Efficacy and costs of controlling eastern redcedar

Abstract

Eastern redcedar (Juniperus virginiana L.) is reducing grassland productivity across much of the Great Plains. Control methods include broadcast prescribed fire, herbicides, cutting, and individual tree ignition. All methods have disadvantages when used alone. Fire can be ineffective against larger trees. Intensive methods can be too expensive for low-productivity grasslands. The objectives of this research were to determine the effects of broadcast prescribed fire alone as measured at 3 weeks after fire; to compare the effects of picloram herbicide application with or without fire, sawing with or without fire, and individual tree ignition with fire; and to compare all treatment costs. Treatments were applied at a central Nebraska rangeland site in 1993 and 1994. Fire mortality was 77% in 1993 and 67% in 1994. Either picloram or cutting after fire provided nearly 100% control of trees < 3 m tall, but cutting was more effective for trees > 3 m tall. Total mortality due to treatment combinations generally was higher in 1993, when burning conditions were more favorable. Burning, at an estimated cost of 4.96 ha-1, before picloram application or cutting reduced total costs by nearly half. Picloram application costs were reduced from 90.10 ha-1 to 47.95 ha-1, and cutting costs from 62.92 ha-1 to 39.26 ha-1. Burning first also reduced cutting time from 362 min ha-1 to 184 min ha-1, but did not significantly decrease picloram application time. Prescribed fire should precede intensive treatment applications if possible, both to reduce costs and improve total effectiveness. Because the costs and effectiveness of burning followed by either picloram or cutting are similar, managers should choose the method most suitable to individual circumstances.