Performance and Host Association of Spotted Lanternfly (Lycorma Delicatula) among Common Woody Ornamentals

Despite the broad host range of Lycorma delicatula, the performance of this invasive pest on non-Ailanthus host plant species is difficult to document realistically without using field conditions given this pest’s requirements for vast amounts of phloem. In spring 2020, we examined the performance of L. delicatula with and without access to Ailanthus altissima by tracking development, survival, host tree association and oviposition in large enclosures planted with one each of Juglans nigra, Salix babylonica and Acer saccharinum along with either one A. altissima or one Betula nigra. We reared nymphs with and without access to A. altissima, released them into the corresponding large enclosures as third instars, and monitored them from early July 2020 through November 2020. Insect survival was higher and development faster with access to A. altissima. Third and fourth instar nymphs were most frequently observed on A. altissima when it was present, while adults were equally associated with A. saccharinum and A. altissima. In the absence of A. altissima, nymphs were most frequently found on S. babylonica, while adults were most often on A. saccharinum. Females with access to A. altissima deposited nearly 7-fold more egg masses than those without access to A. altissima. In another experiment, the offspring of parents that had been reared without access to A. altissima showed similar survival and development time from egg to adult as offspring from parents that never had access to A. altissima. These findings suggest that managers need to be aware that even in the absence of A. altissima in the landscape, several hardwood host trees can be utilized by L. delicatula to develop and reproduce.

Galling Damage to Woody Ornamentals: Diagnosis and Potential Causes

Galling or witch’s broom damage on the newly expanding buds and leaves of woody ornamental plants has become increasingly common. Diagnosing this damage can be difficult because the most common causes are obscure or occur well before damage symptoms appear. This -page fact sheet written by and published by the UF/IFAS is intended to help landscape managers, nursery growers, and pest control professionals diagnose characteristic galling damage, mitigate damage that occurs, and, when possible, prevent it from occurring.

Identification, Chemical and Biological Management of Phytopythium vexans, the Causal Agent of Phytopythium Root and Crown Rot of Woody Ornamentals

Soilborne diseases caused by pathogens such as Phytophthora, Rhizoctonia, Fusarium, Verticillium, and Pythium species are the most important diseases of woody ornamentals. Ginkgo (Ginkgo biloba) and red maple (Acer rubrum) ‘October Glory’ plants grown in containers and fields in Tennessee have shown root and crown rot symptoms with dark brown to black lesions in 2017 and 2018. The objective of this research was to isolate and identify pathogens affecting ginkgo and red maple plants in nurseries of Tennessee and develop fungicide/biofungicide management recommendations for nursery producers. Isolations were made from the infected roots. Several Phytophthora-like colonies with spherical zoospores, filamentous to globose oogoni, and whitish mycelium, were isolated on V8-PARPH medium. For confirming identity, total genomic DNA was extracted followed by the sequence analysis of the internal transcribed spacer (ITS) regions, and large subunit (LSU) of the nuclear ribosomal RNA (rRNA) as well as cytochrome c oxidase subunit I (Cox I) and cytochrome c oxidase subunit II (Cox II) of mitochondrial DNA (mtDNA). Based on morphological and molecular analysis, Phytopythium vexans was described as a causal agent of crown and root rot from the infected ginkgo and red maple plants. To complete Koch’s postulates, a pathogenicity test was performed by drenching 100 ml V8 agar medium slurry of P. vexans inoculum on 1-year-old potted ginkgo plant root systems as well as red maple ‘October Glory’. Necrotic lesion development was observed in the root system 45 days after inoculation and P. vexans was re-isolated from the roots of both ginkgo and red maple. All control ginkgo and red maple plants remained disease-free and no pathogen was re-isolated. In addition, the efficacy of fungicides, biofungicides, fertilizer and host-plant defense inducers (traditionally recommended for management of oomycete diseases) for control of Phytopythium crown and root rot was evaluated on ginkgo and red maple ‘October Glory’ seedlings in greenhouse and field trials. The fungicides such as Empress Intrinsic, Pageant Intrinsic, Segovis and Subdue MAXX were effective in both greenhouse and field trials, and the biofungicide Stargus reduced the disease severity caused by pathogen P. vexans on ginkgo and red maple plants in greenhouse trials. These results will help nursery producers to make proper management decisions for newly reported Phytopythium crown and root rot disease of ginkgo and red maple plants.

Cardamine occulta Hornem. in Hungary, and other stowaways of the ornamental plant trade

During the study of the weed flora of garden centers in Hungary (among 2017–2020), remarkable populations of Cardamine occulta Hornem., a new alien for the Hungarian flora were found. C. occulta was present altogether in 51 of the 53 visited sites. Dominantly the regularly irrigated and continuously moist microhabitats (pots, containers, muddy surfaces of geotextile-covered beds etc.) were colonized. During the revision of our recently collected specimens, deposited in JPU and DE herbaria as Cardamine hirsuta L., further individuals proved to identical with this till overlooked species. One of them (27.08.2004., Heves county: Eger [8088.3; 8188.1], coll. by A. Schmotzer, deposited in DE collection) proved to the third documented occurrence in Europe, comparing to the accessed literature data. Eclipta prostrata (L.) L. and Urtica membranacea Poir. are also new aliens for the Hungarian flora. Several introduced individuals of these taxa were found in containers of imported thermophilous woody ornamentals at 4 and 2 sites, respectively. Tens of individuals of Eclipta prostrata were also found in a sapling-bed at another site. New populations of scarce or rare Euphorbia prostrata Aiton, E. serpens Kunth and Veronica peregrina L. were also documented.

Water Conserving Irrigation Practices, Plant Growth, Seasonal Crop Coefficients, and Nutrition of Container-Grown Woody Ornamentals

Irrigation practices for container nursery crops often result in over-application and can lead to leaching of nutrients and reduced growth. Our objectives were to: (1) compare growth and foliar nutrient content for plants under daily water use (DWU) based irrigation treatments, (2) determine DWU of 14 woody ornamental taxa, and (3) classify taxa into irrigation functional groups based on crop coefficients (KC). Irrigation was applied daily to 8 taxa in 2009 and 2010 using a control of 19 mm and three irrigation treatments: (1) replacing 100% plant DWU (100DWU) each day, (2) alternating 100% DWU with 75% DWU in a 2-day cycle (100-75DWU), and (3) a 3-day cycle replacing 100% DWU the first day and 75% DWU on the second and third days (100-75-75DWU). In 2009, seasonal average DWU ranged between 8.8 and 17.3 mm depending on taxa and treatment. Most DWU-based treatments resulted in less water applied than the control, yet plant growth was not reduced, and for one taxon (Hydrangea paniculata ‘Limelight’) the 100DWU increased plant growth index. Lower foliar P and K concentrations were found for several taxa in control versus DWU treatments. In 2010, DWU for the season ranged between 2.1- and 22.0-mm d−1 depending on taxa and treatment. Growth was lower only for 100-75-75DWU Hydrangea paniculata ‘Limelight’ compared to other treatments and there were no differences in foliar nutrient content.