ISSN:
1573-5036
Keywords:
Fusarium camptoceras
;
Fusarium sp.
;
Medicago spp.
;
neosolaniol monoacetate
;
phytotoxicity
;
toxicity
;
trichothecenes
;
wheat
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The toxicity of 12 South African isolates of an undescribedFusarium sp. from soil and other substrates was tested in plants and animals. TheFusarium sp. resemblesF. camptoceras but differs in several respects. Two reference cultures ofF. camptoceras were therefore included in the toxicity tests. An isolate ofF. graminearum Gr 1, a known pathogen of annualMedicago spp. (medics) and wheat, was also included in the plant tests. Maize cultures of all theFusarium sp. isolates and oneF. camptoceras isolate were toxic to ducklings. Ethyl acetate extracts of cultures of nine of ten isolates of theFusarium sp. were dermotoxic to rabbit skin. In soil infested with sand-bran inoculum of the fungi, allFusarium sp. isolates, oneF. camptoceras isolate andF. graminearum Gr 1 caused significant (P=0.05) mortality of medics, whereas onlyF. graminearum Gr 1 caused mortality of wheat plants. Seven isolates of theFusarium sp. caused stunting of medic and wheat plants as well as discolouration, necrosis and die-back of the tap root of medics and the primary roots of wheat. The fungus could, however, not be isolated from these necrotic roots. In contrast,F. graminearum Gr 1 that caused discolouration of medic roots and typical crown rot symptoms of wheat, was readily isolated from affected roots and crowns. Maize cultures of isolates of theFusarium sp. and ofF. camptoceras were chemically analysed for neosolaniol monoacetate (NMA), diacetoxyscirpenol (DAS) and T-2 toxin. NMA was detected at levels ranging from 310 to 2060 ng g−1 in 10 of theFusarium sp. isolates, but not in theF. camptoceras isolates. The mortality of medic plants and the NMA yields of isolates of theFusarium sp. in maize cultures were significantly correlated (r=0.84,P〈0.05). A solution containing 10 mg litre−1 of pure NMA was only slightly toxic to ducklings. Exposure of seeds to this solution had no effect on medics and wheat, but exposure of seedlings caused marked mortality in medics and reduction of shoot length in wheat. A solution containing 100 mg litre−1 of NMA was acutely toxic to ducklings, but had no effect on medic and wheat plants when added to soil. Phytotoxic effects on medic and wheat plants were obtained with a concentration of 5000 ng NMA g−1 soil. In all tests, the phytotoxic effects were more drastic in medics than in wheat: medics were killed, whereas wheat seedlings were stunted. This is the first report of the phytotoxicity of NMA to medics and wheatin vivo and probably also the first report of the phytotoxic effects of a pure trichothecene added to soil.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02203084
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