Plant Protection Quarterly Vol.26(2) 2011 57 recorded. In a survey of canola (Brassica napus L.) crops, Lemerle et al. (1999), found Association between environmental factors and the fumitory in 42% of the fields. Indeed, it is possible that the substantial increase in the occurrence of six fumitory species (Fumaria spp. L.) area sown to canola across this zone in the in southern-eastern Australia last 20 years may be associated with the in- creasing incidence of fumitory. There are Gertraud M. NortonA,B, Deirdre LemerleC, James E. PratleyA,C and Mark R. two factors that may be related to this in- A,C,D creased fumitory incidence. Firstly, there Norton are no herbicides capable of selectively re- A School of Agricultural and Wine Sciences, Charles Sturt University, Wagga moving fumitory from canola, and second- Wagga, New South Wales 2678, Australia. ly, if fumitory seed is harvested together B Department of Agriculture, Forestry and Fisheries, GPO Box 858, Canberra, with canola, its similar size precludes the ACT 2601, Australia. possibility of decontaminating the canola C EH Graham Centre for Agricultural Innovation (an alliance between CSU seedlot. This scenario indicates that canola and NSW DPI), Private Mail Bag, Wagga Wagga, New South Wales 2650, seedlots might be a means whereby fumi- Australia. tory is spread further across the cropping D NSW Department of Primary Industries, GPO Box 1600, Canberra, ACT zone and indeed fumitory has been found in canola seedlots (Norton 2003). 2601, Australia. Email: [email protected] The work reported here is apparently the first attempt to survey exclusively the distribution of this genus anywhere in the world. Consequently there is little infor- Abstract species are recognized world-wide, some mation available about the natural distri- The occurrence of Fumaria as a weed in of which occur as weeds in agricultural or bution of the genus. No previous surveys south-eastern Australian cropping sys- horticultural crops (Sell 1964, Lidén 1986). within Australia, which have included tems is believed to have increased sub- However, Australian herbarium records fumitories within the suite of weeds un- stantially in recent decades. To study and associated state and nation-wide Flora der study, have identified it beyond the this, a survey was conducted in contrast- works suggest that only seven species are genus and none has attempted to associ- ing regions of this zone, viz. southern present: Fumaria bastardii Bor., F. capreolata ate its occurrence with any environmental New South Wales, mid-north South Aus- L., F. densiflora DC., F. muralis Sonder ex descriptors. Anecdotal information indi- tralia. The survey analysed the pattern Koch, F. officinalis L., F. parviflora Lam. and cates there are differences in susceptibility of occurrence of each of the six natural- F. indica (Hauskn.) Pugsley (Toelken 1986, of the different fumitory species to herbi- ized species found (Fumaria bastardii, Harden 1990, Walsh 1994). While F. indica cides. Therefore, to begin to develop an F. densiflora, F. muralis, F. officinalis, appears to be restricted to inland areas of understanding of the distribution of fumi- F. parviflora and F. capreolata) and the Australia, all remaining species occur in tory across the cropping zone it is essen- natural environmental factors associated the southern winter cropping zone. tial for weed control purposes to identify with their distribution. While five spe- In considering the abiotic factors that plants to the species level. The research cies were primarily found in agricultural control the distribution of vegetation reported here is the first fumitory survey environments, F. capreolata occurred ex- communities and plant species, the works reporting at the species level in Australia. clusively in non-agricultural situations of Woodward and Williams (1987) and To begin to address this shortfall, a tar- characterized by the presence of high Brown (1984) were important in empha- geted survey was carried out in two con- soil organic matter. F. densiflora and sizing the influence of minimum tempera- trasting regions of the south-eastern crop- F. bastardii were the most widespread ture and moisture availability. Species that ping zone designed to: (i) identify natural and abundant species. F. officinalis was become weeds are a unique case however, environmental factors of soil, climate and the rarest. because human management of the eco- topography associated with species occur- Environmental factors were signifi- system or some other human interaction rence, and (ii) extend understanding of the cantly associated with the occurrence of with the plant itself can be instrumental in areas of distribution for each Fumaria spe- each species. Soil texture and/or rainfall facilitating the development of these spe- cies. during one of the autumn months were cies into weeds (Grime 1979). An histori- important. Factors associated with some cal overview of the weed surveys of the Materials and methods species overlapped with other species south-eastern Australian cropping zone Survey and it was common to find more than one suggests a substantial increase of Fumaria The high potential for plants of the Fumaria species at a site. Occurrence over a wide occurrence. In the 1960s, fumitory was genus to become serious crop weeds and range of soil types in some species sug- found in less than 4% of crops in southern the lack of knowledge of the environmen- gests the presence of substantial bio- and New South Wales (Taylor and Lill 1986), tal factors influencing its distribution pro- ecotypical heterogeneity. although occasional serious infestations vided the basis for the survey. As it was Keywords: Generalized linear model, were noted. By the early 1990s, the propor- not feasible to survey the entire southern multiple logistic regression, weed distri- tion of cereal crops infested with fumitory Australian cropping zone where fumitory bution. had risen to 36% in the same area (Lemerle has been known to occur, it was consid- et al. 1996). In Victoria, Wells and Lyons ered that an understanding of the envi- Introduction (1979) showed large regional variations in ronmental influences could be achieved The members of the genus Fumaria L., its occurrence with 8 to 36% of cereal crops by keeping latitude constant while vary- known as fumitory or carrot weed in infested. Velthuis and Amor (1982/83) ing rainfall distribution and soil type. Australia, are annual herbs of semi-erect, observed that, despite being present in The first region covered part of the South trailing or climbing habit, ranging in ori- only 4% of south-western Victorian cereal Australian wheat belt and experiences a gin from Western Europe, throughout the crops, the average magnitude of its infes- typical Mediterranean type climate with Mediterranean Basin and eastward to the tations meant that it ranged from the sixth distinctly dry summers and cool, moist Indian Subcontinent. About 50 different to tenth most abundant of the 38 weeds winters. Soils are predominately neutral to 58 Plant Protection Quarterly Vol.26(2) 2011 alkaline, and 20% of the sites in the survey Statistical analysis i. With each Fumaria species considered were in that region. The second region, A range of different statistical procedures as the dependent variable and each comprising 80% of the survey sites, was and models are available to analyse po- of the environmental factors the inde- characterized by intermittently storm- tential weed distributions (Kriticos and pendent variables, simple logistic re- prone summers, cool-moist winters and Randall 2001). In this survey a general- gressions were undertaken. Initially, acidic soils. This region extended from ized linear modelling approach employ- all regressions were calculated using northern Victoria to the northern bound- ing stepwise multiple logistic regression the complete data set of 161 sites al- ary of the winter cropping area in central was a central component of the statisti- though subsequently data points from New South Wales (Figure 1). cal analyses. This method is increasingly non-agricultural areas were excluded The survey was undertaken from early utilized and was preferred here because in the species that primarily occurred July to the end of September. To maximize of its ability to relate the occurrence of a in agricultural areas, i.e. all species ex- the number of samples found, areas of species (dependent variable) to multiple cept F. capreolata and F. muralis, as these known Fumaria presence were surveyed environmental parameters (independent sites exerted unacceptable leverage in predominantly. From a randomly cho- variables) (Saab 1999, Collingham et al. shaping the slope of the regression sen starting point in the designated area, 2000, Grundy and Mead 2000, Corbacho function. Indeed, as the main interest crops were inspected at intervals of ap- et al. 2003). of the survey was the exploration of Fu- proximately 10 km if Fumaria was present, Due to the categorical nature of several maria presence in agricultural areas, the or less, if absent. Regions with undulating survey variables, logistic regressions with data from only the 146 agricultural sites topography were sampled at greater in- binary response variables (0 = absent, 1 = were used for F. bastardii, F. densiflora tensity. At each point, latitude, longitude present) were used and their significance and F. parviflora. and altitude were recorded with a Trimble was subsequently assessed by analysis of ii. Correlations between