RAIN combined with a total fire ban across the grainbelt this week slowed harvest while large deluges in the Great Southern could see some crops damaged.
The Bureau of Meterology (BOM) recorded rainfall across most parts of WA's south west earlier this week, with the Great Southern the heaviest hit.
Kojonup recorded 30mm, Darkan 26mm, Broomehill 21mm and Katanning 15mm, although Farm Weekly understands farms in the Broomehill area recorded up to 69mm.
Broomehill farmer Damien Boyle said his farm had 69mm, while another farm north of Broomehill recorded 65mm.
He said the deluge had flattened his oat crop, which had been yielding between 4.5 and 5 tonnes per hectare before the rain hit.
"It came out of nowhere - BOM were still predicting a 90 per cent chance of 1-5mm and we thought we were going to be okay, but then it hit," he said.
Mr Boyle said he was also concerned that it could cause staining in the remaining barley that was yet to be harvested.
In Kojonup, Rob Warburton recorded 32mm on his property and said he would wait and see if there was any damage or issues once the crop dried.
In the central Wheatbelt, York recorded 11mm, Beverley 16mm and BOM's Yangedine station north of Beverley recorded 18mm.
York grower John Seabrook said his farm received 9mm on Sunday night with a further 3mm on Monday.
"Fortunately we had finished on Saturday just as the fire ban kicked in, so it was a relief not to have to deal with the rain as well," he said.
Elders Albany agronomist James Bee said while he did not expect a lot of crop damage, growers should keep an eye on staining in cereal crops.
He said clients in the South Stirlings area had more than 30mm in the gauge and many were taking the opportunity of the break in harvesting to drench sheep.
"It's not good and it is a bit of a kick in the teeth for the guys who have also been hit with frost but if it warms up quickly then hopefully it shouldn't be too much of a problem," he said.
"However fungal staining and wheat sprouting could become an issue."
He said the rain could also mean a big flush in summer weeds and growers in the south should consider an early summer spray before the end of the year.
A CBH spokesperson said the co-operative would increase monitoring of falling number results based on harvest running samples.
She said CBH was well-placed to manage sprout damage with an extensive fleet of falling number equipment ready for full deployment if required.
"Over the coming days we hope to gain an understanding of the impact the recent rainfall has had across the State on wheat quality," she said.