Ixodia

Abstract: The effect of annual applications of nitrogen (N), potassium (K) and phosphorus (P) on the yield, growth and nutrient status of Ixodia daisy (Ixodia achillaeioides ssp. alata) grown on a silty loam, was investigated in field experiments conducted during 1989-91 in the Mount Lofty Ranges, South Australia. The experimental design was a randomised block with 3 replications. The N and K treatments, at annual rates up to 200 kg N/ha and 150 kg K/ha, were applied as 2 equal side-dressings. The P treatments, at rates up to 200 kg/ha, were broadcast as 1 annual application. To assess plant nutrient status we sampled the fifth leaf below the growing terminal of 50 stems in October and whole stems at harvest. As rate of applied N increased, there was a significant (P 0.05) affect yield or plant growth. First and second order interactions between N, K and year were not significant. Plant growth and yield responses to P applied as superphosphate were inconsistent and the interaction between P and year was not significant (P>0.05). Coefficients of determination (r2) for relationships between N, K and P concentrations in the fifth leaf samples v. total biomass yield and total stem number, were in the range 0.13-0.52 for the combined 1990 and 1991 data. Based on sensitivity, reproducibility and occurrence of the Piper-Steenbjerg effect, we concluded that N, K or P concentrations in the fifth leaf sampled in October, or in whole stems at harvest, were not reliable indicators of the nutrient status of Ixodia daisy. The application of N and P did not affect the concentration of minor or micronutrients in the fifth leaf. In contrast, the application of K increased calcium (Ca), magnesium (Mg) and sulfur (S) concentrations by 14.3, 33.3 and 12.2%, respectively. For a high density planting (13,000 plants) we estimated that for N, P and K, 69.4, 6.2 and 83.2 kg/ha, respectively, are removed in marketable stems. The application of P increased extractable-P concentrations in the surface (0-15 cm) soil from 22 to 73 mg/kg. We suggest that for surface (0-15 cm) soils, extractable-P and extractable-K concentrations in the ranges 15-95 and 210-260 mg/kg, respectively, are adequate and indicate that a yield response to the application of these nutrients in fertiliser may not occur.

Abstract: The two Tasmanian species of Ixodia (I. angusta and I. achlaena) are re-examined in relation to Ixodia achillaeoides, Haeckeria, Cassinia, Helichrysum and Ammobium. It is concluded that they show as great, if not more, similarity to Haeckeria and Cassinia (especially sect. Rhynea) as they do to Ixodia achillaeoides, and it is proposed that they be segregated as a new genus Odixia. Two new combinations are made: Odixia angusta and 0. achlaena.

Abstract: The endemic Australian genus Ixodia is revised and two species are recognized, namely /. achiltaeoides R. Br. in Ait. f. and I. flindersica Copley, sp. nov. In addition, 3 subspecies of /. achillaeoides, namely ssp. achillaeoides, ssp. alata (Schltdl.) Copley and ssp. arenicola Copley are recognized. Keys, descriptions, illustrations and distribution maps are provided, together with notes on ecology. Nomenclatural History of the Genus The genus Ixodia was first collected by Robert Brown at Memory Cove near Port Lincoln (South Australia) in February, 1802. It was subsequently briefly described by him in the manuscript of his Australian collections and given the name Ixodia gnap haloides. However, Brown did not deal with the Asteraceae in his 'Prodromus' (1810), and this name was never published. The first published diagnosis of Ixodia appeared in W.T. Aiton's "Hortus Kewensis" in 1812. Aiton (1812) acknowledged that the generic name had been supplied by Brown, and in fact Bennett (1866) attributed the compilation of the Compositae, among other families, to Robert Brown. Sims in Curtis's Botanical Magazine (1813), stated that Brown was the author of this species. The correct author citation for Ixodia should therefore be R. Br. in Ait. f. This is in accordance with the International Code of Botanical Nomenclature (1978, p40), which states that "when a name with a description or diagnosis (or reference to a description of a diagnosis) supplied by one author is published in a work by another author, the word in should be used to connect the names of the two authors". Until now the accepted citation has been R. Br. ex Ait. which failed to give Brown credit for the diagnosis and also failed to show that Aiton the younger was responsible for the publication. The validly published type species for the genus is I. achillaeoides, published by Aiton in 1812. However, in Curtis's Botanical Magazine (1813), Sims omitted a letter a from the specific epithet, resulting in the spelling iachilleoides\ This latter spelling was subsequently adopted by De Candolle (1837) and Schlechtendal (1847), and used in nearly all references to this species until Eichler (1965) corrected it in his 'Supplement to J.M. Black's Flora of South Australia'. Only the single species, /. achillaeoides, was orginally recognized. Subsequently, Sprengel (1827) transferred Ammobium alatum to Ixodia as I. ammobium but apparently no later workers accepted this change (Orchard, 1982). Ammobium is currently recognized as a genus consisting of two species, allied, but not necessarily closely related, to Ixodia (Orchard, 1982). In 1847, Schlechtendal described a new species, Ixodia alata, from a specimen collected by Dr Behr in the Barossa Ranges near Tanunda, South Australia. He distinguished this species from I. achillaeoides by its larger stature, longer and broader leaves and greater degree of leaf base decurrence forming wings down the stem. Another species, /. ptarmicoides, was described by Mueller in 1853 from specimens

Abstract: Wilting, yellowing, and dying plants of Ixodia achillaeoides have been observed in commercial plantings in South Australia since 1990. Pathogenicity tests confirmed that Meloidogyne sp., Verticillium dahliae, Fusarium oxysporum, E tabacinum, Phytophthora cryptogea, P. erythroseptica, Oidium sp. and Botrytis sp. are pathogens of Ixodia. Pratylenchus sp. have been found in both the roots of stunted plants and in surrounding soil, and Rhizoctonia solani and F. acuminatum were recovered from diseased root and stem tissue.