Final report: Project CSE 1 Identification of species and the origin of Tribulus found in areas of dried vine fruit production Prepared for The Australian Dried Fruits Research and Development Council Prepared by Dr J. K. Scott and Ms. S. M. Morrison CSIRO Division of Entomology Western Australia 31 August 1994 a DEPARTMENT OF AGRICULTURE C S I RO WESTERN AUSTRALIA AUSTRALIA CSE 1 IDENTIFYING SPECIES AND ORIGIN OF TRIBULUS FOUND IN AREAS OF DRIED VINE FRUIT PRODUCTION Organisation: CSIRO Division of Entomology Location: South Perth Department of Agriculture, W.A. Supervisor: Dr J.K. Scott Time Span: July 1991 to June 1994 Objective: To identify, and determine the origin of Tribulus species (caltrop) that occur in areas of dried vine fruit production as a pre-requisite for identifying suitable control measures. Progress: 1. Burrs of Tribulus terrestris s./. were obtained from 54 collections throughout the world distribution of this weed. 2. Morphological analysis of the burrs indicated that the Queensland and Northern Territory collections form a separate group from collections in southern Australia, and that a third group exists in northern Western Australia. The combination of height and length of burrs was most useful to separate the groups and is a suitable quick technique for the preliminary identification of major taxonomic groups. Morphology however, did not reflect all of the variation detected by cytology and isozyme analysis. 3. Chromosome counts of 2n = 24, 36 and 48 were detected in root tips of germinated seed. This polyploid series appears to have an autopolyploid origin. The cytogenetic studies showed that the Queensland and Northern Territory collections are different from all other Australian collections, except possibly two southern collections. The southern Australian and northern Western Australian collections are similar to those from the USA, southern Africa, Mediterranean and the Middle East, indicating that they are introduced. A separate, unrelated group occurs in north west India and parts of the Middle East. 4. Isozyme analysis of seedlings indicated that the Queensland and Northern Territory collections are very similar to each other, are native to Australia and are possibly a separate species from T. terrestris. Populations in southern Australia which are a problem to agriculture, are genetically similar to populations from the USA, southern Africa, the Mediterranean and the ¥iddle East. It is likely that at least two separate introductions into Australia have occurred and that these populations originated from the Mediterranean, Middle East or southern Africa, but not from north west India. 5. Biological control methods have been effective against T. terrestris, but the few known agents are likely to attack native Australian Tribulus species. Most native Tribulus are found in the central and north western Australia and an option for the control of introduced T. terrestris would be to use biological control agents that are restricted to Mediterranean climates. However parts of the world that have this climate and that are similar to dried vine fruit production areas, have not been surveyed for biological control agents. 6. In summary, the techniques of morphological, cytogenetic and isozyme analysis are useful tools to determine the identity and origins of a poorly-described species. The results of this study show that the form of Tribulus terrestris which is a problem to the Australian Dried Fruit Industry is introduced into Australia and has originated from the Mediterranean, Middle East or southern Africa. The option of biological control is still open, but requires the identification of suitable agents restricted to areas of similar climate to Australian dried vine fruit production. Final report: Project CSE 1 Identification of species and the origin of Tribulus found in areas of dried vine fruit production Contents Page 1. Background to the project. 1 2. Variation in Australian and world-wide populations of Tribulus 2 terrestris L. 1. Burr morphology. 3. Variation in Australian and world-wide populations of Tribulus 23 terrestris L. 2. Chromosome numbers. 4. Variation in Australian and world-wide populations of Tribulus 33 terrestris L. 3. Isozyme analysis. 5. Prospects for biological control of introduced Tribulus terrestris L. 52 in Australia. Appendices 1. The origin of caltrop (Tribulus terrestris L.) in Australia and the likelihood of biological control. (1994). Proceedings of the Fourth Biennial Proclaimed Animal and Plant State Conference. 2. Assessment of the origins of Tribulus terrestris in Australia. (1993). Proceedings ofthe lOth Australian and 14th Asian-Pacific Weed Conference. 3. Feedback articles; number 70, March 1992; number 72, July 1992. 4. Weed Update articles; number 10, November 1991; number 11, March 1992. 5. Collecting instructions for caltrop. 6. List of caltrop collectors. This report contains unpublished material and is not to be quoted or referred to without permission of the authors 1 Background to the project At a workshop held in Mildura, Victoria, 13-14 August 1990, four spiny weeds were discussed, three cornered jack and lesser jack, Emex spp., caltrop, Tribulus terrestris and spiny burr grass, Cenchrus longispinus. Seeds of these plants are important contaminants of dried vine fruits in Australia and the workshop considered short and long term strategies for their control (Johnstone 1990). The reports of the working groups from the meeting (Anon. 1990) recognised that an issue critical to the development of long term strategies for the control of caltrop, such as biological control, is the question of identification and origins of caltrop found in Australia. A co-operative project between the CSIRO Division ofEntomology and the Western Australian Department of Agriculture was established to investigate the identification and origins ofT. terrestris. A grant was obtained from the Australian Dried Fruits Research and Development Council that enabled Ms S. Morrison to join the project. The research was based at the Department of Agriculture Western Australia, South Perth and involved a large number of volunteer collectors from Australian and world­ wide locations, who supplied the burrs used in the study. The project was carried out on a half-time basis, extended over three years, to allow sufficient time to obtain the material. Permission was received from the Australian quarantine and inspection service for the importation of the seeds, which have been stored under quarantine. At the end of the project, voucher samples were lodged in herbaria. All extra-Australian samples were either sterilized by gamma radiation in the case of voucher samples or incinerated so as to comply with Australian quarantine regulations. The project encompassed three approaches to identifying T. terrestris in Australia, using morphological, cytogenetic and isozyme techniques. Morphological characteristics of the spiny burrs were measured from 31 world-wide populations of T. terrestris. Seeds from burrs were germinated, 48 collections examined for chromosome counts and 54 collections were used in isozyme analysis. The report that follows comprises the manuscripts resulting from the study. In the appendices are copies of publications and other material, including in the final appendix, a list of collectors to whom we are most grateful for their time and interest. We also thank the Department of Agriculture Western Australian, Weed Science Branch and especially Drs F. D. Panetta, R. J. Martin and R. Cousins for their continued support. We also thank the Australian Dried Fruits Research and Development Council for making this investigation possible. References Anon. ( 1990). Reports of working groups. Plant Protection Quarterly 5, 129-131 . Johnstone, R. B. (1990). Opening address: the problems caused by weed seeds to the dried vine fruits industry. Plant Protection Quarterly 5, 84. Morphology 2 Variation in Australian and World-Wide Populations ofT. terrestris L. 1. Burr Morphology J K. Scott and S. M Morrison CSIRO Division of Entomology, Private Bag, P.O. Wembley, W.A. 6014, Australia. Abstract Measurements were made of the morphology of Tribulus terrestris s.l. burrs from 31 Australian and world-wide locations. The variables included four size variables, four spine angles and the number of seeds in each burr. Cluster analysis using all variables identified four groups ofburrs, but was influenced by a single site that had spines angled differently from other sites. On some plants the basal spine was absent, so its measurements were excluded from further analyses, Four clusters were indicated on re-analysis, likewise with the removal of other variables, until only the length and height ofburrs and abaxial spine length remained. Southern Australian sites were grouped with southern African, Indian and Israeli sites. Three Western Australian sites formed one group, as did Northern Territory and Queensland sites. A fourth group included one Australian, Iran, Israel and USA site. The relationship between length and height distinguished the northern Australian collections that either have taller burrs or more elongate burrs, from the introduced T. terrestris in southern Australia. Analysis of the morphology showed that it is possible to separate northern Australian burrs from other collections and indicated that southern Australian populations are likely to be introduced. However the morphology only approximately detected groupings within the southern Australian and overseas collections