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Producing Healthy Radiata Pine Seedlings

Producing Healthy Radiata Pine Seedlings

Producing Healthy Radiata Pine Seedlings

The thing that really matters to Kevin and Christine Strawbridge and their son Mark of Northland Forestry Nursery (NFN) is the survivability of the radiata pine seedlings they produce near Kaikohe.

From seed selection and ground preparation to pest control and the lifting process, every aspect of the Strawbridges’ nursery is focused on delivering healthy, strong seedlings to customers across Northland and Auckland.

A comment from Sam Middlemass, of Rayonier Matariki Forests, highlights that this attention to detail pays off: “I was amazed by Kevin’s blunt statement that his seedlings would easily achieve a survival rate well above our target. Kevin was correct and seedlings supplied by NFN have consistently allowed us to achieve survival rates as close to 100 percent as is practicable. Preparation and handling at NFN, combined with daily deliveries, results in a lack of stress to the seedlings. They barely know they’ve been moved and ‘hit the ground running’ when replanted.”

With a Bachelor of Forestry Science, Kevin’s background includes 20 years with Carter Holt Harvey in Auckland. He and Christine then moved to Kaikohe where Kevin became CHH’s Nursery Manager. An opportunity arose to establish NFN in 2001 in Kerikeri, but the nursery soon ran out of land, so Kevin and Christine shifted the operation to Kaikohe. 

With two blocks of land of 16 ha and 30 ha, NFN produces 12.8 million pine seedlings a year. As the largest pine nursery north of Rotorua, NFN supplies seedlings to most large forestry enterprises in the Northland and Auckland regions. They employ eight permanent staff, including their son Mark, Kevin’s brother, and a cousin, as well as more than 20 seasonal workers during harvest. Christine takes care of admin and staff coaching to ensure they meet their business targets, while Kevin is their hands-on nursery manager.

Kevin describes the seedling growing process: “Ground preparation comes first with a pre-sowing herbicide application and forming the seedbed with a purpose-built machine. Every third year, we under-sow with Suscon Green to control pests like grass grub and manuka beetle. The radiata pine seed comes from two South Island suppliers with different genetics according to customer requirements. Bird repellent is added to the seed, then it’s chilled for even germination prior to planting.

“Last year we invested in a Stanhay Vacuum Disc Sower precision drill capable of sowing 85 kg of seed a day; it’s faster and more precise.”

Once sown at the end of September, seedlings are not irrigated, although a bore and dam are being developed to help futureproof the operation during dry years. The growing seedlings are sprayed weekly to control pests.

Mark says: “This is where our close working relationship with Fruitfed Supplies Technical Horticultural Representative Louise Shepherd comes into play, ensuring we have the right mix of pesticides to reduce resistance risk.”

Utilising technology to improve production and reduce operational costs is something Kevin and Mark are passionate about.

“A few years ago, we invested in GPS-guided tractor systems and an RTK base station. These allow us to use the same planting beds with great accuracy and reduce soil disturbance and compaction. We’ve also reduced diesel consumption and operator fatigue and increased productive use of our land."
Once the seedlings are tall enough, mechanical topping commences to produce a 30 cm tall seedling with a good
height-to-diameter ratio. 

“Around March, we start undercutting the roots to allow good growth of secondary and tertiary roots, another aspect which aids survivability of the seedlings after being transplanted.”

Soil health and beneficial soil microbial populations also get close attention.

Mark says: “We’ve moved away from inorganic fertilisers over the past decade with top-up foliar applications of urea, occasional use of trace element supplements and low amounts of resin-coated fertiliser at establishment. We’ve built up organic sources of nutrients, applying dolomite, gypsum, humates, and foliar seaweed and fish-based products to support beneficial mycorrhizal populations in the soil.”

Drawing on research which showed that a higher Brix level meant less insect damage to the plant, Kevin says they’re testing Brix levels and working on how to increase it.

The winter harvest is an incredibly busy period for the Strawbridges with up to a quarter of a million seedlings harvested by hand daily. Seedlings are inspected and counted straight into boxes in the field, then moved into a cool store to minimise lifting stress. Customers note the accurate count of seedlings per box.

Recently, the Strawbridges wanted to benchmark their operation by entering the Ballance Farm Environment Awards. They were pleased to win the Hill Laboratories Harvest Award and the Norwood Farming Efficiency Award for Northland.

They are also active participants in NZ Forestry Growers Nursery Association Inc., which has commissioned research on terminal crook disease in pine trees. Kevin says: “Being involved with the association also helps our son Mark network with other young forestry nurserymen, all part of our future operations.”