Systemic Tree Injection of Propizol (14.3% wt./wt. propiconazole ME) in Austrian Pine (Pinus nigra) for Control of Diplodia Tip Blight (Diplodia pinea)
Joseph J. Doccola, John Joseph Aiken, Marianne Waindle, Donald M. Grosman, and Srdjan Acimovic
Abstract: Diplodia tip blight (Diplodia pinea) affects mature pines, including Austrian (Pinus nigra) and Ponderosa (P. ponderosa) pines. Infections spread from needle fascicles to branch and, if unchecked, to the entire tree. Efficacy studies of fungicide injections in conifers are limited. Minute vascular tissues and resin exudate, a response to drilling, present impediments to injection. The efficacy of Propizol (14.3% propiconazole) for control of Diplodia tip blight in Austrian pines was evaluated. We evaluated (1) time of year, (2) injection spacing, and (3) fungicide dilution with respect to injection efficiency. Late fall injections expedited uptake, which is consistent with the reduced monoterpene emission rates in autumn and winter reported by Kim et al. 2005 and Lim et al. 2008. The time required for the dose to be administered was recorded for close and wide spacing of injection sites. Close spacing had the greatest impact on reducing the application time, irrespective of time of year. Low volume injections required less time to apply compared to high volume. Regardless of the application method, we observed a significant decrease in disease incidence in Propizol-treated trees. Injections applied in late fall resulted in a mean reduction in infections of new candles in the next growing season. Injections in the following spring, however, did not result in improvement in candle condition until a year later. We believe that these differences are based on whether the fungicide was applied prior to or after infection. Based on these findings, we recommend Propizol prior to infection for optimal results.
Keywords: Systemic Tree Injection of Propizol (14.3% wt./wt. propiconazole ME) in Austrian Pine (Pinus nigra) for Control of Diplodia Tip Blight (Diplodia pinea)