How to Get Rid of Gorse

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If you own pasture in New Zealand chances are that a grey-green shrub with painful spines and bright yellow flowers is eating into your bank account. It’s presence damages the returns from a given piece of land by reducing grazeable acreage, and getting rid of it burns up valuable time and labour.

Description and History

Gorse (Ulex europaeus) was originally imported into New Zealand from Europe as a hedge plant. Unfortunately, a favourable climate has led to widespread colonisation and the plant is now a major pest. Gorse is a woody perennial that grows up to 4 metres tall and, if left unchecked, will form thickets. New (or “soft”) growth on the plant hardens into spines, a characteristic which makes the plant both impenetrable and unpalatable to livestock. Between May and November Gorse displays its signature bright yellow flower. New growth and seed pod development occur in late spring. Hardening of new growth generally begins in early autumn.

Characteristics

Gorse thrives in a wide variety of conditions. An average plant will produce about 8,000 seeds each year and each of these seeds can lie dormant in the ground for up to 30 years.

A number of factors contribute to gorse infestation:

  • Gorse readily takes hold where native vegetation has been cleared or other land disturbance has taken place.
  • Fire encourages gorse seeds to germinate.
  • Pugging (the churning up of ground by livestock, particularly in wetter or over-grazed areas) encourages gorse colonization.

Control

Given its virulent nature and the fact that its seeds survive for such long periods of time, gorse is difficult to get rid of entirely. Effective eradication will usually involve a combination of manual removal, herbicide application and pasture management.

Manual Removal

Manual removal of gorse is a labour-intensive process involving the physical uprooting or destruction of the plant. Hand-pulling works well for small stands of new plants. Large infestations, though, will require digging, cutting or mechanized removal. Larger plants can be stumped and then coated with a herbicide gel. Burning is not recommended as it damages surrounding pasture and encourages gorse seed germination.

Herbicide

The application of a herbicide spray is an effective method of gorse control that requires less labour than manual removal. Herbicide application should be carried out immediately after spring flowering. At this point new growth is at a maximum and the plant is most vulnerable to the action of the herbicide. When spraying, it is essential to penetrate to the inner, older areas of the plant. A wetting agent should be used in conjunction with the herbicide to facilitate this. The type of herbicide used should have as little impact on surrounding grasses as possible as the destruction of grasses will create an environment where new outbreaks of gorse can take hold.

Pasture Management

Ensuring that grass and native plant cover are not excessively reduced will leave fewer opportunities for gorse to establish itself. Avoid over-grazing, pugging, bad drainage and low levels of soil fertility.

An Ongoing Battle

The favourable conditions in many parts of New Zealand and the hardy nature of the gorse plant mean that for many farmers getting rid of gorse is an ongoing battle. However, by using an appropriate herbicide, good pasture management techniques and a planned eradication strategy  the problem can be managed effectively and the yearly appearance of those bright yellow flowers kept to a minimum.

Kumara: plant, care, harvest & storage tips

Buy Kumara runners from garden centres in October or start your own by sprouting a Kumara in a pot of moist sand. When the shoots are about 15cm high with leaves and roots, remove them for transplanting.  Push the plantlets into the ground gently at a depth of around 50mm in the shape of a "j" lying down, with the long edge running parallel with the top of the ground. If you plant vertically pointing down, it can be too cold for the Kumara to form off the nodes. Don't cut back the runners. Lift them off the ground regularly to discourage formation of surface roots which waste energy that could go into tuber formation. 

Most growers like to apply lime before planting because Kumara prefer a pH of 6.0-6.5. It is possible to grow Kumara in the same place year after year but some form of crop rotation is preferred to help minimise the build-up of soil diseases. Black beetle, crickets, nematode and white fly caterpillars are the usual Kumara pests. 

WHEN TO HARVEST YOUR KUMARA
It can be hard to tell when to dig for Kumara as the tops don't die down when the tubers are ripe. As a rule, Kumara take five months from planting to harvest, but if the spring and summer have been cold, tubers may be slow to reach maturity.  Before committing yourself to digging up the whole bed, do some careful bandicooting in a couple of places to see what's happening underground. Size isn't the only thing to look for; only mature Kumara will store well, so check the skin is firm and cut one into a couple of pieces. The cut sides will dry quickly if the Kumara is ready to store.

There are other factors to consider when harvesting Kumara. The day you lift your crop should not be too hot – excessive heat is said to blister the Kumara – nor wet. Ideally lift your tubers after three or four days of dry weather (also dig your fingers through the soil to check it feels dry). If you've got a lot of tiddlers, peel or scrub them well and cut into pieces roughly the same size. Blanch in boiling water for two minutes, then free-flow freeze. They'll come in handy for winter soups and stews. 

HOW TO STORE KUMARA
The key thing for ensuring Kumara store well is that they are not exposed to moisture, which will make them rot, or light, which will make them sprout. Create the right conditions by wrapping them in newspaper and keeping them under your bed or in a cool, dark cupboard.

Make sure the Kumara you plan to store have not been bruised or nicked – lift them by hand to ensure the soft tubers don't get damaged by metal tools.  So the best storage area for Kumara is somewhere dark and dry. Avoid putting them in high humidity areas such as your kitchen or laundry. Don't wash your Kumara as they store much better when the skins are dry. Spread them out somewhere cool and airy to dry the skins for a week or so.

According to Wiremu Puke of Te Parapara (the traditional Maori garden at Hamilton Gardens), medium-sized Kumara are the optimum size for storing. Kumara that are very big don't store too well, as they contain a lot of moisture. The old people used to leave Kumara in the ground until the leaves went brown," he explains. "Just make sure to harvest them before a frost, as that will turn them mushy." 

NZ Gardener