The Farmers' Union of Wales is urging farmers to work together over the coming weeks in a concerted effort to reduce incidences of sheep scab.
Lorraine Howells, Chairman of the FUW's Common Land Committee, said: "At this time of year many farms are preparing to treat their sheep for scab.
"However, failure to treat animals at the same time as your neighbours can mean animals becoming reinfected, because the mites which cause the problem can be transferred by direct contact with infected sheep or objects."
Miss Howells said that failure to coordinate treatment in an area could result in a great deal of wasted time and money.
Sheep can be treated by either dipping or injection.
"We fully recognise the concerns which exist in relation to dipping and the withdrawal period following treatment. However, scab can be a major animal health and economic problem, and it is important that we do all we can to eliminate the disease."
Miss Howells also urged commoners to work together to ensure flocks on open mountains are treated.
"Scab can be a great problem on open land, and many graziers work closely together to ensure that commons and open land are cleared and animals treated at the same time.
"Graziers must continue to clear commons at the same time, and if this does not already take place, they should come together in order to coordinate this type of action."
Miss Howells added that no animals should be returned to a common after clearance without being treated.
Further information on sheep scab can be found on the Hybu Cig Cymru website (http://www.hccmpw.org.uk) under the animal health and welfare section.