Q. The leaves on my cucumbers and squash are yellow and the edges look burned. What’s causing this?
A. The potato leafhopper is quietly wreaking havoc on many vegetables, fruit crops and flower gardens right now. It’s an insect that feeds on plants by sucking their sap. While feeding, the hoppers inject a toxic substance into the leaves causing the edges of the leaves to turn yellow or brown. Leafhopper damage on plants is called “hopper burn."
Researchers have found that hoppers feed on nearly 200 kinds of plants. We have seen damage on beans, corn, cucumbers, eggplant, melons, potatoes, pumpkins, rhubarb, and squash. Strawberries and apples are fruits we have seen damaged in the past. Also, dahlia, hollyhocks, marigolds and even roses can be damaged. It doesn't stop with these crops; leafhoppers can severely damage alfalfa and clover.
Potato leafhoppers don’t overwinter in New Hampshire; each year they blow in from the Gulf Coast on wind currents. Potato leafhoppers are very active and fly or jump readily when approached or disturbed. They can move sideways or backward as rapidly as they move forward.
Controlling weeds in and around the garden may help to prevent hopper damage. Weeds serve as an alternate food source for the hopper. Using row covers early in the season can provide minimal protection to young vegetable plants. You can hose hoppers off with water in early morning, before they are active. When hosing, be careful not to damage the plants.
If potato leafhoppers are numerous and are damaging your garden crops, you may need to resort to spraying. Spray for leafhoppers early in the day, when the hoppers are less active. Be sure to spray both sides of the leaves. Select an appropriate insecticide that has both the plant and pest listed on the label.
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