Blotch on crop horizon

Wheat farmers in the Wimmera need to be on the lookout for a fungus which potentially could strip half their wheat yields.

Septoria tritici blotch has already been reported in Wimmera wheat crops and Agriculture Victoria cereal pathologist from Horsham, Dr Grant Hollaway, is urging growers to inspect their crops.

“Septoria was common in the Wimmera in low levels in 2016 and this has provided the carryover of inoculum for 2017,” Dr Hollaway said.

“Given repeated wet conditions which are favourable for the disease, septoria can cause losses greater than 50 per cent.”

Dr Hollaway said growers should look for symptoms on older leaves and fungicide control needs to be considered when septoria is found.

Symptoms growers should be looking for are pale grey to dark brown lesions which contain black fruiting bodies.

The Grains Research and Development Corporation has noted that long periods of leaf moisture are required for disease development. Early sown crops and crops sown into wheat stubbles are at most risk, however the disease has an early airborne component and all wheat crops should be scouted for symptoms.

To manage septoria growers should be spraying at early stem elongation (growth stage 31-32) and follow up with a second application at flag leaf (growth stage 39) if necessary. Dr Hollaway said the timing of fungicide application and choice of fungicide were both important in managing this disease

“Because of increasing levels of resistance to fungicides in the Septoria tritici blotch population in Victoria, it is important that the same active ingredient is not used more than once in any season,” he said.

“Where possible apply fungicides that contain a mix of actives. Growers are reminded to always read the chemical label and only use as directed.”

Adoption of an integrated disease management approach which includes crop rotation, selection of resistant cultivars and if necessary, the application of fungicides were noted by the GRDC as the most effective management tools.

More information on the fungus can be found at the GRDC website.

Source: Agriculture Victoria