combining different control tactics to reduce hydrilla...

Combining Different Control Tactics to Reduce Hydrilla Biomass

James Cuda, Jennifer Gillett-Kaufman, William Overholt, Karen Stratman, Raymond Hix, Eutychus Kariuki, Judy Shearer, Emma Weeks,

Joan Bradshaw, Ken Gioeli, Verena-Ulrike Lietze, Elroy Timmer

University of Florida, Florida A&M University, COE-ERDC, Citrus & St. Lucie Co. Extension, Aquatic Vegetation Control

USDA NIFA RAMP Grant 2010-02825

2014 Aquatic Weed Control Shortcourse, Coral Springs, FL, 5-8 May 2014

Outline

• Background on hydrilla

• Options for hydrilla management

• Overview of Hydrilla IPM RAMP

• Introducing the new IPM model

• Current status of research

• Summary and resources


Outline



Hydrilla, Hydrilla verticillata

• Leaves – small (max. 4/5 inch long, 1/6 inch wide), lanceolate, in whorls of 3-8

• Midrib – distinct and can bear small spines

• Submersed, rooted aquatic plant, propagates tubers, turions, fragments

• Monoecious or dioecious forms

• Stems – long and slender with some branching

Worldwide Distribution of Hydrilla

http://www.discoverlife.org/mp/20m?kind=Hydrilla+verticillata&guide=Aquatic_Invasives

• Introduced in the 1950s

• Occurs in Florida, along southern and eastern coasts, and in California

Hydrilla Distribution

(U.S.A.)

• Continues to spread (top map = records 2002, bottom map = records 2011)

cpDNA haplotypes

China F

China G

China H

Japan

Indonesia

Taiwan

12

19

1 China E 6

5

3

4

2

7

10 19

China A

China C

Korea,

NE U.S.A

Australia,

New Zealand

11

1

11

1

China B,

India

China J China I

Poland

China D

Florida, Texas,

California, Louisiana,

Africa, India,

Panama, Pakistan

22

11

Hydrilla Genetic Studies

Williams et al., unpubl.

Why is hydrilla such a problem? • Non-native plant, introduced without its natural

enemies, outcompetes native vegetation

• Forms dense vegetation mats

• Resistance development to certain herbicides

Withlacoochee River, FL, 1997 Lake Tohopekaliga, FL, 2008

Hydrilla’s Impact on Wildlife

Algae-Harboring Hydrilla Causing Bald Eagle Deaths in

the Southeast

http://animal.discovery.com/guides/wild-birds/a-c/american-coot.html

http://ihunt.com/game/waterfowl/ring-necked-duck

Who Cares? We Do!


Lakefront Homeowners

Elected Officials

Residents

Boaters & Airboaters

Anglers

Duck Hunters

Local Businesses

Federal Government State and

County Agencies

Aquatic Plant Managers

Outline




What are the Options for Hydrilla Management?

• Physical control (drawdowns, barriers)


• Mechanical removal (harvesting)

• Chemical control (herbicides)

• Biological control (herbivores, pathogens)

Chemical Control - Advantages

• Applicable for both small and large areas

• Relatively fast action

• Useful for initial removal of large amounts of biomass

• Selectivity possible through proper choice and rate

• Newer products have good toxicology profiles

• Compatible with other control methods


• Researched since the 1970s

• Foreign exploration in Asia, Africa, and Australia

• Four insect species approved for release – only one established persistent populations with some impact

• Sterile grass carp – successful in closed systems

Bagous

hydrillae

Bagous affinis Asian grass carp

Importation BioControl

Hydrellia balciunasi

Hydrellia pakistanae

Insect images copyright USDA-ARS

• One insect species (native range unknown)

- 1957: First record in the U.S. (Louisiana)

- 1976: First record in Florida (SW, specific location unknown)

- 1992: Detected in Crystal River, Florida

• A fungal pathogen discovered in 1970s; isolated from several U.S. hydrilla populations in 1990s

Augmentative BioControl

Cricotopus lebetis

Mycoleptodiscus terrestris

Hydrilla Miner

• Tip- mining midge

- Larvae feed on living plant tissue

- Rare occurrence

• Prevents “topping out”

• Naturalized in Florida

- No swarms

- Low dispersal distance

- Easily mass reared

Female

Larva

Hydrilla Miner Life Cycle

Female

Larva

Pupa

Egg mass

Cuda et al. (1999, 2002)

Male

Larva and Associated Tip Damage

Credit: D. Denson, RCID

Block 1: Control Block 1: Midge

Cuda et al. (2011)

Lake Rowell, Bradford Co., FL September 2010

Outline





Hydrilla IPM RAMP • Hydrilla Integrated Pest Management (IPM) Risk

Avoidance and Mitigation Project (RAMP)

• USDA-funded

• Collaboration between research and extension experts

• Innovative methods for managing hydrilla in Florida freshwater bodies


Hydrilla IPM RAMP Objectives

• Evaluate compatibility of new hydrilla control technologies

– Insect, pathogen, herbicide

• Demonstrate a novel integrated strategy for controlling hydrilla


Hydrilla IPM RAMP Collaborators


http://entomology.ifas.ufl.edu/hydrilla




Educational Materials & More

• Campaigns with local newspapers & television stations

• Signs for boat ramps are being developed

Why IPM? Potential benefits

• Increased efficacy

• Decreased herbicide use rates & contact times

• Long term control

• Reduced reliance on herbicides alone

• Resistance management


Integrating BioControls & Herbicides

Messersmith and Adkins. 1995. Weed Technol. 9:199-208.

Outline






Players in the New Hydrilla IPM Model

Target weed: Hydrilla verticillata (hydrilla) Herbivorous

insect: Cricotopus lebetis

(hydrilla tip miner)

Plant-pathogenic fungus: Mycoleptodiscus terrestris (Mt)

New chemical herbicide: imazamox

(inhibits acetolactate synthase, ALS)

Expected Interactions

• Imazamox branching

• Larvae develop within plant tissue (mining)

• New shoot tips breeding sites for hydrilla tip miner

• Damage kills growing tips & increases susceptibility to infection by Mt

Integrating BioControl Agents with Herbicides

• Must confirm that herbicide does NOT negatively impact biocontrol agents – Directly- Causes mortality – Indirectly- Herbicide reduces plant density (= food

source) below critical level

• Consider applying herbicides to maximize impact of biocontrol agents (tip miner & Mt) – Location – Timing

Outline







Compatibility Studies

Replicated Tank Tests Conducted in Lewisville, TX & Vicksburg, MS

• Miner/Mt- Jan to Feb 2013

• Miner/Imazamox- Apr to Jun 2013


Compatibility Tests

•Mt and Tip Miner


Courtesy of L. Nelson & J. Shearer, US ACE ERDC

Tank Test Methods

• Untreated Controls

• Low & High Treatments

– Imazamox (Herbicide)

– Mt (Pathogen)

– Tip Miner (Insect)

Tank Test Results

Compatibility Tests

• Tip Miner and Imazamox


0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Mid

ge A

du

lts

Midge Larvae

Midge Larvae + Imazamox

+

Tank Tests- Compatibility

Tip Miner and Imazamox (30 DAT)

0

100

200

300

400

500

Control Tip miner Imazamox Tip miner +Imazamox

Nu

mb

er

of

hyd

rilla

sh

oo

t ti

ps

Treatment

a a a b

Compatibility Tests

•Mechanical Control and Tip Miner


http://www.avcaquatic.com/


Tank Tests- Compatibility

Outline






• Summary and resources


• Research

- Laboratory compatibility studies completed

• Mt and tip miner (2013)

• Tip miner and imazamox (2013)

Mesocosm tests

• Tip miner and mechanical control (2014)

• Extension and Outreach

- Field demonstration sites (2014)


Summary

-

Management Goals

• Integrate Different Control Tactics = IPM

• Eliminate Adverse Effects of Surface Mats

• Reduce Reliance on Herbicides

• Create More Favorable Habitat

Hydrilla IPM RAMP Expected Impacts

• Demonstrate compatibility of different low-risk control tactics

• IPM=> safe, sustainable & cost-effective control of both susceptible and fluridone-resistant hydrilla

• Develop Hydrilla IPM Guide for Florida & other states with hydrilla problems


Resources

• Hydrilla IPM Risk Avoidance and Mitigation Project, http://entomology.ifas.ufl.edu/hydrilla

• Osceola County Hydrilla and Hygrophila Demonstration Project (link available)

• UF/IFAS Center for Aquatic and Invasive Plants (link available)

• Featured Creatures of the UF/IFAS Entomology and Nematology Department (link available)

• Cooperative Extension System (eXtension)





Food for Thought*

• “Are we as a weed science discipline choosing to ignore true integrated solutions to the herbicide resistance problem?”

• “More research on herbicide alternatives is required.”

• “Combinations of a diversity of tactics in [ IPM ] systems augment herbicide-based weed control . . . and lengthen the useful life of valuable herbicide tools.”

*Harker et al. 2012. Our view. Editorial, Weed Sci. 60: 143.

Thanx!


combining different control tactics to reduce hydrilla...

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