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Hey everyone, welcome to this month’s outlook report from your CSD Extension & Development Agronomist’s on the Darling Downs - Larissa Holland, Chris Barry and Rachel Russel!  

Wild weather has been the flavour for the last month, with the heat of October giving way to storms in November. Fortunately, this has allowed the opportunity for late planting of dryland cotton in November and December. Looking ahead to the Christmas month, we will discuss first irrigation, first flower, some information on ThryvOn® and some general information on December planting of cotton (late plant cotton).  

ThryvOn®

What is it? The ThryvOn® trait is built on the integration of Mpp51Aa2.834_16, a single pore-forming insecticidal protein produced by the bacterium Bacillus thuringiensis (Bt), into the cotton genome.  Simply, it is a single protein trait that aims to protect the crop throughout the season from egg-laying and as a feeding deterrent for thrips. It does NOT provide complete control of thrips species and has little impact on adult thrips. It is only registered for thrip suppression, with no on label use for mirids. Trials have been ongoing with Bayer since 2017, with 2025 marking the first year that the CSD Extension Team have been involved. There was an early season field walk in November on the Darling Downs that was well attended and as the season progresses, we will hold additional field days to show how it is progressing through the season  

First irrigation  

First flower is a critical milestone in cotton production that plays a pivotal role in determining crop performance, yield potential, and final harvest outcomes. The first flower stage is when the crop transitions from predominantly vegetative growth to reproductive development. A target is to have 9+ squaring nodes (9 NAWF) to ensure flowering can take place for as long as possible.  

Having a plant conforming to first flower ideals ensures that, regardless of seasonal conditions, these growth metrics will help the crop cope and/or rebound from stress. Cotton crops deficient in nitrogen or moisture stressed during early flowering can rapidly lose canopy vigour, reducing both the production of fruiting sites and yield potential. STEFF can be queried at any time via any device with an internet connection. It is simple to operate, only requiring the user to select the nearest location and the date of seed imbibition – often this is the day of planting if the seed was planted into moisture, or the day of watering up. The tool will then return an estimated date of first flower.  

Late plant dryland    

The dry conditions that were prevalent early season meant that not a lot of dryland cotton was planted. Storm rain has improved this outlook and while a good portion has been planted late in November, the random nature of storms has seen some growers miss out. While the end of the planting window is approaching there is still time for rain and planting, with a few points to remember when considering if late plant dryland is for you.  

• Potential yield of the late-planted crop compared to alternative options 

• Additional resources required, including soil water and nitrogen application 

• Cost of maintaining the fallow as an alternative 

• When the crop will flower 

• Reduced season length 

The crop must complete fibre maturity and boll opening before the first frost, with careful crop agronomy being essential to account for the shortened growing season. A short season variety such as Sicot 714B3F or Sicot 619B3XF may be more responsive to management decisions that favour earliness to the crop. 

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