Members of Western Australia's agricultural industry are frustrated by trespassing visitors trampling plants and potentially spreading disease and pests in their quest for the perfect canola crop photograph.

Posing for a photo in a flowering crop has become popular in recent years, with thousands of posts appearing on social media sites.

The Avon Valley, which is about 100 kilometres from Perth and includes the shires of Northam and York, has become a hotspot for thousands of visitors every week looking for the perfect snap.

But visitors are not always welcome everywhere they want to go.

Some farmers said they dread this time of year as they often found tourists wandering their paddocks without permission.

The Department of Primary Industries and Regional Development has encouraged visitors to enjoy the view from the road reserve and avoid moving from paddock to paddock.

Grains biosecurity officer Jeff Russell said people were not always aware of the risk they were taking — for the plants and themselves.

"The danger is that if they are going from paddock to paddock to get that perfect photo, they themselves could be transporting weeds and maybe soil-borne pests on their vehicles from paddock to paddock," he said.

"It is not exactly what the farmers are wanting at this time of year.

"You don't know if that paddock has been sprayed with a pesticide. Especially with the weather warming you have got aphids coming out and farmers do one or two sprays of a pesticide to keep them in check.

"If you're wandering into that paddock you don't know what effects that may have on you."

Photos in flowering canola crops have become more popular amongst tourists in recent years. ( ABC Mid West and Wheatbelt: Jessica Hayes )

Local governments and businesses in the region are working to balance the benefits of increased visitor numbers with the concerns of canola growers, and safety issues caused by cars parking unsafely on the road reserve.

Local business owner and volunteer with the York Business Association, Joanna Bryant, said the mascot Yorkie the yellow bear had been created — as had printed multi-language fliers and signs for visitors.

"It is not a huge angry do not enter sign, it's quite pretty and it has got canola flowers on it, and it says in four different languages please look, but please do not enter, please don't climb our fences, please don't tread on the flowers, but you are welcome to look," Ms Bryant said.

The Shire of York and local Business Association has printed multi language fliers and signs for visitors. ( Supplied: York Business Association )

Another strategy was to sow specifically for visitors.

For the first time last season, local tourism operators Pam Sealey and Kevin Johnson planted two hectares of canola on their hobby farm specifically for visitors to photograph.

"When we plant our field for display, we know that they want to take their photograph in it so we're quite happy for them to walk through it, lay in it, take photos, whatever they want to do."

"They can sit in it and touch it and take their pictures and they loved it."