Seasonal Spraying Calendar: When and What to Spray in Australia

Timing is everything when it comes to spraying. Whether you’re managing weeds, pests, or crop nutrition, knowing when to spray is just as important as knowing what to spray. Weather patterns, crop cycles, and regional variations all influence how effective your spraying program will be.

Here’s a practical guide to building a seasonal spraying calendar tailored for Australian conditions — and how Silvan’s reliable sprayers can help you make every pass count.

1. Summer (December – February): Pest and Weed Pressure Peaks

Australia’s hot, dry summers bring an explosion of weed and pest activity — especially after rain. During this period, your focus should be on control and prevention.

Key spraying tasks:

• Weed control: Summer weeds like barnyard grass, fleabane, and melons thrive after storms. Use broad-spectrum herbicides early before they seed.
• Insect management: Monitor crops for caterpillars, aphids, and mites, particularly in cotton, vegetables, and pastures.
• Fungal prevention: High humidity can trigger fungal issues in vineyards and orchards — consider preventative fungicide sprays.

💡 Tip: Spray early in the morning or late afternoon to reduce evaporation and drift.

2. Autumn (March – May): Pre-Planting and Pasture Management

Autumn is the time to prepare for planting and reseeding. The first rainfalls trigger weed germination, so early spraying ensures a clean start for winter crops.

Key spraying tasks:

• Knockdown herbicides: Control weeds before sowing cereals, pulses, and canola.
• Residual herbicides: Apply pre-emergent sprays to extend weed control into winter.
• Fertiliser and trace elements: Foliar feeding helps crops establish faster in cooler soils.
• Pasture renovation: Use targeted sprays to clean up paddocks before over-sowing.

💡 Tip: A Silvan trailed or linkage sprayer makes large-area pre-sowing application efficient and precise.

3. Winter (June – August): Disease Prevention and Selective Control

Cooler weather slows crop growth but increases disease risks — particularly rust, mildew, and blight in cereals and legumes.

Key spraying tasks:

• Fungicides: Apply preventatively in wheat and barley before infection spreads.
• Selective herbicides: Control broadleaf weeds that thrive in moist, cool soil.
• Orchards and vineyards: Use dormant sprays to manage overwintering pests and fungal spores.

💡 Tip: Keep an eye on weather forecasts. Spraying just before rain or frost can reduce chemical effectiveness and cause runoff.

4. Spring (September – November): Growth and Flowering

Spring is the most active growth stage for many crops — and the most crucial time for protective spraying.

Key spraying tasks:

• Fungicide programs: Maintain coverage as crops approach flowering.
• Insecticides: Control aphids, thrips, and borers as temperatures rise.
• Foliar nutrition: Supplement nitrogen and micronutrients to boost yield.
• Weed tidy-up: Post-emergent spraying to remove late-season weeds before harvest.

💡 Tip: Calibrate your sprayer regularly — changing water rates and nozzle wear can alter coverage just when your crops need consistency most.

5. Adjust for Your Region and Crop Type

Australia’s vast climate zones mean timing can vary significantly. For instance:

• Northern regions (e.g., QLD, NT): Spraying often aligns with wet and dry seasons rather than calendar months.
• Southern regions (e.g., VIC, SA, TAS): Cooler winters mean a shorter spray window, so pre-season preparation is critical.
• Western and inland areas: Watch for temperature spikes and wind conditions — early morning spraying is safest.

Where possible, record spray dates, products, and weather conditions. A consistent log helps refine future timing and track chemical performance.