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Potato Leafhopper-Resistant Alfalfa
The potato leafhopper (Empoasca fabae) is an insect that feeds on nearly 200 cultivated and wild plants, including potatoes, beans, peanuts and particularly alfalfa. The potato leafhopper (PLH) is among the most destructive pests in agriculture, causing millions of dollars of damage to crops each year. Reduced yield, reduced nutrients, plant stunting, leaf yellowing (hopperburn), slower regrowth and decreased plant survival are all symptoms of PLH damage.
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An adult Potato Leafhopper
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The insects are lime green and wedge-shaped, and have both nymph and adult life stages. Both the nymph and adult damage alfalfa by sucking plant juices from the leaves and stems and then secreting a toxic substance that "plugs" the vascular system. This toxin turns a V-shaped area at the tip of the leaflets yellow, stunting growth. This yellowing is otherwise known as "hopperburn." The most damage is done to the plant if the PLH infestation is early in the re-growth cycle.
Traditionally, insecticides have been used to control leaf-hopper damage to alfalfa. However, some alfalfa varieties have been bred for resistance to PLH. These resistant varieties actually have tiny glandular hairs on the plant surfaces that are tipped with a sticky resin. When the leafhoppers infest these resistant plants, they either die or are repelled from the plants, leaving minimal plant damage.
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Toxin from Potato Leafhoppers turns a V-shaped area at the tip of alfalfa leaflets yellow, known as "hopperburn."
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The exact cause of leafhopper resistance in these plants is debated. The most commonly held theory for the mechanism of PLH resistance is glandular entrapment. Glandular hairs trap many leafhoppers with a sticky substance emitted from the tip of the hairs, after which the insects eventually die. Whether the hoppers die due to starvation or to the sticky substance releasing a toxic chemical is debated. It is known that there is a great diversity between resistant plants concerning type and density of glandular hairs. Some types of hairs are more effective than other hairs in controlling PLH damage.
Both public and private alfalfa field trials are showing that PLH-resistant alfalfa, when combined with elite alfalfa lines, is effective in providing protection against leafhopper damage. Syngenta Seeds offers Arrest alfalfa with HopperGuard™ protection. HopperGuard protection provides a strong defense against the PLH, while providing top yields and quality.
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