There is now a fungicide registered for post emergent treatment of blackleg in canola. Prosaro is registered at 375ml ($26/ha) to 450ml ($32/ha). Application timing is at the 4-6 leaf crop stage.
Promotional material claims an average yield increase of 200kg/ha from the 375ml rate, compared to an untreated control in varieties with low resistance ratings under high disease pressure situations.
Blackleg is most effectively managed by growing varieties with resistance ratings of MR or better, with a separation from last year’s canola stubble of at least 500 metres.
Applying appropriate fungicides as either seed or fertiliser treatments will decrease disease risk in varieties rated lower than MR.
Before applying Prosaro, consideration needs to be given to the extra risk associated with such a cost. There are many factors other than disease which can limit canola yields, so the notion of increasing cost of production to chase elusive and sometimes marginal extra yield should be questioned.