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The Australian Processing Tomato Industry (APTI) has observed a decline in yield over recent years and speculates that soil-borne pathogens may be a contributing factor. The decline is characterised by poor stand establishment and the presence of stunted plants sporadically spread throughout the field. In preliminary surveys, Pythium spp. were commonly isolated from the roots of plants showing symptoms of poor growth. The aim of this study was to identify those Pythium species and assess their pathogenicity. Four field surveys were undertaken during the 2016/17 season and plants exhibiting symptoms of putative Pythium disease were collected. Pythium isolates were identified based on morphology and ITS sequences. Eight species of Pythium were identified including some common pathogens and some species which have not been previously reported on tomatoes. The in vitro pathogenicity test showed P. aphanidermatum, P. ultimum var. ultimum and P. irregulare were the most aggressive pathogens. In a glasshouse test P. ultimum var. ultimum and P. recalcitrans significantly reduced plant height 1 month after inoculation. Overall, the pathogenicity results confirmed that pathogens in the genus Pythium were most damaging in the pre-emergence and early seedling phases of tomato plant growth. However, some species also had the capacity to continue to reduce the growth of plants at later stages, potentially leading to yield reduction. Further studies are necessary to better understand the aetiology of these and additional Pythium species in the APTI context, and their ultimate effect on tomato yield.

The aim of this study was to describe the morphology, anatomy and function of underground structures associated with colonies of Solanum centrale J.M.Black (Australian bush tomato), a perennial sub-shrub found in arid areas of Australia and an important traditional staple food for Aboriginal people. It is known that this species forms clonal communities, but there is little understanding of the mechanisms of formation in either natural or cultivated situations. The underground connections within seven clonal communities from Central and South Australia were documented and samples of secondary roots, thick lateral roots and stems were examined under both laboratory and glasshouse conditions. Clonal communities were observed at all sites with individual ramets arising from lateral roots (root-suckers) that ranged from 2–10 mm in diameter growing in a network 5–15 cm below the soil surface. Lateral roots have dicotyledonous root anatomy and rapidly resprout to form new clonal ramets. They also have the capacity to accumulate starch in parenchyma cells. The morphology and root-suckering ability resemble those of weedy Solanum spp. from other parts of the world, as well as species from a variety of genera adapted to arid climates. Methods to capitalise on the ability of lateral roots to form clonal ramets in cultivated situations, particularly given the difficulties in establishing crops from seed, are discussed.

The goal of this proposed work is to directly address the need for rapid on-line characterization of the physical properties of HLW slurries during all phases of the remediation process, from in-tank characterization of sediments to monitoring of the concentration, particle size, and degree of agglomeration and gelation of slurries during transport. Current technologies are not capable of characterizing the HLW waste stream without dilution. The results from this work will be utilized to develop new methodologies to characterize the HLW stream in-situ. There are three tasks: (1) develop new optical and acoustic scattering measurements to provide the fundamental science needed for successful device development and implementation, (2) develop theories that describe the interrelationship between wave propagation and the physical properties of the slurry, and (3) perform inversions of the theories and compare them with the experimental measurements to non-intrusively characterize slurries.

The benefit of employing continuous, and ideally, non-destructive analysis during chemical manufacturing processes is widely recognized as providing very high rates of return to industry. As markets become increasingly more competitive, feedstocks more costly, and environmental issues escalate, the need for robust, stable, and affordable on-line process analysis systems continues to grow. Among the possible technologies employed in these process applications, optical methods are frequently used. The University of Washington Center for Process Analytical Chemistry (CPAC) has had a core effort in the investigation of sensor systems based on optical waveguide technology since its founding in 1984. These efforts have been broadly based, involving both the use of non-invasive direct optical analysis for species or parameter identification and the investigation of minimally invasive extractive approaches utilizing reagent chemistries. This work is further leveraged through strong interactions with another core CPAC program focusing on the development and use of chemometric multivatiate data analysis techniques. The three examples presented below: fiber optic evanescent wave spectroscopy using extractive coatings, the use of integrated grating and waveguide structures, and applications of low coherence high precision reflectometry for process monitoring, represent on-going optical sensor work at CPAC and demonstrate the synergy between this program and chemometrics.

The benefit of employing continuous chemical analysis during manufacturing processes is widely recognized as providing very high rates of return. Improvements in process control, which affect process efficiency and product quality, can be critically dependent upon on-line chemical analysis. This is evident by the current rapid growth in the development of on-line analytical instrumentation designed specifically for process control applications. Current process automation demands distributed feedback closer to events that require monitoring. As markets become increasingly more competitive, feedstocks more costly, and environmental issues escalate, the need will continue to grow for robust, stable, and affordable on-line chemical analysis systems. Distributed chemical sensors or sensor-based chemical analyzer systems provide an attractive approach to meet this demand. However, the development of sensors for on-line chemical monitoring presents some interesting challenges [1].

The influence of seedling water potential on infection and colonization of wheat seedlings (Triticum aestivum) by Fusarium graminearum Group 1 was studied using wax partitioning of the soil so that the water potential of the seminal root zone was manipulated independently from the water potential of the infection zone in the subcrown internode region. Eleven days after seeds were sown, water was withheld from the root zone to induce water stress in seedlings, while nonstressed seedlings were watered every 48 h to a soil water content of 0.31 g g -1 , favorable for plant growth (...)

The isolation and taxonomic characterisation of 25 isolates of Fusarium species from a New Zealand farm pasture are described. The ability of these isolates to produce mycotoxins both in liquid culture (MYRO and GYEP) and on rice grain culture was assessed. Toxin production was assessed by a combination of chemical analytical methods and by HeLa cell toxicity tests. The toxins produced included zearalenone (by three isolates), zearalenols (one isolate), butenolide (12 isolates), and various trichothecenes (five isolates). An isolate of F. culmorum (DAOM 193612) produced β-zearalenol (from rice culture) as the major toxin, whereas trichothecene production was greatest in MYRO culture by one isolate of F. crookwellense (DAOM 193611). The major trichothecenes produced by this species were 4, 15-diacetoxynivalenol followed by 8-hydroxy and 7-hydroxyisotrichodermin. Several previously unreported compounds were also isolated. Known trichothecenes produced by other species were deoxynivalenol, 15-acetox...

SUMMARY Using the ‘Cambridge method’, the effect of temperature on the colonization of wheat straw by Fusarium culmorum, Gibberella zeae, Cochliobolus sativus and C. spicifer was studied. Within the range 10–30 °C, saprophytic colonization by the four fungi was favoured by lower temperatures. This could not be attributed to the effect of temperature on the growth of the fungi in pure culture, but was probably caused by increased antagonism at higher temperatures from the general soil microflora. Contrary to previous indications, C. sativus strongly colonized straw under suitable environmental conditions.

Summary A theoretical relationship is developed relating growth of a fungus during one cycle of a diurnal temperature fluctuation to the growth at relevant constant temperatures. The theory involves the assumption that the growth-rate of the fungus at a given temperature in the cycle is unaffected by its previous temperature experience. Growth of Gibberelta zeae, Cochliobolus sativus and C. spicifer was measured at each of sixteen diurnal temperature regimes differing in median temperature and amplitude. The measured growth was compared with the expected growth. In general, the analysis supports the derived theoretical relationship. In some instances, growth at a fluctuating temperature is greater than or less than that at the corresponding median and the difference is anticipated, and explained, by the theory.

Two groups of 4 Hereford steers were housed in a controlled environment room and exposed to simulated high summer temperatures. Both groups were fed a barley grain and hay diet ad libitum. The barley in one diet contained 0.5% w/w ergots of Claviceps purpurea. Within one week of feeding the ergot diet mean rectal temperature was significantly elevated (P less than 0.05) each afternoon (up to 41 degrees C) but returned to normal overnight. Elevated rectal temperature was accompanied by other signs of heat stress, reduced feed intake, body weight loss and depression or serum prolactin concentration. Symptoms disappeared within 1 week of ceasing to feed the ergot diet.