Early Season Pest Watch: Mirids & Thrips

With the dry hot weeks, we have experienced early signs of pests being observed. Detection of mirids and thrips during early squaring stage is vital to protect yield potential. Cotton can usually recover from light early fruit loss when conditions are good, so intervention should be based on thresholds, not calendar timing.

Key Management Points

• Monitor twice weekly for pest numbers, fruit retention, and growth rate.
• Avoid unnecessary early sprays, such as adding insecticide to glyphosate applications, this disrupts beneficial insect activity.
• Follow economic thresholds:
  • Warm areas: Early – 4 mirids/m, Mid – 3 mirids/m.
  • Cool areas: Early – 2 mirids/m, Mid – 1.5 mirids/m.
• Select narrow-spectrum products where possible to conserve beneficial insects.
• More detail: Cotton Pest Management Guide

Nitrogen management: making the most of the November rain

As November storms (hopefully) roll through Central Queensland, they offer one of the best opportunities of the season to top-dress urea. Natural rainfall provides ideal     conditions for incorporating nitrogen into the soil, boosting efficiency and reducing losses. Below is an average of the past 10 years for November. (BOM Data) 

From pre-plant to in-crop: evolving strategies

Traditional practice placed most nitrogen pre-plant, following early research by Constable & Rochester (1988). However, modern high-yielding transgenic varieties demand over 300 kg N/ha (Baird et al., 2024), and pre-plant applications are proving less efficient under Dawson and Callide irrigation systems. 

Recent work by John Baird highlights that:

• Pre-plant nitrogen moves vertically with irrigation water during watering-up.
• Extended water-up runs (> 24 hours) push nitrate deep or laterally, beyond the root zone.
• Up to 38 % of pre-plant N can be lost before first square through denitrification and volatilisation.
• Run-off contributes roughly 10 % of total losses, while leaching losses remain minor (< 1 %) in CQ cotton soils (Macdonald et al., 2017).

These findings have driven a strong local shift toward in-crop, staged nitrogen applications that align fertiliser supply with actual crop demand.

In-Crop Application Benefits

• Improved nitrogen recovery efficiency
• Reduced volatilisation and denitrification losses
• More flexibility to adjust to seasonal conditions and crop performance
• Higher yield potential, particularly when early crop growth is vigorous

The CSD × Syngenta FastStart initiative demonstrates that faster crop growth into first flower = higher yield potential. With strong establishment across the region this season, now is the time to support the crop’s rapid vegetative phase with nitrogen.

Why Apply Nitrogen Now?

Even before fruiting, leaves are the plant’s largest nitrogen sink. Top-dressing now allows growers to “bank” nitrogen reserves in vegetative tissues for use later during flowering and boll fill.

November rainfall also creates ideal soil moisture and microbial activity for efficient nitrogen conversion and uptake.  

Understanding the Nitrogen Cycle in Cotton Soils

Both ammonium and nitrate are usable by the plant. Warm soils and recent rainfall create near-perfect conditions for this conversion.

Local management tips

• Top-dress before forecast rainfall to ensure incorporation and minimise volatilisation.
• Use nitrification inhibitors (e.g. eNpower®) to retain nitrogen longer in the root zone. Watch CQ’s alkaline soils — micronutrient availability can be limited; adjust formulations as needed.
• Coordinate nitrogen with growth regulator programs (e.g. mepiquat) to manage internode length and optimise carbohydrate conversion to lint yield.

November’s weather provides the perfect setup for efficient nitrogen use.
By moving away from heavy pre-plant applications and adopting staged, in-crop nitrogen strategies, Dawson and Callide Valley growers can maximise nitrogen recovery, improve yield potential, and set up crops for a strong finish this season.

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