
This guide focuses on the most problematic weeds in western North America for which there are at least some biocontrol agents established and/or available. Multiple photos and descriptions of each weed included in this guide emphasize key identification traits and plant ecology. For each weed included in this guide, all biocontrol agents released or currently found in North America are described individually. Photos highlighting key identification features and damage are included. The release history, current status, and recommended use of each biocontrol agent are described in detail. Because current impact and recommendations often vary between the US and Canada, information is presented separately.
Efficacy Quick Reference Guide 4
Introduction 8
About This Field Guide. 8
Biological Control of Weeds 10
Selected Plant Features 12
Life Cycle 12
Duration 12
Typical Leaf Arrangement and Margination 13
Flower Heads 13
Biological Control Agent Life Cycles 14
Insects 14
Mites 16
Nematodes 16
Fungi 16
Scientific Name Changes 17
Collection Methods 18
Transport Considerations 20
Releasing Biocontrol Agents 22
Monitoring Biocontrol Agents 24
Additional Considerations 27
Weed Biocontrol Systems 28 Weed species are arranged first by flower color, then grouped by related species and listed alphabetically. All biocontrol agents introduced or established on each weed are included in that weed’s section, listed according to efficacy on the target weed. To look up a particular biocontrol agent or weed, refer to the index at the back of this guide.
Pinkish-Purple Flowers 28
Knapweeds 28
Diffuse knapweed, Centaurea diffusa 30
Spotted knapweed, Centaurea stoebe 32
Purple loosestrife, Lythrum salicariam 62
Eurasian watermilfoil, Myriophyllum spicatum 70
Swallow-worts 74
Black swallow-wort, Vincetoxicum nigrum 74
Pale swallow-wort, Vincetoxicum rossicum 76
Thistles 80
Bull thistle, Cirsium vulgare 82
Canada thistle, Cirsium arvense 84
Musk thistle, Carduus nutans 86
Waterhyacinth, Eichhornia crassipes 108
Yellow Flowers 118
Table of Contents Tansy ragwort, Jacobaea vulgaris 118
Common St. Johnswort, Hypericum perforatum130
Toadflaxes142
Dalmatian toadflax, Linaria dalmatica 142
Yellow toadflax, Linaria vulgaris 144
Green Flowers160
Mile-a-minute weed, Persicaria perfoliata 160
Spurges 164
Cypress spurge, Euphorbia crassipes 164
Leafy spurge, Euphorbia esula 166
Tree-of-heaven, Ailanthus altissima 190
White Flowers 194
Alligatorweed, Alternanthera philoxeroides 194
Scentless chamomile, Tripleurospermum inodorum 202
Poison hemlock, Conium maculatum 210
Hydrilla, Hydrilla verticillata 214
Knotweeds 222
Bohemian knotweed, Fallopia xbohemica 222
Giant knotweed, Fallopia sachalinensis 224
Japanese knotweed, Fallopia japonica 226
Melaleuca, Melaleuca quinquenervia 230
Multiflora rose, Rosa multiflora 240
Brazilian peppertree, Schinus terebinthifolius 244
Tropical soda apple, Solanum viarum 248
Waterlettuce, Pistia stratiotes 254
Does not or Rarely Flowers 260
Air-potato, Dioscorea bulbifera 260
Old World climbing fern, Lygodium microphyllum 264
Salvinias 272
Common salvinia, Salvinia minima 272
Giant salvinia, Salvinia molesta 274
Current Studies in Weed Biocontrol 278
Glossary 282
Selected References 288
Appendix 324
Biocontrol Agent Monitoring Form 324
Vegetation Monitoring Form 325
Species Index 326
Farmers, conservationists, agriculture experts and consultants, agriculture colleges and universities, agriculture professors and instructors, agriculture students, weed control experts and manufacturers,
Product Details
- Winston, Rachel
- FHTET 24 08
- Weed Control
- Pest Control