Barley growers across the southern region should remain vigilant when it comes to monitoring their crops for foliar diseases this season, especially if new varieties have been sown.
The variety of barley grown has a significant influence on disease risk factors and with large areas planted in 2018 to the new barley variety RGT Planet, there could be a higher risk of net form net blotch this season, according to SARDI crop pathologist Hugh Wallwork.
Dr Wallwork said NFNB was a barley disease to be wary of this season while spot form of net blotch and scald, were likely to be an issue in medium and high rainfall areas.
He also said leaf rust was a lesser risk than usual owing to the lack of volunteers throughout summer.
NFNB is known to occur more often in higher rainfall areas, while SFNB can be an issue in marginal areas where there is often barley in cropping rotations.
“For growers in SA’s Mallee, SFNB is likely to be a common issue but, in the Lower North, Mid North or South East of SA then NFNB is likely to be a bigger problem,” Dr Wallwork said.
He said growers should look for blotches on the leaves early in the season and recommended monitoring any new varieties closely.
“Once these foliar diseases become established they can be quite hard to rein in,” Dr Wallwork said.
Growers need to be vigilant in monitoring barley crops when conditions are conducive to disease infection.
The latent period of these two diseases, when the inoculum has entered the crop before visual symptoms are identifiable, can help growers know the urgency of spray application.
SFNB has a 14 to 20-day latent period and NFNB has a 10-day latent period.
“Growers have to start monitoring from the time they begin applying herbicide sprays,” Dr Wallwork says.
“If a disease is established then it is important to consider applying a fungicide early in the epidemic’s development. Once it gets into the lower canopy of the crop, it is hard for chemicals to then get control on those older tissues,” he said.
Dr Wallwork believed an early spray was best to get on top of disease and he said trials had also shown seed treatment with fluxapyroxad was highly effective.
