Pistachio

Year-Round IPM Program for Pistachio

(Reviewed: 10/12, Updated 10/12)

These practices are recommended for a monitoring-based IPM program that enhances the use of IPM practices to reduce the risks of pesticides on the environment and human health.

When a pesticide application is considered, review the Pesticide Application Checklist at the bottom of this page for information on how to minimize the risks of pesticide use to water and air quality. Water quality can be impaired when pesticides drift into waterways or when they move off-site. Air quality can be impaired when pesticide applications release volatile organic compounds (VOCs) into the atmosphere.

This year-round IPM program covers the major pests of pistachios in California. Track your progress through the year with the annual checklist form. Details on carrying out each practice and information on additional pests can be found in the Pistachio Pest Management Guidelines.

Dormancy to delayed-dormancy

Why is dormancy to delayed dormancy important in an IPM program?

Special issues of concern related to environmental quality: runoff and drift.

Mitigate pesticide usage to minimize air and water contamination.

What should you be doing at this time?
Carry out dormant season sanitation activities:
Manage orchard floor weeds:
  • Keep records (PDF) of weeds identified in the orchard, noting locations of problematic weeds.
  • If using herbicides, before application:
  • Use drift-reducing spray nozzles where possible, and apply herbicides only when environmental conditions are favorable.
  • Scout the field following treatment and control escaped weeds.
In early- to mid-January, examine one-year-old fruiting wood for live and parasitized soft scales, paying special attention to previously infested areas. Treat if needed in mid-February according to the Pistachio Pest Management Guidelines.
Consider performing a BUDMON test (detects bud infection) in February to mid-March to predict the risk of Botryosphaeria panicle and shoot blight at harvest.
Look for vertebrates and their damage and manage if needed:
  • Ground squirrels
  • Jackrabbits
  • Meadow voles
  • Pocket gophers

Budbreak through Bloom

Why is budbreak through bloom important in an IPM program?

Special issues of concern related to environmental quality: runoff and drift.

Mitigate pesticide usage to minimize air and water contamination.

What should you be doing at this time?
Continue weed management. Mow ground cover before bloom for frost protection and to reduce small plant bug and false chinch bug populations. Do not mow during bloom.
If not done after the last harvest, at budbreak identify trees infested with mealybugs by looking for them on green bud tips. Note infested trees for more intense monitoring from mid-May to early June.
If the orchard has a history of Botryosphaeria panicle and shoot blight, treat when panicles (flower clusters) appear in the spring. If wet and cool weather occurs during bloom, consider treating for Botrytis blossom and shoot blight.
Hang navel orangeworm egg traps on April 1. Check traps once or twice per week to observe the egg-laying peak (typically in May) signaling the first generation.
In April, monitor weekly for:
  • Adult leaffooted plant bugs and stink bugs migrating into the orchard edges from overwintering sites
  • Leaffooted plant bugs, small plant bugs, and stink bugs, using a beating tray in trees
  • Small plant bugs and stink bugs, by using a sweep net in surrounding cover crops and vegetation

Leaffooted plant bugs and stinkbugs may require a pesticide application. Small plant bugs, with the exception of California buckeye bug, are less damaging. Areas heavily infested with green stink bug and leaffooted plant bug will require close monitoring after fruit set.

Look for obliquebanded leafroller strikes and leaf tying. Record observations for future pheromone trapping and treatment decisions.
Look for vertebrates and their damage and manage if needed:
  • Ground squirrels
  • Jackrabbits
  • Meadow voles
  • Pocket gophers

Sporadic or minor pests and disorders you may see:

  • Armillaria root rot (oak root fungus) mushrooms
  • Darkling beetles
  • Delayed leafing
  • Frost damage
  • Thrips (onion, western flower) on newly-budded trees
  • Western tussock moth
  • Wood decay fungi mushrooms (e.g. Schizophyllum spp., Ganoderma spp.)

Fruit development

Why is fruit development important in an IPM program?

Special issues of concern related to environmental quality: drift, and volatile organic compounds (VOCs).

Mitigate pesticide usage to minimize air and water contamination.

What should you be doing at this time?
Avoid severe water stress during rapid shell growth to reduce the incidence of early shell split and thus navel orangeworm infestations, which can introduce fruit molds that cause aflatoxin contamination.
Check pheromone and egg traps once or twice per week:
  • Obliquebanded leafroller. Hang pheromone traps by late April in Kern and King counties, or April 25 in Fresno and northward. Note biofix (the first date when male moths are consistently caught in traps). Continue monitoring traps to determine treatment time.
  • Navel orangeworm. Identify the first (May) and second (late June to early July) generations. In late July use degree-days and check egg traps to identify the beginning of the third generation for treatment.
Monitor weekly for bugs, small plant bugs, and stink bugs and treat if needed according to the Pistachio Pest Management Guidelines. Look for:
  • Plant bugs, stink bugs, and leaffooted plant bug nymphs, using a beating tray on clusters.
  • Black (darkened) nuts and epicarp lesions. Cut open nuts to confirm if there is bug feeding (stink bug, leaffooted plant bug, small plant bugs).
  • Stink bugs and leaffooted plant bug eggs on leaves or fruit.
  • Calocoris norvegicus and lygus bugs, by sampling with a sweep net in weeds and groundcover. Once nut shells harden in late May, small plant bugs no longer cause damage.
In mid-May to early June, check trees where mealybug infestations were noted after harvest or at budbreak. Look for adult females on the rachises and manage as needed at peak crawler emergence in early June according to the Pistachio Pest Management Guidelines. If no treatment was made in June continue monitoring.
In July, sample 100 nuts weekly for early splits. Apply an insecticide for navel orangeworm if more than 2 early splits per 100 nuts are found.
Monitor for fruit scabbing and rachis darkening caused by citrus flat mite. If detected, consider a pesticide application.
Manage orchard floor weeds:

Apply herbicides for weeds that escaped initial management using drift-reducing spray nozzles where possible. Apply herbicides only when environmental conditions are favorable.

Monitor for diseases:
  • Alternaria blight (lesions) on foliage starting in mid-July. Manage if needed according to the Pistachio Pest Management Guidelines.
  • Botryosphaeria panicle and shoot blight. Consider performing an ONFIT assay in June to predict blighted fruit at harvest. You may need to adjust your fungicide spray program accordingly.
  • Verticillium wilt. Note trees for future removal.
Look for vertebrates and their damage and manage if needed:
  • Ground squirrels
  • Jackrabbits
  • Meadow voles
  • Pocket gophers

Sporadic or minor pests and disorders you may see:

  • Botrytis blossom and shoot blight
  • Epicarp staining (due to rain)
  • Darkling beetles
  • False chinch bugs
  • Nut collapse
  • Pistachio pop
  • Webspinning spider mites (particularly where soils are alkaline)

Preharvest

Why is preharvest important in an IPM program?

Special issues of concern related to environmental quality: runoff, drift, volatile organic compounds (VOCs).

Mitigate pesticide usage to minimize air and water contamination.

What should you be doing at this time?
Treat for navel orangeworm at hull split (hull slip) according to the Pistachio Pest Management Guidelines, especially if early splits are abundant and infestation levels of early splits exceed 2%.
Monitor newly budded trees for insect pests such as aphids, darkling beetles, and earwigs.

Look for:

Invertebrates
  • Citrus flat mite
  • Mealybugs
Diseases
  • Alternaria late bight
  • Botryosphaeria panicle and shoot blight
Vertebrates
  • Birds
  • Ground squirrels
  • Jackrabbits
  • Meadow voles
  • Pocket gophers

 

Manage as needed according to the Pistachio Pest Management Guidelines.

Prepare the orchard floor before harvest by managing weeds according to the Pistachio Pest Management Guidelines.

Harvest

Why is harvest important in an IPM program?

Special issues of concern related to environmental quality: none.

Mitigate pesticide usage to minimize air and water contamination.

What should you be doing during this time?
Expedite the harvest of problematic orchards infested with Alternaria late blight and navel orangeworm. If harvest is delayed or a second shake is planned, consider a treatment for navel orangeworm to reduce the incidence of aflatoxin, according to the Pistachio Pest Management Guidelines.
Clean and wash harvest equipment before moving it to uninfested orchards, to avoid spreading mealybugs.
Evaluate this year's pest management program using the processing plant grade sheet to prepare for next year's program.
Monitor the orchard for:
  • Alternaria late blight lesions (on foliage) and Botryosphaeria panicle and shoot blight. Note the severity of infected trees for next year's management.
  • Cotton aphid (on first-year newly-budded trees). Manage if needed according to the Pistachio Pest Management Guidelines.
Hull and dry nuts within 24 hours of harvest to reduce incidence of postharvest disease.

Postharvest

Why is postharvest important in an IPM program?

Special issues of concern related to environmental quality: runoff, drift, volatile organic compounds (VOCs).

Mitigate pesticide usage to minimize air and water contamination.

What should you be doing during this time?
Carry out postharvest sanitation activities:
During the fourth week in October for 1 to 6 year-old trees, consider applying zinc sulfate to induce defoliation (prevents winter frost damage) and enhance zinc nutrient levels for spring growth.
Monitor for mealybugs. Look for sooty mold on leaves and mealybugs within the clusters. Once leaves fall, check tree trunks. Note infested trees for monitoring next season.
Survey weeds and keep records (PDF). Manage weeds according to the Pistachio Pest Management Guidelines.
Look for vertebrates and their damage and manage if needed:
  • Ground squirrels
  • Jackrabbits
  • Meadow voles
  • Pocket gophers
During the fourth week in October for 1 to 6 year-old trees, consider applying zinc sulfate to induce defoliation (prevents winter frost damage) and enhance zinc nutrient levels for spring growth.

Pesticide application checklist

When planning for possible pesticide applications in an IPM program, review and complete this checklist to consider practices that minimize environmental and efficacy problems.
  • Choose a pesticide from the UC IPM Pest Management Guidelines for the target pest, considering:
  • Before an application:
    • Ensure that spray equipment is properly calibrated to deliver the desired pesticide amounts for optimal coverage. (For more information, see Pesticide Application Equipment and Calibration)
    • Use appropriate spray nozzles and pressure to minimize the off-site movement of pesticides.
    • Avoid spraying during these conditions to avoid off-site movement of pesticides:
      • Wind speed over 5 mph
      • During inversions
      • Just prior to rain or irrigation
      • At tractor speeds of over 2 mph
    • Identify and take special care to protect sensitive areas (for example, waterways or riparian areas) surrounding your application site.
    • Review and follow the labels for pesticide handling, storage, and disposal guidelines.
    • Check and follow restricted entry intervals (REI) and preharvest intervals (PHI).
  • After an application:
    • Record application date, product used, rate, and location of application.
    • Follow up to confirm that treatment was effective.
  • Consider water management practices that reduce pesticide movement off-site.
  • Consider practices that reduce air quality problems.
    • When possible, reduce volatile organic compound (VOC) emissions by decreasing the amount of pesticide applied, choosing low-emission management methods, and avoiding fumigants and emulsifiable concentrates (EC) formulations.
    • Use the Department of Pesticide Regulation calculators to determine VOC emission rates from fumigant and nonfumigant pesticides.

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