A few weeks back, on Dec 7, I took this picture on a roadside pongpong tree ( Cerbera odollam ). Looks pretty weird that the entire stretch of pongpong trees along the road had these bumps. I emailed prof Tan who helped me consult his friend at Nparks.
"Pimples on pongpong trunk"
Heres the reply; apparently its nothing to be a cause for concern and no definite answers for its appearance.
"Such structures are not limited to Cerbera odollam . You can see them on Samanea saman (rain tree), Swietenia macrophylla and quite a few of our common roadside trees. From experience, they are often associated with epicormic growth (mainly, they are points where water shoots proliferate). I suspect that they may be just "callus like" tissues which have not decide what they should be, probably due to hormonal imbalances?"
"We do know they are not indicators of internal rot or other structural inadequacies or anomalies. They also do not appear to give any added information on possible adverse tree health and is unlikely the result of pest attacks. As such, we have not dedicate much effort to elucidate the Reasons behind the structure. "
