Increased populations of grasshoppers cause problems in fruit crops

Dry conditions in some areas of Michigan have sparked grasshopper problems in fruit orchards.

The dry conditions in some regions of Michigan have resulted in significant damage to young orchards by grasshoppers (Photo 1). Although not as bad as the major Minnesota invasion of the 1930s when grasshoppers reportedly chewed the paint on houses, in some newly planted peach and cherry orchards in southwest Michigan, young trees have been stripped of more than 50 percent of the leaf area (Photo 2). Under drought conditions, grasshoppers will move from brown, weedy fields to feed on green foliage and sometimes fruit of orchards. Mowing may also remove food sources and cause grasshoppers to invade nearby orchards.

grasshopper on peach leaf
Photo 1. Grasshoppers feeding on peach foliage can cause
considerable damage in a few days.

Grasshopper damage
Photo 2. Young tart cherry tree with severe leaf loss due
to grasshopper feeding

Similar to Japanese beetles, heaviest infestations and damage by grasshoppers will be along orchard borders adjoining grassy fields. There may be a tendency to blame leaf feeding damage on Japanese beetles, the usual suspect. It can be tricky to verify that grasshoppers are, indeed, the culprits causing the damage because this insect is easily startled by movement.

Although Michigan has four major and many minor grasshopper species, control strategies are generally similar for them all. Grasshopper control options in orchards include a range of insecticides (Table 1). Biological control options, such as those containing Nosema locustae spores, are relatively slow acting. Use of insecticides to manage grasshoppers will be more difficult next to grassy areas with large insect populations that will reinvade the orchard being protected. Monitoring and possible reapplication may be needed. Hot conditions will shorten the residual effectiveness of pyrethroid insecticides. Be sure to check the insecticide label for restrictions on use, especially concerning minimum days between application and harvest.

Table 1. Details of insecticide options for grasshopper control in fruit crops

Compound trade name

Chemical class

Life-stage activity

Spray rates per acre*

Imidan

Organophosphate

Nymphs

1.3 lb

Malathion

Organophosphate

Nymphs

1 to 2 pt

Sevin XLR

Carbamate

Nymphs

1 to 2 pt

Asana

Pyrethroid

Nymphs

5.8 to 9.6 oz

Battalion

Pyrethroid

Nymphs

7.7 to 11.5 oz

Baythroid

Pyrethroid

Nymphs

2 to 2.8 oz

Danitol

Pyrethroid

Nymphs

10.6 to 21.3 oz

Mustang Max

Pyrethroid

Nymphs

3.2 to 4 oz

Warrior

Pyrethroid

Nymphs

2.5 to 3.8 oz

Pyganic***

Pyrethrin

Nymphs

16 to 32 oz

Azera***

Pyrethrin   + Azadirectin

Nymphs

1 to 2 qt

Dimilin**

IGR

Nymphs

2 oz

* In most cases, the product’s label does not specifically list grasshoppers under a fruit crop section, but the pest is labeled for control by the compound within another crop group.
** Registered for use in pears only (14-day PHI).
*** OMRI approved for certified organic production.

Dr. Wise’s work is funded in part by MSU‘s AgBioResearch.

Additional information:

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