June 19, 2009

Eastern redcedar is a problem on grasslands because it reduces forage production and complicates livestock handling. Developing trees alter the microclimate, which encourages a shift from desirable warm season native grasses to introduced cool season grasses such as Kentucky bluegrass. All these adverse effects can be reflected in lower rental rates or sale prices for infested grassland.

Integrated management of eastern redcedar on pasture and grassland should be based on a combination of cultural, mechanical, biological, and chemical tools to keep this invasive tree under control and protect grass land production and profits.

Treat eastern redcedar (Juniperus virginiana L.) when small to achieve the most effective and often least expensive control. Use tree-height as a determining factor for selecting effective control options.

• Trees up to 2 feet tall: Burning, cutting, digging, mowing, goats, and broadcast herbicides are effective.
• Trees 2-10 feet tall: Cutting and herbicide application to individual trees are effective.
• Trees over 10 feet tall: Cutting is the most economical treatment.

Management

Nebraska eastern redcedar infestations developed over several decades and it will take a similar period to control them. While eradication isn't possible, control is. To achieve control, you'll want to develop a both a short-term and long-term plan. Long-term selective management is considerably less expensive than a more intensive, short-term approach, although it's important to begin treatment as soon as possible to catch as many small plants as possible.

If the goal is to just reduce overall number of trees, and stop further spreading, cut female trees only. Female trees produce the berry-like fruits. This would allow "male trees" to grow and provide much needed cover for wildlife or land beautification, while reducing further spreading.

Mechanical Control

Manual and mechanical control involves digging trees, cutting, and mowing. It is effective for small areas and is most efficient on trees up to 2 feet tall. Cutting works because eastern redcedar is a non-sprouter — trees cut below the lowest branches will not regrow. While effective, cutting can be time consuming and labor intensive. Cut trees need to be gathered and burned or permanently removed.

Biological Control

Goats are one of the natural enemies that can reduce redcedar populations to economically acceptable levels. Eastern Nebraska research found that most cedars less than 24 inches tall were killed by goats managed through a paddock grazing system. Adding one or two goats per cow and letting the goats and cattle run together works well for low to moderate infestations. If the goal is to suppress denser stands more quickly, use temporary fencing and at least 10 goats per acre. Moderate infestations should incur significant damage within 30 days. Higher stocking rates require moving the fence more often.

Prescribed Fire

This method is very effective against smaller tress, but its effectiveness declines as tree size increases. Adequate fine fuel such as last year's dead grass is necessary for satisfactory results. With this practice, safety and unintended damage also are concerns. Be sure to develop a fire plan and get a prescribed-burning permit from your local fire jurisdiction, as required by state law.

For information on conducting safe, prescribed fires, see

• Grassland Management with Prescribed Burning (EC148)
• Conducting a Prescribed Burn and Prescribed Burning Checklist (EC121)

Chemical Control

Table 1. Percent eastern redcedar control and grass injury levels at about 100 days after treatment as influenced by the tree height (feet) where herbicide treatments were broadcast applied.
	Dose	Tree Height (ft)				Grass Injury
Treatments1	pt/ac	0-1	1-2	2-4	4-6
Surmount	4	84	70	42	12	35
Surmount	5	95	81	46	20	55
Grazon P&D	6	90	59	51	16	15
Grazon P&D	8	95	79	60	18	20
Tordon 22K	2	85	65	33	25	20
1Treatments 1, and 2, were mixtures of picloram + fluroxypyr, each at 0.66 lb ae/gal Treatments 3 and 4 were picloram at 0.54 lb ae/gal + 2,4-D at 2.0 lb ae/gal Treatment 5 was picloram at 2.0 lbs ae/gal

Table 2. Percent of eastern redcedar and grass injury at 100 days after various individual-tree treatments.
Treatment 1	Dose (v/v) 2	Tree Injury	Grass Injury
Surmount	1.0	75	39
Surmount	1.4	89	48
Grazon P&D	2.0	90	50
Tordon 22	1.0	94	60
Roundup Ultra	1.0	5	55
Roundup Ultra	2.0	31	91
1 Treatments 1 and 2 were mixtures of picloram + fluroxypyr, each at 0.66 lb ae/gal Treatment 3 was picloram at 0.5 lb ae/gal + 2,4-D at 2.0 lb ae/gal Treatment 4 was picloram at 2.0 lb ae/gal Treatments 5 and 6 were glyphosate at 3.7 ae/gal 2Dose was a herbicide/water solution on a volume/volume basis.

Herbicides also can provide control, but, depending on the application method and chemical type, they should be viewed as just another tool in integrated management. Effectiveness will vary with tree size, herbicide selection, and application method. Generally, herbicides for redcedar control can be applied either by broadcast application or individual tree spraying. Always read and following label directions. For current herbicide recommendations, check the Nebraska Guide for Weed Management, available online and from local Extension offices.

Broadcast Application.In the Nebraska research, tree height was the most important factor influencing chemical control with broadcast applications. (See Table 1 for product efficacy.)Recommended herbicides for trees upto two feet tall include:  Surmount,Grazon P&D, and Tordon  (Table1).  Surmount atthe rate of 5 pt/ac can cause short-term grass injury in the form ofleaf yellowing and top growth burning (Table 1).Broadcast applications of Grazon P+D and Tordon 22 K cost $21-$26 per acre.

Individual Tree Treatment.Individual-tree treatments can be applied directly to the tree foliage or to the soil around the tree base, preferably in the spring or fall. Soil treatments minimize the amount of herbicide used and the exposure to non target species; however, they won't be effective unless applied before rainfall.In the Nebraska research grass injury was evident as temporary yellowing and burning of top growth among all treatments, especially Tordon 22K. Roundup is not recommended for use in pasture settings due to poor activity on cedar trees and high injury level to the grass (Table 2).

For individual tree treatments, prepare 1 gallon of spray solution using 1.3 oz of Tordon or 2.6 oz of Grazon P&D, or 2 oz of Surmount. For larger spray tanks adjust herbicide rates accordingly. Recommended herbicides for soil application around tree base include Tordon 22K at the rate of 1 cc (ml) per every foot of tree height, Velpar-L at 4 (cc) ml and Spike 20P at 1cc (ml) per every inch of tree diameter. Tordon costs about $85 per gallon, Velpar, about $65 per gallon, and Spike 20P, about $9 per pound. Cost of Grazon P+D and Tordon 22 K is $11-$16 per acre.

Resources

For more information on control of eastern redcedar and the related Nebraska research, see Integrated Management of Eastern Redcedar, EC186.

Stevan Knezevic, Extension Weeds Specialist
Haskell Agricultural Laboratory, Concord