Large recent rainfall events (November 15-16, 2017) across the Wimmera and Mallee may pose a sprouting risk in cereal crops, particularly if further rainfall events occur in coming weeks.
Rainfall amounts as high as 95mm were reported in the Northern Mallee and variations of between 30 and 50mm in the Wimmera and West Wimmera. Climate models are currently predicting a strong chance (70%) of a weak La Nina over the summer period, increasing the likelihood of rainfall during harvest.
The risk of sprouting can increase significantly with large and prolonged rainfall events (cumulative days of wetting of the crop), preventing the crop canopy from drying out quickly.
Sprouted grain in malting barley can lead to a decreased ability to germinate during the malting process, resulting in undesirably high levels of beta glucan. In wheat, it can reduce the flour/baking quality.
Additionally, grain that has sprouted is not suitable for malting or sowing the following year because of lost seed viability, reduced capacity for long storage time and decline in feed value.
BCG researcher Linda Walters said there was significant damage to cereal crops in the Mallee in 2010 as a result of large amounts (150mm) of rainfall during harvest. This rainfall provided a conducive environment for sprouting to occur, as rainfall fell at regular intervals resulting in a prolonged moist canopy as well as humid conditions.
“Varieties can differ in their tolerance to pre-harvest sprouting and are influenced by factors such as the amount, timing and duration of rain events, environmental conditions, architecture of the plant and seed dormancy,”
BCG conducted barley and wheat (one year) trials in 2014 and 2015 at Wemen (Northern Mallee) under overhead irrigation sprinklers to simulate rainfall events at harvest. The trials included three different harvest timings and three different water treatments (combination of actual rainfall and irrigation).
Ms Walters said falling numbers and grain quality were tested on six malt (or pending malt accreditation) varieties and seven wheat varieties. A falling numbers value below 300 seconds is unacceptable for malt barley and hard wheat.
“The trials concluded that Scope CL barley is the most tolerant variety to sprouting, falling number values were the highest amongst all barley varieties,”
“Spartacus CL, La Trobe, Commander and Hindmarsh were the most susceptible to sprouting (low falling numbers) when subjected to wet weather at harvest and in favourable conditions. Grain quality (test weight and retention) also reduced.”
BCG research concluded that there was no difference in the susceptibility of wheat varieties to sprouting in this trial. In the 2010 season, the wheat variety Kord CL showed sprouting susceptibility under very favorable conditions, however, in this trial it was no different to any other variety.
The barley showed a greater susceptibility to the wheat, and in severely lodged plots were also more prone to sprouting, as extra moisture is likely to be retained in the canopy for longer, providing a humid, moist environment suitable for sprouting to occur.
Prioritising barley at harvest time, and those varieties more prone to sprouting is important to reduce the likelihood of losing grain quality. Furthermore, barley is susceptible to head loss and lodging that will occur from significant rain events.
With a large harvest operation, best management is to ensure timely harvest of susceptible varieties such as Spartacus CL, La Trobe, Hindmarsh and Commander to mitigate the likelihood of sprouting.
BCG’s barley research has been carried out through the GRDC-funded ‘Barley agronomy for the southern region’ project (DAN00173).
This article was published in the Stock and Land, 30 November.
