Mint-Garden symphylan

Scutigerella immaculata

Pest description and crop damage Small (less than 0.25 inch), white, centipede-like animals that feed on hairs and meristematic tissue of roots and underground stems. Heavy feeding causes plant stunting, poor stem elongation, and small, chlorotic leaves. This arthropod is a severe pest of many crops in western Oregon.

Biology and life history Populations build rapidly in spring and summer, and usually migrate downward from late summer through fall as soil temperatures rise and moisture content drops. Populations migrate up toward top six inches of soil in the fall as soil moisture increases with the onset of rain. They may damage roots during mild winters.

Scouting and thresholds There are two modes for scouting symphylans-the potato bait method and soil sample method. The potato bait method allows greater visibility and likelihood of identifying high numbers. To bait symphylans, dig approximately four to six inches into soil and place half a potato and cover with solid plastic container. Check baits after 1 to 3 days. Lift potato and count symphylans on soil and then on potato. For soil sampling method, take soil samples roughly a standard shovel width (roughly 1 cubic ft) to a depth of 8 to 12 inches. Symphylans usually are sampled in April, May, and June shortly after irrigation or rain when soil is moist. Soil should be nearly at carrying capacity, but sufficiently dry so it fractures or crumbles easily, exposing symphylans in natural tunnels, crevices, worm holes, etc. Damage to mint likely occurs at densities of five to ten per cubic ft of soil.

Management-chemical control

  • 1,3-dichloropropene (Telone II) at 18 to 35 gal/A only as a broadcast treatment. REI 5 days. See labels for use rate and application methods.
  • ethoprop (Mocap EC or 15G) at 3 lb ai/A (6 lb ai/A if nematodes also a problem). PHI 225 days. REI 48 to 72 hr. Make only one application whether pre-plant or post-harvest per growing season. Apply in 20 to 30 gal water/A. Broadcast over the field and incorporate into the soil to a depth of at least 2 to 4 inches, during or immediately following application by mechanical means, including by rotary tiller, rotary hoe, springtooth harrow, or by double discing, or by immediate application of 1 to 2 inches of overhead irrigation. Repeat irrigation before soil dries. Restricted use.

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