Apples with sunburn will be downgraded, or rejected, for aesthetic and storage reasons. Surround with Du-Wett Super-Spreader stops harmful damage.
Maximise returns, stop harmful skin damage
Apples with sunburn will be downgraded, or rejected, for aesthetic reasons but UPL NZ.’s Adjuvant Product Manager David Lingan says it goes much deeper than that.
“Sun damage also impacts how well the apples will store because, below the visible effects, it can cause the apple’s flesh to become brown and/or spongy.” He says the knock-on effects of sun harm on crops to orchards’ bottom lines can be significant. “It has been known for up to 40% of a crop to be rejected on that basis.”
David says the unpredictability of the weather, New Zealand’s notoriously high UV, and 2-D growing systems all contribute to the sun damage risk. “With modern growing systems, more fruit is exposed to the sun. There isn’t that cover from foliage that you had with bigger trees. Apples get the sun during the day on one side and, at sunset, on the other. That’s two hits. It’s a challenge – especially as Granny Smith and some newer varieties are particularly susceptible. “The sun’s effects can be harmful to both crops and humans. And, obviously, that risk is not going away. And, in New Zealand, our rays are pretty intense.” David says keeping an eye on Met Service is vital. “It’s not just about ambient temperature – radiant heat can catch out the unwary.
Surround protects!
“Surround is a fantastic product – particularly for Granny Smiths. Cosmetically, with Granny Smiths, sun damage will present as yellow patches. That doesn’t look good. In red varieties you may get orange patches.”
David recommends going in early (at the beginning of December) applying Surround sun protection to the crop before the heat and UV become a real threat. He says, much like sunscreen for humans after they’ve been swimming, Surround does need to be reapplied. “As apples grow the surface area increases, and after there has been heavy rain, reapplication is vital. The product does weather-away.”
Doing the heavy lifting in Surround is super-fine Kaolin clay. It is derived from earth and is also widely used in porcelain, along with pharmaceuticals, including cosmetic facemasks. Surround works by deflecting UV rays, protecting the fruit. And the efficacy is quantifiable. David says treated apples are even physically cooler than untreated.
Surround also has other orchard management benefits. David says it reflects light back into the canopy, benefitting fruit on the shadier side of the tree. “It also helps cool the tree itself – reducing heat stress.
“Surround can even enhance photosynthesis and fruit size. But, a lot like when we apply sunscreen on ourselves, or our kids, good coverage is essential. Adding water is not the best solution as it tends to end with all the Surround being concentrated at the end of the fruit, which doesn’t really get the sun anyway. That means coverage is really blotchy.”
As always, coverage is key
Ideally, Surround’s fine particles should be applied with a super spreader like Du-Wett. Du-Wett is a non-ionic organosilicone surfactant blend developed to give better coverage. It has excellent crop and environmental safety.
“In addition, using Du-Wett also means you’re spraying at a lower water volume with the benefits and savings that provides (2000 L/ha compared with 400-500 L/ha.) Optimising water use is now something farmers and growers are factoring into their systems, to improve efficiency, and ROI.” David says users will see a benefit in getting the spraying job done quicker. “There’s less filling time and getting around the blocks or orchard is more efficient. It means there can be gains in time and efficiency and significant savings in fuel and labour costs – both major pain points for.”
As always, David advises growers to read the label carefully. “Unfortunately, Surround is not the solution for all apple varieties.”
