Rising fuel and labour costs, and increased awareness of water use, are encouraging apple growers to take a fresh look at adjuvants such as UPL’s Du-Wett® super-spreader.

As an example, David says if an application volume of 2000 litres of water/ha is normal practice, the addition of Du-Wett super-spreader to the tank can achieve the same level of product performance with 500 to 1000 litres of water/ha depending on tree size, and orchard management practices.

“The fuel and labour savings are measurable and can be calculated,” says David.

The traditional attitude for spray applications that more water is better has changed. Research with Du-Wett and crop protection products used in pipfruit commenced in 2004 with several large-scale commercial trials, all showing equivalent or greater efficacy compared to conventional water volumes.

Another benefit shown by a Pipfruit NZ (now Apple & Pears NZ) trial¹ found that the residue of dodine, captan and tebufenozide on fruit at harvest was lower in the Du-Wett treated fruit compared to fruit with high water volume treatments.

David explains: “This was due to the crop protection products being more evenly spread and distributed across the fruit surface. This reduced the number of drip points where concentrations of active ingredients can typically be found. This is an advantage as we all work to meet demand from international markets for apples with no detectable pesticide residues. “The incidence of russet was also lower in this trial’s Du-Wett treated block which aids the all-important fruit appearance. Weather is a risk factor for the development of russet but some varieties, such as Fuji, Envy and Pacific Queen, are particularly susceptible to russet.”

Over the last eight years, independent trials² on Du-Wett include 16 replicated and 13 commercial split block grower trials in Hawke’s Bay and Nelson. Fruitfed Crop Monitoring Services were also engaged in the 2006 to 2007 season to monitor for pests and diseases in six blocks in Nelson and one in Hawke’s Bay on Jazz and Royal Gala. In all cases, the Du-Wett low water volume spray programme delivered an equivalent result to the standard water volume in terms of pest and disease control.

Du-Wett is an organosilicone super-spreader with improved deposition to enhance the spreading and foliage deposition of fungicides, insecticides, plant growth regulators and nutrients. A BioGro-certified version called Du-Wett Organic is also available.

Add Du-Wett to your apple crop protection programme with your late winter dormant oil applications. David recommends first mixing Oilmate adjuvant with the oil to enhance the oil’s spread and coverage, while Du-Wett spreads the water more evenly over trees. From the first pink appearance, low water applications of Dodine and Du-Wett can be used for black spot control. Bond Xtra, a spreader containing synthetic latex, helps crop protection products stay on trees longer when wet weather is anticipated.

In all cases, talk to your local Fruitfed Supplies Technical Horticultural Representative for advice.

1 2005-06 Pipfruit NZ trial, Hawke’s Bay and Nelson.
2 2013-21 Etec/UPL commercial trials, Hawke’s Bay and Nelson.