Grasshopper populations are heavily influenced by climate. Long, warm autumns, followed by warm, dry springs contribute to the building of grasshopper populations. With early scouting and careful management, grasshoppers can be controlled. Economic damage can be minimized.

SCOUTING
Scout for nymphs and adults in areas with historically high populations. The edges of cropping systems show the earliest grasshopper feeding. Start scouting at the edge of fields in late April or early May and continue through late June or early July.

To scout, walk and isolate a 1 square foot area. As you approach that area, count how many grasshoppers move. Observe at least 20 sample areas. Take the total number of grasshoppers counted in all squares, divide by number of squares and multiply this average by 9 to get the average number of grasshoppers per square yard.

Control when populations reach threatening levels. In field margins this is 50 to 75 nymphs or immature grasshoppers per square yard or over 21 adults. Inside crop fields, control if nymphs exceed 30 per square yard or 8-14 adults exceed per square yard.

CONTROL
Timing of grasshopper control depends on:

• the potential for crop damage, especially seedling dicots
• size of grasshoppers present
• whether hatching is completed

Treat crop borders when nymphs are small and numbers are moderate. Treat crop borders and grasshopper production areas, if nymph numbers are high, early in the season. As nymphs get larger, move treatment production sites and enlarge treated areas within cropping systems. When nymphs are very high (100+ / yd2), it is easier and safer to treat production areas than to allow nymphs to enter crops.

ALWAYS FOLLOW LABEL DIRECTIONS WHEN USING CHEMICAL CONTROLS. Sevin XLR Plus (Carbaryl) is labeled for most crops, vegetables and flowers. Other chemical controls such as Orthene (Acephate) are labeled for crop borders but not edible crops and vegetables. Some chemicals such as Asana are available only to certified applicators.

In home gardens, leaving border areas well watered and unmowed, or using row covers or screens may protect plants.

Contact your county Extension office for specific recommendations.

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