Cold establishment periods provide many challenges for the cotton grower and consultant from a management perspective. Establishing enough plants and keeping those plants alive until the season warms up involves many management decisions and factors to consider when making these decisions.

CSD tools CottonTracka® and Day Degree Calculator (DDC) are two useful tools that track season conditions at each stage of growth, visually displaying how the climate is progressing in your region. For example, figure 1 uses the DDC to look at the historical 1532 accumulation during the establishment period for Coleambally.

Abiotic and biotic seasonal influences that can affect crop growth include:

• Daily minimum and maximum temperatures.
• Days to emergence (average temperature).
• Length of control from planting insecticides.
• Pest populations.
• Irrigation.
• Rainfall and cloud cover.
• Disease – Rhizoctonia, Black Root Rot, Altenaria.

Average temperature is defined as the sum of the maximum and minimum divided by half for a period of 24 hours. A reduction of daily average temperature can exacerbate the presence of soil borne disease such as rhizoctonia and black root rot. This can have negative influence on plant vigor and overall growth rates, particularly node production due to the root structures being inhibited by disease.

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Below ideal growing conditions results in plants producing minimal growth as a direct result from temperature. While the plant sits in cold conditions, growers and consultants are faced with the prospect of having to protect a small plant, primarily focusing on the terminal for when favourable conditions eventually prevail. The use of insecticide and fungicide during early season conditions is often timed with the first in-crop herbicide. Even with low pest and disease presence, there is value to protect the slow growing plant until conditions are favourable.

Early season stress can encourage:

Later initiation of first fruiting position (Figure 2)

Delay in days to first flower.

Higher retention threshold.

To help track your crop’s progression check out CottonTracka.

Cold temperatures during the establishment period can influence the timing of first square production and time to first flower. Delay in average temperature in the lead up to first square will encourage growers to run a higher retention leading up to and during first flower, to make up for lost time during challenging establishment periods.

Maximising days of flowering is important in Central and Southern NSW. In cold seasons, first flower is often delayed due to low average temperature. Unfortunately due to the location of these regions, season length is not abundant. Therefore, late flowering crops cannot be matured during ‘late season’ as the climate historically does not prevail.

Pushing crops to flower past 10-15th of February in these regions comes at a yield and quality risk. Flowers that occur on or past the 10-15th February are candidates for immature fruit. These late position bolls are factored into defoliation decisions and as a result can introduce very low quality lint into the sample. Furthermore, minimal yield is attributed to these late flowering bolls due to lack of season length to fill and mature these late flowers.