These canola crops in the Eudunda area of the Lower North in South Australia were infected with BWYV at the rosette stage. SARDI pathologists and entomologists first visited them in on the 17th of June.
In late June the young plants initially dropped all leaves and then started to re-shoot so some of the farmers optimistically retained these crops hoping they would grow out of the problem.
The photo (right) shows that these crops have only developed to the rosette stage again and are not progressing much further. It is doubtful that there will be anything to harvest.
Our initial estimates stand that up to 5,000 ha in this region has been affected to this level.
A number of crops were sprayed out and replanted with barley. There are individual crops in other regions of SA that are also affected to this degree, while many canola crops in SA appear to have been infected at a later stage, and these display the reddening/yellowing of leaves but are progressing through flowering. It will be difficult to quantify the impact that this will have on yield.
Further research has been funded by GRDC and SAGIT funds.