Di ch a petalu m Cym os um (POISON -L EAF/GI F B LAAR) . A NEVERENDING PROBLEM .

F.V. BESTER

Ministryof Agriculture,Water and Forestry, PrivateBag 13184, Windhoek. .

ABSTRACT characteristicsof the distributionarea of gifblaaris a sandy, welldrained and nutrientpoor soil. The plantsgrow mainly at Gifblaaris an extremelypoisonous that results in the foot of the northernslope of dunes,although the dunes livestockmortality. Gifblaar is found in South Africa, , themselvesand depressionsbetween the dunesare notfree Zimbabweand Namibia.In Namibia,gifblaar occurs in the from this plant(Opperman and La Grange1969; Du Plooy east and north-eastof the countryand is confinedmainly to 1972). Gifblaar grows in associationwith trees such as the fine,well drained and nutrientpoor sandy soils. Combretumsoecies. and Terminaliasericea (Opperman& La Grange1969; Du Plooy1972; Van Vuuren Duringthe 1960s the farmers in the GrootfonteinDistrict 1960).According to VanVuuren (1961) gifblaar was initially approachedthe South West AfricaAdministration (SWAA) identified as cymosum and Dichapetalum for assistanceregarding livestock mortality due to gifblaar venenatum(Steyn 1934). The acceptedscientific name for "Gifkommissie" poisoning.During 1961 the (Departmentof theplant in Namibiais D. cymosumand the two most common AgriculturalTechnical Services in SouthAfrica) was tasked namesare gifblaar and magougif.Correia and Van Rensburg to investigatethe issueof gifblaarpoisoning in thisarea. The (2000)also refer to anotherspecies, D. rhodesicum,which is SWAAthen purchased property in the GrootfonteinDistrict for foundin the Kavango. the sole purposeof establishingthe SonopResearch Station to conductresearch on gifblaar.Two projectswere launched Thefirst recording of gifblaarpoisoning was in 1890,although with the objectivesof determiningthe possibilityof judicious researchon itonly commenced in 1910(SWAA 1961). Steyn's managementsystems and lick supplementationto alleviate (1928)study and descriptionof the symptomsof gifblaar livestockmortality, and the possibilityof eradicatinggifblaar poisoning- itstoxicology-were complemented by Leemann's by meansof herbicides. (1935)work on the anatomy,morphology and physiologyof the plant.Nearly a decadelater, Marais (1943) isolated and Fromthe resultsobtained it was evidentthat gifblaar could be synthesizedmonofluoroacetate as the activetoxic compound controlledby means of herbicidal control. However, this method in the plant.This breakthroughenabled further research on is costly and not accessibleto all farmers.The alternative the plant'stoxicology and pharmacology.Nonetheless, by the of judiciousmanagement and proteinsupplementation to 1960s,the vagueness in the literatureregarding the treatment reducelivestock mortality proved to be the answer.From this of poisonedanimals was beinglamented (SWAA 1961). And researchguidelines were established thatwere essential in the despitefurther research,Remington's (1935) despair that "the managementprocedures. Grazing of gifblaarinfested areas hope of finding any specificprophylactic or curative andgifblaar free areas can be regulatedduring the two critical substance(antidote) for usein gifblaarpoisoning has become poisonousperiods (spring and autumn)of the plant.Heavy veryremote" remains true today. stockingrates and overgrazing must be avoidedat all costs. Healthcare of theanimals is essential.Animals must be kept Duringthe 1960sthe farmersfrom the Horabeand Nurugas free of internaland externalparasites at all times.During the blocks in the GrootfonteinDistrict approached the South criticalpoisonous periods of the plant,female animals should WestAfrica Administration (SWAA) for assistanceregarding have preferentialaccess to gifblaarfree areas.Handling of livestockmortality due to gifblaarpoisoning. Mr. L.F. La animals,such as dosing, should be avoidedin gifblaar infested Grange,an ExtensionOfficer in Grootfontein,and a botanist, areasand a managementprogramme planned accordingly. lf Mr.D.R.J. Van Vuuren, from the administration were appointed possible,planted pastures should be establishedthat could be to investigatethe issueof livestockmortality in this area. They utilizedduring the criticalperiods. Game are lesssusceptible compileda reportregarding the issueof gifblaarpoisoning. "Gifkommissie" to gifblaarpoisoning and can be consideredas an alternative During1961 the (Departmentof Agricultural optionto livestockfarming. TechnicalServices in South Africa) was also tasked to investigatethe issueof gifblaarpoisoning in this area.The INTRODUCTION SWAAthen purchasedproperty in the GrootfonteinDistrict for the solepurpose of establishingthe SonopResearch Station Gifblaar is an extremelypoisonous plant that results in to conductresearch on gifblaar.Two projectswere launched livestockmortality. Gifblaar is found in SouthAfrica, Botswana, by the livestockresearcher P.A.J. Brand, and the pasture Zimbabweand Namibia. In Namibia gifblaar occurs in the east researcherD.P.J. Opperman. The objectivesof these two and north-eastof thecountry and is confinedmainly to thefine projectswere (a)to determinethe possibilityof management sandysoils of the Kalaharigeological system underlain with systems and lick supplementationto alleviate livestock Karoo basalt(Opperman and La Grange 1969).According mortalityand (b)to eradicategifblaar by meansof herbicides to Correiaand Van Rensburg(2000) the generalecological ordigging the plant open and treating it with herbicides. During

AGRICOLA2OO5 1982,a similarproject to the feedingtrial conductedin the 1920sby theVeterinary Services in SouthAfrica (Steyn 1928) with domesticatedanimals, was conductedin Namibiawith game (Basson,Norval, Hofmeyer, Ebedes & Schultz1982). In 1982the DepartmentofAgriculture and Nature Conservation was requestedto compilea reporton researchdone in the past regardinggifblaar poisoning and eradication.A report was compiledby the authoras requestedand laterpublished in the Agricolaof 1998.The issueof livestockmortality due to gifblaarpoisoning remains never ending,and recently farmersfrom the OmahekeRegion also soughtinformation concerningmeasures to eradicatethe plant.These requests ledto a demonstrationtrial launched by J.A.J.Van Eck (2000) in OmahekeRegion. Gifblaar is a uniqueplant and is very Figure3. Flowerof the Gifblaar plant. difficultto eradicateif certainprecautions are not taken.The

aim of this paper is, therefore,to enlightenthose who are concernedabout what has beendone regardinggifblaar and precautionsto be takenwhen attemptingto controlgifblaar (Figures1,2 and3).

CHARACTERISTICSOF GIFBLAAR

Leemann (1935) providesan in-depthdescription of the anatomicaland morphologicalproperties of the plant,which are of interestnot only from a botanicalpoint of view,but also insofaras its eradicationis concerned.The plantconsists of a set of branches(stems) just belowsoil level,spreading in a horizontaldirection from a main stem that penetratesthe Figure1. Gifblaarplant. soilvertically (Figure 4). Thesebranches every now andthen sendtufts of leavesabove ground (Figure 5). This branching belowground level may stretchfor many meters,forming an extensivenetwork of stemshorizontally and verticallyaway from the main stem (Figures6, 7 and 8). This branching networkbelow ground may appear as a system of the gifblaarplant but is anatomicallythe stem of the plant.The gifblaarplantfroma botanical pointof view is a climberthathas gone underground.The plantstill retains the characteristics "the of a climbingplant below ground and planttakes every opportunityto twist and climb even underground"(SWAA 1961).

In 1935, the VeterinaryServices Division in South Africa conductedfeeding trials in orderto determinethe exactstage

Figure2. Gifblaarplant with fruit. Figure4. Mainstem and itsnumerous branches

AGRICOLA2OO5 Figure5. Mainunderground stem, with above ground

FigureB. Stem system of gifblaar plant growing vertically

in the plant'sgrowth cycle when the toxicity was at its highest. Theyestablished that this occurredin spring,when the plant producednew shoots,and in autumn,when it formed new leaves(Leemann 1935). Thus, the concentrationof mono- fluoroacetateis highestwhen the plantsprouts. lt is obvious, therefore,that climaticconditions play a role in determining

Figure6. Extensivestem systemof the gifblaarplant branching horizontally.

,,i'l

Figure7. Stemsystem of gifblaarplant growing horizontally. Figure9. Maturegifblaar plant

AGRICOLA2OO5 when and for how long the plant is toxic enough to kill the gifblaarleaves forming arches (Figure 10) livestock. Even as it matures, although the concentration A feature of utmost importanceis the ability of the gifblaar of acid decreasesthe plantnever ceases to be toxic(ibid.). plantto sproutwhere stems have been damaged (Figures 11 Moreover,further research(Steyn 1928)found that all parts and 12) or to propagateitself by settingroots and forminga of the plantcontained the toxin. newplant from cuttings of thestem that may remain in thesoil aftereradication (Leeman 1935). As the plantmatures (Figure 9) the concentrationdecreases but it neverceases to be toxic(Leemann 1935). Therefore, it METHODSOF CONTROLLINGGIFBLAAR is obviousthat climaticconditions play a role in determining when the plant is toxic and the lengthof the toxic periodthat Prior to the 1950s before herbicides(weed killers)were results in livestockmortality. According to Steyn (1928) all available,farmers tried any possible measure to eradicate partsof the plantcontain the toxin monofluoroacetate(SWAA gifblaar.Measures that were testedwere to pile salt over the 1961). leavesor spraythe leaveswith paraffinor insecticide(locust poison).All these methodswere haphazardand led to no definiteresults. Leemann (1935), therefore, saw the necessity of investigatinggifblaar eradication on a scientificbasis. He was, accordingto Meissner(1964), the first researcherto control gifblaar successfully.Until the late '1960sdifferent methodswere researchedin SouthAfrica and Namibiato try and controlgifblaar. The methodsthat were tested were (a) diggingopen and uprootingthe whole plant,(b) diggingthe mainstem open and usingmeasures to treatthe stem,and (c)foliage and soiltreatment with chemicals and herbicides.

Uprootingof the Whole Plant

Diggingthe plantopen (uprooting)and removingthe main stem (wholeplant) appeared not to be very successful.The reasonis becausethe planthas the abilityto form new suckers Figure10. Gifblaar leaves, showing the characteristic arches made if damaged,or evenworse, small cuttings of thestem that may bythe veins. remainin the soiltend to propagatethemselves, forming new .Pioneer farmers experienced that ploughing increased the gifblaarinfestation and thereforeabandoned this method Accordingto Phillips(1927) a few otherplants that occurin (Leeman1935). Leeman (1935) warns againstthis method the samehabitat as gifblaar,are verysimilar in growthhabit. "the and states that evil is only increased".Van Eck (2004) Theyalso have well developed underground stems and grow demonstratedthat removingthe plant15 cm belowsoil level in clumps,the same as gifblaardoes. The leavesof these manuallyis not a propositionand that the plantsrecovered plantslook very much gifblaar the same as the leavesof the 100percent. plant,which may easily lead to confusionbetween the different plants.lf the leavesare opposite or hairy(felt-like) the plantis When using this method to control gifblaar,it is therefore notgifblaar. Avery importantanatomical feature of thegifblaar necessaryto make sure that every part of the plantis dug out plantis the peculiarvenation of the leaves- the mainveins of and removed.In practicethis is very nearlyimpossible and is dependenton the degreeof infestation(number of plants) and areaof infestationconcerned.

Digging the Main Stem Open and Using Measures to Treat the Stem

. Diggingthe main stem open and stem burning

Accordingto VanVuuren (1960) it is possibleto controlsmall areasof gifblaarby diggingthe stemsopen and stem-burning them.However, this method is alsodependent on the number of plantsper area and the sizeof the areaconcerned.

. Diggingthe main stem open and treating plants with chemicals

The work initiatedby Leemann (1935) was to test the Figure11. Damaged planl Figure12. Damaged stem effectivenessof different chemicals and combinationsof sprouting. sprouting. these chemicalsto kill the gifblaarplant. From the onsetof

10 AGRICOLA2OO5 and the plant,in effect,dies of hunger.These herbicidesare usuallyregistered to controla certaingroup of plantsand are marketedunder a certaincommercial name.

With the developmentof new herbicides(weed killers) with a hormoneactive component, new hopewas raised.Despite the fact that these herbicideswith a hormoneactive component were not specificallydeveloped to control gifblaar,most of themwere tested on gifblaarwiththe hope thatthey may killthe Figure13. Multiplicationby sendingdown new stemsfrom lateral plant(Meissner 1964). Most of the resultswere disappointing. branches.Stem 1 is the originalplant. Stems 3, 4, 5, and 6 are However,Meissner (1964) reported success with a few of the secondarystems sent down from branches. productssuch as 2,4,5f, Erobonand Fenac.These products are no longeravailable on the market.Methods of application his experiments,Leemann's approach was to dig open the that were testedwere foliageapplication and soil application mainstem and apply the chemicalsubstance to it. Inthe case of the herbicidewith a rucksackand fine spraynozzle. The where there were severalstems going down vertically,each herbicidesapplied were absorbed either by the leavesor the one had to be treatedseparately (Figure 13). According to rootsof the plant. Leemann(1935) no lastingeffect can be obtainedunless the main stem is treated.This contentionwas also confirmedbv . Foliageapplication his experiments. Meissner(1964) reviews the researchdone during the 1960s In his trials, Leemann (1935) tested chemicalssuch as in South Africa with these newly developed herbicides. coppersulphate, sodium chlorate and sodiumarsenate. In Oppermanand La Grange(1969) also tested some of these order to get a wide range of informationhe appliedthree herbicidesat the Sonop ResearchStation in the Grootfontein treatmentsusing the differentchemicals. In the firsttreatment Districtin Namibia. the chemical (crystalform) was applied directlyagainst the main stem, and in the secondtreatment the chemicaldid The results with the foliage spray were disappointing. not make directcontact with the stem.A third treatmentwas Accordingto Meissner(1964), this was due to the low ratio eitherfrilling (ring-barking or girdling)the stem,or leavingit of aboveground leaves, compared to the mass of stemsand uninjured. below ground. There were too few leaves to absorb enough herbicideto effectivelykill the mass of stems and Frillingand placingthe chemical in contactwith the stemgave rootsbelow ground. The poorresults were alsoascribed to the the best results.However, the successrate was unsatisfactory. slow metabolismof the plant. The absorptionof the herbicide From the experimentsit was concludedthat the treatment throughthe leavesand transportationthereof from foliageto shouldnot be too violent,because the treatedpart of the plant the rootswas slow.Phillips (1927) describes the appearance dies too quicklyand does nottranslocate the substanceto the of the leaves of the gifblaar plant as leathery,as the plant remoteparts of the plant.To overcomethis, Leemann (1935) matures.lt was foundin Namibiathat woody plants that have placedsand, thoroughly drenched with a solublemixture of the similar leaves or hairy leaves,were difficultto control with chemicals,around the mainstem that had beengirdled. With foliageapplication. this method the success rate increasedsatisfactorily. Good resultswere obtained with all the chemicals. However, copper The research done in South Africa showed that the best sulphatewas recommendedbecause it was not poisonous resultswere obtainedwhen applied on to the soil and the and thereforenot harmfulto animalsor humans. herbicide absorbed through the stems. The reason was that these herbicideshad a long residualaffect in the soil At the Sonop ResearchStation, Opperman & La Grange (1969) obtainedgood resultsby treatingthe girdledmain stem with prussicacid. However,they found it tediousand time consumingto locatethe main stem of the plantto be treated.Like all the previousmethods, this methodis also dependenton the numberof plantsper areaand the size of the areaconcerned.

Foliageand Soil Treatmentwith Herbicides

At this pointit would be appropriateto enlightenthe reader that many authors refer to chemical control of plants. The correctterm would be herbicidalcontrol of plants.The newly developedherbicides have hormoneactive components that are mainlyorganic compounds. The herbicideis absorbed by the plant and affects the metabolismof the plant. For Figure 14. Herbicideregistered to control instance,the photosyntheticfunction of the plantis inhibited gifblaarwith prescription.

AGRICOLA2OO5 tl comparedto foliageapplication. lt wastherefore also possible to applythe herbicideson to the soilthrough the year.That is, from when the plantsprouts in the springuntil autumn, when the plantdies. lt was also foundthat the best results withfoliage application were obtained when the leavesof the plant were thoroughlywetted with the herbicide.The costs of the applicationwere then additionally increased. The main drawbackof all the herbicideswas that not one of them could controlgifblaar successfully with only one seasonof application.One or morefollow up treatmentswere needed, which raisedthe cost of controlconsiderablv.

Oppermanand La Grange(1969) also obtained better results with applicationsto the soil. However,they found that the best resultswere obtainedwhen the herbicidewas applied to the soil duringthe spring,compared to latesummer. The penetrationof the herbicideduring the springwas betterthan Figure16. Cluster of gifblaarleaves. in the latesummer. They also found the gifblaarcould not be controlledwith a singleseason's application. and even eradicatedgifblaar from the farm.This methodmay be cheapbut is also dependenton the degreeof infestation Wessels(1983) reportssuccessful results with the herbicide of theplant (Figures 18, 19 and 20). Tordon 225. Tordon 225 was registeredas an herbicideto control woody plants. Another Tordon product, K22 was REDUCINGLIVESTOCK MORTALITY THROUGH registeredlater as a herbicideto controlgifblaar (Figure 14). JUDICIOUSMANAGEMENT

The mostrecent work done on herbicidalcontrol of gifblaarin Despitethe fact that many farms,according to Steyn (1934), Namibia,was doneby Van Eck (2004).Herbicides that were are so heavilyinfested that fencingoff would not be practical, tested were TordonSuper, Access and Savana SC. Access and if undertakenwould impairthe carryingcapacity of the yieldedthe best resultswith a 100 percentsuccess rate. The farm, he still recommendsspare camps and avoidingover costs per plantwere also the lowestwhen usingthe herbicide utilizedareas. Opperman and La Grange(1969) refer to the " Access.The costs per plant were, (a) Access 0.81 cent, (b) harmfuleffect of milking"that obviouslyleads to over TordonSuper 1.99centand (c) SavanaSC 1.40 centper utilizationof areas,forcing animals to graze gifblaar. plant.The costper plantplays an importantrole, considering thatplant densities may be in the orderof 100000 to 200 000 Accordingto Steyn(1934) it is well knownthat animalsthat plantsper hectare(Figures 15, 16 and 17). grew up on areaswhere other poisonous plants occur, do not necessarilybecome poisoned. Owing to the tastelessnessof the gifblaarleaves and buds,animals that grew up in areas where gifblaaris prevalentare always liableto get poisoned (Steyn,1934). Contradictorily, in Namibiathe experienceis thatanimals that grew up in a gifblaararea tend to avoidthe plant.A measurethat is taken by farmers is to removethe above ground leavesof the plant beforehandand only then to allowthe animalsto graze the area.The practicalityof this measureis onceagain dependent on the degreeof infestation (VanVuuren 1960).

Figure15. Foliage application of herbicide.

. Removing leaves and feeding plant through translocation

A method used by farmers is to cut off the leaves above- groundand feed the plantthrough a plasticpipe connected to the stem (translocation),from a bottle containingcopper- sulphate (Van Vuuren 1960). According to the popular literature,many farmershave used this methodwith success Figure17. High density of gifblaarleaves

tz AGRICOLA2OO5 There was no prophylactictreatment available that could musthave free access to waterto avoidherding and waiting. be recommendedbefore, or a remedyafter, an animalhad Animalsthat have eaten gifblaarand show symptomsof grazedgifblaar plants (SWAA 1961). Symptoms and death poisoningmust not be chasedor allowedto drinkwater. may occur a few hours or up to 24 hours after ingesting gifblaarplants. In acutecases, there is no time to applyany DISCUSSIONAND RECOMMENDATIONS medicineafter the animal shows symptomsof poisoning. However,this is dependent on theamount of gifblaaringested. Ownexperience and researchdone in the pasthave enabled Manylocal remedies have been used with success. However, farmersto overcomelarge scale mortalityof livestockand to the successesare ascribedto rate of excretionof the toxin farm successfullyin gifblaarinfested areas. However,there rather than to the treatmentapplied (SWAA 1961).Eland are still requestsfrom some farmersfor meansof eradicating and kudu are much less susceptibleto gifblaarpoisoning the plant.The reasonfor thispublication is to enlightenthose than largestock and (Basson, Noval, Hofmeyr, Ebedes who have the need for such informationin orderto reduce '1982). and Schultz Goats are more susceptibleto gifblaar livestockmortality due to gifblaarpoisoning. poisoningthan largestock becauseof their feedinghabits. It is worthmentioning that the goatson the SonopResearch Becausethe gifblaar plant has the ability to setroots and build Stationwere movedto the UitkomstResearch Station durino up a new plantfrom fragments left in the soilafter uprooting the 1980s. it, it is not recommendedthat this methodbe use to try and eradicategifblaar. lt may be arguedthat the few fragments From the above-mentionedreports and the observationsof that may remaincan be eitheruprooted when a new plant farmers,Opperman and La Grange(1969) concluded that has establisheditself or treatedwith herbicides.The fact losses of livestockwere considerablyincreased by poor remainsthat it is a tediousand a timeconsuming method that managementpractices and overstocking. By thefacts that the is dependenton the rateof infestationand the size of the area highestinfestation of gifblaaroccurred mainly on the northern that is infested.Should this methodbe used,care shouldbe slopes of the dunes and that gifblaarwas not necessarily takento removeall fragmentsin the soilto avoidnew plants poisonousthroughout the year, they were convincedthat forming. livestockmortality could be restricted by judicious management practices.Therefore, the projectcommenced in collaboration Whendigging the plant open and treating the main stem with a with P.A.Brand. chemicalor herbicide,girdling (ring-barking) is essential,as it increasesthe uptakeof the herbicidethat is applied.Treating The mainobjective of thetrial was to fenceoff the dune areas, the girdledstem with a chemicalis not recommendableas where the gifblaar occurred most, from the area between thereis not a 100 percentguarantee of successdespite the the dunes,where no or littlegifblaar occurred. These two fact that chemicalshave been tested. lt is also essential areas were grazed separatelywith oxen and cows at three that the main stem must be locatedand treated.Leemann stockingintensities. The camps were grazed accordingto (1935) guaranteespoor results if the main stem is not the conventionaltwo campsystem, the onlydifference being treated.The many stemspenetrating the soil must also be that the campswith gifblaarplants were not grazedduring treated,rendering this methodvirtually impossible in highly the criticalsprouting period. The gifblaarfree camps were infestedareas. Damaging a stemalso results in multiplestem unfortunatelygrazed during spring every year.The control formation.Digging the stemopen and stem burningwill also groupgrazed a partiallyinfested camp continuouslyat a low be dependenton the degreeof infestation. stockingrate. Researchresults show that it is possibleto controlgifblaar by Therewere no mortalitiesin any of the stockingintensities. usingherbicides that are availableon the market.lt mustbe The higher intensitycaused the rangelandto deteriorate kept in mindthat whilegifblaar can be controlledwith these drasticallyand the performanceof individualanimals to drop. products,it will not be possibleto eradicatethe plant, although However,production per hectarewas higher.The weaning this may be possiblein areasthat are not denselyinfested weightsof the calvesin the highergrazing intensity camp with gifblaar.When applying the herbicideto the leaves,it is tendedto be lower. essentialthat the leaves are thoroughly drenched with the fluid in orderto ensurethe bestresults. Herbicides are expensive From the resultsobtained at Sonop ResearchStation, and and not always within the reach of many farmers.When observationsduring the trial period, Opperman and La Grange using herbicides,it is essentialthat the recommendations (1969)concluded that judiciousmanagement could reduce on the labelbe followedto ensurethe best results.Taking or even stop mortalityof livestockdue to gifblaarpoisoning. shortcuts to cut costs,such as dilutingthe herbicide,is not The main objectivesof judiciousmanagement would be to recommendedas it willonly lead to poorresults. avoidover grazing even in areasthat are slightly infested with gifblaarand not to grazeheavily infested areas when the plants Dueto the highcosts of herbicidesand the impracticalitiesof are sprouting.Areas should be restedin orderto accumulate manyof the methodsthat have beenfound successful, and sufficientgrazeable material that can be utilizedduring the on the basisof informationgained by experiencedfarmers, criticalperiods when plants are most poisonous.Animals thetrial to testjudicious management as a measureto reduce that were agitated,under stress or ill,were likelyto die after livestockmortality due to gifblaarpoisoning was launched ingestinggifblaar. Animal health is thereforea prerequisite. on the Sonop ResearchStation. From observationand the Fastingfor extendedperiods should be avoidedand animals quantifiableresults obtained, it was concludedthat it was

AGRICOLA2OO5 13 possibleto stop livestockmortality. A set of guidelinesand duringthis dry periodand shouldbe providedfrom early recommendationswere compiled in orderto assistfarmers. wrnter.

Animalsthat are adaptedto the area will not eat gifblaarif The largestproportion of animallosses occurs when animals sufficientgrazeable material is available.lt is thereforeof are handledor afterhandling, for instancedosing or chasing utmostimportance that sufficientgrazeable material is made them. lt appearsthat an animal might have ingesteda available.The toxicityof monofluoroacetateis highest during thresholdamount of gifblaarthat would not normallyaffect springwhen the plantsprouts and most of the other plants it, but due to the physicalactivity poisoning becomes acute, are stilldormant. As the plantmatures, the toxicitydeclines. resultingin the death of theanimal. Mortalitiesare lessinclined to occurwhen gifblaar sprouts for a secondtime duringthe autumn.Based on thesefindings . When animals are grazing gifblaar infested areas, the mangementprocedures that are recommendedare as handlingof animalsmust be reducedto a minimum follows: and managementpractices should be planned and implementedaccordingly. . Farmsmust be plannedand fenced so as to havepoison free campsavailable for the dry periodsof earlysummer It is alsofound that cows, especially pregnant cows, are more and springwhen the gifblaarsprouts. A good systemof susceptibleto gifblaarpoisoning than maleanimals. rangemanagement is essential,and sufficientnumbers of campsmust be provided. . lf sufficientgifblaar free camps are notavailable preferen- tial accessto the availablecamps or gifblaarfree areas . Animalsmust grazegifblaar free areasduring the most mustbe givento the femaleanimals. criticalperiod that extends for 2Io 3 monthsin the spring when plantssprout. . lf possible,planted pastures are an optionthat can be grazedby theseanimals during critical periods. . Areas or campsshould be withdrawnfrom grazingand restedto buildup sufficientgrazeable material that can . Supplyingextra feed, especially a proteinrich supplement, be grazedduring the mostcritical periods when gifblaar is to the femaleanimals may also be an option.However, mostpoisonous. purchasingthe extrafeed is costly.

. lf it is unavoidableand areas that are infested with gifblaar . The lattertwo optionscan be generalized,and appliedfor have to be grazedduring the criticalperiods, stocking allfarm animals. ratesshould be low and the camp not heavilygrazed. lt is recommendedthat stocking rates should at alltimes be Other managementaspects that must be taken into adaptedto the amountof availablegrazeable material. considerationin orderto reducelivestock mortalitv are:

. lf it is possible,areas infestedwith gifblaarand gifblaar A healthcare programme is necessary. freeareas should be separatedby meansof camps.lf it is not possible,the areasmust be grazedaccordingly. Animals must not be fasted (kraaled)for an extended periodof time,which is thecase when animals are milked. . Overgrazingmust be avoided at all costs as it is uneconomical,since production peranimal drops, weaning Animalsmust have free access to licksand water in order weightsare reducedand the rangelandis damaged.This to avoidagitation and stress. makesa farmermore vulnerable to periodicand disastrous droughts. Where possible,water pointsand kraalsshould not be erectedin a gifblaarinfested area. However, this may not . Animal numbers should be adapted annuallyto the be possiblein manycases and such areas can be cleared availablegrazeable material to avoidovergrazing and the by meansof the variousmethods described above. chancesof animallosses through gifblaar poisoning. Animals that are chased from one place to another, . The physiologicalprocesses and healthof the grazeable tend to grab any plantin sightwhile being chased. In plantsmust be compliedwith, thereforeresting of the the processgifblaar plants are also ingested.Service rangelandis of utmostimportance. corridors(passages) can be erected to ease animal movementon the farm.These areas can also be cleared lf winteris precededby late rains,a good springsprouting of gifblaarby the differentmethods of eradication.They of gifblaarand foragebushes can be expected.However, in can also receivea rest at certainoeriods and serveas someyears spring is dryand the quality of the grazingis such grazingduring critical periods. that animalscannot ingestsufficient feed for maintenance. Theywill then search for green growth, resorting to thegifblaar From researchit was establishedthat game are less thatsprouts earlier than other plants. susceptibleto gifblaarpoisoning and thereforegame farmingcould be an optionin orderto avoid largescale . Proteinrich supplementation licks are absolutely essential mortalityof animals.

14 AGRICOLA2OO5 '1928. REFERENCES Steyn, D.G., Gifblaar poisoning. Directorate Veterinarian '187-198. Educationand Research.Reports 13 and 15,pp Basson,PA., Norval,A.G., Hofmeyer, J.M., Ebedes, H. andSchultz, Steyn,D G., 1934.The toxology of plantsin SouthAfrica. C.N.A. R. Anitra, 1982. Antelopeand poisonousplants l Gifblaar SWAA/SouthWest Africa Administration., 1961. Die Gifkommissie. Dichapetalumcymosum (Hooker) Engler and Prantl.Mardoqua, South WestAfrica AdministrationReporI, March-July. Vol13 No 1. VanEck, J., 2004.Chemicalcontrol of gifblaar.Spotl ight on Ag riculture Correia,R. l. De S. and van Rensburg,L., 2000. Geographical No77. March,2004. plantkundige distributionand local occurrenceof Dichapetalumcymosum Van Vuuren, D.R.J., 1960. Verslag van die oor (Hooker)Engler (Gifblaar) in Namibiaand surroundingareas. die ondersoek na gifblaar (Dichapetalumcymosum) in die Agricola,11 . Horabeblok.South West Africa AdministrationReport, August, Du Plooy,P.J , 1972. Ondersoekna die voorkomsvan gifblaar 1960. (Dichapetalum cymosum) wat die weidings potential van Wessels, H., 1983. Herwonnegifblaarveld nou nood weiding. Boesmanlandbelnvloed. Windhoek: Departement van Bantoe- Landbouweekblad. Julie, 1 983. Administrasieen -Ontwikkeling. Leemann,A.C., 1935. The eradicationof Gifblaar.Boerdery in Suid- PHOTOGRAPHS Afrika.June. 1935. Leemann,A., Departmentof Agricultureand Forestry,South Africa. Meissner,Ruth., 1964. Gifblaar- rateltaaimaar tog uitroeibaar' Van Eck,J.A.J., Directorate of AgriculturalResearch and Training; Boerderyin Suid-Afrika,December, 1964. Ministryof Agriculture,Water and Forestry,Private Bag 13184, Marias,J S.C., 1943 Mono-flour-aceticacid: The toxic principleof Windhoek.Namibia. gifblaar.Onclerstepoort Journal of VeterinarianResearch, 19 '1969. Bester,F.V, Directorateof AgriculturalResearch and Training; Opperman,D.J.P and la Grange,L.A., Gifblaarcontrolin South Ministryof Agriculture,Water and Forestry,Private Bag 13184, WestAfrica. Boerdery in Suid-Afrika,May 1969. Windhoek,Namibia. Phillips,E.P., 1927. Gifblaar en Gousiektebossie.Boerdery in Suid- Afrika.Maarl, 1927.

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