Alfalfa

Year-Round IPM Program

(Reviewed 3/17, updated 3/17)

Established stands

Use these guidelines for a monitoring-based IPM program to effectively manage pests, while reducing 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 applies to fall-planted alfalfa hay in California. Details on carrying out each practice, information on additional pests, and additional copies of this form are available from the UC IPM Pest Management Guidelines: Alfalfa. Stand establishment is the most critical single factor affecting successful IPM strategies in alfalfa. Follow the practices below to establish and maintain a healthy vigorous stand that resists pest problems.

For IPM practices during the preplanting and stand establishment period, see Establishing a stand.

Winter (November through January)

Special issues of concern related to water quality: drift, runoff due to rain.
What should you be doing during this time?
Survey winter weeds in December through January.
Determine weed management strategy based on last year's weed types and abundance. Consider:
Note any special weed problems such as dodder and perennial weeds. Manage, if needed, according to the Pest Management Guidelines.
Begin to monitor for aphids in January.
Monitor for weevils :
  • Look for chewed leaves, especially on stands putting on new growth, and take sweep-net samples when alfalfa height allows.
  • Keep records on a weevil monitoring form (PDF).
  • Manage if needed according to the Pest Management Guidelines.
Look for signs of vertebrate pests, such as gophers, meadow voles, or ground squirrels.
  • Manage, if needed, according to the Pest Management Guidelines.
Scout for signs of stem nematode (generally from December through March or April).

Spring

Special issues of concern related to water quality: runoff due to rain, irrigation or drift.
What should you be doing during this time?
Time harvests by considering:
  • Alfalfa growth, vigor and quality
  • Pest problems including:
    • Aphids
    • Leaf and stem diseases
    • Weevils
  • Irrigation and wheel traffic

Consider border-strip harvesting to conserve natural enemies.

Determine appropriate weed management strategies based on last summer's weed species and numbers. Note any special weed problems such as:
  • Dodder
  • Grasses
  • Nutsedge

Manage if needed according to the Pest Management Guidelines.

Look for signs of stem nematode in early spring.
  • Prevent the spread of nematodes by cutting fields first or cleaning harvesting equipment between infected and clean fields.
Monitor for weevils. Consider early harvest if Egyptian alfalfa weevil is a problem in your field.
  • Keep records on a weevil monitoring form (PDF).
  • Manage if needed according to the Pest Management Guidelines.
Monitor aphids and their natural enemies.
Look for cutworms if damage is apparent.
  • Manage if needed according to the Pest Management Guidelines.
If you see thrips or evidence of thrips feeding, no pesticide application is needed.
Watch for signs of diseases and nematodes.
Consider field sanitation:
  • Harvest disease- and stem nematode-free fields before infested fields.
  • Avoid moving contaminated farm machinery or livestock from a field infested with nematodes or disease to a clean field.
  • Be careful when using return water because pathogens and nematodes can be carried in recirculated irrigation water.

Summer

Special issues of concern related to water quality: drift, runoff due to irrigation.
What should you be doing during this time?
Time harvests by considering:
  • Alfalfa yield, quality, and stand persistence. Early harvests result in poor stand persistence, encouraging weeds.
  • Pest problems, specifically how close the pest damage is to harvest
  • Irrigation and wheel traffic (avoid wet soils)
  • Alfalfa market and price differential for different quality grades
Survey weeds, especially weedy grasses.

Keep records on a weed survey form (pdf) for next spring's weed management decisions.

Monitor cowpea and spotted alfalfa aphids.

Manage if needed according to the Pest Management Guidelines.

Monitor caterpillars and armyworms. Consider early harvest to reduce losses.
Monitor leafhoppers at the first sign of damage. Consider early harvest to reduce losses.
  • Keep records on a monitoring form (PDF).
  • Manage if needed according to the Pest Management Guidelines.
Look for cutworms if damage is apparent. Manage if needed according to the Pest Management Guidelines.
Watch for signs of diseases and disorders (such as nutrient deficiencies, yellowing due to anoxia, or abiotic factors like scald).
Keep records of other invertebrates.
Look for signs of vertebrate pests, such as gophers, meadow voles, or ground squirrels. Manage, if needed, according to the Pest Management Guidelines. Manage if needed according to the Pest Management Guidelines.
Use proper field sanitation:
  • Harvest disease- and stem nematode-free fields before infested fields.
  • Avoid moving contaminated farm machinery or livestock from a field infested with stem nematodes or disease to a clean field.
  • Be careful when using return water because pathogens and nematodes can be carried in recirculated irrigation water.
Manage irrigation water to prevent standing water, which can kill alfalfa plants through scald, especially at the tail-ends of fields. If possible, avoid watering on hot days (above 104F), but if unavoidable: avoid standing water in fields for over 8 hours.

Fall

Special issues of concern related to water quality: drift, runoff due to rain, irrigation.
What should you be doing during this time?
Time harvests by evaluating pest problems, irrigation, and weather.
Survey weeds just after the alfalfa is cut.
  • Keep records on a monitoring form (PDF).
  • Plan on late fall through winter weed management strategies.
Monitor aphids and their natural enemies.
  • Keep records on a monitoring form.
  • Manage if needed according to the Pest Management Guidelines.
Monitor caterpillars. Consider early harvest to reduce losses.
  • Keep records on a monitoring form (PDF).
  • Manage if needed according to the Pest Management Guidelines.
Consider field sanitation:
  • Harvest disease- and stem nematode-free fields before infested fields.
  • Avoid moving contaminated farm machinery or livestock from a field infested with stem nematodes or disease to a clean field.
  • Be careful when using return water because pathogens and nematodes can be carried in recirculated irrigation water.
Look for signs of vertebrates, such as gophers, meadow voles, or ground squirrels.
  • Manage if needed according to the Pest Management Guidelines

For IPM practices during the preplanting and stand establishment period, see Establishing a stand.

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 amount for optimal coverage.
    • Use appropriate spray nozzles and pressure to minimize off-site movement of pesticides.
    • Avoid spraying during these conditions to avoid off-site movement of pesticides.
      • Wind speed under 3 mph or over 10 mph
      • Temperature inversions
      • Just prior to rain or irrigation (unless it is an appropriate amount, such as when incorporating a soil-applied pesticide)
      • At tractor speeds over 2 mph
    • Avoid spraying areas of bare soil, such as weevil-damaged areas, with pesticides prone to cause water quality problems. Consider overseeding these areas with grasses.
    • Identify and take special care to protect sensitive areas (for example, waterways or riparian areas) surrounding your application site.
    • Review and follow labeling for pesticide handling, personal protection equipment (PPE) requirements, storage, and disposal.
    • 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 the pesticide application 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 concentrate (EC) formulations.
    • Use the Department of Pesticide Regulation calculators to determine VOC emission rates from fumigant and nonfumigant pesticides.

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