The occurrence, pathogenicity (1997 isolates only) and fungicide sensitivity of pathogens causing dry tuber rots in Scottish seed potatoes was investigated over three storage seasons between 1997 and 2000 in relation to region of production, cultivar, class and generation of seed potatoes, type of temperature control in store and earthiness of tubers. A total of 156 samples, each comprising up to ten rotted tubers, was received over the three seasons. The relative importance of each pathogen in causing rots was summarised by calculating a mean rot index that combined the prevalence of a pathogen in the samples with the incidence of tubers affected by the pathogen within those samples. Phoma foveata (gangrene) had the highest rot index, which was five times greater than for P. exigua and ten times greater than for P. eupyrena. This relationship was mirrored by the relative pathogenicities of P. foveata and P. eupyrena, as measured by size of rots developing at inoculated wounds in test tubers. Fusarium avenaceum appeared to be the greatest cause of Fusarium dry rots, having a rot index at least twice as great as that for F. solani var. coeruleum. Infection by F. sulphureum was relatively uncommon. In the pathogenicity test, F. avenaceum, F. solani var. coeruleum and F. sulphureum produced rots of similar depths and widths and larger than those of F. culmorum. The mean rot index for Cylindrocarpon spp. was slightly more than that for F. avenaceum, whereas C. destructans produced smaller rots in the tuber pathogenicity test. Region of production affected the prevalence of P. foveata and F. avenaceum, but only the occurrence of P. foveata was affected by class and generation of seed potatoes. Isolate sensitivity to thiabendazole and imazalil was examined in vitro over

Australian grass-finches are widely reported to consume large quantities of green seed when it becomes available, and the opportunistic breeding of wild Zebra Finches in the arid zone has been correlated with the occurrence of rain. In this study, green and ripe seeds were harvested from seven pasture and weed grasses grown in experimental plots and, along with three cereal flours and whole-egg powder, were analysed for the amino-acid composition of their protein. The relative levels of ten amino acids essential in the diets of growing birds were compared between samples using a cluster analysis dendrogram generated from Raabe's Similarity Index. The protein of all green seeds clustered with whole egg, and away from all but one of the ripe seeds and seed products. Green and ripe seed profiles were found to be significantly different by a two-sample multivariate test of significance (Hotelling's T^). Histidine, lysine, phenylalanine and threonine were the amino acids most different. Of these four amino acids, lysine and threonine (along with methionine) were potentially limiting in ripe seeds when compared with whole-egg protein. In green seeds, lysine was only marginally limiting, threonine was no longer limiting, but methionine was still limiting when compared with whole-egg protein. These results indicate that the benefit of green vs ripe seed in the diet of breeding Zebra Finches is partly a higher level of the limiting essential amino acid, lysine, and partly a higher intake and throughput of sofr green seed and consequent greater extraction of limiting essential amino acids.

Olives (Olea europaea ssp. europaea), dispersed from 19th century orchards in the Adelaide area, have become established in remnant bushland as a major environmental weed. Recent expansion of the Australian olive industry has resulted in the widespread planting of olive orchards in South Australia, Victoria, New South Wales, Western Australia, Queensland and parts of Tasmania. This paper reviews the literature on the activity of vertebrate (principally avian) olive predators and their potential as vectors for spreading this plant into Australian remnant bushland. The effects of feralisation on the olive plant, which enhances its capacity for dispersal as a weed, place wider areas of south-eastern Australia at risk. A number of approaches for the control of olives as woody weeds are addressed. Proponents of new agricultural crops have moral and environmental obligations to assess the weed potential of these crops.

A procedure is described for the accurate determination of the maintenance nitrogen requirement (MNR) of small granivorous birds. When used with the zebra finch (Taeniopygia guttata), it yielded a MNR of 403 mg kgW(-0.75) d(-1). This is lower than most other passerines so far measured and more similar to some nonpasserine species. Similarly, the value for endogenous nitrogen loss estimated for the zebra finch (153 mg kgW(-0.75) d(-1)) is less than that for passerines in general but higher than the nonpasserine value. We suggest that the low MNR of the strictly granivorous zebra finch is primarily an adaptation to seed diets in which high-quality protein is a limiting factor. Comparison with a wider range of species reported in the literature was restricted because inappropriate methods have been used to estimate MNR in many cases, including the use of growing or reproducing birds and the assumption that maintenance of body mass necessarily coincides with maintenance of zero nitrogen balance.

SummaryOver 2 years, seed tubers or stems were inoculated with Fusarium sulphureum Schlecht. (F. sambucinum Fuckel f. 6 Wollenw.) and the incidence of dry rot on daughter tubers assessed by standardised wound tests. The amount of stem and soil inoculum was also measured in one year.Inoculating stem bases resulted in greater concentrations of spores on the stem bases, greater soil populations at harvest and more dry rot on tubers than inoculating the seed tuber. Overall, the incidence of dry rot and the amount of stem and soil inoculum was similar for the three methods of haulm destruction: cutting and removing the stems, applying sulphuric acid or applying diquat dibromide to the growing plants.