Running the Farm : Weeds
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AgResearch weed scientist Trevor James says he didn't know what he was looking at, at first. It was a photograph of velvetleaf (Abutilon theophrasti), one of the worst weeds in America and possibly the world. And it had just been found growing in the Waikato.
Famously known as the poison which killed Socrates, hemlock is alive and living in New Zealand, and is still capable of causing death or at least birth defects in pregnant animals which eat the foliage. . Regarded as a noxious weed in many parts of NZ, if it appears on or around your land, it would pay to check its status with your local regional council.
Ranging from low weeds to large bushes the nightshades all have one thing in common – they are definitely not for eating. Of interest is the fact that, while we are likely to refer to the small varieties as ‘deadly nightshade’, that is actually a whole different species (Atropa bella-donna) which is extremely rare in New Zealand.
There are two native nightshades (Solanum aviculare and Solanum laciniatum) both known by their Maori name of ‘poroporo’. Tall and spreading bushes with long and heavily veined and hairless dark green leaves, green or purplish stems, trumpet shaped mauve flowers with yellow centres, and drooping single oval green berries which turn orange as they ripen.
Do you remember seeing photos of brides from the 1930s each clutching a huge and unwieldy spray of what are commonly called arum lilies? They grew so well in New Zealand that they could be found in most gardens some years ago.
But like so many introduced plants from other parts of the world moderation was left behind in the host country, and they took off here like weeds in any damp places they could find, including pasture, particularly in the northern North Island.
“Write about fireweed” said a friend, “I’ve got it growing all over the place”. But ’fireweed’ is one of those all-embracing terms which attaches itself to different plants in different places. And all these plants have one thing in common – they are the first to colonise soils exposed by forest fires or forest clearing.
Despite their alarming names these are two rather inoffensive weeds, more often found in gardens and crops rather than pasture as they prefer loose, fertile soils.
Although they have different scientific names they are both members of the Lamiaceae, and to the unitiated eye they can appear identical.
Barley grass is one of nature’s survivors. Not only does it grow where and when other grasses fail to thrive, but it has developed a flexible seeding technique which allows it to grow unnoticed until the day length, temperature and soil moisture level is suitable for seedhead development and dispersal.
Stinking mayweed is an annual that grows up to 40cm high and flowers from December to March. Flowers are white and yellow and 15-30mm across. Leaves are feathery and dark green, grow up to 8cm long and are divided three times into awl shaped segments.
Most pastures in New Zealand consist of mixtures of both grasses and clovers.
Are you wanting to identify an unknown weed, but not sure where to start? Here are some useful information sources:
A weed that belongs to the brassica family, creeping yellow cress is found in cultivated ground, damp pasture and river beds.
Oxeye daisy is a perennial weed commonly found in poor and wetter pastures – especially where there is pugging and is common on dairy pasture sidelings in the Waikato.
Stinking mayweed is an annual that grows up to 40cm high and flowers from December to March. Flowers are white and yellow and 15-30mm across.
The new interest in ornamental grasses is potentially bad news for Northland farmers.
Everyone needs to do their bit to control wild ginger. The name wild ginger is applied to two species. The most common and most invasive of the two is the seed bearing kahili ginger, with the non-seeding yellow ginger being less common and also less invasive.
Topping two or three times a year, and a follow-up grazing, provides very good Californian thistle control.
Thistles were already a problem in New Zealand by the 1850s. They were probably introduced accidentally by early farmers in seed mixtures, and are now a nation-wide problem. There are over a dozen species of thistles in New Zealand,
Stinging nettle is an erect annual that grows up to 60cm tall.
Tutsan is a semi woody, semi evergreen, perennial shrub that grows upto 1.5m tall.
Black nightshade is an annual to short-lived perennial plant that has white or mauve flowers followed by berries that are first green, but change to black as they ripen.
With un-mown lawns and pasture sprinkled with the cheerful yellow flowers of dandelions and other ‘flatweeds’ at this time of year it seemed a good time to investigate the various different species to find their names and characteristics.
Despite their alarming names these are two rather inoffensive weeds, more often found in gardens and crops rather than pasture as they prefer loose, fertile soils.
Although they have different scientific names they are both members of the Lamiaceae, and to the unitiated eye they can appear identical.
These days, with the heavy emphasis on achieving maximum production from our pastures, the ‘preferred’ species are perennial ryegrasses and white clover. Yorkshire Fog (or velvet grass as it is known in the US) is generally regarded as a ‘nuisance’ grass, almost classified as a weed.
“Write about fireweed” said a friend, “I’ve got it growing all over the place”. But ’fireweed’ is one of those all-embracing terms which attaches itself to different plants in different places. And all these plants have one thing in common – they are the first to colonise soils exposed by forest fires or forest clearing.
When is a weed not a weed? Well possibly when it’s a plantain. The Saxons recorded the broad leafed variety as one of the nine sacred herbs, and migrants through the ages have taken it with them to other countries, so that in countries like New Zealand and America it has often been called ‘Englishman’s foot’.
The paddock and roadside nasties are taking advantage of the advance of more spring like weather, and the base rosettes of several types of thistle are already appearing, particularly in bare spots. So now is the time to attack before they shoot upwards.
Do you remember seeing photos of brides from the 1930s each clutching a huge and unwieldy spray of what are commonly called arum lilies? They grew so well in New Zealand that they could be found in most gardens some years ago.
Cleavers is that maddening hairy/clingy weed which appears everywhere in early summer and climbs through, round and over grasses and low shrubs, trying to smother everything. Sometimes mistakenly called bidibidi (which is a NZ native with much larger hooked spheres as seedpods), the seeds, stems and round seed pods catch and cling to clothing and animal hair.
Hedge mustard is a sneaky weed. Initially it grows as a flattish rosette, and may, to the uninitiated, look like a dandelion. But the indentations (or teeth) in the leaves go right to the stem with a slight gap between each, and the stems themselves turn purple from the centre outwards.
Has a cheerful yellow tinge spread across the tops of your pasture in the last month? If so, it’s just the various buttercups telling you “Here we are again!"
Barley grass is one of nature’s survivors. Not only does it grow where and when other grasses fail to thrive, but it has developed a flexible seeding technique which allows it to grow unnoticed until the day length, temperature and soil moisture level is suitable for seedhead development and dispersal.
Famously known as the poison which killed Socrates, hemlock is alive and living in New Zealand, and is still capable of causing death or at least birth defects in pregnant animals which eat the foliage.
Ranging from low weeds to large bushes the nightshades all have one thing in common – they are definitely not for eating. Of interest is the fact that, while we are likely to refer to the small varieties as ‘deadly nightshade’, that is actually a whole different species (Atropa bella-donna) which is extremely rare in New Zealand.
There are two native nightshades (Solanum aviculare and Solanum laciniatum) both known by their Maori name of ‘poroporo’. Tall and spreading bushes with long and heavily veined and hairless dark green leaves, green or purplish stems, trumpet shaped mauve flowers with yellow centres, and drooping single oval green berries which turn orange as they ripen.