Objectives: Demonstrate simultaneous establishment
of grass ground cover of Pili grass and Hawaiian hardwoods.
In this reporting period maintenance work was conducted on an
existing Koa/Pili grass mixed planting at the Poamoho Station.
This work included pruning Koa tress to reduce wind damage and
mulching established trees with Pili grass clippings. Chemical
herbicides were also used in the Koa/Pili grass planting to determine
the response of the grass to incidental contact with herbicide
sprays. A spray mixture containing Gramoxone Extra (paraquat) and
Goal 2X (oxyfluorfen) was applied to weeds mingled with the Pili
grass and encroaching upon the base of the Koa trees. Applications
were made with a backpack sprayer to simulate small farm technology
anticipated in Hawaiian plantings. Weed control from the spray
application was excellent and the Pili grass showed injury only
on foliage that was contacted. Pili grass recovered from the herbicide
injury and no harmful effects were observed on the Koa trees.
This experimental maintenance spray application provides evidence
that weeds in a mixed planting of Koa and other tropical hardwoods
with a Pili grass ground cover can be successfully controlled with
currently available herbicides. This clean up spray application
will be an important and useful tool for growers that want to use
Pili grass in their tropical hardwood forest plantings.
Outputs and Outcomes
An important outcome during the current reporting period is the
demonstration of successful post emergence weed control in a mixed
planting of Koa and Pili grass with currently available herbicides.
Successful weed control in any mixed species planting is difficult
without causing injury to desirable species. The successful demonstration
of the Goal/Gramoxone spray mixture will be helpful in requesting
support to legalize this experimental technique from the companies
representing these herbicides.
An extension to the project will be required to more fully address
the objectives of this project.