Ashleah Smyth and her husband live in a small house near the orchard property.
Mrs Smyth said she was first alerted to the fire when she heard loud popping sounds followed by a "massive" loud explosion which caused her house to shake.
She said she was relieved when told that no one had been hurt.
Mr Pearce said at least eight fire appliances attended the blaze, with more than a dozen paid and volunteer fire fighters coming from all parts of the district.
The large contingent of firefighters had to proceed with caution because of the number of chemicals inside the shed, including the common kiwifruit spray Hi-cane, he said.
Mr Pearce said due to the explosion the fire spread to a nearby shelter belt resulting in about 25m area damaged on both sides.
Police and St John Ambulance staff also attended the blaze, but no one required medical attention.
Mr Pearce said fighting the blaze proved challenging due to the explosion which appeared to be linked to an oxy-acetylene welders kit and the various chemicals inside the shed.
There was no immediate risk to life because of the precautions taken by the firefighters, but the potential for injury was real given the nature of these chemicals, he said.
Mr Pearce said although the shed was destroyed, fire crews managed to isolate the fire and save the nearby house.
It was not known whether the property owner had insurance cover, he said.
Mr Pearce said firefighters left the property about 2.30pm yesterday but the fire investigation was ongoing.
Facts about fighting this blaze
A 111 call comes in at 8.36am
At least eight Western Bay appliances attended
That included fire fighters from Tauranga,
Greerton, Te Puke and Maketu stations,
Three water tankers, and a hazardous chemicals unit
were also dispatched to the fire
Fire crews finally left the scene at 2.30pm