For people travelling out of Western Australia across the Eyre Highway (Nullarbor), the quarantine checkpoint is at Ceduna. If you are travelling into Western Australia the quarantine checkpoint is at the Border Village (WA/SA) state border.
For people travelling to South Australia, make sure you eat your fresh fruit and vegetables before you get there! You will not be allowed to take any fresh produce (fruit & veg) through. Good news! You can keep your honey! and the Esperance Visitor Centre stocks locally made honey. Soil is another issue, if you are taking any plants through, check at the border village and ask for assistance.
To South Australia from Western Australia
Fruit and Vegetables - There are pests in Western Australia of fruit, fruiting vegetables (including tomatoes, leaf vegetables and potatoes that are not present in South Australia. Conditions and treatments may apply however; most types of fruit and vegetable are prohibited.
Plants - Rooted plants grown and transported in a soil free medium (potting mix) or bare-rooted may enter South Australia if they are free of pests and diseases, and certified as being grown more than 25km from a green snail outback or from an accredited nursery.
Hay and Fodder - Hay and Fodder is prohibited if grown within 25km of a green snail outbreak. From outside this area, certification is required.
Packaging and Branding - Any packing (package) of fruit, plants or other applicable goods must either be new, or if used, free of soil, plant residues or other organic matter.
Soil - Soil required for scientific or commercial purpose must not enter South Australia if it was collected north of a line through the town of Bunbury.
Livestock - Livestock entering South Australia must have a health certificate from an inspector.
The above details apply to Western Australia from South Australia except no honey is to be brought in to Western Australia.