Preparation for a Manuka Plantation in 2016

Posted on July 30, 2015

Demand for Manuka plants for Manuka plantations is increasing rapidly.

Plant Selection

Manuka plants produced in the nursery for Year 2015 deliveries have already sold out and orders have started coming in for Year 2016 plantings. It is advisable to prepare early for a new Manuka plantation, to ensure that you have the best chance to secure the provenances, quantities, grades and delivery dates that you prefer.

Kauri Park Nurseries have established a plant selection and breeding program aimed at identifying Manuka cultivars which exhibit high DHA and increased productivity. KPN has identified certain provenances with higher average DHA levels in the nectar but have also selected high DHA plants from a wide range of provenances including South Island provenances and semi alpine provenances.

Although there is likely to be a number of factors that increase Methyl Glyoxl (MGO) in Manuka honey, the key drivers are improved plant genetics and large areas planted in Manuka.

Higher MGO levels in the honey is mostly derived from high dihydroxyacetone (DHA) levels in the nectar of the flower. Kauri Park Nurseries (KPN) are testing the DHA in the nectar in large numbers of plants from many provenances throughout New Zealand. This is leading to identification of superior plants which are currently being multiplied by cuttings and seed.

Manuka plantings of these superior genetics is expected to result in a quantum leap forward in MGO levels and volume of honey harvested per ha.

For Year 2016 deliveries, Kauri Park Nurseries will be offering a reasonable quantity of plants grown from seed harvested from mother plants recorded for superior DHA levels. It is important to place early orders if you wish to secure these recorded plants.

Site Selection

The other key driver is the total area planted in Manuka. Manuka is not a preferred nectar species of honey bees. Honey bees prefer clover and also other native species such as kamahi, towai and rewarewa, which will dilute the Manuka honey and reduce the MGO levels. Therefore the larger the area planted in Manuka the less likely the bees are going to collect nectar from other sources. It is advisable to position bee apiaries in the center of a Manuka forest. An ideal forest size would be 50ha or more.

For a new plantation of Manuka, Kauri Park Nurseries would generally recommend planting the local provenance along with plants grown from other provenances, to spread the flowering duration over a minimum of 12 weeks. Consideration is also taken for the ability of a provenance to withstand hard frosts and winter snow.

When selecting a site for a new forest, take into consideration the proximity of indigenous Manuka forests, physical barriers for bees such as a wide block of pines or wide expanse of water which may help to isolate the bees from travelling to non Manuka nectar sources. A good planting site is a sheltered valley with high hills on either side. Manuka thrives particularly well on northern and eastern facing hillsides. Try to avoid planting a new site that is nearby to a large source of non Manuka nectar.

Manuka do well in a wide range of soil types including sand, volcanic, clay, peat, limestone, alpine and pakihi soils. They seem to grow well in swampy soils where the roots of the plant never dry out. They also grow well in barren windswept hillsides where they are constantly battered by salt laden winds.

Other factors that may increase the MGO in the honey include the acidity of the soil, especially plants growing in sandy/peat swamps, lower fertility in the soil, and warmer prevailing climatic temperatures.

Plants and Planting Services

In year 2016, Manuka plants will be available in 20 different provenances, along with more than 10 individual selections from DHA recorded mother plants.

Plants will be available in three separate forestry grade sizes.

Kauri Park Nurseries supplies plants and planting services. The traditional planting rate is 1111 plants per ha. For more gentle contoured land, Manuka should be grown in hedgerows at a planting rate of 2500 plants per ha. The hedgerows can be kept trimmed, with the trimmings being able to be sold for leaf oil extraction. The trimmed plants can be maintained in a juvenile state thereby substantially increasing the plants longevity.

Financial subsidies and grants are available for forestry establishment through MPI and through many of the Regional Councils. It is recommended that anyone considering planting Manuka, talk to MPI and to their local Regional Council to find out what grants are available.

Site Preparation

If gorse, tobacco weed, or wilding pines are present, spray the whole block with Metsulfuron methyl to eradicate these weeds. Wait a minimum of 12 weeks before planting so that the Metsulfuron methyl residues have dissipated.

For a weed infested ex pine block, it may be necessary to do two blanket weed sprays over a 9-12 month period, before planting into Manuka.

If gorse, tobacco weed, or wilding pines are not an issue then only use Roundup to eradicate the grass and weed species. Wait a minimum of 1 week before planting so that the Roundup residues have dissipated.

For planting, loosen the soil so that there is enough loose soil surrounding the plant to make it easy for the roots to spread outwards.

It may be necessary to release the plants from grasses, one year after planting. Research is continuing on the use of selective herbicides and their effects on Manuka.

Manuka produces higher MGO honey in low pH and low fertility soils. It is not necessary to add lime or fertilise the soil for Manuka. If the pH is too high, it may be necessary to add Sulpher to the soil to reduce the pH.

Goats, deer, wallabies and hares are known to chew the tops out of plants and chew off the whole plant, especially in the first year after planting. If culling is not possible then Kauri Park recommends using tree protectors around the plants.

Kauri Park supplies tree protectors as part of their planting services.

Advantages of Commercial Manuka forests compared to Wild Manuka forests.

It is possible that hive stocking rates will increase to 2-4 hives per ha when the superior plant selections begin to flower.

It is possible that the price per kg will increase with the higher MGO activity produced by the superior plant selections and also the increasing world demand for Manuka honey.

The flowering period can be lengthened from 6 weeks to 12 weeks by planting several provenances which each flower at different times. This should increase the volume of honey harvested per ha.

Manuka Leaf Oil production can substantially increase the income per ha and should not have a detrimental effect on Honey production.

By Andrew Wearmouth