![]() ![]() The one well-proven herbicide active ingredient is triclopyr, whether alone or in combination with picloram. Horned oxalis, like most of the oxalis species, is able to tolerate most of the commonly used selective herbicides, and results with common sprays like MCPA750 and 2,4-D 720 Amine can be very disappointing, as can treatment with sprays containing clopyralid. It also appears in lawns, ornamental and sporting turf, though the smaller, native creeping oxalis is more common in those locations in NZ. It particularly favours gardens as well as closely grazed pastures. Horned oxalis is found across most of the world, and is common throughout New Zealand. There have been reports from Australia of sheep being poisoned by horned oxalis, though nothing similar reported in New Zealand. fishtail oxalis, Bermuda buttercup, pink shamrock and others) The plant also spreads via seeds, but does not have the underground bulbs found on some other similar species (e.g. This allows the plant to form quite dense patches in pastures, turf and lawns. Horned oxalis spreads readily because of its stolon's, which is a stem that creeps along the ground and produces new roots at the stem nodes. ![]() The creeping oxalis flowers are also smaller, and nearly always appear only singly rather than in clusters. the flowers are normally only up to 10mm across). The similar native creeping oxalis mentioned above also has yellow flowers and trifoliate leaves but it’s smaller in all respects (e.g. The leaves are generally up to 20mm across. ![]() This forms the classic ‘three-leafed-clover’ shape. ![]() Leaves are trifoliate, which means they are made up of three leaflets each of which is notched on the outer end. It flowers from December to January in most locations. The flowers are yellow, and grow up to about 1cm in diameter, sometimes singly, but more often in clusters of from two up to five flowers per stalk. Horned oxalis is a perennial weed species that grows low to the ground. The other smaller, common relative that looks similar is creeping oxalis (Oxalis exilis), which is a native oxalis. Used carefully and for specific hard-to-deal-with problems - such as Oxalis pes-caprae - glyphosate can be a real boon.This species of oxalis is the larger one and is the one of more concern. But as weedkillers go it is remarkably non-toxic - one formulation is even authorised here in the UK for use on wetlands and water plants, although stream and pond creatures are very highly susceptible to almost all other herbicides and pesticides. Glyphosate is not a magic potion (in the UK some weeds of farmland such as willowherb have developed strains that are highly resistant to it, and the same has happened in the USA there seems also to be some evidence that its use on the same spot year after year, as happens on many arable farms, may in the long run damage soil structure). But any detached bulbils which do not have any above-ground parts will survive (glyphosate is inactivated by contact with the soil). If the glyphosate is applied to the leaves of a bermuda clover plant, all parts of the plant including the attached underground bulbils will die. They supply it under the brand name Roundup this includes a surfactant and spreading agent, which help in applying it. In Europe as in the USA Monsanto, the original developer of this weedkiller, is still the main supplier of glyphosate, even though their patent expired some years ago. The remaining plants are so tiny their stems are threadlike but I can't let them live or they'll recolonise. Now I'm chasing the last little plants hiding in the lawn using just a 2 litre icecream container. The first years here I literally pulled out wheel barrow loads. If you are diligent the yellow peril can be defeated. If you leave them on the ground the uprooted plants will form bulbils and you will be back at square one. The other important thing is to burn or very deeply bury the pulled plants. There are two key things pull them up early so as to exhaust the bulbs then repeat as the plant regrows. I now have a patch left in the lawn but the rest have been defeated by persistent hand weeding. When I moved to my current home 11 years ago the garden was yellow in late winter/spring. However it can be eliminated in smaller gardens by being persistent. In broadacres glyphosate is the only way to go. Pes-caprae is a menace in southern Australia too. ![]()
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