Northwest berry Foundation

Management Detail

Lygus Bugs

in Strawberries

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Latin name: Lygus lineolaris (tarnished plant bug) and other species

Description:

Reason for Concern:
1) Lygus bug are a serious pest in day-neutral/everbearing strawberry growing regions.
2) Lygus bug feeding on buds, bloom and immature fruits results in deformed fruits (cat-facing) which reduces yield and fruit quality.
3) Lygus bugs reproduce quickly and are harder to manage in their adult life stage than their immature stage.

Identification:
Adults are 0.25 to 0.5 inches long, oval, and rather flattened. Adults are greenish to brownish and have a distinct yellow or pale green triangle/”V” on their back. Immature forms are pale green and look similar to an aphid but move quicker. Nymphs are wingless, green and characterized by five black dots on the back.

Lifecycle:
Adults overwinter in plant debris until they emerge to lay eggs on the stems of host plants in January and hatch in March. Nymphs begin feeding as bloom begins and continue feed predominately on blooms and immature fruit into adulthood. There can be up to three generations a year though number of generations in the Pacific Northwest may vary as Day Neutral production is still relatively new to the region.

Links:

Scouting:

  • Begin monitoring for nymphs at flower bud stage.
  • Divide the strawberry field into blocks and sample four 200-foot lengths of row in each block.
  • Sample one plant in each 20 feet of row by placing beating tray under the plant.
  • Inspect leaves for adults and shake the plant (particularly the flower parts) with your hand to drop any nymphs on beating tray. A plastic milk jug cut in half may act as a good beating tray as it keeps specimens in a somewhat confined area and provides more protection from wind.
  • A sweep net can also be used to capture fast moving Lygus bug.
  • Management is often recommended when one Lygus nymph/adult is found in a 20 plant sample.
  • Using a degree day model can help determine Lygus bug life-cycle making management more effective.
  • Yellow sticky cards strategically placed in the field is an additional option to track pest migration.
  • Inspect immature fruit for deformation.  Lygus bug cause damage by puncturing individual seeds; this, in turn, stops development of the berry in the area surrounding the feeding site causing cat-facing. Note: Other causes of cat-facing can be due to poor pollination, boron or calcium deficiencies, frost damage to blossoms, hail or herbicide damage. Positive Lygus bug catches while scouting, as well as the time of year which Lygus bug population typically builds, usually rules out other causes of berry deformation.
  • Time insecticide sprays to manage Lygus nymphs as registered materials are most effective at this stage.
  • Target your management plan (rotate chemistries and apply when most economical to do so) to promote a natural enemy population and prevent Lygus bug from building resistance to materials used.

 
Cultural Controls:

  • Control weeds along roadways, ditches, and in borders adjacent to strawberries especially in the fall, winter and spring.
  • To avoid adult migration, disc or mow cover crops  in spring, before they flower.
  • Refrain from planting strawberry around other host plants/crops (vegetables, clover, weeds).
  • Pay particular attention when alternate host plants in the area are past their prime as Lygus bug will quickly move into the strawberry field causing extensive damage in a short period of time.

 

For information about chemical controls, check with our Pesticide Guide.

images


Lygus bug - photo by J. Myer


Deformed ends of strawberries (monkey facing) - photo T. Peerbolt

 

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