HortResearch scientists have formulated Treet, a superior treatment for silverleaf in stone and pipfruit, and an
innovative system for injecting it into tree trunks, Stemject®.
Leading apple growers in most areas are trialling the technology, which has been available to them now for a full
Treet is injected into the tree trunk using a deep injection system, Stemject®, which pumps under high pressure into
the pith areas within the trunk. All other systems use shallow injection techniques to inject the treatment into the
outer cambium or layer of the tree trunk. The Stemject® system can also pump large volumes of treatment, over 100mls,
into the tree within minutes compared to shallow injection techniques that may take 12 hours or more to get 20 to 30mls
into the trunk.
HortResearch scientist Brian Ward, who with Lynn Cate at Ruakura developed the Stemject® injector, says, “Treet is
extremely effective for controlling silverleaf in pipfruit and is the only curative method. All other treatments
currently available are primarily promoted as preventative treatments.”
Treet is based on a natural compound already present in plant material. When applied to trees using Stemject® no
residue is left in the fruit.
The first trials looking at the principle of deep injection in trunks for controlling silverleaf were initiated in 1993
and the treatment and injector were released just last year.
The Stemject® technology was developed by Adrian Spiers, while working as a scientist for HortResearch. Dr Spiers has
recently moved to Idein Technology, a subsidiary company of Chemcolour Industries, to pursue further commercial
opportunities for this technology to control pests and diseases found in foreign countries.
Chemcolour has taken up the licence for the manufacture and marketing of the technology and now distributes it through
Orion Crop Protection Limited.