A fungal disease has hit long-suffering Australian wine regions and is likely to drive more growers out of business. Humid weather and heavy rainy has hit inland Australia, particularly in the Riverland and the Riverina regions, causing widespread downy mildew problems. Premium regions including the Barossa and Hunter Valley are now threatened. The outbreak has been made worse by a shortage of chemicals to treat the diseases. Demand for the fungicide that eradicates downy mildew, Ridamil, has soared and chemical companies have been caught napping. Ashley Ratcliff of Yalumba says 'Large stocks are not available because these areas have been in drought for a lot of years and there was little demand. The chemical companies are now madly trying to keep up with demand.'