Cleavers

Cleavers

Galium aparine L.

Family: - Rubiaceae.

Names:

Cleavers

Other names:

Bedstraw
Burrweed
Catchweed Bedstraw
Goosegrass
Small Goosegrass
Sweethearts

Summary:

The mature plant has a distinctive sticky feeling and rings of 6-8 leaves on the prostrate or scrambling and climbing, square stems with curves spines on the angles. The leaves have backward directed tiny spines on the edges and midrib on the underside and curved spines on the upper surface. The fruit is a pair of globular fruitlets covered with hooked spines on a straight stalk and is produced from small, white 4 petalled flowers in spring.

Description:

Cotyledons:

Two. Oval to egg shaped. Blade 7 to 15 mm long. Tip indented with a distinctive apical notch. Edges smooth. Base tapered to squarish. Surface hairless. Petiole shorter than blade an 4-5 mm long. The seedling has a long hypocotyl and a long epicotyl.

First leaves:

Develop in a ring around the stem (whorl) with initially 4 then 5-6 leaves to a whorl. Leaves club shaped. Tip pointed. Edges smooth and bristly. Base tapered. Surface somewhat warty. [Some authors suggest 5-6 leaves for the first whorl of Cleavers (Galium aparine) and 4-5 leaves for the first whorl of Three-horned Bedstraw (Galium tricornutum)].

Leaves:

Later whorls have 6 to 8 leaves.
Stipules - Whorled.
Petiole - Absent.
Blade - Lance to club shaped, 10-60 mm long with a fine point, 1.5 mm long, formed by the midrib extending beyond the tip. On the upper surface they carry stout hooked hairs. The edges are often rolled backwards. The edges and midrib on the underside have backwardly directed spines similar to those on the stem. Mid stem leaves are the longest, lower leaves are very narrow.
The whole plant has a distinctive sticky feeling.

Stems:

In the early stages stems are semi-erect and become straggling, weak, twining and prostrate, much branched especially from the base, up to 1500 mm or more, square in cross section with ridges on the corners, hollow and stout. They carry stout downward directed curved spines on the corners of the stem.

Flower head:

Axillary or terminal cyme. Stalk (peduncle) is longer than the leaves and carries 1-5 flowers on short, 2-4 mm long, straight stalks (pedicels) that are almost at right angles to each other.

Flowers:

Small and white 4 petalled flowers.
Bracts - At the base of the peduncle.
Ovary -
Sepals -
Petals - 4, white, 1 mm long with pointed tips.
Stamens -
Anthers -

Fruit:

2 globular to kidney shaped fruitlets, 3-4 mm long on a straight stalk that is longer than the fruit. They are covered in spiny, hooked hairs that are thickened towards the base and have a sticky feeling. They adhere readily to clothing or animals.

Seeds:

Up to 1000 brown to grey seeds which are round, 1-3 mm in diameter and with the surface covered with hooks are produced on each plant ²⁹⁴. Tip rounded. Surface covered in short hooked spines. Base indented

Roots:

Key Characters:

Whorls of 6-8 leaves, Stout stems. Fruit kidney shaped and bristly with hooked hairs.

Biology:

Life cycle:

Annual. Germination occurs mainly in Autumn.
Seeds need vernalisation. The moisture regime and amount of light were unimportant for the timing of flowering. Nutrition had some influence on the timing of flowering, but day length and maximum temperature were the most important factors in this respect. A formula developed from the product of day length and the effective max. temp. (⁰C above the base temp. of 5.3⁰C) enabled relevant developmental rates of arable field populations of Galium aparine to be predicted over a broad range of environmental conditions. The flowering date in the field could be correctly predicted for cohorts of plants emerging at different dates at 2 sites ²⁹⁵.

Physiology:

The cuticle has an amorphous wax which makes penetration by most herbicides more difficult ²⁹⁶.

Reproduction:

Flowering times:

Spring in western NSW.
Spring in WA.

Seed Biology and Germination:

Ensiling or passage through the intestinal tract does not affect germination of seeds ²⁹⁴.
Freshly harvested seeds are in a state of primary dormancy; They then enter a period of secondary dormancy that diminishes in spring. The seeds were able to germinate at 20øC in light and to a lesser extent in the dark. Alternating between 10 and 20ø did not seem to promote germination ²⁹⁷.
Herbicide applications later than normal but before peak flowering were most effective at reducing seed production ²⁹⁸.
²⁹⁹ has some data on seed dormancy.
Seed bank is probably exhausted in 3-4 years in UK ³⁰⁰.
Seed can not be effectively removed from rape with screens or a trieur ³⁰¹.
Seed has a high annual rate of decrease (about 80% per year) and for which seedling emergence represented an av. of 15% of the annual seed bank ³⁰².
Seeds died after 2-4 weeks in cattle manure ³⁰³.
Has an extended germination period ³⁰⁴.

Vegetative Propagules:

Hybrids:

Allelopathy:

Seed extracts inhibited the germination and growth of Digitaria sanguinalis and Medicago sativa seedlings but it did not inhibit Trifolium repens. The extracts also inhibited germination of G. aparine itself.
Lettuce placed together with G. aparine seed had inhibited germination and growth ³⁰⁵.

Population Dynamics and Dispersal:

COMPETITION
Densities of 100/m2 reduced rape yield by 65% and increase lodging to 35% in Poland ³⁰⁶.
More competitive under hi N conditions in spring wheat ³⁰⁷.
More competitive than sterile brome and less competitive than field poppy ³⁰⁷.
Main competitive effect is to reduce 1000-grain wt in wheat ³⁰⁸.
Had no effect on 1000-seed wt in Russia ³⁰⁹.
5 times more competitive than wild oats. For Galium aparine the economic threshold was as low as 2 plants/m2, Avena sterilis 7 and 12/m2, Lolium multiflorum 25 - 35/m2, Bromus sterilis 40/m2, Vicia sativa 5 -10/m2 under high N conditions in winter wheat in Italy ³¹⁰. Not competitive under low N conditions in winter wheat in Italy ³¹⁰ or the UK ^311;312 or Germany ³¹³ especially if no water stress ³¹⁴. Yield decline due to one G. aparine plant/m2 was 0.24% in winter barley and 0.14% in winter wheat in Russia ³⁰⁹.Minimum threshold level for cleavers was 0.2 plants/m2 in rape in Germany ³¹⁵. Control resulted in 12-14% increases in 1000 grain wt and up to 25 dt/ha grain yield in winter wheat in Germany ³¹⁶. No crop yield advantage from removal of G. aparine prior to GS 32 in winter wheat in UK. Damage thresholds for G. aparine and V. arvensis were 80 plants/m2 in wheat in the USSR ³¹⁷.With a full nutrient supply, cleavers were more competitive than wheat ³¹⁸. A decision model supporting weed control in cereals based on economic thresholds including cleavers is available for Germany ³¹⁹. 0.1-0.5 plants/m2 threshold for winter cereals in Germany ³²⁰. 38-fold av. increase in winter wheat over a 2-year period in Italy ³²¹. Control of >2 weeds/m2 gave higher yields in winter wheat in Germany ³¹³. 1 plant/m2 reduced yields on loess soils by 0.020 and 0.011% in spring barley in Germany ³²². G. aparine competition reduced the number of ears and the number and wt of grain/ear and the 1000-grain weight in wheat in Poland ³²³. Wheat at high plant density suppressed late-germinating G. aparine in Germany ³²⁴. Losses varied from 0.7 to 2.9% per plant/m2 in wheat in the UK ³²⁵. 96-100 plants/m2 decreased yields of rape from 2.6 to 0.9 t/ha in Poland ³²⁶. More competitive than chickweed and mayweed in winter oilseed rape in Britain ³²⁷.
Increasing wheat seeding rate reduced biomass and seed numbers of cleavers ³²⁸.
TILLAGE
Increased with tillage in Canadian crop rotations ³²⁹. More common under minimum tillage than ploughing in UK ³³⁰. G. aparine densities built up most rapidly with no-tillage, followed by shallow tine cultivation, and least rapidly with ploughing. ioxynil + bromoxynil + mecoprop in Jan, followed by fluroxypyr in April reduced seed banks by 60%/yr. A population model for G. aparine showed that almost complete control (97-99%) would be needed to prevent populations from increasing ³³¹. Germination and establishment could be markedly reduced by cultivation between 1 h after sunset and midnight in Germany ³³². Population increased 5 times more rapidly with shallow cultivation systems than with ploughing. 7.8, 9.3 and 0.4% produced plants after shallow tine cultivation, no tillage and ploughing, respectively ³³³.
NUTRITION
More weed seed was produced under Hi N conditions in winter wheat and less seed produced at higher wheat densities ³³⁴. Increased N fertilisation promoted Galium aparine ³³⁵. 0.4-9.9 plants/m2 reduced yields of winter oilseed rape by 5% in UK ³³⁶. Threshold levels for the weed in rape and winter wheat were approx. 0 and 0.1 cleavers plants/m2 respectively in Germany ³³⁷. Wild oats (A. fatua) were more competitive than cleavers in wheat in the UK ³³⁸. Galium aparine in gaps of a winter wheat crop produced up to three times more DM compared to gap-free conditions ³³⁹. Cleavers outgrew the crop on plots receiving high N ³⁴⁰.
ECOLOGY
Abundance increased after fire in Utah USA ³⁴¹.
Mean rate of migration in forest was >2m/yr which was one of the highest rates in North America ³⁴².
Shade tolerant species ³⁴³.
Requires 325-340 degree days to get to 2 leaf stage ³⁴⁴.
Low-red:far-red light ratio under the plant cover prevented germination ³⁴⁵.
Increases after annual chemical treatment stops in a Bavarian study ³⁴⁶.
Harvesters tended to spread seed from clumps of the weed over a wide area ³³⁷.
Population modelling to describe G. aparine populations, the parameters required and their predictive value ³⁴⁷.
Weed species with a high population growth rate, infestation was determined mainly by seed production, plant survival and rate of emergence. For those with a low growth rate, seed survival in soil was critical ³⁴⁸.
Cleavers increased in a winter Wheat/Bean rotation in Germany ³⁴⁹.
The root system of cleavers was shallower than wheat but was often of greater total length ³¹⁸.
Galium aparine were the main weeds in the inorganic crops; these weeds were only present at very low levels in some of the organic fields in the UK ³⁵⁰.
46.6% of the seed was shed onto the soil surface while 42.0% appeared with the harvested seed in wheat and rape in Germany ³³⁷.

Origin and History:

Europe. Asia.

Distribution:

ACT, NSW, SA, TAS, VIC, WA.
Cleavers are found in most parts of Tasmania.
Introduced to WA in 1996 as a contaminant of Canola from New Zealand and now under an eradication program.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate.

Soil:

Occurs equally over podsolic, brown, rendzina and chernozem soil types in Poland ³⁵¹. Grows better on heavier soil types ³⁵².

Plant Associations:

Significance:

Third most important weed of wheat in Hungary ^353;353.
4th most common weed in winter wheat and barley fields in the UK ³⁵⁴.

Beneficial:

It is used in traditional medicine in China ³⁵⁵, Australia ³⁵⁶, India ³⁵⁷, and Portugal for its diuretic and spasmolytic properties ³⁵⁸.

Detrimental:

It is predominantly a weed of waste land and gardens, but occurs occasionally in crops. In Europe it is a major weed of crops and it is capable of being strongly competitive. its climbing habit allows it to overwhelm crops and cause lodging, while the mature stems impede harvesting.
Rarely eaten by stock because the four sharp toothed edges on the stems injure the mouth.
Weed of dry land crops associated with Vicia sativa and Avena fatua in China ³⁵⁹.
Weed of cereals in Denmark ³⁶⁰, dry-land cereals in Spain ³⁴⁴, flax in Romania ³⁶¹, forage mallow ³⁶², peppermint in Montana ³⁶³, strawberries in Ireland ³⁶⁴, sugar beet in Poland ³⁶⁵, wheat in Poland ³⁶⁶ and China ³⁶⁷, white clover ³⁶², root crops in Poland ³⁶⁸
Weed in Pakistan ³⁶⁹
Common weed of clover (Trifolium spp.), winter wheat, spring barley, potatoes, winter wheat and oats in Czechoslovakia
³⁷⁰.
Common garden weed in the UK ³⁷¹.
Host for Mycocentrospora acerina, a disease of carrots in Norway ³⁷².
Small pieces of cleavers stems and leaves impaired the efficiency of the straw walkers and sieves ³³⁷.
Carries a Powdery mildew ³⁷³.
Contaminates grain and impedes harvest of cereals ³⁷⁴.

Toxicity:

Addition of up to 3% G. aparine seeds to diets did not affect duck performance, whereas 0.3% supplement of weed seeds negatively affected growth and health condition of broiler chickens ³⁷⁵.
Contaminated feed reduced growth in cockerels ³⁷⁶.
Obstruction of gizzard occurs in fowls through selective picking up of seed from contaminated grain ³⁷⁷.
0.68% cleavers in chicken feed caused 0.42% deaths and 10.06% showing symptoms of poisoning. Treat with Biolent Forte at 1 mL per bird. Post-mortem examination showed that the seeds had caused gastric obstruction and intestinal atony ³⁷⁸.
Both plant and seed contain saponins, hesperidin, quinolinic acid, glucosides and coumarin ²⁹⁴.
Mixed feed with 0.75% Catchweed, resulted in high mortality of chickens 5 days old. In the gizzard of week-old chickens there were up to 29 Catchweed seeds, and in 2 week-old chickens there were up to 72 Catchweed seeds ²⁹⁴.
Turkey chicks were not affected by 3% in feed ³⁷⁹.

Legislation:

Noxious weed of WA.

Management and Control:

See Control of Cleavers with Herbicides

Thresholds:

Probably around 1-2 plants/m².

Eradication strategies:

Ryegrass and Kikuyu pastures
Graze pasture continuously from the break of the season to keep it less than 5 cm tall. Apply 6 L/ha in May/June when Cleavers are less than 10 cm long. Grazing 7 days after spraying may improve control. This treatment will adversely affect Clover production.

Herbicide resistance:

The cuticle has an amorphous wax which makes penetration by most herbicides more difficult ²⁹⁶.
Triazine resistant populations in France ³⁸⁰.
Tolerates some phenoxy herbicides ³⁶⁹.

Biological Control:

Related plants:

Slender Bedstraw (Galium divaricatum)
Small Bedstraw (Galium murale)
Three horned Bedstraw (Galium tricornutum) has curved fruiting pedicels (stalks) and no hairs on the fruit or upper surface of the leaves.
(Galium spurium)

Plants of similar appearance:

Field Madder (Sherardia arvensis). Cleavers can be distinguished from Field Madder by the shape of the cotyledon in the young stage, and in more advanced plants by the size of the leaves and the number in a whorl, and the colour of the flowers. Cleavers have hairs on the edges of the leaves that point backwards (away from the leaf tip) whereas Field Madder has hairs that point forward.
³⁸¹ has colour photos and identification tips.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P218. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P800.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P339.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P620. Photo.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P210. Photo.

Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P61. Diagrams.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #571.1.

Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P115. Diagrams. Photos.

Figures in brackets, for example ³⁰⁰, refer to the main reference database. Contact HerbiGuide for more information.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.