When Gouldiae also commented on canola it was time to investigate.
The go-to organisation for crop forecasting is ABARE (if you wish to check detail you might have to search that site a bit as I did). Note that the data for 2011-12 was calculated by me from 2012-13 numbers and % change.
Here is the data (Click to get a readable version):
Both correlation coefficients are pretty good so I am inclined to say that the apparent increase - at least in the medium term is real. Although cotton is drooping a bit compared to the previous two years. Presumably the continued increase in canola reflects the tough climate in the US this year.