Wayside Alien Fabaceae ( Faboideae ) @ Seremban2

Wayside Alien Fabaceae ( Mimosoideae ) @ Seremban2

Leucaena leucocephala ( petai belalang ) has been described as a ‘miracle tree’ for its multiple uses, yet also dubbed as a ‘conflict tree’ as a noxious weed.

Described as the world’s most widely used forage tree legume by FAO, L. leucocephala in an excellent source of high-protein fodder for animal feed and excellent firewood, and efficient in nitrogen fixation.  The young shoots, young pods, and mature seeds are consumed as food for human.  However, it contains mimosine, a toxic amino acid to non-ruminant vertebrates.

Yet, it is listed as one of the 100 worst invasive alien species by IUCN Invasive Species Specialist Group.  It can grow wide range of soil and rainfall environment, grows quickly and forms dense thickets and produces large quantity of seeds.

Key words : allelopathic, N-fixation, mimosine. 

Neptunia plena ( aquatic sensitive plant ) is an invasive plant thriving on waterlogged area and watercourses.  It is not confined to wetlands but tolerates considerable flooding.  During dry period, the plants become dormant and persist as seeds.  It can lead to increased algal blooms reduce water quality by preventing light penetration and reduce oxygenation of water. 

N. plena and N. oleracea are both referred as ‘water mimosa’.  Water mimosa is a restricted invasive plant under Queensland’s Biosecurity Act 2014.

Key words : allelopathic, N-fixation, mimosine. thigmonasty

Mimosa pudica ( sensitive plant )  is most probably the well-known for its rapid plant movement.  It is most often grown as potted plants for its curiosity value.  It also became an ideal plant for experiments regarding plant habituation and memory.

M. pudica has been listed in the Global Invasive Species Databease 2010.

Key words : allelopathic, N-fixation, nyctinastic, mimosine. thigmonasty

Mimosa diplotricha ( giant sensitive plant ) includes 3 varieties : diplotricha, odibilis and inermis. 

Although M. diplotricha is an excellent ground cover and green manure, it is restricted invasive plant under Queensland’s Biosecurity Act 2014.

Key words : allelopathic, heliophytic, N-fixation, nyctinastic, mimosine. thigmonasty

Chrysopogon aciculatus : The Hated Lovegrass

Chrysopogon aciculatus (Retz.) Trin.

Synonyms

Andropogon aciculatus, A. javanicus, A. subulatus,

Centrophorum chinensis,

Chrysopogon acicularis, C. subulatus, C. aciculatus var longifolius,

Holcus aciculatus,

Raphis aciculatus. R. javanica, R. trivialis, R. zizanioides var aciculatus.

Common Names

love grass, kemuncup

Origin

Tropical Asia

Distribution

Tropical and subtropical regions

Description

A vigorous creeping grass with stout, tough rhizomes, the culms ascending to 45 cm. Inflorescence a small panicle, 7.5-10 cm long, with numerous slender branches. Spikelets narrow. Awn bristly, short and fine. The branches at first ascend almost vertically, spread obliquely at flowering and then bend upward again at fruiting. Each branch has three spikelets at its tip, one sessile and two pedicelled.

Drought tolerance

fairly drought tolerant.

Soil requirements

favours sandy acidic loams with pH 5.1-6.1.

Economics

An extremely common grass in village pasture in the plains of Asia because the prostrate, creeping stems resist overgrazing and trampling.

It used to be used as a cover for coconut plantations in the Philippines, and in Guam the straw was used for making hats and mats.

Its creeping rhizome and its capacity to resist hard grazing makes it useful for stabilizing embankments and similar sites.

Useful for rough lawns, forming a dense, hard-wearing turf, but a troublesome weed when uncontrolled because of the sharp-pointed seeds.

The seeds work through clothing and cause irritating sores.

Grazing animals suffer severely from the ripe fruits becoming attached to their hair by the sharp basal callus. By this means the fruit works its way into the flesh and causes extensive ulceration. Dogs frequently develop abscesses between the toes from the same cause, and germinating seeds of this grass can sometimes be pressed out of large bags of pus in the dog's flesh

A serious pest in north Queensland.  It is listed in USDA’s Federal Noxious Weed List 2012.

Salvinia minima - Common Salvinia

Salvinia minima is a species of aquatic, floating fern of Salviniaceae family native to South America. 

The leaves of S. minima are small and oval, ranging from 0.4 to 2.0 cm in length.  The leaves grow in sets of three, with two leaves floating on the surface and one leaf dissected, hanging underneath.  Fine white hair grow uniformly on the leaf surface.  Brown hairs present on the underside of leaves.  S. minima is rootless.

Salvinia minima is classified as an invasive species on the Global Invasive Species Database.  It can be a nuisance to recreational watercraft, have adverse affects on fish farming, rice farming, and poses a serious threat to native species and biodiversity.

  

Salvinia minima grows on the surface of still freshwater.  Although it is sterile, S. minima can reproduce quickly very quickly asexually through fragmentation.  Buds and rhizome fragments can also remain dormant for long period of time when growth is less favorable.

S. minima undergoes 3 stages of growth.  In the primary stage, the leaves will lie flat on the water surface.  In the secondary stage, the leaves multiply and curl upward.  In the tertiary stage, the leaves become more dense and almost vertical due of crowding.

S. minima can easily out-compete and inhibit the growth of native water plants.  Mats of S. minima can block sunlight from entering the water.  S. minima, which has no nutritional value, is not favoured by fish or bird species as a food source.

In order to protect native ecosystems, numerous effort have been taken to control or eradicate the growth of Salvinia minima.   Herbicides that have been used with best success include : fluridone, imazamoz, and penoxsulam.  Successful biological control agent includes Crytobagous salviniae,  the salvinia weevil native to South America ; and Samea multiplicalis, the salvinia stem-borer moth native to southern US.

Herbicide

Herbicide, commonly known as a weed killer, is a substance used to kill weed.

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A weed in a general sense is a plant that is considered as a plant in an undesired place, at an unwanted time. Weeds may be unwanted for a number of reasons : they might be unsightly, or crowd out or restrict light to more desirable plants or use limited nutrients from the soil. They can harbor and spread plant pathogens that infect and degrade the quality of crop or horticultural plants. Some weeds are nuisance because they have thorns or prickles, some have chemicals that cause skin irritation or tare hazardous if eaten, or have parts that come off and attach to fur or cloths

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Herbicides can be grouped by activity, use, chemical family, mode of action, or type of vegetation controlled.

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Classification by Activity :.

1.Contact

Destroy only the plant tissue in contact with the chemical. Generally, these are the fastest acting herbicides. They are less effective on perennial plants, which are able to regrow from rhizomes, roots or tubers.

2.Systemic

Translocated through the plant, either from foliar application down to the roots, or from soil application up to the leaves. They are capable of controlling perennial plants and may be slower acting but ultimately more effective than contact herbicides.

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Classification by Use :.

Soil-applied herbicides are applied to the soil and are taken up the roots of the target plant..

1.Pre-plant incorporated herbicides are applied prior to planting and mechanically incorporated into the soil. The objective for incorporation is to prevent dissipation through photodecomposition and/or volatility..

2.Pre-emergence herbicides are applied to the soil before crop emergence to prevent germination or early growth of weed seeds..

3.Post-emergence herbicides are applied after crop has emerged.

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Classification by Mechanism of Action.

The classification by mechanism of action ( MOA ) indicates the first enzyme, protein or biochemical step affected in the plant following application..

1.ACCase inhibitors

Acetyl coenzyme A carboxylase ( ACCase ) is part of the first step of lipid synthesis. Thus ACCase inhibitors affect cell membrane production in the meristems of grass plant. ACCase of dicot plants are not sensitive to these herbicides..

2.ALS inhibitors

Acetolactate synthase ( ALS ) enzyme, ( acetohydroxyacid synthase, AHAS ) is the first step in the synthesis of the branched-chain amino acid ( valine, leucine & isoleucine ). These herbicides slowly starve affected plants of these amino acids which eventually lead to inhibition of DNA synthesis.

ALS inhibitors affect both grasses and dicots.

ALS inhibitors includes : sulfonylureas ( SUs ), imidazolinones ( IMIs ), triazolopyrimidines ( TPs ), pyrimidinyl oxybnzoates ( POBs ), and sulfonyamino carbonyl triazolopyrimidines ( SCTs ).

ALS is a biological pathway that exists only in plants and not in animals, thus making the ALS inhibitors among the safest herbicides..

3.EPSPS inhibitors

The enolpyrubylshikimate 3-phosphate synthase enzyme ( EPSPS ) is used in the synthesis of the amino acids tryptophan, phenylalanine and tyrosine.

EPSPS inhibitors affect both grasses and dicots.

Glyphosate is a systemic EPSPS inhibitors, but inactivated by soil contact..

4.Photosystem II inhibitors

Photosystem II inhibitors reduce electron for from water to NADPH⁺ at the photochemical step in photosynthesis. They bind to the Qb site on the D1 protein, and prevent quinine from binding to this site. Therefore this group of compounds cause electrons to accumulate on chlorophyll molecules. As a consequence, oxidation reaction in excess of those normally tolerated by the cell occure, and the plant dies.

Triazine and diuron are photosystem II inhibitors..

5.Photosystem I inhibitors

Photosystem I inhibitors steal electron from the normal pathway through FeS – Fdx – NADP leading to direct discharge of electron on oxygen. As result, reactive oxygen species ( ROS ) are produced and oxidation reaction in excess of those normally tolerated by the cell occure leading to plant death.

Diquat, paraquat hit Fe – S – Fdx step.

Nitrofen, nitrofluorfen, acifluoren hit Fdx – NADP step..

6.Synthetic auxin

Synthetic auxin is effective in the control of dicot plants.

2,4-D is a synthetic auxin herbicide.

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Classification by Type of Chemical

Herbicides
Anilides/Anilines	Acetochlor · alachlor · asulam · butachlor · diethatyl · diflufenican · dimethenamid · flamprop · metazachlor · metolachlor · pendimethalin · pretilachlor · propachlor · propanil · trifluralin
Aromatic acids	Aminopyralid · chloramben · clopyralid · dicamba · picloram · pyrithiobac · quinclorac · quinmerac
Arsenicals	cacodylic acid · copper arsenate · DSMA · MSMA
Organophosphorus	bensulide · bilanafos · ethephon · fosamine · glufosinate · glyphosate · piperophos
Phenoxy	2,4D · 2,4DB · dichlorprop · fenoprop · MCPA · MCPB · 2,4,5-T
Pyridines	dithiopyr · fluroxypyr · imazapyr · thiazopyr · triclopyr
Quaternary	diquat · MPP · paraquat
Triazines	ametryn · atrazine · cyanazine · hexazinone · prometon ·prometryn · propazine · simazine · simetryn · terbuthylazine · terbutryn
Ureas	chlortoluron · DCMU · metsulfuron-methyl · monolinuron
Others	3AT · bromoxynil · clomazone · DCBN · dinoseb · juglone · methazole · metham sodium · sulfentrazone

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Major Herbicides in Use

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2,4,-D

- broadleaf selective, systemic herbicide

- group : phenoxy, synthetic auxin

- MoA : absorbed through leaves, translocate to meristem, increase growth rate

- developed during WW2 by researchers from Rothamsted Experimental Station, lead by Judah Hirsch Quastel

- trade name : Amine®, Rumputox®, Weedtox®

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DCMU

- broad-spectrum herbicide

- group : Urea

- MoA : photosystem II inhibitor

- released in 1954 by Bayer

- trade name : Diuron®

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Dicamba

- broad-sprectrum herbicide

- group : benzoic

- MoA : increase growth rate

- toxic to human being by ingestion and inhalation

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Glyphosate isopropylamine

- broad-sprectrum, systemic herbicide

- group : organophosphorus

- MoA : absorbed through leaves, translocate to meristem, EPSPS inhibitor

- developed in 1970 by John E. Franz for Monsanto

- Trade name : Roundup®, Spark®, BM Glyphosate 41®

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Glufosinate ammonium

- broad-spectrum, contact herbicide

- group : organophosphorus

- trade name : Basta®, Hallmark 15®, Bufos 135®,

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Paraquat dichloride

- broad-sprectrum, contact herbicide

- group : pyridine

- MoA : inhibit photosystem I

- toxic to human being by ingestion

- produced in 1961 by Sinon Corporation for ICI ( now Syngenta )

- BM Parawin 130® , Paranox 13®, CSH-Paraquat®

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Fluazifop-butyl

- grass-selective, systemic herbicide

- group : phenoxyl

- MoA : absorbed through leaves, acetyl CoA carboxylase inhibitor

- trade name : Fusilade®