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Quick Reference Guide to Major Sunflower Insects

Wednesday, February 1, 2012
filed under: Insects

Cutworms (several species)

E.T. – 1 per sq. ft. or 25-30% stand reduction. Appear in early spring when plants are in the seedling stage, chewing them at or slightly above ground.

Palestriped Flea Beetle

E.T. – 20% of the seedling stand is injured and at risk to loss due to palestriped flea beetle feeding. Scout for flea beetles by visually estimating population on seedlings or using yellow sticky cards placed close to the ground.

Sunflower Beetle

E.T. – 1 to 2/seedling (adults), or 10 to 15/seedling (larvae). Adults appear in early June, larvae shortly thereafter. Both adults and larvae chew large holes in leaves.

Sunflower Bud Moth

E.T. – None. First generation adults appear in late May to mid-June, second generation adults in mid-summer. Larvae from 1st generation damage terminals and stalks whereas 2nd generation larvae feed in receptacle area.

Longhorned Beetle (Dectes)
No scouting method or E.T. has been developed. Adults are present from late June through August. Larvae tunnel and feed in the petioles and stem pith and girdle the base of plants. Stalks often break at the point of larval girdling.

Sunflower Stem Weevil

E.T. – 1 Adult/3 plants in late June to early July. Adults appear in mid to late June with larvae in stalks from early July to late summer.

Thistle Caterpillar (Painted Lady Butterfly)

E.T. – 25 percent defoliation provided that most of the larvae are still under 1.25 inch in length. Adults appear in early to mid-June with larvae appearing shortly thereafter. Larvae chew holes in leaves.

Sunflower Midge

E.T. – None. Adult emergence begins in early July. Larvae feed around head margin and at base of the seeds causing shrinkage and distortion of heads.

Sunflower Seed Weevils

E.T. – Generally 8 - 14 adult red sunflower weevils per head (oil) and one per head (confectionery). Adults appear in late June to early July. Treat for red sunflower seed weevil at R5.1 to R5.4. Larvae feed in seeds from mid to late summer.

Sunflower Moth

E.T. – 1 to 2 adults/5 plants at onset of bloom. Adults are migratory and usually appear in early to mid-July. Larvae tunnel in seeds from late July to late August.

Banded Sunflower Moth

E.T. – Use either egg or adult sampling methods for determining E.T. Sampling should be conducted in the late bud stage (R-3), usually during mid-July. Adults appear about mid-July to mid-August. Larvae present in heads from mid-July to mid-September.

Lygus Bug

E.T. for confection sunflower only – 1 Lygus bug per 9 heads. Two insecticide sprays are recommended: one application at the onset of pollen shed or 10% bloom, followed by a second treatment 7 days later.

Sunflower Headclipping Weevil

E.T. – None. Adults appear in mid to late July and create feeding punctures around stalk just below the heads. Heads drop off.

Note: The insects discussed above are listed in the order that they are likely to occur throughout the growing season; however, the various insects may or may not appear, depending upon overwintering survival and environmental conditions as the season progresses. This table is intended simply as a guide to when fields should be checked for possible presence of the various insects known to infest sunflower.

SOURCE: Sunflower Production A-1331 (Revised EB-25 Revised). 2007. D.R. Berglund (editor). NDSU Ext. Serv.
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