Pistachio

Year-round IPM Program for Pistachio

(Reviewed: 10/14, Updated 10/14)

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, example monitoring forms, 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 effects 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 colonization and 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 or pheromone traps on April 1. Check traps once or twice per week to monitor the first flight (typically in April to mid June with a peak in May) in pheromone traps and to observe the egg-laying peak (typically in May) using egg traps.
In late March through April, adult leaffooted plant bugs and stink bugs may migrate into the orchard edges from overwintering sites. Monitor weekly for:
  • Leaffooted plant bugs, small plant bugs, and stink bugs using a beating tray.
  • Plant bugs and stink bugs 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 (rolled or folded leaves). 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:

Invertebrates
  • Darkling beetles
  • Thrips (onion, western flower)
  • Western tussock moth
Disease and abiotic disorders
  • Armillaria root rot (oak root fungus) mushrooms
  • Delayed leafing
  • Frost damage
  • 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 effects to minimize air and water contamination.

What should you be doing at this time?
Avoid severe water stress in mid-May during stage one of kernel development (bloom through shell expansion) to reduce the incidence of early shell split and 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 mid- to late April in Fresno and northward. Note biofix (the first date when male moths are consistently caught in traps). Continue monitoring traps to determine treatment timing if needed.
  • Navel orangeworm. Identify the first (May) and second (late June to early July) generations using egg or pheromone traps. In late July use degree-days, pheromone trap catches, and inspections for eggs on early split nuts 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 July, 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 (typically the first week of 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 and manage 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 a fungicide application in early June or if rain occurs. 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:

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

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
  • Verticillium wilt (late strikes)
  • Other canker diseases
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 damage as well as 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 current 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 effects to minimize air and water contamination.

What should you be doing during this time?
Carry out postharvest sanitation activities:
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, consult the Pest Management Guidelines, and review and complete this checklist to consider practices that minimize environmental and efficacy problems.

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