Published on 21/01/2026
Nufarm’s ReTain has long been recognised for its ability to optimise harvest logistics, yet its value extends well beyond smoothing out peak picking periods.
Paul Greenbank, Nufarm business development manager Hawke’s Bay and Wairarapa, says ReTain has played a key role in helping New Zealand exporters lift both harvest efficiency and post-harvest fruit quality and performance.
“Much of that focus has – understandably – been on its value as a tool for manipulating harvest dates, smoothing out harvest peaks, and optimising available picking and post-harvest workforce.”
Equally important, however, ReTain improves firmness, reduces greasiness, reduces weight loss, slows background colour change, and improves storage potential.
“And this can make a measurable difference down the track when fruit is packed and shipped. The better the fruit quality going into storage, the better it comes out of storage, delivering a superior quality apple to the consumer.”
ReTain contains a naturally occurring plan tgrowth regulator that temporarily inhibits production of ethylene in developing fruit, slowing maturation, ripening, and development of abscission tissue while allowing continued fruit growth.
This in turn can extend the apple harvest by up to seven to 10 days while maintaining high fruit quality.
“Labour has been such a pressing issue for the industry in recent years we have perhaps overlooked the other ways ReTain can help us once we do get the crop off the trees.”
Capturing the full benefit of this delay is all about careful planning, Greenbank says.
“Many growers will have already started reviewing their ReTain programme, to allow optimal lead times, but to also workaround other key activities like calcium and kaolin clay applications, and temperature fluctuations.”
For example, growers need to allow for a minimum seven-day interval between calcium sprays and ReTain, and ReTain should not be applied if calcium residues are visible or if previous calcium use has damaged lenticels.
Historical crop harvest records can help determine application timing for different blocks, and it’s also very important to monitor weather conditions around planned time of application.
“ReTain has to be applied with Freeway organosilicone adjuvant at the correct rate for the variety being treated to get the greatest benefit, as high rates of the adjuvant increases the risk of lenticel damage.”
Greenbank says other key guidelines for optimal results include: apply ReTain in the cool of the morning; after a ReTain application, wait 24 hours before applying any other sprayed horticultural productor overhead irrigation; wait to lay down foil mulch or reflective film until after the ReTain application, not before; and avoid spraying if rain is expected in six hours.