Given the benefit of sunny, warm weather during the next month, Central Queensland cotton growers are quietly optimistic that they will be able to record average yields this season.
This is despite the 2008-09 Central Highlands planting of 12,000 hectares of irrigated cotton being subjected to prolonged cloudy, wet weather and a 125mm deluge on February 17.
Department of Primary Industries and Fisheries and Cotton CRC cotton extension officer, Susan Maas, said that with harvest due to start in early March, it was difficult to assess wet weather yield losses attributable to boll rot and tight lock or the damage caused by Helicoverpa caterpillar survivors identified in late December Bollgard II cotton crops.
With plans to start defoliating their 228ha crop of Bollgard II Flex from February 22, Andrew and Julie Geddes and their son Cameron have set an enviable benchmark for consistent production of quality cotton during the past 30 years.
The Geddes family describe themselves as committed cotton growers who grow cotton every year on their Emerald Irrigation Area (EIA) holding, Laikipia.
Andrew Geddes said that unlike last season’s restricted cotton planting influenced by severely restricted water availability and low cotton values, this season’s cotton plant had the benefit of a 100pc Fairbairn Dam water allocation.
"We are also working in conjunction with CSR on a cotton nutrition trial based on a pre-plant application of biodunder, a by-product of the distillation of molasses that produces ethyl alcohol at CSR Ethanol’s Sarina Distillery," Mr Geddes said.
"A standard rate of urea and phosphous fertiliser was added to the potassium-rich liquid biodunder and the mix was applied across the whole farm at a rate of 2.7 cubic metres/ha.
"The concept is that the fertiliser mix in liquid form will make the nutrients more readily available to the cotton plant and lift plant performance and cotton yield."
Mr Geddes said a limiting factor based on current cotton market value would be the cost of transporting big volumes of biodunder from Sarina to the Central Highlands.
This season, Mr Geddes was one of the first EIA growers to alert Monsanto that there were medium to large Helicoverpa caterpillar survivors in Bollgard II which resulted in significant boll damage in late December.
"We opted to aerial spray to protect the crop from further damage," he said.
Mr Geddes said they encountered a similar problem at exactly the same date, December 24, in their 35ha Bollgard II crop in 2007-08 and opted to spray as a precautionary measure.
Ms Maas said surviving larvae had been collected and tested from multiple EIA farms this season but there was no evidence of Bt resistance.
"One theory put forward is that at the peak flowering stage, there could be a dip in expression of the plant gene conferring the toxin," Ms Maas said.
Further research on the thresholds for Bt susceptible Helicoverpa survivors in Bollgard II was being undertaken this year by University of New England and Cotton Catchment Communities PhD student Boaqian Lu.
Mr Geddes said he remained a firm advocate for Bt technology which was a far better option to pesticide spraying.
This year the cotton was sprayed early in the season to control mirids and on January 1, a build up of silver leaf whitefly was effectively controlled with an aerial application of Pegasus.
The Geddes family invested in an irrigation water management project in 1993 that had cut water use by 30pc annually thanks to a tailwater recycling system incorporating 150Ml of on-farm storage in three ring tanks.
Water use efficiency was further enhanced in 1998 with the installation of 35ha of drip line irrigation on sandy loam country unsuited to syphon furrow irrigation. Drip lines had reduced the irrigation output by 0.75Ml/ha with minimal labour input.
Mr Geddes said because of the limited water availability, the 35ha drip line paddock was the only cotton sown in 2007-08 and ironically this crop was inundated for a week in 30cm of water by record January floods from the Nogoa River.
"Although we lost all the lower bolls, we picked close to 6.2 bales/ha from this flooded crop and received a premium for the high quality cotton," he said.
To take advantage of attractive grain prices in 2007-08, Mr Geddes has successfully double-cropped wheat followed by an early January-sown sorghum crop harvested in June and replanted to cotton in September.
Mr Geddes said that where chickpeas were sown in the rotation, the soil moisture was severely depleted and the follow-up cotton crop had not performed quite as well.
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