Calcium Application Method Impacts Botrytis Blight Severity on Petunia Flowers

Abstract

<jats:p>Two application methods of calcium (Ca), fertigation and spray, were investigated regarding their effects on Botrytis blight on petunia (<jats:italic>Petunia</jats:italic> ×<jats:italic>hybrida</jats:italic>) flowers. Plants were grown for 6 weeks with three nutrient solutions consisting of 0, 100, or 200 mg·L<jats:sup>−1</jats:sup> Ca and weekly calcium chloride (CaCl<jats:sub>2</jats:sub>) sprays of 0, 750, or 1500 mg·L<jats:sup>−1</jats:sup> Ca for a total of nine treatment combinations. Flowers were harvested, inoculated with <jats:italic>Botrytis</jats:italic> spores, placed in humidity chambers, and evaluated for Botrytis blight severity. Disease severity decreased by 57% and 70% when flowers were treated with Ca spray applications of 750 and 1500 mg·L<jats:sup>−1</jats:sup> Ca, respectively; however, no change in disease severity occurred across the Ca fertigation applications. Ca concentration in the flower petal tissue increased with the Ca spray applications: the flower petal Ca concentration increased from 0.26% to 0.65% of tissue dry mass (DM) as the Ca spray application rate increased from 0 to 1500 mg·L<jats:sup>−1</jats:sup>. However, no change was observed across the Ca fertigation treatments. Leaf tissue Ca concentration increased from 2.1% to 3.2% DM as the fertigation solution increased from 0 to 200 mg·L<jats:sup>−1</jats:sup> Ca, whereas spray application had no significant effects of leaf tissue Ca concentration. The results demonstrate that spray application is a more effective technique than fertigation application to provide higher Ca tissue concentrations in flowers, and that the Ca concentration in flower petal tissue is an important consideration when evaluating tissue susceptibility to Botrytis blight. Because of the high rate of fungicide resistance to <jats:italic>Botrytis cinerea</jats:italic> found in commercial greenhouses, spray applications of CaCl<jats:sub>2</jats:sub> are an important disease management tool for commercial growers.</jats:p>

Evaluation of Calcium Sources for the Management of Botrytis Blight on Petunia Flowers

“…Flowers were arranged in the chamber with six flowers per treatment grouped together with three locations per treatment randomized within the humidity chamber. The same isolate was used for this study with the same preparation, storage, and maintenance as described by Bennett et al (2020b). The experiment was conducted twice.…”

“…For Expt. 2, a one-factor ANOVA was performed to analyze the effect of spray treatment on Botrytis blight severity as quantified by calculating the area under the disease progression as described by Bennett et al (2020b). The area under the disease progress curve is a cumulative measure from which a single value is calculated for each flower, and these values were used in the ANOVA.…”

“…Latent infections may occur during shipping where botrytis spores have infected plant tissue in the greenhouse but remain quiescent until the environment is ideal for sporulation (Muñoz et al 2019). Symptoms of Botrytis blight typically occur as tan necrotic spotting on the flower petals that coalesce as the disease progresses, resulting eventually in the complete collapse of the flower petal tissue (Bennett et al 2020b).…”

“…Fruit and flowers are supplied mainly with nutrients through the phloem, where Ca transport is low. Increasing Ca in the nutrient solution does not provide adequate Ca distribution to low-transpiring plant tissues, such as petunia flowers, whereas spray applications increase the Ca concentration significantly and reduce the disease severity in flower petal tissues (Bennett et al 2020b). Alvarez (2012) Based on previous work, several sources of Ca have been evaluated for improving plant quality or reducing disease severity on vegetable, fruit, and ornamental crops; however, studies evaluating multiple sources of Ca at rates greater than 1000 mgÁL -1 Ca have not been done for flowering crops.…”

Innovation in Propagation and Cultivation of Ornamental Plants

“…Phytosanitary problems associated with the production of ornamental plants are at an era of technological revolution. Using the pathogenic fungi of the genus Botrytis as an example, efforts have been made toward the integration of biotechnological and genetic engineering tools, including transgenics and omics [14], in addition to the use of management techniques or best management practices that are considered to be more sustainable, such as the use of beneficial microorganisms [15] and applications of calcium under spray on flowers [16] as compared to simple applications of pesticides.…”