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Department of Entomology

Department of Entomology
123 W. Waters Hall
1603 Old Claflin Place
Kansas State University
Manhattan KS 66506-4004

785-532-6154
785-532-6232 fax
entomology@ksu.edu

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Alfalfa Insects

Potato Leafhopper, Empoasca fabae.

nymph

Leafhopper nymph

adult

Leafhopper adult

hopperburn

Feeding symptoms on alfalfa

Small (1/8-inch long), yellow-green, wedge-shaped insects that move sideways, jump or fly when disturbed. Nymphs and adults damage alfalfa during midsummer. Injured plants typically exhibit V-shaped yellowing of the leaf tips (“hopper-burn”). During some years, this insect substantially damages alfalfa. More attention needs to be devoted to scouting for and managing this pest. Stunted, yellowed plants are less valuable for livestock feed because of reduced protein levels. Controls should be applied before yellowing begins. If required, one spray applied to the stubble is usually adequate to control leafhoppers. Suggested treatment guidelines are found at left. Sample values represent the average number of leafhoppers per sweep from at least 20 pendulum sweeps per location, gathered from at least five representative locations per field. Stem length refers to the average plant height in the sampled areas. If infestations are not detected before alfalfa becomes yellowed and stunted, then it may be helpful to harvest, before making an insecticide treatment, to remove eggs. Where insecticide treatment has been justified for potato leafhopper control, the lowest recommended rates have often proven effective and re-infestation seldom occurs.

Resistant Varieties

Kanza and Riley varieties had some resistance to potato leafhoppers and were recommended for establishing new plantings. Newer varieties with higher levels of resistance to potato leafhoppers are now for sale by various companies. Check with seed suppliers for additional information on potato leafhopper resistance in varieties adapted to Kansas conditions.

Potato Leafhopper Thresholds

Average number

Stem length (inches) of leafhoppers per sweep
3 or less 0.2
6 0.5
8 to 10 1.0
12 to 14 2.0

Please refer to the most recent Alfalfa Insect Management Guide for specific control alternatives.

Page last updated 10/29/2013 by J.P. Michaud.