Terminal Weevil Management

Question 1

What are some direct controls?

Answer 1

too labor intensive and expensive to pursue

1 Leader Clipping to remove bug as soon as it is effected

Insecticides

PPP (hard to achieve synchrony). Can’t get it to work.

Question 2

Methods of hazard rating?

Answer 2

• Surveys to capture actual occurrence
• Ecosystem zones give a good indication of climate
• Heat sum (accumulated warmth in degree days from spring-spring)

Question 3

What is the heat sum for IWS on the coast?

Answer 3

888 degree days. You can use an online web tool to narrow the value down to your specific stand by using Lat and Long coordinates.

Question 4

What to do in low hazard?

Answer 4

Plant S with carefree abandon

Question 5

If hazard medium?

High?

Answer 5

Med: Plant up to 20% S; need MSS of other spp.

High: Plant up to 10% S; need MSS of other spp.

Question 6

What hazard at harvest?

Answer 6

• clear cut creates warm optimal conditions for IWS

- Shading helps (partial retention, maintain non merch, leave deciduous) but… Mistletoe and safety concerns increase

Question 7

Management at planting?

Answer 7

Follow S% by hazard rating unless

• improved ‘A’ seed (allows 50% S in mod-high hazard)
• naturally resistant ‘Bplus’ seed (up to 30% allowed)

More research required

Question 8

Planting dense stands is recomended. Why?

Answer 8

1600 Sph on coast

More shading leads to smaller leaders

Less effective on high hazard sites

Question 9

Planting mixed species is said to help, how?

Answer 9

Mixed species can reduce attack (up to 15% in study) probably because other species mask silhouette of leaders.

Question 10

Considerations when brushing and weeding?

Answer 10

• eliminates shading and competition, increases survival and growth, but increases host susceptibility to weevil attack.
• maintaining some brush provides shade and produces smaller leaders, reducing likelihood of attack during critical years.

Can’t let it get so bad that stagnation and mortality are imminent in the crop tree population.

Question 11

What is the greatest site hazard and risk factors ***

Answer 11

Warm sites

Rich sites

Spruce stands

Low density (larger leaders)

Shade (obscures leader, smaller leader, cooler microclimate)

Question 12

What are some JS considerations ?

Answer 12

Dense stands less affected

Delay JS if: High hazard with significant S component

Delay until population declines (>25years and >12m)

Question 13

When to consider “total recall”

Answer 13

Only if: S required for minumum stocking (NSR without S)

Current attack >30%

Unacceptable damage (2 forms) 1: tree stunted. 2: forks crooks

No other high resource value (water fish back channels).

Question 14

Tree Breeding considerations?

Answer 14

Antixenosis (repellents and deterrents) - targeting higher concentrations of terpenes to deter feeding and oviposition.

Sclerid cell density (increasing toughness of cellular matrix)

Antibiosis - (chemical mimics juvenile hormone to retard development of eggs and larva).

Question 15

2 resin types, how can breeding for resin help?

Answer 15

Resin can kill eggs/larva before they kill leader and its effectiveness is based on chemical properties.

2 types: constituent resin

Traumatic resin - mono terpines, better flow, soak egg site, made to “F” those weevil eggs and larva right up.

Question 16

What are some phenology characteristics?

Answer 16

Less damage if buds burst before attack

Synchrony - lifecycles of weevil, parasitoids and preds