Latest Reports and Publications

January, 2015

Acta Hort. (ISHS) 2015, 1064: 247-251.
The article is available here to individuals with subscription.

Abstract: Rumen Conev and Parminder Sandhu. Many landscape roses have poor and erratic seed germination which poses significant challenge to hybridizers. A series of multi-factorial replicated experiments have been conducted in Vineland, Canada since 2010 to study the effect of achene coat scarification, maceration, and warm and cold stratification on seed germination in garden roses. The response of 11 garden rose cultivars to six different seed treatments (T) was studied in 2010-2011. Morden Snow Beauty, Morden Sunrise and Carefree Spirit did not respond to any treatment. Six-week cold stratification alone (6WCS) (T1) did not induce germination in any genotype. Scarification with 50% sulphuric acid for 30 or 60 s followed by 6WCS (T2 and T3) slightly increased the germination in Parkwood Scarlet and Lupo. Adding three weeks warm stratification (3WWS) prior to the cold stratification (T4) provided modest benefit only to Morden Blush, which along with Cape Diamond had the highest germination response (31 and 16%, respectively) when sulphuric acid was replaced with 0.5% cellulase for 36 h (T5). The combination of extended exposure to warm and cold stratification 9WWS + 12WCS (T6) gave the best germination in 6 out of 11 genotypes (up to 52% in Lupo). In a second experiment conducted in 2011-2012, achenes from cultivar Morden Blush were subjected to nine scarification and maceration treatments followed by uniform stratification regime (5WWS + 15 WCS). Overall, the treatments involving achene coat maceration with cellulase resulted in significantly higher germination (32-49%) compared to the seed scarification treatments with sulfuric acid (15-17%). The treatment with 0.5% cellulase for 50 h gave the best germination.

December, 2014

Journal of Economic Entomology, 2014, 107(6): 2107-2118.
The article is available here to individuals with subscription.

Abstract: Justin M. Renkema, Rosemarije Buitenhuis and Rebecca H. Hallett. Drosophila suzukii Matsumura (Diptera: Drosophilidae) is a recent invasive pest of fruit crops in North America and Europe. Carpophagous larvae render fruit unmarketable andmaypromote secondary rot-causing organisms. To monitor spread and develop programs to time application of controls, further work is needed to optimize trap design and trapping protocols for adult D. suzukii. We compared commercial traps and developed a new, easy-to-use plastic jar trap that performed well compared with other designs. For some trap types, increasing the entry area led to increased D. suzukii captures and improved selectivity for D. suzukii when populations were low. However, progressive entry area enlargement had diminishing returns, particularly for commercial traps. Unlike previous studies, we found putting holes in trap lids under a close-fitting cover improved captures compared with holes on sides of traps. Also, red and black traps outperformed yellow and clear traps when traps of all colors were positioned 10–15 cm apart above crop foliage. In smaller traps, attractant surface area and entry area, but not other trap features (e.g., headspace volume), appeared to affect D. suzukii captures. In the new, plastic jar trap, tripling attractant volume (360 vs 120 ml) and weekly attractant replacement resulted in the highest D. suzukii captures, but in the larger commercial trap these measures only increased by-catch of large-bodied Diptera. Overall, the plastic jar trap with large entry area is affordable, durable, and can hold high attractant volumes to maximize D. suzukii capture and selectivity.

Controlled-release fertilizer application rates for container nursery crop production in southwestern Ontario, Canada
November, 2014

HortScience, Published November 2014.
By Erin Agro and Youbin Zheng

Abstract
Region-specific trials examining optimum controlled-release fertilizer (CRF) rates for the Canadian climate are limited. This study was conducted to determine an optimum range of CRF application rates and the effect of the application rate on growth, nitrogen (N), and phosphorus (P) losses of six economically important container-grown woody ornamental shrubs using typical production practices at a southwestern Ontario nursery. Salix purpurea ‘Nana’, Weigela florida ‘Alexandra’, Cornus sericea ‘Cardinal’, Hydrangea paniculata ‘Bombshell’, Hibiscus syriacus ‘Ardens’, and Spiraea japonica ‘Magic Carpet’ were potted in 1-gal pots and fertilized with Polyon® 16N-2.6P-10K (5–6 month longevity) incorporated at rates of 0.8, 1.2, 1.7, 2.1, and 2.5 kg·m−3 N in 2012. The experiment was repeated for the 2013 growing season with rates of CRF incorporated at 0.05, 0.35, 0.65, 0.95, and 1.25 kg·m−3 N. Plant performance (i.e., growth index) and leachate electrical conductivity (EC) and pH were evaluated once every 3 to 4 weeks during the respective growing seasons. The amount of N and P lost to the environment was determined for the 2012 growing season. The interaction between nutrient supply rate and target species affected most response variables. Although higher levels of fertilization produced larger plants and had the potential to decrease production time, increased losses of N and P and higher EC leachate values occurred. Results of this study indicate that an acceptable range of CRF application rates can be used for each species depending on the production goals, i.e., decreased production time, maximum growth, or decreased nutrient leachate. Overall, the highest acceptable CRF rates within the optimal range were: 1.25 kg·m−3 N for Spiraea; 1.7 kg·m−3 N for Hydrangea; 2.1 kg·m−3 N for Cornus; and 2.5 kg·m−3 N for Weigela, Salix, and Hibiscus. The lowest acceptable rates within the optimal range were: 0.35 kg·m−3 N for Hibiscus; 0.65 kg·m−3 N for Cornus, Weigela, Salix, and Spiraea; and 0.80 kg·m−3 N for Hydrangea.

Corporate brochure 2014
September, 2014

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September, 2014

IOBC WPRS Bulletin, 2014, 102: 23-28.
The article is available here at a cost

Abstract: Michael Brownbridge, Rose Buitenhuis, Taro Saito, Angela Brommit, Paul Côté and Graeme Murphy. Historically, poinsettia cuttings shipped into Ontario from offshore production facilities have carried very low levels of immature Bemisia whiteflies. These have been successfully controlled by preventative releases of parasitoids (Encarsia formosa, Eretmocerus mundus). In 2012 though, cuttings arrived into Ontario carrying large numbers of Bemisia eggs and nymphs. Parasitoid releases proceeded as normal but failed to regulate whitefly populations; multiple pesticide treatments were required to provide effective control. Endemic whitefly resistance (owing to heavy pesticide use in production facilities) means that insecticides registered in Canada frequently have reduced efficacy. Furthermore, pesticide residues on imported material can have a detrimental effect on parasitoid survival and performance. To ensure greater sustainability in poinsettia production, new methods of control are required to mitigate incoming pests on cuttings and ensure that biological control systems can be maintained through the crop production cycle. Several reduced-risk products, biopesticides and combination treatments, applied to infested cuttings by dipping immediately prior to sticking, were therefore evaluated to determine their relative efficacy against whitefly, ensure compatibility with parasitoids and to assess possible phytotoxic effects. A combination of insecticidal soap and Beauveria bassiana (BotaniGard® WP; BioWorks Inc., Victor, NY) was the most effective treatment tested; phytotoxic effects were minimal (some variation across cultivars) and survival of Encarsia and Eretmocerus was not affected following release onto treated leaves. The project has allowed effective treatments to be identified that can be readily implemented on a commercial scale.

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