"It could be the colour or the hairless skin or storage capabilities or the difference in supermarket shelf life. So it's spray, spray, spray and we narrow it down to 8000 from 100,000 cultivars." Then they had to be tasted and he was first to admit some were horrible.
"You only eat a slice of it otherwise at the end of the month your mouth will be full of blisters. We do have a sensory panel but, of course, the sensory panel are lucky because they only taste the good ones."
However, it was developing methods and machinery to do the job that could also grab different flavours as well, he said.
Some of the kiwifruit in the breeding programme came from Russia, Korea, Japan, Siberia and China.
Choosing the winner was difficult as the combinations were endless, Mr Gea said.
"It's like choosing your lotto numbers in the lottery. Picking the winner is not simple because you have to have all your markers right.
"Instead of using statistics to choose the numbers we are using markers to say this one has the science attributes we are looking for. We are using genetic markers to identify the winner and the one we want to propagate."
Blue and orange kiwifruit could be bred, however, the brief from Zespri had its own criteria.
"Zespri was very clear, give me a green fleshed and yellow fleshed kiwifruit and a red kiwifruit and a kiwiberry so those were the targets." The process could take 10 years from the moment a seedling was selected, but it was hoping to speed up the process, he said.
"If you are looking at crops it takes 10 years, apples it takes 10 years with every new cultivar it takes 10 years to breed something new. And there are challenges all the way through and breeding is only one of the issues."
Mr Gea said he was passionate about the programme and found it fascinating. "It's very exciting." Zespri grower liaison manager Sue Groenewald said once Plant and Food was finished the kiwifruit was given to growers to trial on a commercial basis.
"That is to make sure it works on the orchard in a commercial situation ... that fruit is sold so we can do some test marketing on how much a consumer would pay for it."
Luckily G3 was ready to go when Psa hit, she said.
There were 2700 kiwifruit growers in New Zealand and 2200 orchards.
Usually Zespri only trialled about five hectares of new varieties of .25 per hectare around the country that involved about 30 to 40 trialists.
"We go out to all high and low altitude to see how it works."
Zespri operations manager for the joint breeding programme Bryan Parkes said not all cultivars would pass the testing stage and meet the quality required to carry the Zespri brand.
"New varieties need to show strong consumer liking, good disease tolerance, good yield, and satisfactory storage and market potential before release. This stage of testing can take five years."
Zespri had green and red varieties in pre-commercial trials at present, but could not disclose any details as they were commercially sensitive, he said.
Development of a superior kiwiberry cultivar was another part of the Zespri-Plant and Food Research breeding programme, he said "and we are screening candidates for a kiwiberry cultivar that meets the expectations of our consumers".
Three new varieties were commercialised by Zespri in 2010 - SunGold (Gold3), Sweet Green (Green14) and Charm (Gold9).
"Sweet Green is sold through our premium markets of Japan and China, and Charm was de-commercialised in 2015.
SunGold has gone on to enormous success in the marketplace and has almost entirely replaced Hort16A, the previous gold variety which was badly affected by Psa.
"Its sweet-sour taste balance appeals to customers and consumers across our markets and we have 4800 hectares now planted in New Zealand, with licence for another 400 hectares this year and for three more years to follow, subject to review."
Zespri SunGold had also been established in Northern Hemisphere locations to supply fruit in the New Zealand off-season, he said.
Zespri SunGold is on track to earn $1 billion in sales by 2017.