Summary of Arundo Control Methods

CHEMICAL APPLICATION

CUT STEM HERBICIDE APPLICATION

This method involves cutting the Arundo stems and then applying herbicide to the cut stem surface. Herbicide may either be sprayed on (generally with a backpack sprayer using 100% glyphosate ) or for smaller projects herbicide may be applied using a hand pump sprayer or a sponge dauber. If treatment is in or adjacent to water then Rodeo^®must be used because it is approved by the EPA for use in wetlands. There are varying success rates for this method, ranging from about 50% to 90% kill in the first year. The difference in success rate may be due to factors such as: size and age of the Arundo clump/s, proximity to water, herbicide concentration, time between cutting and herbicide application, etc. On projects on the Santa Margarita River the cut and spray method has generally only been about 50% successful in the first year, and in some cases even less. Whatever the success rate, there is always some resprouting. It is hypothesized that the action of cutting the stem triggers the resprouting response, causing the production of new stems from the rhizomes. This method always requires follow-up treatment. Follow-up treatment of resprouts can either be the foliar spray method or the cut and spray method again. The foliar spray method works pretty well because the sprouts are much smaller, so it is easy to target them with little overspray.

Depending on the situation, the cut Arundo stems may be left on site (but not in a moist area where they may sprout or in a floodprone area) or the Arundo biomass can be disposed of. For a summary of different options for dealing with Arundo biomass see: What to do with Arundo biomass.

PROS:

• Targeted application of herbicide to the cut Arundo stems generally prevents overspray onto native vegetation.
• The aboveground Arundo biomass is cut and can be removed from the site. This reduces flood and fire hazard.
• Chipped Arundo stems can be used as mulch or whatever else (but the Arundo must be chipped fine enough so that resprouting will not occur). See section on what to do with Arundo biomass for more details.

CONS:

• Must deal with the cut Arundo stems if they cannot be left on site. Removing the stems off site can be time consuming and costly.
• Resprouting of Arundo always occurs to some degree. This method has been reported as being up to 90% effective after one treatment. However, in many projects in San Diego county that the WMA is aware of, there has been a lot of resprouting after the cut and spray treatment, and many years of treatment have been required to completely control the Arundo.

IMAGES OF:

Unsuccessful cut and spray treatment with extensive resprouting

Successful cut and spray treatment with little resprouting