Defoliating figs may be stressed
By LEE McDOUGALL
JOHN Shaw admits he is 'scratching his head' in exasperation.
The Coffs Harbour City Council's city parks manager and his staff, are perplexed over the cause of the defoliation of fig trees in the city centre's Harbour Drive.
The council late Thursday received the results of test samples for triazine herbicides and phenoxyacetic acid herbicides, with the results being negative on both counts. The matter was raised for discussion at Thursday night's council meeting.
"At the moment, I am truly scratching my head," Mr Shaw said.
"We are working on this as hard as we can. There are high levels of magnesium iron but it is not significant enough to harm the trees."
While Cr Ian Hogbin raised the question of removing the trees in order to perhaps increase their survival rate, Mr Shaw said it was unclear if it was their current environment that was making them defoliate.
Cr Jenny Bonfield said that her 20-year experience with figs through Jenny's Plant Hire led her to believe that the trees were suffering from being water-logged, a term known as 'wet feet', and if 'pruned back' would probably refoliate.
Coffs Harbour arborist Nigel Smith said figs were known for defoliating when subjected to stress, whether it be too much or not enough water.
"Especially in a potted situation, which to a lesser degree exists in the soil where these trees are planted," Mr Smith said.
Mr Smith said the stress placed on the Harbour Drive trees was more than likely a change in oxygen levels in the soil immediately around the root zones.
"This, in effect, severely restricts the ability of the root system to fulfill its role of providing nutrients for the wellbeing of the canopy of the tree," Mr Smith said.
"The trees' first reaction is to shed its foliage. These trees have been planted in an area that over the years has been heavily compacted and provides minimal subsoil drainage.
"Root barriers have also been installed which also restricts water movement within the soil."
Mr Smith said that heavy rainfalls in January meant that the root systems of these trees were now probably immersed in water.
If this is the problem with the figs, the trees will refoliate once growing conditions improve.