Grains challenges and opportunities flow from summer rainfall

Author: | Date: 02 Jan 2019

Significant summer rainfall in some areas is presenting southern region grain growers with a fresh set of agronomic challenges and opportunities.

Significant summer rainfall in some areas is presenting southern region grain growers with a fresh set of agronomic challenges and opportunities.

Summer weed control, preserving precious soil moisture, sprouting grain, storage of high moisture grain and retaining weather-affected seed for sowing will be front of mind for many growers.

Recent heavy rains in some areas will provide valuable soil moisture for the 2019 cropping season, but only if summer weeds are kept in check.

Grains Research and Development Corporation (GRDC) research investments have shown that early summer weed management can significantly boost water use efficiency, crop establishment and yields, herbicide efficacy, pest and disease control, nutrient availability and overall grower profitability.

GRDC Grower Relations Manager – South, Randall Wilksch, says managing summer weeds at the earliest opportunity will generate the greatest dividends.

“We know that herbicide efficacy is generally highest when summer weeds are young and actively growing,” Mr Wilksch says. “Uncontrolled weeds also rob the soil of moisture and nitrogen, depriving following winter crops of precious reserves.”

Mr Wilksch says an important benefit of eliminating summer weeds and volunteer cereals (known as the green bridge) is reduction of the habitat which harbours pests and diseases between seasons, potentially reducing winter crop performance.

More information on the importance of summer weed control, the latest research on problem weeds in the southern cropping region and advice on spraying – including tips for minimising spray drift – is included in the GRDC GroundCover™ Summer Weeds Supplement, available at

Growers are reminded to adhere to best practice when spraying summer weeds to reduce the risk of off-target spray drift and to be aware of new restrictions to the use of 2,4-D.

The Australian Pesticides and Veterinary Medicines Authority (APVMA) suspended the labels of all products containing the active ingredient 2,4-D from October 4, replacing them with a permit.

Key changes for using 2,4-D under the permit include: applicators must now use at least a Very Coarse (VC) spray quality; when using a boom sprayer, boom heights must be 0.5 metres (or lower) above the target canopy; and downwind buffers now apply (typically less than 50 metres, subject to rate and product being applied) between application sites, downwind sensitive crops and environmentally sensitive aquatic areas.

Grain growers and spray operators can access a practical guide explaining how to maintain efficacy when using coarser spray qualities in line with new restrictions to the use of 2,4-D. A ‘Maintaining efficacy with larger drops’ fact sheet, available at, has been developed by the GRDC to assist industry understand the on-farm implications of the new restrictions.

For more information about best practice spray application go to

Meanwhile, wet conditions just prior to or at harvest can result in grain that has sprouted. The degree of sprouting depends on the duration and number of rain events and the conditions immediately after the rain.

Sprout-damaged grain has a severe impact on end-product quality, which is why it is so important for grain to be tested at grain receival depots.

Blending is not recommended as a method of reducing the impact of sprout damage when grain is to be graded. Blending sprouted grain can spoil good quality grain, according to the GRDC-supported Australian Export Grains Innovation Centre.

More information on the impact of sprout-damaged grain is outlined in a GRDC GroundCover™ article available at

Mr Wilksch says recent wet weather through parts of the southern region could also impact on the viability of grain that growers are planning to retain for sowing in 2019.

“Growers should closely scrutinise seed being set aside for planting because grain subjected to wetting at harvest is more susceptible to poor germination, low vigour and degradation during storage and handling,” he says.

“Determining whether damage to grain caused by rain at harvest is purely cosmetic or the symptom of a seed-borne disease which will impact on germination is important,” Mr Wilksch says.

To assist growers in determining whether grain is viable for sowing and what is an appropriate and effective seed management program, the GRDC offers a detailed Retaining Seed Fact Sheet, available at

Mr Wilksch says heavy rainfall is also likely to result in growers paying increased attention to stored grain.

“High-moisture stored grain can lead to mould and insect growth, so growers are advised to take prompt action to avoid damage.”

Grain at typical harvest temperatures of 25-30°C and moisture content greater than 13-14 per cent provides ideal conditions for mould as well as insects. Monitoring grain moisture and temperature daily will enable early detection of mould and insect development.

More detailed information on how to manage high moisture grain in storage can be found in the GRDC Dealing With High Moisture Grain Fact Sheet at and in the GRDC Grain Storage GrowNotes™ at

Further information on grain storage best practice is available from the GRDC’s Stored Grain Information Hub at and via the GRDC Communities Stored Grain web portal at

Contact Details

For interviews

Randall Wilksch, GRDC
0437 769098


Sharon Watt, GRDC
0409 675100

GRDC Project code: CSP00111, CSP00208, BGC00003, ICN00012