Managing Insect Pests of Pecan Ted Cottrell USDA, Agricultural - - PowerPoint PPT Presentation

Managing Insect Pests of Pecan

Ted Cottrell USDA, Agricultural Research Service SE Fruit and Tree Nut Research Laboratory Bryon, GA Ted.Cottrell@ars.usda.gov

1) Invasive brown marmorated stink bug (BMSB) 2) Nut fumigation to control pecan weevil 3) Obscure scale

The Brown Marmorated Stink Bug: An exotic species now in Georgia

Brown Marmorated SB Brown SB Green SB Southern Green SB Dusky SB

Identifying the BMSB

Bugwood: Susan Ellis Bugwood: Susan Ellis Bugwood: Steven Valley Bugwood: Steven Valley

Invasion History of the BMSB

• From east Asia
• Detected as early as 1996
• 2004 – found on farms and

in forests.

• 2010 – “catastrophic”

damage in many mid- Atlantic states.

• Commonly overwinter in

buildings.

• Known to be moved to new

areas when overwintering in RVs.

Some of the known host plants of the BMSB:

• Corn
• Okra
• Tree of Heaven
• Catalpa
• English Holly
• Southern

Magnolia

• Apple
• Crab Apple
• Mimosa
• Paulownia
• Cotton
• Soybean
• Beans
• Sweet corn
• Pepper
• Sunflower
• Egg Plant
• Tomato
• Peach
• Black Cherry
• Pear
• Redbud
• Pecan
• Shagbark

Hickory

• Maples
• Privet

5 10 15 20 25 30 35 40 Brown Marmorated Brown Dusky

Stink Bug Capture in Pheromone-baited Traps Byron, GA Fall 2015

• Avg. Stink Bugs per Trap

Found on peach at Byron, GA during Aug. 2015

Can we control BMSB on pecan?

• Yes.
• We know it’s here.
• Attraction pheromone has

been developed.

• Insecticide options
• Similar as for the brown stink

bug.

• Past research has identified

products providing best results.

• We don’t know how large the

population will be this season or when the peak population(s) will occur.

A B B B B B B 20 40 60 80 100 % Moribund + Dead Treatment

7DAT 24hr

B A 20 40 60 80 100 Control Brigade 32oz % Dead + Moribund

Treatment

7 DAT 24hrs

A B B B B B B 20 40 60 80 100 % Moribund + Dead Treatment

7DAT 48hr

A B B B B B B 20 40 60 80 100 % Moribund + Dead Treatment

7DAT 72hr

In-Shell Fumigation for Control

• f Pecan Weevil Larvae?
• Collaborators:
• Dr. Ellen Thoms

Douglas Products

• Dr. Thomas Phillips

Kansas State Univ.

(with ProFume)

• Test Objective:
• Expose weevil-infested

pecans to different concentrations of sulfuryl fluoride to calculate an LD99.

Can larval pecan weevil be controlled in-shell?

Putting weevil larvae into pecans…..we must be nuts!

Cotton plug Weevil Agar

Fumigation

• Five concentration

x time dosages:

• 150, 300, 450,

600, and 750 g- h/cm3

• Pecans exposed to

SF gas for 24 h.

• Weevil mortality

examined 10 DAT.

Sulfuryl fluoride lethal dose against pecan weevil:

• An LD99 was calculated at

1080 g-h/cm3.

• Confirmatory assays found

100% mortality at 1300 g- h/cm3.

• This information will be

used to develop a treatment schedule based on a target dose of 1300 g-h/cm3.

• Bottom line: Sulfuryl

fluoride is active against pecan weevil larvae in nuts.

Some pecan insects receive more

attention than others…..

Scale Insects on Pecan

• A large group of minute and highly

specialized herbivorous insects

• do not look like insects
• many are inconspicuous on plants
• infestations can be highly damaging
• > 20 species of scale insects attack pecan
• Most species found ‘occasionally’ but some

found ‘commonly’ on pecan

• Obscure scale is usually the most damaging.
• Giant pecan scale is the most striking;

common but rarely seen.

Scale Insects Attacking Pecan

• If you spray pecan with pyrethroid insecticides you

should expect to see scale.

• If you spray pecan with pyrethroid insecticides, you

should be aware of what to look for regarding scale insects.

Armored Scale Insects

• Armored scale insects live under a

protective ‘scale’ made from wax secreted by the insect

• The protective scale covering is free

from the insect

• Immobile insects - only newly hatched

nymphs (crawlers) and adult males are mobile

• Dispersal: crawlers move to new sites
• n same host plant, birds may carry

some, wind may move some

Live insect Protective scale covering

Obscure Scale

• Attacks hickory, chestnut and oak species:
• Chinese chestnut
• Pecan
• Hickory
• Oaks (black, blackjack, chestnut, English, live, pin,

post, red, scarlet, Spanish, swamp white, water, white, willow)

• Reservoirs for infestations are many!

Photographer: J.A.Davidson

Obscure Scale

• Known as a pest of pecan for many years

“Pecan trees, on which large branches were completely killed, have been frequently observed, and in a few instances the trees were so badly infested that they were completely incrusted with this scale from top to bottom.”

H.L. Dozier. 1925. The obscure scale attacking pecan trees. The Quarterly Bulletin, State Plant Board of Florida, v. IX, no. 4.

“…a serious pest on both seedling and improved varieties in Texas, Louisiana, Arkansas, Mississippi, and Alabama.”

• H. Baker. 1933. The obscure scale on

the pecan and its control. USDA Circular No. 295.

Damage

• Immature scale and adult

females use piercing/sucking mouthparts to feed on plant sap (adult males do not feed)

• Infestations typically start on

the lower, inner portions of the tree, spreading toward terminals

• Severe infestations can

weaken and kill limbs

Obscure Scale: Biology

• Life cycle
• One generation per year

Eggs – Summer (July to early Sept.) Immature stages – Summer, Fall, Winter* Adults – Spring/Summer *Must overwinter on living tissue; not found on leaves and nuts

Obscure Scale: Biology

• Life cycle on pin oak at Auburn, AL
• Eggs laid from June through early September (most laid in

June and July)

• Crawlers: mid-June through mid-Sept. (most occurred

from mid-June through July)

Monitoring Scale on Pecans

• What to monitor:
• Search for scale on bark (not
• n leaves or nuts)
• A hand lens is needed!
• Older Trees: search

smoother bark on limbs and terminals

• Younger Trees: search bark
• n trunk and limbs

Monitoring Scale on Pecans

• Finding scale is just the

beginning…..

• Although the insect may be

dead, the scale covering will continue to adhere to bark

• Must be able to differentiate

live vs. dead scale

• Accurate scouting pays: Don’t

spray dead scale!

• The hand lens will help to

determine live vs. dead scale

Scale Management

Monitoring for crawlers: Use black electrical tape, sticky side out, wrapped around infested limbs. A degree day model was developed for obscure scale on pin oak in Kentucky.

Byron, GA: Adult male emergence - April 11, 2014 Crawler emergence – June 5/6, 2014

Scale Management

• Biological Control
• predators (certain

species of lady beetles, predatory mites)

• parasites (several

species of parasitic wasps)

• pathogens (pink scale

fungus [Nectria diploa])

Scale Management - Oils

• Dormant oil application
• Typically applied to approach runoff using 2% oil with a

repeat application 10- 14 days later

**Death is by suffocation

• Thorough coverage is required
• Typical coverage by airblast for scab or aphids is not enough
• Scale covering can protect the insect from the treatment
• live scale can be covered by one or more layers of dead scale.

Precautions for applying dormant oil

• Do not apply oils during freezing weather. This can cause the

emulsion to break down and produce uneven coverage.

• Do not apply oils if plant tissues are wet or rain is likely. These

conditions inhibit oil evaporation. High humidity (above 90 percent) also may contribute to plant injury risk, while low humidity generally reduces plant injury risk.

• Do not spray when shoots are growing.
• Avoid treating plants during the fall until after winter hardening

has occurred. Fall treatments have sometimes caused increased susceptibility to winter injury.

• Do not apply oils in combination with sulfur or sulfur-containing

pesticides; they can react with oils to form phytotoxic compounds.

• Follow label directions; hickories can be sensitive to oil

applications.

Scale Management - Insecticides

• Chemical Insecticides: Timing sprays

against the vulnerable crawler stage can be effective.

• Various insecticides are effective against the

crawlers (e.g., dimethoate, chlorpyrifos, diazinon, malathion, acephate and carbaryl – read the label).

• Movento is good against San Jose Scale. In

apples, peaches, etc. it is applied to expanding foliage using a penetrative, spreading surfactant for maximum systemic activity.

• Insect Growth Regulator
• pyriproxifen

Acknowledgments:

• Georgia Agricultural Commodity Commission for

Pecan – funding for stink bug research.

• Collaborators: Bill Ree (Texas A&M), Ellen Thoms

(Douglas Products), Tom Phillips (Kansas State Univ.).

• Technical Assistance: Ann Amis, Merry Bacon,

Shannon Day, Emily Kemp, Saleah Starks.