This step-by-step editorial outlines an integrated approach to controlling fog grass in temperate ryegrass based pastures in southern Victoria. Key strategies include increasing autumn grazing pressure, establishing dense ryegrass stands, correcting soil fertility, using summer crops with trifluralin, applying ethofumesate in autumn, and implementing tactical spring management. The goal is to replace poor competition and low fertility with vigorous, well-managed pastures that naturally suppress fog grass over time.

Why control fog grass?

Fog grass is a cool-season perennial grass that thrives in low-fertility soils, acidic conditions, and thin non-productive, non competitive pastures. It establishes quickly in gaps and can dominate the pasture. Its palatability and feed value are low, especially in late season. Knowing its lifecycle and weaknesses is the key to control.

Existing pasture – Increase Grazing Pressure in Autumn and Early Winter

Targeted grazing in late autumn and early winter is a simple but critical first move. Fog grass is slow to establish in colder months compared to ryegrass and clovers. Often these areas can become waterlogged throughout winter and spring, so its ultra important to hard graze these areas for as long as possible.

Grazing hard during this window:

  • Prevents fog grass tillering and seeding
  • Creates opportunities for ryegrass and clovers to dominate
  • Helps expose gaps for chemical or renovation follow-up

Tip: Don’t allow rank, open pasture to develop—keep grazing rotations tight.

Summer grazing before renovation

Grazing hard in late summer/autumn opens the sward and knocks fog back just as it’s trying to seed or regrow. This creates a cleaner slate and ensures better herbicide contact and seed-to-soil contact when sowing.

Establish Dense Ryegrass Pastures

A dense, competitive ryegrass base is your best long-term defense.

Use a well-known, densely tillering diploid ryegrass like Vibe Italian Ryegrass, renowned for its strong autumn and winter growth. Sow at 30–35 kg/ha to ensure rapid establishment and a thick pasture canopy. A dense ryegrass sward effectively blocks out light and space—two things fog grass can’t compete with—helping to smother any regrowth before it gains a foothold.

Apply a starter fertiliser such as DAP (18:20:0) or MAP (10:22:0) at sowing to provide readily available nitrogen and phosphorus. This promotes early root development and rapid seedling establishment—crucial for dense ryegrass cover. A typical rate of 80–120 kg/ha delivers around 15–25 kg/ha of nitrogen and a solid phosphorus boost.

As the ryegrass develops, follow up with urea applications—typically 40–60 kg N/ha—around 4–6 weeks after sowing, and again as needed through winter. This boosts nitrogen availability during critical growth phases, driving vigorous tillering and rapid canopy closure.

Boost Soil Fertility and pH

Fog grass thrives in acidic, nutrient-poor soils, so flip the script.

  • Apply lime where pH is below 5.5 (CaCl₂), targeting 5.8–6.0 for ryegrass dominance.
  • Address deficiencies, particularly phosphorus (P) and potassium (K), guided by soil tests.
  • A well-fertilised, balanced paddock will support ryegrass and clovers over fog grass.

Summer Cropping as a Reset – Use Trifluralin

Summer cropping with a full renovation is a powerful reset tool, especially after severe fog grass infestation.

  • Spray out fog grass with glyphosate in late spring or early summer.
  • Cultivate and sow a summer crop such as forage sorghum, millet, or brassicas.
  • Incorporate trifluralin pre-sowing to knock out germinating fog grass seeds.
    • Best suited to cultivated seedbeds, not direct drill
    • Ensure correct incorporation and label compliance

The summer crop chokes regrowth and resets the paddock for autumn pasture establishment.

Use Ethofumesate in Autumn to Control Re-establishing Fog

Ethofumesate (e.g. Nortron) can selectively control fog grass seedlings in newly sown ryegrass.

  • Apply early post-emergence when ryegrass is at 1–2 leaf stage
  • Ideal after summer cropping or direct drill renovation
  • Watch timing closely—delayed application reduces effectiveness

This step helps protect your new pasture investment by stopping early fog re-infestation.

Long-Term Follow-Up and Monitoring

This is a multi-year strategy, not a one-hit solution.

  • Keep pressure on fog grass in all seasons—autumn grazing, spring topping, and summer cropping if needed.
  • Monitor paddock composition yearly. Use tools like pasture cages or transect counts.
  • Rotate paddocks through cropping or lucerne phases if long-term reform is needed.

Conclusion

Controlling fog grass is all about replacing weakness with strength. Weak competition, poor soil, and lax grazing create the perfect environment for it. Flip that around with strong grazing, competitive ryegrass, smarter chemistry, and summer resets, and you’ll turn the tide.