The overuse of a chemical that helps fruit grow faster is causing a rash of exploding watermelons in eastern China. The same chemical is being used by a large number of kiwifruit growers in NZ.
An investigative report by China Central Television found farms in Jiangsu province were losing acres of fruit to the problem. It said farmers sprayed too much growth promoter, hoping they could get fruit to market ahead of season and make more money.
China is battling rampant misuse of pesticides, fertilizers and food additives, like dyes and sweeteners, meant to make food more attractive and boost sales.
The sprays contain a synthetic cytokinine, forchlorfenuron and if farmers sprayed their fruit too late in the season and during wet conditions, it caused the melons to explode like “landmines”.
In NZ there has been a jump in registrations of hormone sprays which have been shown to increase average kiwifruit weights by up to 46 percent.
The chemical has been registered in New Zealand since 1993, under the trade name Caplit, as a “plant growth regulator for sizing kiwifruit”.
Field trials carried out at Goldwood Orchard near Waihi in the western Bay of Plenty showed that forchlorfenuron sprays could boost the average fruit weight by 27 percent to 46 percent without affecting the proportion of fruit rejected for export.
But the United States’ Environmental Protection Agency (EPA) — which said tests showed the chemical damaged rat kidneys — announced in 2001 it would ban the import of fruit with forchlorfenuron residues.
NZ kiwifruit exporter, Zespri, won’t allow export of hormone-boosted kiwifruit. A Zespri spokesman told NZPA the policy on Caplit remained the same.
“Any grower found to have been using it will not have their fruit accepted for export by Zespri,” he said.
“Kiwifruit growers are well aware of the fact they cannot use it.”
There was random testing of fruit from up to a quarter of all orchards which submitted fruit.
But the spokesman said he could not explain why in recent years there had been a jump in the number of products being registered for enhancing kiwifruit size: agricultural chemical company Cropstar registered powder and liquid formulations of forchlorfenuron in 2008 as a “plant growth regulator for sizing kiwifruit”, and manufacturer Agrinova NZ Ltd registered Ambitious in 2009 as a “plant growth regulator for sizing kiwifruit and apples”.
Agrinova said in its application to have the chemical registered that it could boost kiwifruit size by 20 percent, but when extra-large fruit were needed for special markets, it should be used at a higher concentration. It also suggested also spraying small apple cultivars such as jazz and royal gala to boost fruit size.
However, a spokesman for the company told NZPA Zespri did not allow its growers to use the hormone.
Agrinova had not yet sold the product for use on apples, though it had just gained the registration for that, after five years of development work, he said.
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