Bondi Junction NSW, Australia
Fact Sheets
2021-09-08T03:13:35.6124213Z
   9
Johnson grass (487)
Pacific Pests, Pathogens and Weeds
Pacific Pests, Pathogens and Weeds

Summary

  • Worldwide distribution. In Australia, New Zealand, most Pacific island countries.
  • Major invasive weed. Produces abundant seed. Invades many crops (e.g., cotton, maize, soybean, sugarcane), wastelands, natural vegetation, roadsides; spreads pests (midge, viruses, fungi, bacteria); toxic to livestock (especially after drought); fire risk. Allergenic pollen. Produces root chemicals inhibiting competitors.
  • Numerous erect stems up to 3m, from extensive, purple-spotted scaly, rhizomes. Leaves hairless with prominent white midribs. Pale green-purplish, branched flower seedheads, up to 35cm. Spikelets (flowers) in pairs or triplets along and at end of branches.
  • Spread: rhizomes and seed on the wind, water, seed lots, fodder, vehicles. Rhizomes assist survival.
  • Biosecurity: check for seed in livestock fodder, maize and sorghum seeds.
  • Biocontrol: none.
  • Cultural control: hand-weed; plough; mow (but rhizomes regrow); heavy grazing to deplete reserve; geese; fire (follow-up with herbicide). Clean machinery/vehicles; check clothing; quarantine livestock 1 week between infested and ‘clean’ pastures. Avoid seed-infested soil, sand, gravel.
  • Chemical control: in Australia, butroxydim; clethodim; glufosinate-ammonium; glyphosate; haloxyfop; imazapyr; oxyfluorfen; quizalofop-p-ethyl; trifluralin; diquat + paraquat.

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