Angular leaf spot is a common but rarely studied disease of muscadine grapes (Vitis rotundifolia Michx.) in the southeastern United States. During 1994 and 1995, we performed two field evaluations of angular leaf spot on 30 muscadine cultivars. Based on disease severity data, no cultivar was immune to angular leaf spot; however, `Albermarle', `Doreen', `Higgins', `Noble', `Regale', `Scuppernong', `Southland', and `Summit' showed high degrees of resistance. `Alachua', `Darlene', `Dixie Red', `GA-3-9-2', `Jane Bell', `Janet', `Jumbo', `Pam', and `Rosa' were susceptible.
Richard J. Henny and J. Chen
Richard J. Henny and J. Chen
R.J. Henny and J. Chen
Jianjun Chen and Richard J. Henny
ZZ (Zamioculcas zamiifolia), a member of the family Araceae, is emerging as an important foliage plant due to its aesthetic appearance, ability to tolerate low light and drought, and resistance to diseases and pests. However, little information is available regarding its propagation, production, and use. This report presents relevant botanical information and results of our four-year evaluation of this plant to the ornamental plant industry.
Richard J. Henny and Jianjun Chen
David J. Norman and Jianjun Chen
This study is the first report of using titanium dioxide (TiO2) to control Xanthomonas bacterial blight on geranium and leaf spot on poinsettia. Potted zonal geranium ‘Patriot Bright Violet’ and poinsettia ‘Snowcap’ were grown in a greenhouse and treated with a foliar spray of TiO2 at 25 and 75 mm, respectively, twice. Titanium-treated and control geranium plants were inoculated with Xanthomonas hortorum pv. pelargonii and poinsettias were inoculated with Xanthomonas axonopodis pv. poinsettiicola. The experiment was repeated once. The numbers of lesions on geranium leaves sprayed with TiO2 at 25 and 75 mm were 53% and 67%, respectively, less than in control plants in the first trial, but there were no significant differences among treatments in the second trial. Results on poinsettia, however, showed significant decrease in lesion numbers in both trials. Plants treated with TiO2 at 25 and 75 mm showed 85% and 93% reduction in lesions, respectively, in the first trial and 87% and 92% reduction in lesions in the second trial. No symptoms of phytotoxicity were observed. This study suggests that TiO2 has potential as an alternative to currently labeled products for controlling Xanthomonas bacterial blight in geranium and leaf spot on poinsettia.
Richard J. Henny, J. Chen and D.J. Norman
R. J. Henny, J. Chen and D.J. Norman
Species and cultivars of Dieffenbachia Schott. (Araceae Juss.) have been important ornamental foliage plants for many decades. Their attractive foliar variegation, adaptability to interior environments, and ease of production are major reasons for their importance as ornamental foliage plants. Approximately 20 cultivars are commercially produced in Florida. Previously, most new cultivars were clones introduced from the wild or chance mutations of existing cultivars. Currently, cultivars are introduced into production from plant breeding programs (Henny 1995a, b; Henny and Chen, 2003; Henny et al., 1987). The hybrid Dieffenbachia `Sterling' was developed by the tropical foliage plant breeding program at the Mid-Florida Research and Education Center.