Mr MacLean said the virus would continue to spread for 12-14 weeks after release.
"Now is the time for land owners to plan secondary control for rabbits that they can carry out over winter. By then the virus should be well established, and winter is also the optimal season for rabbit control."
The K5 virus is spread from rabbit-to-rabbit contact and also through flies acting as a vector and Mr MacLean said landowners should not intervene.
"Human intervention can potentially result in rabbits becoming immune to the virus, so people need to be patient and leave any rabbit carcasses in place so the virus can take hold biologically.
"This not only gives the virus the best chance to be effective, but also means it will have a better ongoing impact for years to come."
Farmers who are noticing dead rabbits on their property should contact a biosecurity officer at ORC on 0800 474 082 so samples could be taken for testing.
ORC expected the virus to spread in a 20km radius from each of the 100 release sites throughout Otago over the next couple of months, which will cover the majority of the region.
Traditional rabbit management methods would not be replaced by the virus, and secondary control was important to keep rabbit numbers down.
• Information can be found on the ORC website at www.orc.govt.nz