Crop Updates 2000 Cereals - part 3

This session covers eighteen papers from different authors: BARLEY AND OAT AGRONOMY 1. Unicorn barley must meet malting specifications to be a viable option, Roslyn Jettnerand Blakely Paynter, Agriculture Western Australia 2. Optimum oat seed rates, Glenn McDonald, Agriculture Western Australia 3. Production and Quality of export Oaten Hay (1998 and 1989), Pierre Fievez, Pierre Fievez and Associates FROST 4. Climatology of Frost in Southern Western Australia, Ian Foster, Agriculture Western Australia 5. Flowering calculator, David Tennant, Agriculture Western Australia 6. Some options for managing the risk of frost damage, Wal Anderson, Agriculture Western Australia PASTURE 7. TIMERITE® Control of redlegged earth mite in south western Australia with a spring spray to pastures, James Ridsdill-Smith and Celia Pavri, CSIRO Entomology, University of Western Australia 8. The pattern of seed softening in subterranean clover in relation to presicted false break risk, Ross Chapman and Senthold Asseng, CSIRO Plant Industry, Centre for Mediterranean Agricultural Research 9. Charano serradella – a viable option for 1:1 cropping, Steve Carr and Brad Nutt IAMA Agri-Services Western Australia and Centre for Legumes in Mediterranean Agriculture, University of Western Australia 10. Alfalfa mosaic virus in alternative annual pasture and forage legumes, Lindrea Latham and Roger Jones, Crop Improvement Institute, Agriculture Western Australia and Centre for Legumes in Mediterranean Agriculture, University of Western Australia 11. Pasture mixture performs better than single-species-based pasture – 1999, Anyou Liu, Clinton Revell and David Ferris, Centre for Cropping Systems, Agriculture Western Australia 12. Better pasture management improves performance of following crops – 1999, Anyou Liu, Clinton Revell and David Ferris, Centre for Cropping Systems, Agriculture Western Australia 13. Lucerne Benefits Crop Production, Roy Latta1, Lisa-Jane Blacklow2, Chris Matthews1 1Agriculture Western Australia 2University of Western Australia 14. Does size count? Determining optimum release number of red apion for biocontrol of doublegee, Tim Woodburn and Paul Yeoh, CSIRO Entomology/CRC Weed Management Systems, Perth 15. Herbicide tolerance of some new cultivars of annual pasture legumes, Clinton Revell and Ian Rose, Centre for Cropping Systems, Agriculture Western Australia 16. Lucerne – crop rotations in the Esperance region, Anita Lyons, Roy Latta and Chris Matthews,Agriculture Western Australia PRECISION AGRICULTURE 17. Assessing the results of on-farm experiments using yield monitors, Simon Cook and Matthew Adams, CSIRO Land and Water 18. Achiever: A GIS based achievable yield and fertiliser recommendation system for precision agriculture, Robert J. Corner, Matthew L. Adams, Precision Agriculture Research Group CSIRO Land and Wate

Adapting pest management strategies to changing climates for the redlegged earth mite, Halotydeus destructor

Abstract As climate change continues to modify temperature and rainfall patterns, risks from pests and diseases may vary as shifting temperature and moisture conditions affect the life history, activity, and distribution of invertebrates and diseases. The potential consequences of changing climate on pest management strategies must be understood for control measures to adapt to new environmental conditions. The redlegged earth mite (RLEM; Halotydeus destructor [Tucker]) is a major economic pest that attacks pastures and grain crops across southern Australia and is typically controlled by pesticides. TIMERITE® is a management strategy that relies on estimating the optimal timing (the TIMERITE® date) for effective chemical control of RLEM populations in spring. In this study, we assessed the efficacy of control at the TIMERITE® date from 1990 to 2020 across southern Australia using a simulation approach that incorporates historical climatic data and field experimental data on life history, seasonal abundance, and population level pesticide responses. We demonstrate that moisture and temperature conditions affect the life history of RLEM and that changes in the past three decades have gradually diminished the efficacy of the TIMERITE® strategy. Furthermore, we show that by incorporating improved climatic data into predictions and shifting the timing of control to earlier in the year, control outcomes can be improved and are more stable across changing climates. This research emphasises the importance of accounting for dynamic environmental responses when developing and implementing pest management strategies to ensure their long-term effectiveness. Suggested modifications to estimating the TIMERITE® date will help farmers maintain RLEM control outcomes amidst increasingly variable climatic conditions

Direct and indirect impacts of infestation of tomato plant by Myzus persicae (Hemiptera: Aphididae) on Bemisia tabaci (Hemiptera: Aleyrodidae).

The impacts of infestation by the green peach aphid (Myzus persicae) on sweetpotato whitefly (Bemisia tabaci) settling on tomato were determined in seven separate experiments with whole plants and with detached leaves through manipulation of four factors: durations of aphid infestation, density of aphids, intervals between aphid removal after different durations of infestation and the time of whitefly release, and leaf positions on the plants. The results demonstrated that B. tabaci preferred to settle on the plant leaves that had not been infested by aphids when they had a choice. The plant leaves on which aphids were still present (direct effect) had fewer whiteflies than those previously infested by aphids (indirect effect). The whiteflies were able to settle on the plant which aphids had previously infested, and also could settle on leaves with aphids if no uninfested plants were available. Tests of direct factors revealed that duration of aphid infestation had a stronger effect on whitefly landing preference than aphid density; whitefly preference was the least when 20 aphids fed on the leaves for 72 h. Tests of indirect effects revealed that the major factor that affected whitefly preference for a host plant was the interval between the time of aphid removal after infestation and the time of whitefly release. The importance of the four factors that affected the induced plant defense against whiteflies can be arranged in the following order: time intervals between aphid removal and whitefly release > durations of aphid infestation > density of aphids > leaf positions on the plants. In conclusion, the density of aphid infestation and time for which they were feeding influenced the production of induced compounds by tomatoes, the whitefly responses to the plants, and reduced interspecific competition

Development of "best practices" for sampling of an important surface-dwelling soil mite in pastoral landscapes.

In this study, we analyzed 1145 vacuum samples of redlegged earth mites (RLEM) [Halotydeus destructor (Tucker) (Acari: Penthaleidae)] from 18 sampling events at six locations in pastoral landscapes of Western Australia during three growing seasons (2012-2014) (total of 228,299 RLEM individuals). The specific objectives were to determine: (1) presence/absence effects of a range of vegetation characteristics, (2) possible factors influencing RLEM sampling performance during the course of the season and day, (3) effects of size of area sampled and duration of sampling, (4) the spatial structure of RLEM counts in uniform pastoral vegetation, and (5) develop "best practices" regarding field-based vacuum sampling of surface dwelling soil mites in pastoral landscapes. We found that sampling of completely bare ground will lead to very low RLEM counts but spots with sparse vegetation (presence of bare ground) probably increases the presence of microhabitats for mites to shelter in and therefore lead to higher RLEM counts. RLEM counts were positively associated with the height of vegetation, at least up to about 15 cm in height. In early season (May-August), highest RLEM counts will be obtained in the afternoon hours (2-4 pm), whereas in late season sampling (August-November), highest RLEM counts will be obtained around noon. Higher RLEM counts should be expected from spots with grazed/mowed vegetation including cape weed and without presence of grasses and stubble. Variogram analyses of high-resolution data sets suggested that considerable range of spatial autocorrelation should be expected from fields with fairly uniform vegetation, especially if RLEM population densities are high. We are therefore recommending that samples are collected at least 30 m apart, if the objective is to obtain independent (spatially non-correlated) counts. The results from this study may be used to develop effective sampling protocols deployed in field ecology studies of soil surface dwelling mesofauna in pastoral landscapes and other ecosystems

Development of "best practices" for sampling of an important surface-dwelling soil mite in pastoral landscapes.

In this study, we analyzed 1145 vacuum samples of redlegged earth mites (RLEM) [Halotydeus destructor (Tucker) (Acari: Penthaleidae)] from 18 sampling events at six locations in pastoral landscapes of Western Australia during three growing seasons (2012-2014) (total of 228,299 RLEM individuals). The specific objectives were to determine: (1) presence/absence effects of a range of vegetation characteristics, (2) possible factors influencing RLEM sampling performance during the course of the season and day, (3) effects of size of area sampled and duration of sampling, (4) the spatial structure of RLEM counts in uniform pastoral vegetation, and (5) develop "best practices" regarding field-based vacuum sampling of surface dwelling soil mites in pastoral landscapes. We found that sampling of completely bare ground will lead to very low RLEM counts but spots with sparse vegetation (presence of bare ground) probably increases the presence of microhabitats for mites to shelter in and therefore lead to higher RLEM counts. RLEM counts were positively associated with the height of vegetation, at least up to about 15 cm in height. In early season (May-August), highest RLEM counts will be obtained in the afternoon hours (2-4 pm), whereas in late season sampling (August-November), highest RLEM counts will be obtained around noon. Higher RLEM counts should be expected from spots with grazed/mowed vegetation including cape weed and without presence of grasses and stubble. Variogram analyses of high-resolution data sets suggested that considerable range of spatial autocorrelation should be expected from fields with fairly uniform vegetation, especially if RLEM population densities are high. We are therefore recommending that samples are collected at least 30 m apart, if the objective is to obtain independent (spatially non-correlated) counts. The results from this study may be used to develop effective sampling protocols deployed in field ecology studies of soil surface dwelling mesofauna in pastoral landscapes and other ecosystems

The different treatments with three infestation durations (A₁ = 24 h, A₂ = 48 h, and A₃ = 72 h), three aphid densities (B₁ = 20 aphids/leaf, B₂ = 50 aphids/leaf, and B₃ = 80 aphids/leaf) in direct influence assays.

<p>The different treatments with three infestation durations (A₁ = 24 h, A₂ = 48 h, and A₃ = 72 h), three aphid densities (B₁ = 20 aphids/leaf, B₂ = 50 aphids/leaf, and B₃ = 80 aphids/leaf) in direct influence assays.</p