Using CottASSIST’s ‘LEFT’ tool to optimise the timing of cut out

17 January, 2019

Cottassist_cdt_snip

Cut out is the point at which the crop ceases to produce new fruiting sites (squares). Later cut out means later crop maturity.

The timing of cut out (resources permitting) balances the opportunity for further fruit production with potential losses in fibre quality and harvesting difficulties associated with too late maturity.

The timing of cut out is important to:
• Avoid adverse weather conditions at picking,
• Ensure defoliation practices are effective to reduce trash,
• Avoid instances where there are too many immature bolls at harvest that may increase neps,
• Optimise yield.

Management tips:
• Monitor cut out at least weekly using the Nodes Above White Flower (NAWF) technique. NAWF = 4 is generally the accepted time of cut out.
• Use the CottASSIST Crop Development Tool to assist you to track your crops rate of cut out compared with the optimal rate.
• Crops approaching cut out too rapidly are stressed (either not enough water or nutrition or carrying a very high fruit load). So use a strategy to provide new growth such as irrigation or nutrition.
• Consider how much time is left in the season. This can be done by estimating the date of the last effective flower (See table below). This can be determined through the CottASSIST Last Effective Flower Tool. This tool can be used to select your own data using your nearest weather station.
• Crops approaching cut out too slowly can indicate that there has been a loss of fruit and/or plenty of water and nutrition. These crops should be monitored to determine if a growth regulant is necessary. Use the CottASSIST Crop Development Tool to check your VGR.

Table: Average dates for the last effective flower for various locations for different times when crops are expected to finish. These have been calculated by the CottASSIST Last Effective Flower Tool (www.cottassist.com.au) using historical climate data since 1957.

Average target date of your last effective flower

Date when you want your crop to be finished (Date of last harvestable boll)

Town 1st March 15th March 1st April 15th April 1st May
Jerilderie 30th Dec 11th Jan 22nd Jan 30th Jan 5th Feb
Griffith 31st Dec 12th Jan 24th Jan 31st Jan 7th Feb
Hillston 5th Jan 17th Jan 29th Jan 5th Feb 12th Feb
Warren 6th Jan 18th Jan 29th Jan 6th Feb 13th Feb
Bourke 13th Jan 25th Jan 6th Feb 15th Feb 22nd Feb
Walgett 11th Jan 22nd Jan 4th Feb 13th Feb 20th Feb
Wee Waa 8th Jan 20th Jan 2nd Feb 10th Feb 18th Feb
Gunnedah 4th Jan 16th Jan 29th Jan 6th Feb 14th Feb
Spring Ridge 31st Dec 12th Jan 24th Jan 1st Feb 9th Feb
Moree 8th Jan 20th Jan 2nd Feb 11th Feb 20th Feb
Mungindi 11th Jan 23rd Jan 5th Feb 14th Feb 22nd Feb
St George 12th Jan 24th Jan 6th Feb 15th Feb 23rd Feb
Goondiwindi 8th Jan 20th Jan 2nd Feb 11th Feb 19th Feb
Dalby 2nd Jan 14th Jan 28th Jan 6th Feb 15th Feb
Theodore 9th Jan 21st Jan 5th Feb 15th Feb 25th Feb
Emerald 11th Jan 24th Jan 7th Feb 18th Feb 28th Feb

By Bob Ford, Extension & Development Agronomist – Namoi Valley