More than half of 40 trees lining a road between Mrieħel and Santa Venera have wilted and appear to have died, three months after they were planted.
Two environmental experts told Times of Malta that the withered Aleppo Pine saplings along L-Industrija Road have probably died.
But Infrastructure Malta says they may only have 'leaf scorch'.
PN candidate Clifford Zahra Fenech shared pictures of the saplings on Facebook on Friday, claiming that 20 are dead.
Environmentalist and former MEPA assistant director Alfred Baldacchino said there is "no doubt" that they are dead.
"These are imported trees, that are forced fed in glass houses, and then are put in harsh conditions in the environment which they cannot survive," he said.
Sandro Lanfranco, the head of the university's Biology Department also said that the trees in the picture appeared to be dead.
"They are wilted, brown and the soil appears to be very dry," he said. "If they are not dead, they are not in a healthy environment and are suffering."
He said that such species are common in Malta and can tolerate high temperatures, yet saplings need more care and attention.
"A saplings root system is still not fully developed and without regular watering and the symbiotic fungi to help the roots grow, the young tree struggles to grow and gets less nutrients."
Investigation ordered
Infrastructure Malta said an independent arborist had been asked to investigate.
"Allegations that the trees died are not confirmed since most probably the dried needles are a sign of leaf scorch," a spokesperson said.
He said that 40 pine trees, along with another 26 palm trees and over 500 shrubs were planted in May.
The agency has asked the contractor to check why the trees have dried up, despite each tree getting between 90 to 120 litres of water per week.
Infrastructure Malta estimated that the watering and upkeeping of trees, uncluding pruning, staking and cleaning is estimated to cost an average of €24 per tree, every year.
The amount is estimated higher during the first year after a tree is planted as it requires more frequent watering.