Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 11, 2008
Publication Date: January 1, 2009
Citation: Copes, W.E. 2009. Concentration and intervals of hydrogen dioxide applications to control Puccinia hemerocallidis on daylily. Crop Protection 28:24-29. Interpretive Summary: Hydrogen dioxide is a disinfestant labeled for application on plants. Disinfestants, in general, will kill spores on contact but not provide residual protection similar to a fungicide. In these studies, hydrogen dioxide provided disease control, but frequent applications (2 to 5 days per week) would be needed to be effective. Furthermore, the level of disease pressure appeared to affect the level of control. Hydrogen dioxide should provide control when disease pressure is low, therefore good sanitation practices (discarding diseased plants, etc.) could improve results. This information provides knowledge about how to use these products and will help extension specialists and ornamental plant producers use the products effectively.
Technical Abstract: ZeroTol is a disinfestant labeled for direct application on plants. Laboratory, field, and greenhouse experiments were performed to determine the rates and intervals in days between applications needed to control daylily rust. In laboratory trials, a very high rate was required to achieve 100% mortality of Puccinia hemerocallidis urediniospores. When weekly applications were made in an outdoor field trial, rates considerably higher than those stated on the label were required to achieve control comparable to a fungicide. For a more critical evaluation, label rates were tested on plants in a greenhouse experiment. In the greenhouse study, multiple applications per week (three to five applications per week) of the label rate of ZeroTol did not damage daylily plants and provided rust control equal to fungicides when rust incidence was relatively low, but provided poor control when rust incidence was high. However, ZeroTol still imparted some disease control even when disease incidence was high as a result of higher disease pressure, as evidenced by lower disease severity levels compared to the water treatment. Results indicate that disease levels (pressure) will influence the number of applications per week required to achieve desirable control, and additional research is needed to define the rates and number of applications per week (daily to every-second or third day) that would be appropriate for different diseases and disease levels.