Source: GRDC Crop Doctor

Greg Platz won’t go along the suggestion that barley is a “disease sucker”. The reality, he  says, is that diseases are the exception rather than the rule in northern region barley crops.

Mr Platz  says several factors led to the “disease sucker” tag, particularly  leaf spot epidemics in 1998, when “very susceptible” barley varieties were devastated by a combination of exceptional circumstances.

As well, he says, there are a number of barley varieties still in the system that are very susceptible to some diseases, while the crop itself responds to a number of stresses by developing dark spots on leaves which can be mistaken for disease lesions.

Mr Platz leads the foliar pathology component of the Grains Research and Development Corporation’s (GRDC’s) Strategic Initiative “Barley improvement and industry development”.

He’s based at the Queensland Department of Primary Industries and Fisheries (QDPI&F) Hermitage Research Station outside Warwick.

The component provides support for resistance breeding and marker discovery through  assessment of genotypic response to endemic and exotic diseases of barley, as well as ,  research into target diseases and their control.

The aim is improved disease control in barley through genetic, chemical and/or cultural strategies.

“We are working hard to deliver new varieties with good resistance to all the major diseases of the northern region but, in the meantime, alternative disease control strategies can be very effective,” Mr Platz says.

“Prevention is better than cure with barley diseases and, because they are generally specific to barley and mostly stubble borne, rotations are an effective option for disease control.

“Ideally growers should aim to have at least two years between barley crops, allowing time for any diseased stubble to break down, and they should aim to sow in the appropriate planting window for their area. 

“Fungicides give good control of some diseases when applied as a seed treatment and/or a foliar spray, but three things are important when growers consider spraying – economics, accurate disease diagnosis and timing of application.

“Accurate diagnosis is important, and I fear some crops were sprayed with fungicides last year when they didn’t need it.”

Mr Platz said growers who saw black spots on barley leaves should not immediately assume they had net blotch. Some varieties could  develop dark leaf spots in response to unsuccessful powdery mildew infection.

Paddock history should be a guide and a couple of good GRDC publications – “Cereal Leaf and Stem Diseases” and a Ute Guide on the same subject – would help growers with diagnosis.