Rather, according to City of Ballarat senior arborist David Grant, it is Ballarat's plane trees shedding their leaves in an attempt to cope with the hot and dry weather.

Mr Grant said the shedding response was typical.

"If there is not enough moisture to sustain the canopy, they basically shed leaves in response," he said.

"And even with adequate moisture, extremely hot winds and weather can see the trees shed leaves earlier than normal."

Mr Grant said last week's hot spell had had a big effect.

"The combination of dry ground conditions, and hot weather and winds last week, really knocked around a lot of trees, young and old," he said.

"To have a follow-up to that again isn't good.

"I would expect quite a few more trees shedding a lot more leaves and foliage and really showing some severe stress if this hot weather keeps up."

But the city's oaks, on the other hand, are coping much better.

"The oak trees have been pretty amazing," Mr Grant said.

"They are one of the few trees around Ballarat that really haven't shown many symptoms of being drought-stressed, which is good."

He said council continued to keep a close eye on them.

"Sometimes you do have to be a bit careful though, because they sometimes don't show any symptoms until they are actually dying," he said.

A sugary substance noticed on some oaks was aphids, which often fed on the foliage of the trees, Mr Grant said.

"They secrete this sugary, shiny substance on the foliage. Some years we don't get any and other years we get quite a bit," he said.

The only answer to giving the trees a bit of relief from the heat was water.

"But where you get the water from and how you apply it is a bit difficult," he said.

"We are doing a watering program down Sturt St at the moment as we've done in past years, and we are also doing some water injection work in Victoria St and at Bakery Hill.

"Any water you can get on any tree would be of benefit, but you really need a large volume of water to soak in slowly so it goes down deep."