Dalmatian Toadflax Workshop March 30, 2019 LCCC Bruce Shambaugh - - PowerPoint PPT Presentation

Dalmatian Toadflax Workshop

March 30, 2019 LCCC

Bruce Shambaugh Plant Health Director USDA APHIS Plant protection Quarantine Cheyenne, WY

Dalmatian Toadflax (Linaria dalmatica)

• Upright, herbaceous perennial plant
• Deep taproot with lateral roots
• Flowers are bright yellow and snap-dragon

like

• Likes wastelands, roadsides, pastures,

various elevations, etc.

Bio control agents for toadflaxes

• Multiple agents with poor to excellent success
• The first Bio agents for control of toadflax in North America

were introduced accidently

• Mecinus spp. (believed to be M. janthinus) were released

in USA in 1996 on both yellow and Dalmatian toadflaxes

• M. janthiniformis was part of the USA release and

practitioners recognize the different Mecinus species

Stem boring weevils – Mecinus janthiniformis & Mecinus janthinus

• Mecinus janthinus – more effective on

yellow toadflax

• Mecinus janthiniformis – more effective
• n Dalmatian toadflax

Stem boring weevils – Mecinus janthiniformis & Mecinus janthinus

• Mecinus species very similar
• Larvae are white with brown head capsules, up to 5

mm long

• Adults are bluish-black, with long snouts and are up to

5 mm long

• If a Mecinus weevil is established on YTF, collect

and release on YTF

• If a Mecinus weevil is established on DTF, collect

and release on DTF

Stem boring weevils – Mecinus janthiniformis & Mecinus janthinus

• The rest of this discussion will

concentrate on Mecinus janthiniformis

• n Dalmatian Toadflax.

Mecinus weevil lifecycle

• Overwintering adults emerge in early spring and feed on shoot tips
• Females chew holes in toadflax stems and lay eggs singly (up to

45 times in lifetime)

• Hatching larvae feed in short tunnels chewed into toadflax stems
• Pupation occurs in late summer within chambers inside the

feeding tunnels

• Adults overwinter inside pupal chambers

Mecinus Stem Boring weevils

• One generation per year

Damage:

• Adult feeding stunts the shoots and

roots and suppresses flowering

• Larval mining severs water/nutrient

conducting tissues, causing desiccation and death of the plant

Mecinus Stem Boring weevils

Collection and redistribution:

• Adults can be collected in the spring through mid

summer, when plants are bolting to late flowering

• Late May through the second week of July in WY
• Adults should be readily visible, mating and

congregating on shoot tips and leaf axils

• Normally active in warm, calm, sunny weather

Sweeping for weevils

Mecinus Stem Boring weevils

Collection and redistribution:

• Collect adults by:
• Knocking them from plants
• sweeping
• Aspirate adults directly from plants, sweep

net or catch tub

• Place adults in tight container with a few

stems for redistribution

Aspirating weevils

Mecinus Stem Boring weevils

Collection and redistribution:

• Collect adults/larvae by:
• Cutting infested stems in October –

November

• Place at a new release site
• Collecting adults is most effective

Mecinus Stem Boring weevils

Collection and redistribution:

• Release suggestions:
• 200 adults per release site
• 20-25 infested stems per release site
• Release sites ideally should be in areas with

snow accumulation ad no/little chemical control

PPQ efforts

PPQ has conducted releases, collections and redistributions across Wyoming since the late 1990s Release sites have had varied success PPQ has multiple locations where we can usually collect – field insectories

PPQ efforts

PPQ has periodically received both Mecinus weevils from Montana and Colorado for release into Wyoming Concentrated releases in SE Wyoming in recent years Collected and maintained data

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Effectiveness of Mecinus janthiniformis

Classical bio control can be quite effective but most often relatively slow to see large impact

Effectiveness of Mecinus janthiniformis

• Abundant on Dalmatian toadflax in the

USA and Canada

• Reduced Dalmatian toadflax dramatically

throughout most of its range

• Have seen varied success in local areas

Effectiveness of Mecinus janthiniformis

• Observed dramatic stand reductions
• ver the years
• Takes time – need to be patient
• Can find some level of Mecinus on DTF

throughout Laramie County

Effectiveness of Mecinus janthiniformis

• Parasitism, cold climates, preferred micro

habitats affect Mecinus establishment and success

• Weather and climate events impact DTF

stands so impact is difficult to measure from year to year

DTF Bio control - an IPM approach?

• Bio control takes time, but may have

long term impact

• Caution should be used when

mowing/grazing in areas where Mecinus has been released – larvae/pupae/adults are in the DTF stems

DTF Bio control - an IPM approach?

• Select release sites in areas where

chemical use is problematic (tree rows, etc.), very large DTF populations and in areas of snow accumulation.

• Select release sites with Long term

commitment to bio control – aversion to chemical use, next to tree rows, etc.

DTF Bio control - an IPM approach?

• Potential long term strategy?:
• Chemical control in a EDRR location or at leading

edge of DTF populations – minimize the spread

• Combine bio control and some chemical

management within the larger areas of the DTF population – potential for long term, less expensive management

• Utilize bio control in areas where not suitable for

chemical control – any bio control will help the effort

Questions & Contacts:

Bruce Shambaugh – USDA APHIS PPQ 5353 Yellowstone RD, Suite 208 Cheyenne, WY (307) 432 – 7979 Bruce.a.Shambaugh@usda.gov Kathleen King – USDA APHIS PPQ 5353 Yellowstone RD, Suite 208 Cheyenne, WY (307) 432 – 7979 Kathleen.m.king@usda.gov