Monday, July 15, 2013

Control of Maile Pilau, a Weedy Vine

The weedy vine, Paederia foetida, or in Hawaiian maile piau, is able to grow 30 feet in length, climbing up into tree canopies or crawling along the ground. The vines can engulf and cover trees and shrubs. The weight of the vine climbing over vegetation can cause branches or entire trees to break or collapse. Crawling vines can form a dense layer of vegetation that smothers other plants. This leafy vine is pervasive in vacant lots and forests on the Hawaiian Islands.

Since broken stems of maile pilau are able to root readily in soil, care must be taken when disposing of the plant. When crushed, the leaves release a foul odor. The species, foetida, is Latin for stinky.

Chemical control is one of the most effective means for controlling maile pilau.  Yet, because of resprouting, single applications usually do not provide complete control; follow-up applications are necessary.  The herbicide recommended is one with the active ingredient, triclopyr, sold as Crossbow, Garlon, Pathfinder; unfortunately, they are rather expensive. Along with the herbicide, a non-ionic surfactant at 2 teaspoons per gallon of spray solution is suggested.  A 2% to 3% solution of glyphosate (Roundup, etc.) may also be effective, although some report it is not.  If you have Roundup, you may want to try it first before purchasing triclopyr.  

Presently biological control agents are being collected in Japan and Nepal.  It is hoped that these  ‘good guys’ which include a leaf and root feeding chrysomelid beetle will be able to help control the spread of this weed pest.

Photos by Forest and Kim Starr