Grains Research and Development

Date: 01.09.2002

Controls against the blotch

Resistant varieties

this was the main form of control. But with the fungus population changing, the resistance of some varieties has been reduced and researchers will have to re-evaluate the resistance levels of the different varieties.

Clean seed

the disease may be spread on stubble or seed. Clean seed is required to minimise infection of new paddocks. Treating seed with thiram will minimise disease carryover. In these situations thiram should be used in conjunction with other seed fungicides to control powdery mildew.

Rotations and stubbles

most inoculum survives in stubbles, and from there spores are carried by wind to infect crops in other paddocks. Paddocks located close to infected stubbles will receive more inoculum than those more distant. Crop disease levels will therefore be higher in districts where barley crops are grown in close rotation.

Time of sowing

early sowing favours development of the disease, but growers should weigh up other agronomic risks before changing sowing date for this reason.

Foliar fungicides

foliar fungicides that use the active ingredient propiconazole (Tilt, Bumperi", Aurora, Tyrant) are the most effective products currently available. Trials are planned to determine the level of control they provide and identify products for registration.

Crop pathologists would not like to see an increased reliance on foliar fungicides and are keen to emphasise that fungicides must not be seen as a substitute for growing varieties that are more resistant.

Region North, South, West