It's crunch time for canola farmers in southern Australia.

They need to decide whether to hold out for rain to ensure a decent grain crop, or cut their losses and opt for hay, or silage instead.

A lack of rainfall is the most immediate concern, but many have also struggled with frost and Beet Western Yellows Virus.

There haven’t been many winners.

Some farmers, including most in the south east of South Australia, avoided the canola virus, but only because they missed out on rain earlier in the season.

The dry start to Spring has therefore hit them much harder.

Others started a perfect season with plenty of rain in February and March followed by a warm May; conditions that also enabled pests and disease to flourish.

Throw frost and poor prices into the equation and it’s no wonder the Australian Oilseed Federation (AOF) predicts a 20 per cent decrease in the amount of canola planted in 2015.

Cutting for hay and silage provided some relief for canola farmers during the 2006/ 07 drought, with many using it as an alternative to expensive feed sources.

AOF vice-president Trent Potter says farmers need to figure out whether a below average grain crop will be worth more than high quality hay.

"It’s the time people would need to be making a decision," he said.

"As the crops just get to the end of flowering the quality for hay or silage decreases, you get less protein [and] lower digestibility.

"In the south east one reasonable rain would help change things around so I think it’s probably a pretty difficult decision for people to make at the moment."

Mr Potter says up to 85 per cent of plants in mid-north SA were affected in some way by Beet Western Yellows Virus.

"It’s had a huge effect," he said of the virus.

"All those crops, the guys were letting them sit there at the moment and hopefully finish off.

"It was going to be a matter of how much damage winds did on Saturday and Sunday but I think most are being left to be harvested for grain."

Source - http://www.abc.net.au/