Control of giant reed Arundo

donax in the Nueces and Sabinal

Rivers

A Case Study of Arundo donax on the Sabinal River

Luci Cook-Hildreth, Earl Chilton, Sky Jones-Lewey

Background Information

• Spanish origin

• Imported to the US in 1820’s

• Can grow over 20ft tall

• Facultative plant – colonizes in wet and

dry areas

• Dramatically decreases flow rates

• Possibly changes water chemistry

Arundo donax in Texas

Where?

How is Arundo donax spreading?

• Possibly spread by

Nutria

• Feasting Nutria break

and scatter stalks

• Broken stalks sprout

new plants at each

node

Big Drinkers = Big Problems

Treatments For Arundo

• Herbicides

– Glyphosate

– Imazapyr

• Biological

– Arundo wasp

– Scale bug

The Plan

• NRA proposed multi

year project

• Pulling newly sprouted

plants

• Killing plants with

herbicide and killing

nutria

• Native plant restoration

The Players • NRA is working with

– Texas Parks and Wildlife

– US Fish and Wildlife Services

– Texas State Soil and Water

Conservation Board

– Local organizations and land owners

• TPWD contract with NRA for

$150K for first year of project

(Total FY11 project budget =

$290K)

Sabinal River

Nueces River

TPWD $

Sabinal River Case Study

• Comparing effects of

Imazapyr, Glyphosate,

and combination

• Data collection prior to

spraying and for one

year after

• Possible introduction

of Arundo wasp after

spraying

Where was that again?

Case Study Details

• Five ½ meter plots per each of the three treatment areas and a control

• Data collected

– Height of plant

– Number of nodes

– Number of side shoots

– Alive or dead?

– GPS coordinates

Progress on Case Study

• Data collection on all treatment and control

sites is complete (thanks to Sky, NRA

interns and biology teachers/students from

Utopia High school!)

• Statistical data analysis is on going

• Initial trends in data show herbicides to be

effective at expected rates

• No biological controls have been deployed

in the area

Preliminary Findings

• Average growth of plants after treatment (m)

– Glyphosate 0.24

– Imazaphyr 0.14

– Combination 0.21

– Control 0.34

• Percentage of dead vs. live plants

• Percentage of side shoots after treatment

Thank You!

Luci Cook-Hildreth

Inland Fisheries