Acacia Varnesiana - mimosa bush

A vigorous perennial shrub much branched growing to 3 - 5 m high. Stems are light coloured, leaves bipinnate with a pair of straight sharp thorns as stipules. Flowers are yellow, globular and produce pods 5.0 -7.5 cm long. It can provide useful dry season forage as scattered plants, but as thickets undersown grass productivity is severely compromised. Generally thorns are <20 mm long but a variant with thorns up to 40 mm long is found. Such plants have been quarantined at Vila wharf growing adjacent to containers from New Caledonia. It is a common weed in rain shadow areas and occurs in significant numbers in the Siviri area of North Efate. Controlled by basal bark spray with Garlon 480 (2% in diesel).

Achyranthes aspera - chaff flower

A perennial herb growing to a height of 70 cm. Stems are jointed and break off easily. Short white hairs occur on leaves, stems and flowers. Leaves are opposite with short stalks. Flowers are terminal spikes with buds that turn downwards as they flower. There are two spiny bracteoles that aid seed dispersal. Often a weed of pastures during the first 18 months of establishment. Timely slashing will encourage dominance of pasture species as will careful grazing management. Seedlings can be controlled by spraying with Butoxone at 1.0%.

Ageratum conzyoides - goatweed

An erect soft stemmed annual herb. Leaves opposite with toothed margins. Flowering heads small and terminal, flowers blue-violet or white. Fruit is black, angular ribbed with a pappus of pale brown coloured scales. It is a weed of newly established pastures that have failed to attain a rapid cover, or of overgrazed pastures where soil is exposed. Control with 2, 4-D or by slashing.

Alocasia macrorrhiza - wild taro, wael taro

An erect, succulent herb with a large tuberous storage root and spreading by short thick rhizomes. Wild taro can form dense thickets if left uncontroHed. Where isolated plants exist they can be dug out together with all root sections and left to dry. Roots will readily shoot from all root, stem or leaf pieces. Thickets can be controlled by thoroughly wetting leaf and stem with 1.0% Butoxone plus 0.4% wetting agent.

Amaranthus Spinosus - spiny amaranth; amarant

An erect, annual herb growing to 60 cm high. Stems are often red, broad and much branched. Leaves are alternate with the larger ones on long stalks. Flowers occur as dense axillary clusters with strong sharp spines. The plant is suspected of poisoning stock. Scattered young plants can be controlled by hand weeding or spot-spraying with 2, 4-D. Amaranthus is a major weed problem when establishing improved pastures in Efate and Tanna.

Dense infestations are controlled by mechanical or hand slashing 8-~0 weeks after planting pastures. In smallholder sitnations on Tanna effective control has been obtained by deferring the first grazing to 7 months after planting which allows the climbing legumes glycine and siratro to smother the weeds. This weed is often severely checked by leaf eating insects.

Annona muricata - Soursop; corossol; korosol

This is a small tree to 7 m tall with simple, alternate entire leaves. Flowers are yellowish and produce dark green oval fruits 15-25 cm long covered with recurved fleshy spines. Soursop occurs on South Santo, Aore, Malo, Epi and the Devil's Point area on Efate. It is a problem in both smallholder and plantation pastures Soursop regrows vigorously after cutting and is difficult to control without the use of herbicide. Garlon 48( ® 7% in diesel, applied to cut stump or to basal bark gives control, as does Starane applied as a 1% foliar spray.

Asclepias curassavica - Gendarme

A perennial shrub growing to 2 m tall; has a fine fibrous bark. Leaves are opposite; flowers on long stalked cymes; seeds are flat and winged with a bunch of long fine hairs at the apex. Hand weeding is the recommended control. Where dense infestations occur Grazon DS spot spraying @ 0.5% or Butoxone at 1.0% is recommended. Poisoning of stock is most likely to occur during periods of over-grazing. It is a minor weed occurring mainly on Santo, Efate and Tanna.

Cassia occidentalis - Coffee senna

Erect shrub growing 1 -2 m high, leaves pinnately compound, alternate, leaflets mostly in 3 - 6 opposite pairs, ovate to oblong in shape with an acute tip, 3 - 10 cm long. Flowers yellow with 10 unequal stamens, flattened, slightly curved linear pods, 9 - 15 cm long containing 40 - 50 seeds. Usually occurs as isolated plants and best pulled out. Dense stands are controlled with Tordon 50 - D at recommended rates.

Cassia tora - wild peanut/pistache; wael pistas

Erect annual growing to 1.5 m tall. Stems pubescent when young with strong smelling foliage. Alternate pinnate leaves with leaflets mostly with 3 opposite pairs, obovate in shape with a rounded tip, leaves 3 4.5 cm long, lower surface pubescent. Yellow flowers occur in pairs with stamens of unequal length producing curved linear pods 10 15 cm long containing 20 - 30 seeds.

C. tora is probably of Indo - Malayan origin whereas C. obtusifolia is of tropical American origin. Numerous authors have confused these two species. The former has a gland between the leaflets of each of the two lower pairs and a broad areole on both sides of the seed often as wide as the seed itself, whereas the latter usually has a gland only between the leaflets of the lowest pair and a narrow areole on both sides of the seed (0.3 - 0.5 mm wide).

C. tora is effectively controlled with Grazon DS at the rates recommended in the accompanying table. C. obtusifolia is effectively controlled with 2, 4-D + picloram at the rates recommended.

In Vanuatu limited damage by the leaf eating larvae of Stegasta variana has been observed. Pistache is a greater problem for the plantation rather than the smallholder sector in Vanuatu. The key to its management is the persistence of vigorous, grass/legume (native or introduced) pastures which do not have their weed suppressing ability impaired by over-grazing.

Pistache has vast soil seed reserves that may remain viable for 20 years and can produce up to 1000 emerged plants/square metre following a particular germinating rain and is unpalatable to stock. Thus under bare soil conditions following (a) the sowing of a new pasture or (b) the overgrazing of an improved or native pasture, pistache can readily dominate, reducing animal carrying capacity directly in proportion to its percentage ground cover.

Attributes of pistache which can be exploited for weed control purposes arc:

Codiaeum variegatum - nasasa

Shrub often multi-stemmed growing to 3 m high in coastal, often saline areas, and if uncontrolled, forming dense, low thickets. Frequently a problem on some ni-Vanuatu plantations on Santo, Aore and Malo. Leaves are commonly dark green, very shiny and 15-20 cm long, altough nasasa is extremely variable in leaf habit colour and growth habit. Flowers are white and occur in open, terminal panicles. Garlon 480 (2% in diesel) applied as a cut stump or frill or Grazon @ 1% for plants < 1 m high offers cost effective control.

Crassocephalum crepidioides - thick head; big hed

An erect annual growing to 1.0 m tall. It has a thick soft stem and few branches. Leaves are alternate with deep lobes and toothed margins. Flowers are corymbs which become erect as flowers open. Fruit is dark brown with a pappus of long hairs. The plant is readily eaten by livestock.

Easily controlled with slashing or hand weeding and correct grazing management. Usually a temporary weed of newly established pastures or a product of severe over-grazing and exposure of bare soil.

Crotalaria pallida - Streaked rattlepod

An erect annual herb with branched stems. Leaves consist of three leaflets, are dull green and oblong, blunt at the tip but with a tiny point. Flowers in dense terminal racemes, are bright yellow streaked with dark lines. Pods are narrow and straight, dark brown when ripe and turn downward. The plant is poisonous but rarely eaten by stock. Controlled with Starane spot sprayed at 0.4% or 300 I/ha.

Scattered populations occur on Tanna and hand weeding is recommended under these conditions.

Cuphea carthagenensis - tarweed

An erect branching herb to 60 cm tall. Stems red to purple, sticky. Leaves opposite, entire margins, ova! to elliptical in shape with acute tip. Flowers pink to purple, small on short stalks in leaf axis. Fruit is capsule with 4-8 seeds. Tarweed invades overgrazed native or degraded improved pastures and can become troublesome due to its persistence and hardiness. Its' strong tap root makes it difficult to manually control.

Control with foliar spray of 0.35% Starane or 1.4% Butoxone.

Cyperus rotundus - nutgrass; anien grass

A perennial sedge growing to 60 cm high, with very dark green, shiny leaves. It has underground rhizomes and tubers. The rhizomes are white and fleshy when young and go brown and wiry when old. Stems are erect, unbranched, smooth and triangular in cross-section Flowers are reddish purple.

Controlled by spraying with glyphosate when 20% of plants are flowering, at 6 l/hectare.

Dendrocnide spp. - nangalat, nettle tree

A small tree to 10m but more commonly 5m, with waxy, bright green leaves with distinctive red or whit venation. Nangalat occurs commonly in regrowth bush and is well known for the stinging hairs on the undersurfaces of the leaves. Smallholders have trouble controlling nangalat in recently cleared bush because of its' tenacity.

It can be controlled by continually cutting back new shoots over a period of months or by spraying regrowth with 1.3% Butoxone and 0.4% wetting agent. Thorough coverage is essential.

Elephantopus mollis - broadleaved tobacco weed; big lif wael tobako

An aggressive perennial herb growing to 70 cm high, sparsely branched. Leaves are concentrated towards the base, narrow, ovate and to 15 cm long. The flowering heads are small and produce fruit that are ribbed with a ring of barbed spines.

Control with a foliar spray of 1% 2,4D ester but rarely occurs in dense stands and can easily be hand pulled.

Eleusine indica - crow's foot grass

A tufted annual to 50 cm high. Leaves are narrow and fold inwards. hiflorescence has 3-5 digitate spike. Spikelets in two rows. Eleusine occurs on poorly drained soils and on disturbed or heavily trafficked area. It is recommended that heavily trafficked areas be planted to Koronivia grass to prevent die spread of crow foot grass. It can be controlled with paraquat or dalapon at 2-4 kg/200 1 or glyphosate at 1.4%.

An small annual herb, prostrate in isolation, ascending when among other plants to 40 cm. Leaves are opposite, stalked and with a toothed margin. Yellow flowers occur in the leaf axils. Fruits are black, urn-shaped, about 3 mm long and bluntly four angled. A seasonal weed of new pasture that has failed to attain rapid cover and more commonly of food gardens. In new pastures crash grazing, rolling or slashing allows sown species to dominate. Eleutheranthera is palatable to livestock and easily kept out of a vigorous pasture.

Euphorbia hirta - asthma plant

An erect, annual herb to 60 cm tall with a few reddish branches. Stems and leaves are hairy; leaves opposite, 2-5 cm long with toothed margins. Flowers occur as dense axillary inflorescences; seeds are red-brown. F. hirta is a weed of bare, heavily trafficked areas and is not a problem in well managed pastures. Control by spraying with Starane.

Hibiscus tileaceus - burao

Small tree to 10 m, often forming dense thickets. Crown branching low and irregular. Leaves simple, heart-shaped to ovoid with short pointed tip and broadly lobed base, 10-15 cm long. Flowers on terminal racemes, Large light-yellow trumpets with dark red centre in the morning and slightly pink before falling in the afternoon/evening of the same day. Fruits - green ripening to brown ovoid pointed dry capsules splitting into 5 sections. Small dull brown seed. Dispersal by seed falling around parent plant and by vegetatively layering from branches. Locally very abundant throughout Vanuatu.

Sometimes a weed of old fence-lines or bush regrowth areas. Controlled by spraying cut-stump and other regrowth with Butoxone (2,4-D + Dicamba) @ 1% solution.

Imperata cylindrica - blady grass; kunai

Perennial grass, up to 2 m high with strong rhizomes. Leaves are flat, broad with sharp margins, usually 30 -80 cm long originating from the base of the plant. Seed is produced in white silvery panicles up to 30 cm long. Blady grass is frequently competitively advantaged by indiscriminate use of fire. Heavy grazing of ground foliage following a burn and subsequent establishment of vigorous, twining, smothering legumes or tall, shading shrub legumes offers the best option for management over large areas. In garden lands apply glyphosate spot spray @ 1.3% to actively growing plants when most have just reached the seed head stage.

Indigofera suffruticosa - anil indigo

A much branched shrub to 2.0 m high. Leaves are grey-green above, yellowish underneath. Pink flowers occur in dense spikes producing crescent shaped pods 15 mm long x 3 mm wide. This weed is serious in some coastal areas of Efate. When it forms dense thickets pastures are severely shaded and thus weakened. Problem usually arises following prolonged over-stocking during the dry season and domination by this weed from the next wet season onwards.

Thickets should be slashed to 30 - 40 cm height and young regrowth sprayed with Grazon DS as recommended. Through wetting of foliage is important. Young seedlings should be spot sprayed @ 0.4% solution strength. Spraying is pointless where there is not an adequate understorey of native or improved grass and legume. Under such circumstances recommended pastures should be sown.

Kyllinga polyphylla - navua sedge; big anien gras (syn. Cyperus aromaticus)

An aggressive creeping perennial up to 50 cm tall with knotty purple rhizomes. Leaves are lanceolate and mainly clustered at the base of the plant. Stems are erect and triangular in cross-section. Flowers occur as clusters at the apex of the flower stalk, subtended by 6 leaf-like bracts - 3 long and 3 short.

This is a major weed of the Melee plain and appears to be spreading in plateau areas of Efate. Seed is spread by cattle, unlike its relative, nut-grass. In wet areas there is considerable promise with the use of Splenda setaria to provide stronger competition than para grass. Patches of this weed should be spot sprayed with glyphosate @ 1.5% or with repeated applications of MSMA + 2, ~D each @ 0.7%. Boom spraying large areas with glyphosate @ 61/ha when 30% of plants are flowering and actively growing will provide effective control. The use of rope wicks either hand operated or tractor mounted allows reasonable control provided multiple passes are made, without damaging undersown pasture.

Lantana camara - lantana

A perennial, scrambling shrub. Young stems are angular with stiff hairs and small downward pointing prickles. Leaves are opposite with toothed margins; flowers occur in stalks in leaf axils. Lantana can form dense thickets and is poisonous to stock.

This is a major weed of Efate and Tanna and locally significant on other central and southern district islands. Smallholders should slash and dig out roots and constantly weed any recently emerged plants. Farmers with access to machinery where large infestations occur are unlikely to have salvageable undersown pastures and should slash/windrow or burn, prepare a conventional seedbed and sow recommended pastures. Small thickets can be controlled by 2,4 D, butoxone, dichlorprop, Grazon sprays or basal bark spraying with Garlon as per recommendations. Natural enemies of lantana, Teleonemia scrupulosa and Uroplata girardia were released in 1935 and 1985 respectively and have suppressed the growth of this weed in some cases.

Merremia peltata - big lif rop

A coarse climbing vine with underground tubers. Stems are smooth and may be up to 20 m long and twine at the tips. Leaves are simple, alternate with purple veins beneath; leaf margins are waxy. White funnel shaped flowers are borne in clusters on stalks 15 30 cm long. It is readily grazed by cattle, which can be used to control the weed. Grazing by cattle offers considerable cost savings prior to the establishment of permanent cover crops and tree crops. Non-grazed areas could be slashed, hand weeded or sprayed with 2,4 -D or glyphosate at recommended rates.

Mikania micrantha - mile-a-minute; minit mael

A vigorous twining vine that roots from nodes on the stems when prostrate. Leaves are opposite, heart shaped with toothed margins. White flowers occur as dense clusters produce small black seeds (2 mm) with a terminal tuft of white bristles. Heavy traffic or extended dry periods tend to control mikania, however it can become dominant during prolonged periods of rain or cloud. Whilst mikania is eaten by stock palatabillty tends to decrease as the moisture content of mikania increases. Where mikania becomes dominant heavy crash grazing can alleviate the problem. Isolated plants should be spot-sprayed with 2,4 -D or hand pulled.

Mimosa invisa - giant mimosa; big gras nil

A biennial/perennial scrambling shrub 1.5 m high with angular branching stems that become woody with age. Stems have many recurved thorns. Leaves are alternate, bipinnate, flowers are pink-purple, and occur in the leaf axils. An extremely vigorous weed able to dominate large areas of pasture land. Whilst it is an established weed on Malekula as yet it is under control in other islands. Outbreaks of giant mimosa should be reported to the Rural Lands Department so that it can be controlled.

It can be controlled with Grazon DS or Starane.

Mimosa pudica - sensitive plant; gras nil

A perennial, low growing, much branched shrub. Stems are stiff, reddish brown with scattered thorns. Leaves are alternate, bipinnate and hairy and fold in when touched. Pink flowers occur on short stalks in leaf axils. The plant contains "mimosine" which can affect stock health. It is not a weed in continuously grazed situations and in fact is a valuable legume, growing on a wide range of soil types and adding useful amounts of nitrogen to the pasture system. Deferred grazing can lead to dominance in native grasses.

Control: as for M. invisa.

Momordica charantia - balsam pear

A vigorous, twining vine with soft, mid-green leaves, deeply divided into 5 to 7 lobes. Flowers are yellow and about 2 cm in diameter. Balsam pear is an invader of recently cleared, plateau soils in areas of high rainfall. It is generally kept under control by trampling and light grazing by cattle. In ungrazed situations balsam pear may become dominant, smothering out less aggressive species.

Balsam pear can be substantially controlled by hand or tractor slashing or by heavy, rotational grazing. It is resistant to 2,4-D but can be killed by spraying with Grazon at 0.5%.

Nephrolepis hirsutula - sword fern; fisbon fen

An erect fern to 1 m tall. It has a short base with brown overlapping scales and has slender spreading runners. The frond is long and narrow divided into lanceolate pinnae with long acute tips and wrinkled margins. Sori close to margins of pinnae.

Sword fern often dominates in shaded situations and may persist after excess shade is removed. Improved pastures easily outcompete sword fern.

It does not respond well to herbicides but some control can be obtained by spot spraying young plants with paraquat at 2.0 ml/I in water. In smallholder situations it should be slashed and planted to improved pastures.

Ocimum gratissimum

A much branched shrub to 2 m tall, with ovate, coarsely toothed leaves to 10 cm long on a 2 - 5 cm petiole. Flowers a slender raceme with close set whorls.

Control with 0.7% 2,4 - D sprayed on young growth.

Pangium edule - big ball tree

A small to medium tree with large, heart-shaped leaves and an irregular crown. It is conspicuous by its large, spherical fruit hanging on thick stalks. Both leaf and fruit contain hydrogen cyanide. Although rarely consumed, cattle have been known to eat both leaf and fruit, usually after a period of instability such as after a cyclone or a drought. In such cases cattle die within one hour of eating either portion. For this reason it is recommended that the trees be eliminated from pastures when the pastures are being spelled. Frill cut application of Garlon 600 at 5% in diesel would be expected to control big ball tree.

Parthenium hysterophorus - parthenium; patenium

An erect annual to 2.0 m tall much branched; deeply divided leaves to 20 cm long but upper leaves less divided and smaller. It has small white flowers. Whilst parthenium has been declared as noxious weed in Vanuatu it has not been as aggressive as was feared. Its' presence in pasture seed imports is prohibited.

Control with atrazine plus 2,4 - D / picloram mixture.

Paspalum conjugatum - T-grass

A perennial forming small tufts with stolons that root from the nodes. Lead blades flat and narrow to lanceolate and to 10 cm long. Inflorescence a pair of racemes, spikelets on very short stalk, fringed with hairs. Grows under partial to heavy shade. It is usually the first native grass to invade recently cleared areas. T-grass is the least palatable of the native grasses, particularly at flowering.

Smallholders upgrading t-grass pastures will find signal grass more aggressive and able to dominate more quickly than Koronivia grass. Cattle will selectively avoid t-grass in mixed pastures and crash grazing may be necessary to prevent its spread. When preparing a conventional seed bed t-grass is more easily ploughed out than carpet grass. It can be controlled with glyphosate at 1.5 - 2.0 I/ha.

Perennial forming coarse clumps, leaves to 50 em long and 2.5 em wide. Inflorescence 7 - 60 racemes each 4 - 12 cm long. Dark brown spikelets paired in 4 rows. Glumes with very small hairs. A tufted perennial grass growing to 1.0 m tall. Leaves to 2 cm wide with soft white hairs. Seed heads may have 20 or more spikes each 5-7 cm long. This grass is less palatable than t-grass when mature but similar in palatability to Koronivia when young. This presents an opportunity to improve these pastures by heavy grazing when young and oversowing with Koronivia/hetero. Heavy crash grazing must be continued until the Koronivia/hetero pasture dominates. Glyphosate at 2 I/ha effectively controls P. paniculatum. This grass is a major problem in nitrogen deficient pastures on Santo.

Passiflora foetida - foetid passion fruit; wael pasinfrut

An herbaceous vine with hairy leaves and stems. Leaves are alternate and 3 - lobed. Single flowers in leaf axils produce a rounded fruit, orange when ripe. The plant is suspected of poisoning stock.

Control: foliar spray of 0.4% Starane or 0.4% Grazon DS. Trampling from heavy rotational grazing will generally control this weed.

Pseudoelephantopus suicatus - narrow leaved wild tobacco weed; wael tobako

An aggressive perennial herb with hairy leaves and stems. It first forms a rosette at ground level. Leaves have rounded tips and taper to a short stalk. Flowering stems arise from the centre of the rosette, are branched and carry numerous flower heads, each with 3-4 pink flowers. Wild tobacco is one of the most serious weeds of central and northern Vanuatu, spreading quickly into overgrazed native pastures. Infestations can be controlled by planting a mixture of smothering and creeping legumes with improved grass. At Tisman plantation wild tobacco has been controlled using minimal mechanisation by planting alternating rows of smothering legumes and signal grass. Irrespective of method used careful grazing management is required to encourage the smothering of the wild tobacco by legumes without smothering the sown grass and finally allowing the grass to spread. Isolated plants can be manually controlled or young actively growing leaves sprayed with Butoxone at l.3 %.

Psidium guajava - guava; kwava

A small perennial tree to 5 m high. Trunk slender with scaly bark, branches close to the ground. Leaves oval to oblong shiny green, hairy under surface. Flowers are small and white producing a pear shaped fruit, golden yellow when ripe containing many seeds which are dispersed by birds and animals.

Seedlings or small plants to 1 m high are controlled by cutting the stem about 5 cm below ground level and covering the cut stump with soil. Alternatively, apply Garlon 480 @ 5% in diesel to cut stump. Chemical control of regrowth is obtained by spraying with 1% Starane, or applying Velpar granules.

Sida acuta - broom weed; smol lif brum

A small woody perennial shrub, growing to 1.0 m high. The main stem branches near the base. Leaves are alternate, lanceolate with toothed edges and hairy on the undersurface. Single pale yellow-orange flowers produce a capsule that breaks into segments when mature, each with two sharp curves. The leaves are narrower than those of S. rhombifolia and have almost no stalk.

Control: Chain slashing at late flowering will kill around 50% of narrow leaf broom, however regular, low slashing encourages the weed. Death is common in prolonged dry spells. Can be sprayed with Starane @ 0.7% or hand weeded. A vigorous, aggressive pasture is essential to prevent re-infestation.

Sida rhombifolia - broom; big lif brum

A perennial shrub to 1.5 m tall with spreading branches. It has tough fibrous stems. Leaves are alternate and hairy. The flowers are yellow-pale orange and produce a single seeded fruit. Young leaves are readily eaten by cattle. Whilst rarely considered a serious weed of pastures big leaf broom can become dominant in undergrazed native pastures.

Chain slashing at late flowering will provide control as will manual weeding or spraying actively growing plants with 0.7% 2,4D amine.

Solanum torvum - pico, wild aubergine

A perennial, erect shrub (to 4.0 m tall) much branched with scattered thorns. Stems are hairy with flattened spines 3-7 mm long. Leaves are alternate, lobed, with a hairy undersurface. White flowers with a yellow centre occur as clusters in leaf axils. The plant can form impenetrable thickets and is probably poisonous to stock. Partial control of dense thickets can be achieved by heavy chain harrowing in opposite directions, but unless salvageable pasture exists new pico seedlings will quickly establish. Infestations in establishing pastures can be controlled by using low rates of 2,4D amine, (0.3 - 0.5%). Common legumes, with the exception of siratro and Shaw vigna, are tolerant of low rates of 2,4 -D if applied more than six weeks after planting. Established plants can be killed by applying 2, 4-D ester to cut stumps. More commonly large plants are slashed and the two week old regrowth is sprayed with 2,4-D amine at 0.5%. Seedlings controlled with 2, 4-D amine. Pico is a major weed on Santo and Efate.

Stachytarpheta urticifolia - blue rats tail; blu rat tael

A perennial shrub to 1.5 m tall, branches curving upwards. Leaves are opposite (10 cm long), soft, dark green, with strongly toothed margins. Stems are smooth, reddish and square in cross section with pointed tips. The flower is a terminal spike, the flowers growing from depressions in the rachis. Flowers are dark blue-purple. The fruit splits into two nutlets flat on the inner side. Blue rats tall can become dominant in overgrazed pastures forming dense, low thickets. Young plants can be controlled by 2,4-D but older ones should first be slashed. Aggressive pastures are essential to prevent future outbreaks. S. jamaicensis is similar but has light blue flowers and leathery leaves with rounded tips and finely toothed margins.

Stictocardia tiliaefolia - wael kumala

A large perennial vine with stems to 10 m long, twining at the tip. Leaves are simple, alternate, heart shaped with a short acuminate tip. Leaf margins are entire, lower surface has small black dots. Produces large funnel shaped pink flowers but is not a prolific seeder. However individual plants can cover a large area. Stictocardia can become dominant in overgrazed coastal pastures, being unpalatable, (and probably poisonous), to livestock. Control can be obtained by slashing or hand weeding.

Certain large tree species can be economically controlled by frill cut application of Garlon 600 at 5% in diesel. Antiaris toxicaria (melek tree), Endospermum medullosum

(whitewood), Dracontomelon vitiense (nakatambol), Samaneus saman (rain tree) and Dysoxylon spp. (stinkwoods) are very susceptible to this treatment. Deciduous species such as Garuga floribunda (namalous) and Pterocarpus indicus (blue water) should be treated when new leaves are flushing and may require follow-up treatment. Other species such as Myristica fatua (bloody wood) and Kleinhovia hospita (namatal) are best controlled by other means. As well as being cost effective, chemical tree control has the advantages that it requires no high maintenance machinery (eg. chainsaws) and because tree leaves fall over a one month period shading is progressively decreased, allowing existing pasture to steadily invade with minimal risk of erosion or serious weed infestation.For information about the frill cut technique see page 48.

Trema aspera - poison peach

A shrub or small tree to 4.5 m high; bark is brown with small grey spots. Leaves alternate, spreading out horizontally, tendency to drop, are rounded at the base but tapering to a fine tip; margins finely toothed. Flowers pale green, small in groups in forks of leaves. Fruit is black and fleshy.

Toxic to livestock but toxicity varies. Mortalities generally in hungry stock. Controlled by hand pulling or spray with 2,4-D at 2.8 kg / ha, high volume, or Garlon 480 as a basal bark spray.

Urena lobata - hibiscus burr

An erect annual shrub to 1.5 m tall with a stringy bark. Leaves alternate, hairy on both surfaces. Pinkish flowers in leaf axils producing a 5-celled fruit each with one seed. There are barbed spines on the fruit.

Seed of hibiscus burr is readily spread by stock. It is becoming a serious weed of overgrazed native pastures in the central and northern regions. It has been successfully controlled on Santo by heavy rotational grazing of the young leaf or can be chemically controlled with 2,4 -D sprayed on seedlings.

Erect perennial shrub to 2 m tall. Strongly rhizematous stems branching primarily close to the ground. Secondary branching in alternating opposite pairs, dull grey/blackish-green in appearance. Stem light greyish brown, finely pubescent, soft to touch, with distinctive black horse shoe shaped leaf scars below branches on upper stems. Leaves decussate, trifoliate, leaflet blade elliptic to obovate with pointed tip, and tapering notched, mid-veins and 5-10 primary laterals conspicuous; terminal leaflet up to 8 cm long, 2 cm wide; darkgreyish green, finely pubescent, dull above, pale greenish grey (appears white from a distance) finely pubescent, soft to touch, dull below. Strong distinctive smell. Flowers on terminal panicles, white to pale blue, 3-5 mm long. Fruit ovoid, c. 5 mm diameter, lower third on closed in light-grey irregularly lobed bracts, thin sub-fleshy coat over hard single seed; green ripening black.

Control: Difficult/impossible to pull out by hand due to rhizomatous habit. Two or three sprayings of Grazon DS at 10% strength in diesel on basal bark and young regrowth will control vitex.