April is Diego Bonetto's favourite month of the year.

The professional forager and wild food advocate usually spends his autumn days in the state forest in Sydney's south, picking mushrooms.

But this year he has been studying weather maps instead of the gills of fungi, as unusually hot weather and little rain has delayed the mushroom season.

"We're all just sitting here waiting for the weather to cool down and for the rain to come," Mr Bonetto said.

"It's been extremely late, the latest we can ever remember."

Diego Bonetto was born in Italy where mushroom foraging is an annual tradition. ( Supplied: Aimee Crouch )

The experience follows reports from the Bureau of Meteorology that Australia experienced the hottest March on record and parts of Sydney endured the hottest April day earlier this month.

April to early May is usually the peak time for mushroom foraging.

The species favour humid conditions and usually emerge after lots of rain.

However, the season is unusually late, said Mr Bonetto, who has had to cancel several of his foraging workshops which had been booked out for months.

Mushroom picking tips You must correctly identify your mushrooms. Don't pick any mushrooms other than saffron milk cap and slippery jack.

You must correctly identify your mushrooms. Don't pick any mushrooms other than saffron milk cap and slippery jack. Let someone know where you are picking mushrooms.

Let someone know where you are picking mushrooms. Be aware that timber harvesting is often carried out in the state forest.

Be aware that timber harvesting is often carried out in the state forest. The best way to clean mushrooms is to wipe them with a damp cloth.

The best way to clean mushrooms is to wipe them with a damp cloth. It is best to avoid the older mushrooms in favour of the young fresher ones.

It is best to avoid the older mushrooms in favour of the young fresher ones. The better areas for mushrooms are where pines are reasonably mature. Oberon Visitor Information guide



"There's been a few showings here and there, but no harvesting season of any description as yet," he said.

"We're all kind of a bit surprised and we don't want to say too much because we don't know, we just want to see what happens."

Mr Bonetto was born in Italy, where mushroom foraging was an annual cultural activity.

He exclaims when asked how self-picked mushrooms compared to those bought in a store: "Ahh, so much better!"

"The sweet taste of free food."

While foraging has spread in popularity with the rise of farmers markets and food advocacy, Mr Bonetto warned mushroom picking was dangerous if people did not know what they were looking for.

"First rule — if you don't know what you're doing, don't do it," he said.

"If in doubt, go without."

The Oberon Visitor Information Centre in the Blue Mountains recommends on its website that beginners only go foraging with an experienced guide.

Its brochures show pictures of saffron milk caps and slippery jacks which are the safest species to pick and eat.

Last year, 10 people became seriously ill after eating poisonous mushrooms such as death cap mushrooms and ghost fungi.

The safe-to-eat saffron milk cap mushroom can be identified by its reddish-orange cap, ribbed gills often spotted with green and cream spores. ( Supplied: Skye Manson )

What about plants?

The warm April weather has not only affected the mushroom season.

Dr Brett Summerell, mycologist and director of science at the Royal Botanic Garden, said plants growing in Sydney that normally favoured colder temperatures were yet to flower.

"Fruit trees, ornamental fruit trees like flowering cherries that need a period of cool weather to be able to flower in spring haven't started," Dr Summerell said.

"There's a potential that they will flower poorly or they might not flower at all."

Summer flowers are continuing to bloom in the April weather while spring flower growth has been interrupted. ( Supplied: Jaime Plaza )

Dr Summerell said growers were concerned that poor flower performance among food crops would deliver a poor production of fruit in the coming season.

The late blooms would also affect creatures that relied on nectar in flowers and trees for food such as possums, birds and bats.

"The changing climate will select out those species that are better adapted to it," he said.

"But the climate is changing faster than the rate of evolution and the rate in which plants react, so that has a negative effect.

"We have to be more clever with how we sustain our gardens, that our water use is directed right at the roots, and choose plants that can adapt to those changing conditions."