ADVICE: Chickweed – almost sounds like something out of Austin Powers. in fact it wouldn’t surprise me if it was.
Officially known as Stellaria media chickweed is an annual species. It grows low to the ground and spreads (actually, it sprawls or scrambles) to about 50-60cm across.
This clever little beast is able to grow up and over other plants, and this, coupled with its speed of growth, can make it a right royal pain in both pastoral and cropping situations.
It may germinate at any time of the year, but most commonly it appears in the autumn and grows through the winter. It does not easily survive in the drier conditions of late spring and summer, but while growing it’s a prolific and early seeder, and this will ensure its unwelcome return when the right conditions roll around again. So as we move into autumn this is one weed that you can have a crack at.
The leaves are light green in colour, hairless, and oval in shape with a distinctly pointed tip. They grow in opposite pairs on the stalk. Leaf size is around 30-40mm in length, and 15mm in width. The stems are very fragile, and easily broken.
The branched stems permit extensive sprawling and climbing and are equipped with a row of hairs.
Flowers are small and white, with five very deeply divided petals that appear at a casual glance to be 10 separate petals, giving the flower a daisy-like structure. Chickweed flowers predominantly from September to February. The flowers grow in clusters at the ends of the stems.
Note that chickweed is not the same species as the weed known as “mouse-eared chickweed”.
HABITAT
Chickweed is common throughout New Zealand. It prefers cooler and damper conditions, and is most commonly found in coastal sites, in gardens and in cultivated land, as well as roadsides and waste places. This seems to be the one weed that I have been getting in the garden lately and although easy to pull it is still work.
It will grow in new crops, where its scrambling, covering nature can be a significant threat to the optimum development of the crop. It is a particular problem in sites that are autumn-cultivated for cropping or pasture renovation.
Although the weak and fragile stems mean that it breaks up by stock trampling, if a pasture is saved in autumn for winter feed any chickweed present can grow very rapidly and seriously diminish the feed value.
LIVESTOCK
Stock do not like eating chickweed, so any control via grazing is limited to the effects of trampling. There have also been some reports of lamb and horse deaths from eating it.
MANUAL CONTROL
Chickweed is readily removed from a garden by pulling it out and disposing off-site, but in other situations manual removal is rarely practical.
HERBICIDE CONTROL
MCPA, MCPB and 2,4-D are not effective against chickweed. Flumetsulam 80g/L WD granules give useful control in pasture (including new pasture), as well as in certain crops including lucerne, chicory, maize and clover.
Best results will come from spraying as early as possible after the appearance of chickweed, not only because it is more easily controlled at that stage but also because chickweed can produce viable seeds within six weeks of germination. In new pasture, chickweed can be safely sprayed with Flumetsulam after the emergence of the true two-leaf stage of clover.
• Flumetsulam 80g/L WD granules at 30g/ha when applied to seedling and smaller chickweed, or at 65g/ha when applied to larger chickweed plants. For best results add Organosilicone penetrant at 100ml per 100 litres of water. Water rate should be about 100-300L/ha, with the higher volume required when the growth is dense.
• Thisulfuron-methyl 750g/kg when applied at 20g/ha for controlling buttercups will also give reasonable control of chickweed.
credit:stuff.co.nz
