PRIMARY WESTERN PECAN INSECT PESTS

New Mexico Pecan Short CourseSeptember 8-10, 2010

Outline• Background• Aphid Complex

– Species– Biology– Management Considerations

• Pecan Nut Casebearer– Biology– Management Considerations

• Pecan Weevil– Current Status– Prevention

Two Distinct Pecan Growing Regions

Regionalization of Pecan Pest Management Practices

1. Yield 2. Profitability 3. Pest Pressure4. Primary vs. Secondary Pest5. Cultivar

Pecan Leaf vs. Leaflet Leaf/Compound Leaf Leaflet

Pecan Aphid Complex

Black Pecan Aphid Yellow Pecan Aphid Complex

Blackmargined Pecan Aphid Yellow Pecan Aphid

Pecan Aphid Biology

Overwinter in bark as eggs

IJ. Park

Spring-eggs hatch, stem-mothers arise

Populations build and decreaseover the season, winged and non-winged females produces

Fall-males produced and mate with wingless (apterous) femaleseggs produced

No alternate-host in the area

Aphid Feeding

1. Aphid manipulates stylet between cells to find sieve elements

2. Remove products produced by photosynthesis

3. May compete with other tree “sinks” for these products

• Susan Dunford, University of Cincinnati –Photo Credit

Black Pecan Aphid1. Adults dark black, nymphs dark grey

2. Wings extend past abdomen

3. Approximately 15 day lifespan

4. Produce approximately 35 offspring

5. Populations tend to be “clumped”

6. Little “honeydew” produced

7. Feed both sides of leaflet

Louis Tedders

Black Pecan Aphid Damage

1. Interveinal necrosis/defoliation

- Reductions in photosynthesis2. May reduce nut quality*

3. Possible reductions in fruiting sites (following year)*

4. Historically considered economic

5. Damage is visible

Yellow Aphid Complex

1. Yellow Pecan AphidPresent in western orchards,

low populations

2. Blackmargined Pecan Aphid Dominate species throughout the season

Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org

Mike Quinn

Blackmargined Aphids

I.J. Park

Aphid Skins

Parasitized blackmargined aphid (do not mistake for black pecan aphid)

Mike Quinn

Non-Winged Female“apterous” stem mother

Winged Female“alate”

Blackmargined Aphid

1. Adult females both winged and non-winged2. Characteristic “black band” on wings3. All forms “lime green”4. Lifespan approximately 30 days5. Produce approximately 150 offspring6. Populations tend to be uniform across the orchard7. Feed primarily on underside of the leaflet

Blackmargined Aphid Damage

1. Compete with the tree for photosynthates “sinks”*

2. May reduce nut quality*3. May reduce # flowers (next year)*4. Historically considered “secondary pest”

in other pecan growing regions5. Provide a food source for sooty mold* (honeydew)6. Damage not visible7. Premature defoliation

Quick Summary

1. Aphid species2. Damage differences3. Difference in fecundity rates

Pecan Production Basics(Aphid Control Considerations)

1. Pecans alternate between “heavy” and “light” production years.

2. Number and location of flowers are determined the previous year.

3. Pecans are considered a “high value” crop.

Aphid Control Considerations

I. Economic Threshold Levels (internet)• Black pecan aphid 1-3 per leaf• Blackmargined aphid 10 per leaf

II. Yield reductions (regional) • Approximately 2%+ reduction in meat (“heavy”

production year)• Reduce number of flowers following year (“light”

production year)• Increase in “husk retention” at harvest (“heavy

production” year)

Aphid Control Considerations(Treat or No-Treat)

I. Scout (insect) - Species- Density- Location (within, proximity to neighboring orchards)- Aphid forms (winged, stem, nymphs)- Damage (black)- Honeydew production (blackmargined)- History (how many, how long)

Aphid Control Considerations (Treat or No-Treat)

II. Scout (orchard information) - Yield estimate- Overall orchard condition - Foliar requirements (zinc)- Soil moisture

III. Equipment availability IV. Dollars

- Expected market price - Application costs (chemical, labor)

V. Climate (treatment, honeydew, sooty mold)

Insecticide Selection & Application• Number of insecticide active ingredients and activity for

aphid control– Foliar trans-laminar systemics (neonicitinoids)– Foliar true systemics (Movento*)– Soil applied systemics (neonicitinoids)– Contact (organophosphate, pyrethroids)

• Restricted vs. non-restricted• Costs $5/acre to $30+/acre • Resistance issues• Adjuvants • Application (coverage, air vs. ground, speed)

Status of Conventional Insecticides Used to Control Pecan Aphids

I. Foliar•1) Pyrethroids (co-packs) •2 ) Non-specific feeding blockers (Fulfill) •3) Neonicotinoids •4) Chlorpyriphos (Lorsban 4E to Lorsban Advanced)•5) Pyriproxyfen (Knack) •6) Spirotetramat (Movento)•7) 2012 ??

II. Systemic (soil applied)Carbamates (Aldicarb removed 2010)

Neonicotinoids

OMRI Approved Insecticides for Aphids

• Sulfur• Pyrethrin• Potassium salts of fatty acids• Aromatic Oils (i.e. rosemary, peppermint)• Azadiachtin• Plant Growth Regulator

Decisions

Pecan Nut Casebearer Basics

• Most recent pest introduced into western area*• Overwinter as a diapaused larvae in the base of pecan bud• Emerge in spring • Normally three generations throughout the growing season• Larvae feed on developing pecan nuts (direct impact), or buds• Smaller the nuts, more nuts damaged by larval feeding• Populations monitored with pheromone traps and scouting

for eggs and damage• Economic threshold levels dependent on yield

Pecan Nut Casebearer Basics

PNC Life StagesSTAGE LOCATION APPROX DURATION

(days)

Egg Nutlet, Bud 5 - 10

Larvae Nutlet, Base of Bud (overwintering)

25 - 30

Pupae Nutlet, Base of Bud 10 – 15

Adult (100-150 eggs) Omnipresent 7-10

Pecan Nut Casebearer (Western Region)

PNC Infested

Pecan Growing, PNC Uninfested

Three Pecan Nut Casebearer Generations (Moth activity)

10 16 20 DAYS

Detecting PNC Adult Populations (Pheromone Traps)

10 16 20

Placement of Pheromone Traps

Wind

1. Location2. Minimum of two traps3. Record moths and #

nights since last count4. Used to time egg

scouting5. Replace pheromone

every month6. Consider access

A

PNC Economic Decisions

• Economic Threshold Levels: (Internet)– 1% egg infested clusters for 1st generation– 2% egg infested clusters for 2nd and 3rd generation

ON-YEAR 1st GENERATION-2,500 Lbs/Acre-65 Nuts/Lb-$1.80/Lb Market-40,000 clusters/Acre-At 1% infested = 400 Clusters/acre-3 damaged nuts/cluster =1200 nuts or 18 lbs or $32 Loss

OFF-YEAR 1st GENERATION-1,500 Lbs/Acre-60 Nuts/Lb-$1.80/Lb Market-26,000 clusters/Acre-At 1% infested = 260 Clusters/acre-3 damaged nuts/cluster =780 nuts or 13 lbs or $23 Loss

Western PNC may have a high egg mortality (up to 80%)Used to thin crop load?

Pecan Nut Casebearer Management A. Timing Insecticide

Application1) Field Scouting 2) Modified Degree-Day Models

(1st gen. only)a. Biofix (Texas A&M)b. Traditional (egg survey)c. Forecast Model

3) Calendar Baseda. 12 days following accumulation

of 25 moths*

Egg

Egg Hatch, Larvae and Nut Entry

Treatment Decision

Mot

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tche

s

TIME

PNC Insecticides (General Characteristics)

Broad Spectrum• Older chemistries, less

expensive, residual less than 10 days, high degree of familiarity, reduce moth population, tend to increase aphid density

Narrower Spectrum• Newer chemistries, more

expensive, primarily target larvae, conserve beneficials, longer residual (some), good OMRI approved products

Alternative PNC Management Strategy

PNC Adult Suppression Program

No Eggs

Countable MothsSpray

Countable MothsSpray

1. Not considered IPM2. Can treat every other row3. Inexpensive4. No investment in scouting

Addition of Pecan IPM PIPE Website

• Maintained by Texas A&M• Information contributions by all pecan

belt entomology researchers• Early development phase• www.pecan.ipmpipe.org • Caution: recommendations may not be

appropriate for all growing regions

Pecan Weevil

Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org

H C Ellis, University of Georgia, Bugwood.org

Texas A&M

Recently Infested

1998/2002

1999/2003

2000/2003

Weevil Infested

Pecan Weevil (1st trapped/Last trapped)

2008

Pecan Weevil Prevention

• Restrict the movement of in-shell pecan and potted pecan nursery stock from pecan weevil infested areas.

• NMDA , WPGA, NMPG, WTPGA, APGA support statewide cleaning plant and buying station inspection programs.

• NMDA, NMSU, WPGA, NMPG support pecan weevil eradication programs.

Primary pest objective is to prevent the movement of pecan

weevil into, and eradicate establishing populations in New

Mexico

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