Farmers are being warned to take extra precautions when moving stock this year because of a recent outbreak of the destructive plant disease myrtle rust.

Moving Day is occurs around June 1st every year, and biosecurity is front and centre. There has been 20 confirmed cases of the destructive plant disease myrtle rust in the North Island. Sixteen properties in Taranaki, three in Northland, and one in Waikato all have infected plants.

Myrtle rust is a significant disease of plant species from the Myrtaceae and has been spreading rapidly around the world in recent years.

Waikato Regional Council's pest plants team leader Darion Embling believes farmers have the most important role to play in preventing the spread of pests such as myrtle rust and velvetleaf.

"They've got a lot to lose if they get it wrong," he said.

"I think they've got a big part to play, making sure things are clean when they leave, asking the questions around where has all the gear been before it arrives at their farm."

Embling says precautions need to start at the farm gate, with farmers making sure that all machinery - including quads and utes - is clean before they go.

Many common garden plants are members of the myrtle family and any new growth is susceptible, so people are being asked to carefully examine the underside of new leaves in Lily-Pily (Eugenia), bottlebrush, mānuka, gum, guava and feijoa, especially if they are recently purchased plants from nurseries or ordered online.

Any suspected signs of myrtle rust can be reported to MPI's Exotic Pest and Disease Hotline on 0800 80 99 66, which has received well over 450 reports of suspected symptoms.