologia 2018, 110, 347 -360.
AMA StyleRubén Damián Elías-Román, Rosario Medel-Ortiz, Dionicio Alvarado-Rosales, John W. Hanna, Amy L. Ross-Davis, Mee-Sook Kim, Ned B. Klopfenstein. Armillaria mexicana, a newly described species from Mexico. Mycologia. 2018; 110 (2):347-360.
Chicago/Turabian StyleRubén Damián Elías-Román; Rosario Medel-Ortiz; Dionicio Alvarado-Rosales; John W. Hanna; Amy L. Ross-Davis; Mee-Sook Kim; Ned B. Klopfenstein. 2018. "Armillaria mexicana, a newly described species from Mexico." Mycologia 110, no. 2: 347-360.
Since the myrtle rust pathogen (Austropuccinia psidii) was first reported (as Puccinia psidii) in Brazil on guava (Psidium guajava) in 1884, it has been found infecting diverse myrtaceous species. Because A. psidii has recently spread rapidly worldwide with an extensive host range, genetic and genotypic diversities were evaluated within and among A. psidii populations in its putative native range and other areas of myrtle rust emergence in the Americas and Hawaii. Microsatellite markers revealed several unique multilocus genotypes (MLGs), which grouped isolates into nine distinct genetic clusters [C1–C9 comprising C1: from diverse hosts from Costa Rica, Jamaica, Mexico, Puerto Rico, and USA‐Hawaii, and USA‐California; C2: from eucalypts (Eucalyptus spp.) in Brazil/Uruguay and rose apple (Syzygium jambos) in Brazil; C3: from eucalypts in Brazil; C4: from diverse hosts in USA‐Florida; C5: from Java plum (Syzygium cumini) in Brazil; C6: from guava and Brazilian guava (Psidium guineense) in Brazil; C7: from pitanga (Eugenia uniflora) in Brazil; C8: from allspice (Pimenta dioica) in Jamaica and sweet flower (Myrrhinium atropurpureum) in Uruguay; C9: from jabuticaba (Myrciaria cauliflora) in Brazil]. The C1 cluster, which included a single MLG infecting diverse host in many geographic regions, and the closely related C4 cluster are considered as a “Pandemic biotype,” associated with myrtle rust emergence in Central America, the Caribbean, USA‐Florida, USA‐Hawaii, Australia, China‐Hainan, New Caledonia, Indonesia and Colombia. Based on 19 bioclimatic variables and documented occurrences of A. psidii contrasted with reduced sets of specific genetic clusters (subnetworks, considered as biotypes), maximum entropy bioclimatic modelling was used to predict geographic locations with suitable climate for A. psidii which are at risk from invasion. The genetic diversity of A. psidii throughout the Americas and Hawaii demonstrates the importance of recognizing biotypes when assessing the invasive threats posed by A. psidii around the globe.
J. E. Stewart; A. L. Ross‐Davis; R. N. Graҫa; A. C. Alfenas; T. L. Peever; J. W. Hanna; J. Y. Uchida; R. D. Hauff; C. Y. Kadooka; M.‐S. Kim; P. G. Cannon; S. Namba; S. Simeto; C. A. Pérez; M. B. Rayamajhi; D. J. Lodge; M. Arguedas; R. Medel‐Ortiz; M. A. López‐Ramirez; P. Tennant; M. Glen; P. S. Machado; A. R. McTaggart; A. J. Carnegie; N. B. Klopfenstein. Genetic diversity of the myrtle rust pathogen ( Austropuccinia psidii ) in the Americas and Hawaii: Global implications for invasive threat assessments. Forest Pathology 2017, 48, 1 .
AMA StyleJ. E. Stewart, A. L. Ross‐Davis, R. N. Graҫa, A. C. Alfenas, T. L. Peever, J. W. Hanna, J. Y. Uchida, R. D. Hauff, C. Y. Kadooka, M.‐S. Kim, P. G. Cannon, S. Namba, S. Simeto, C. A. Pérez, M. B. Rayamajhi, D. J. Lodge, M. Arguedas, R. Medel‐Ortiz, M. A. López‐Ramirez, P. Tennant, M. Glen, P. S. Machado, A. R. McTaggart, A. J. Carnegie, N. B. Klopfenstein. Genetic diversity of the myrtle rust pathogen ( Austropuccinia psidii ) in the Americas and Hawaii: Global implications for invasive threat assessments. Forest Pathology. 2017; 48 (1):1.
Chicago/Turabian StyleJ. E. Stewart; A. L. Ross‐Davis; R. N. Graҫa; A. C. Alfenas; T. L. Peever; J. W. Hanna; J. Y. Uchida; R. D. Hauff; C. Y. Kadooka; M.‐S. Kim; P. G. Cannon; S. Namba; S. Simeto; C. A. Pérez; M. B. Rayamajhi; D. J. Lodge; M. Arguedas; R. Medel‐Ortiz; M. A. López‐Ramirez; P. Tennant; M. Glen; P. S. Machado; A. R. McTaggart; A. J. Carnegie; N. B. Klopfenstein. 2017. "Genetic diversity of the myrtle rust pathogen ( Austropuccinia psidii ) in the Americas and Hawaii: Global implications for invasive threat assessments." Forest Pathology 48, no. 1: 1.
Diminishing milkweed (Asclepias sp.) populations are contributing to the conspicuous decline of the iconic monarch butterfly (Danaus plexippus). This research sought to improve milkweed propagation success, a core component of summer habitat restoration projects. Specifically, this research assessed the effects of container volume and fertilizer application rate on growth and first year field survival of two species of milkweed common to western North America, namely showy milkweed (A. speciosa) and narrowleaf milkweed (A. fascicularis). Generally, larger roots and shoots developed when plants were given the high rate of fertilizer (6.5 g·L−1) and when reared in the largest containers (2600 mL). For narrowleaf milkweed, nearly all plants developed a firm plug (i.e., one in which the root system remained intact when removed from the container) after 22 weeks. Most narrowleaf milkweed plants flowered 15 weeks after sowing when grown in the largest container with either the low (2.7 g·L−1) or high fertilizer rate or the midsized container (444 mL) with a high rate of fertilizer. For showy milkweed, a firm plug developed for nearly all individuals by the end of the growing season only when given the high fertilizer rate. None of the showy milkweed plants developed an inflorescence by 15 weeks. Results of this research improve our understanding of milkweed propagation and will aid in the efforts to restore the monarch butterfly’s summer breeding habitat by providing propagation protocols across a range of stocktypes.
Nikki Hanson; Amy L. Ross-Davis; Anthony S. Davis. Growth and Survival of Two Western Milkweed Species: Effects of Container Volume and Fertilizer Rate. HortTechnology 2017, 27, 482 -489.
AMA StyleNikki Hanson, Amy L. Ross-Davis, Anthony S. Davis. Growth and Survival of Two Western Milkweed Species: Effects of Container Volume and Fertilizer Rate. HortTechnology. 2017; 27 (4):482-489.
Chicago/Turabian StyleNikki Hanson; Amy L. Ross-Davis; Anthony S. Davis. 2017. "Growth and Survival of Two Western Milkweed Species: Effects of Container Volume and Fertilizer Rate." HortTechnology 27, no. 4: 482-489.
Amy L. Ross‐Davis; Anthony S. Davis; R. Kasten Dumroese. Nursery Culture Impacts Cold Hardiness in Longleaf Pine (Pinus palustris) Seedlings. Restoration Ecology 2011, 19, 717 -719.
AMA StyleAmy L. Ross‐Davis, Anthony S. Davis, R. Kasten Dumroese. Nursery Culture Impacts Cold Hardiness in Longleaf Pine (Pinus palustris) Seedlings. Restoration Ecology. 2011; 19 (6):717-719.
Chicago/Turabian StyleAmy L. Ross‐Davis; Anthony S. Davis; R. Kasten Dumroese. 2011. "Nursery Culture Impacts Cold Hardiness in Longleaf Pine (Pinus palustris) Seedlings." Restoration Ecology 19, no. 6: 717-719.
Douglass F. Jacobs; Barrett C. Wilson; Amy L. Ross-Davis; Anthony S. Davis. Cold hardiness and transplant response of Juglans nigra seedlings subjected to alternative storage regimes. Annals of Forest Science 2008, 65, 606 -606.
AMA StyleDouglass F. Jacobs, Barrett C. Wilson, Amy L. Ross-Davis, Anthony S. Davis. Cold hardiness and transplant response of Juglans nigra seedlings subjected to alternative storage regimes. Annals of Forest Science. 2008; 65 (6):606-606.
Chicago/Turabian StyleDouglass F. Jacobs; Barrett C. Wilson; Amy L. Ross-Davis; Anthony S. Davis. 2008. "Cold hardiness and transplant response of Juglans nigra seedlings subjected to alternative storage regimes." Annals of Forest Science 65, no. 6: 606-606.
Douglass F. Jacobs; Amy L. Ross-Davis; Anthony S. Davis. Establishment success of conservation tree plantations in relation to silvicultural practices in Indiana, USA. New Forests 2004, 28, 23 -36.
AMA StyleDouglass F. Jacobs, Amy L. Ross-Davis, Anthony S. Davis. Establishment success of conservation tree plantations in relation to silvicultural practices in Indiana, USA. New Forests. 2004; 28 (1):23-36.
Chicago/Turabian StyleDouglass F. Jacobs; Amy L. Ross-Davis; Anthony S. Davis. 2004. "Establishment success of conservation tree plantations in relation to silvicultural practices in Indiana, USA." New Forests 28, no. 1: 23-36.