Rice Root Aphids

Rhopalosiphum abdominalis

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Hosts

• Greenhouse-grown hemp (documented in 2011, not in Utah)
• Small grains of North America

Description

• Dark, olive-green insect with a round body. Wingless forms are primarily located on roots and in the soil around host plants. Winged forms may occasionally be found on the aboveground portion of the plant.

Life Cycle

Nymph | Adult (winged or wingless)

• Populations in the U.S. reproduce without mating (no eggs). Only female offspring are produced.
• Winged adult females disperse to host plants in spring.
• Female aphids give birth to live young and live for about a month.
• Populations double about every 2 days until mortality increases in winter.

Damaging Lifestage(s): Nymphs and adults feeding on roots in soil or in hydroponic systems.

Damage Symptoms

Feeding on roots causes reduced vigor, slow growth, wilting, and leaf yellowing.

Time for Concern

Has not been observed on hemp outdoors; may be present year-round in greenhouses/hydroponic operations.

When and Where to Scout

Periodically examine the soil at the base of the plant and the surfaces of leaves for dark-bodied winged aphids throughout the year. Hang yellow sticky traps in the greenhouse to determine presence of winged aphids.

Threat Level

Will not cause severe economic damage unless present in high populations.

Occurrence in Utah

Found rarely in greenhouse hemp production only.

General Management

• Avoid excess levels of nitrogen.
• Encourage natural enemies.
• Manage weeds in or around crop
  areas, especially grasses and sedges.
• Approved insecticides are available,
  but need to contact aphids to be
  effective.

When to Consider Treatment

If populations are high and causing economic damage.

Look-alikes

On foliage, other winged aphids.

Insecticides

Utah-Registered Product	Active Ingredient(s)	Notes
Bayer Advanced NATRIA Insecticidal Soap Ready-To-Use	potassium laurate
Bonide All Seasons Horticultural & Dormant Spray Oil Concentrate, Ready to Spray	mineral oil	Commercial use allowed in greenhouse only
Bonide Insecticidal Soap MultiPurpose Insect Control Ready To Use	potassium laurate	Greenhouse use only
Bonide Rose Rx 3 in 1 Concentrate	clarified hydrophobic extract of neem o	Greenhouse use only.
Brandt Ecotec Plus	rosemary oil	Greenhouse use only.
Bug Buster-O Extinguish Ant Bait	pyrethrins	Greenhouse only
Dr. Earth Final Stop OMRI Fruit Tree Insect Killer (RTU); Concentrate	rosemary oil	Outdoor use only
Dr. Earth Final Stop OMRI Vegetable Garden Insect Killer (RTU)	rosemary oil	Only to non-blooming plants
Dr. Earth Final Stop ProActive Yard & Garden Insect Killer (spray)	rosemary oil
EcoWorks EC	neem oil, cold pressed
Evergreen Crop Protection EC 60-6	pyrethrins
Garden Safe Brand Insecticidal Soap Insect Killer	potassium laurate	Outdoor use only.
Kopa Insecticidal Soap	potassiums salts of fatty acid
Mammoth Cancontrol	thyme oil
Mite-E-Oil	mineral oil	Greenhouse use only.
M-Pede Insecticide Miticide Fungicide	potassium laurate	Foliar or basal applications.
Natural Guard Brand by Ferti-lome Insecticidal Soap Concentrate	potassium salts of fatty acids
Natural Guard Brand Neem	clarified hydrophobic extract of neem oil	Only for outdoor use, or transplants intended for outdoor fields
Omni Supreme Spray	mineral oil
Organocide 3-in-1 Garden Spray Concentrate, Ready to Spray; Ready to Use	sesame oil	Greenhouse use only.
Organocide Bee Safe 3-in-1 Garden Spray Concentrate; RTU	sesame oil
Ortho Tree & Shrub Fruit Tree Spray Concentrate	clarified hydrophobic extract of neem oil
Prizefighter	ammonium nonanoate	Many uses including greenhouse
PureCrop1	soybean oil
Pycana	pyrethrins	Greenhouse use only.
Pyganic Crop Protection EC 1.4 II; 5.0 II	pyrethrins
Pyrethrum TR Total Release Insecticide	pyrethrins
Rango	neem oil, cold pressed
Safer Brand #567 Pyrethrin & Insecticidal Soap Concentrate II	potassium salts of fatty acids	Use prior to flowering only.
Safer Brand Neem Oil Concentrate	clarified hydrophobic extract of neem oil
Safer Brand Yard & Garden Insect Killer II	potassium salts of fatty acids
SaferGro Pest Out	cottonseed oil
SuffOil-X	mineral oil
Tersus Insecticide	pyrethrins
Triact 70	clarified hydrophobic extract of neem oil
Trilogy	sulfur
TriTek	mineral oil
Venerate CG; XC	Burkholderia sp. strain a396
Whitney Farms Insecticidal Soap	potassium laurate
Xpectro OD	pyrethrins

Photo Credits 

• Whitney Cranshaw, Colorado State University, Bugwood.org

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