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. Namibia. ABSTRACT characteristicsof the distributionarea of gifblaaris a sandy, welldrained and nutrientpoor soil. The plantsgrow mainly at Gifblaaris an extremelypoisonous plant that results in the foot of the northernslope of dunes,although the dunes livestockmortality. Gifblaar is found in South Africa, Botswana, 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. Burkea africana 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 Dichapetalum 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 stems horizontallyand verticallyaway from the main stem (Figures6, 7 and 8). This branching networkbelow ground may appear as a root 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 leaves 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