Scientists should know in six months whether 14 Norfolk pines along Mount Maunganui beach can be saved.
The trees, thought to be suffering from a pathogen in the soil, are being injected with agri-chemical phosphite by scientists from crown research institute Scion this week.
Twenty-one trees are being treated. Fourteen are actually sick and seven are being used as a control for Scion's research.
Tauranga City Council arborist Richard Conning said Scion would review the trees in six months and would then be able to give a good indication of whether the trees had improved.
Mr Conning said the project was funded entirely by Scion and the results would also be used to treat trees in a similar condition in Gisborne.
"It's all coming to a head this year because of the drought. That just stresses the trees out and allows the pathogens to attack the trees more effectively." The treatment will be kept up for two years.
"We're also applying fertiliser to grass areas, which improves the soil's ability to retain moisture and transfer nutrients to the trees. We're also looking at the watering regime throughout summer."
Mr Conning said the chemicals used in the treatment were not harmful to humans and would be buried deep inside the trunks.
Mount Maunganui Progressive Association chairman David Burnett said the pines were a part of Mount Maunganui's identity.
"If they have to be cut down, and if they are diseased beyond repair, they should be cut down.
"The community will feel sad about it, if that's how it has to be. You can't make a tree live if it doesn't want to live."
Scion science leader in pathology Rebecca Ganley said she and her colleagues had been unable to find a single cause of the trees' deterioration.
"We suspect it is a complex combination of pathogens and site disturbances following on from the severe drought conditions earlier in the year."
Treatment began under city council supervision yesterday.