Agricultural Science Commons^™

Invertebrate Pests, Plant Pathogens, And Beneficial Organisms In Extensive Natural Grassland, J G. Watts, L W. Burgess, E W. Huddleston

IGC Proceedings (1977-2023)

After many decades of research on their control, insects and weeds still arc a major factor in semi-arid grassland ranching. Much has been learned concerning their biology, habits and chemical control but penetrating study of the microbial world surrounding them is quite recent. Plant pathogens are credited with little damage to semi­arid grasslands. Potentially, their most important role may be one of toxigensis among grazing animals after unusual weather that promotes exceptional increase of any one or a combination of several indigenous toxigenic fungi on senescing grasses. Objective cost-benefit consideration of pest and disease control was limited in past decades …

Resistance Versus Susceptibility To Verticillium Albo-Atrum In Alfalfa, B W. Pennypacker, K T. Leath, D P. Knievel, E J. Pell

IGC Proceedings (1977-2023)

Alfalfn (Medicago saliva L.) clones, susceptible and resistant to Verticillium albo-atrum (Van), were systematically infected with Vaa via stubble inoculation with conidial suspensions. Progress of infection and anatomical host responses was monitored by sequential sampling, sectioning, staining and examination with light microscopy. Effect of infection on photosynthesis was assessed in vivo by measuring net photosynthesis and activity of ribulose 1, 5-biphosphate carboxylase­oxygenase (rubisco) via a CO2 drawdown curve. hr vitro activity of rubisco was determined by protein extraction and uptake of radioactive CO2. Susceptible and resistant clones exhibited leaflet chlorosis and abscission. Also, the pathogen produced spores that germinated …

Breeding For Multiple Pest Resistance As A Strategy To Improve White Clover Persistence, G A. Pederson, G L. Windham, M R. Mclaughlin, R G. Pratt, G E. Brink

IGC Proceedings (1977-2023)

White clover (Trifolium repens L.) cultivars grown in the USA are susceptible to many pathogens, pests and environmental stresses which have been shown to affect persistence adversely. The strategy used in our breeding programme is to first develop white clover populations resistant to individual pathogens and pests, and then incorporate this resistance into multiple-pest-resistant populations. Germplasms with resistance to peanut stunt virus (PSV), alfalfa mosaic virus (AMY), and clover yellow vein virus (CYVV), and with drought tolerance have been released. From these germplasms and other source materials, we have developed additional populations with resistance to southern root-knot nematode ( …

Clover Cyst Nematode Resistance In White Clover, J Van Bosch, C F. Mercer, J L. Grant, I K. Black

IGC Proceedings (1977-2023)

White clover (Trifolium repens L.), a key legume in New Zealand pastures, is parasitised by Heterodera trifolii, the clover cyst nematode. Resistance breeding is the most feasible control, and screening of 1st generation crosses has made considerable progress. Progeny of parents selected for resistance had only 39% cysts/g root dry weight of susceptible lines, and all resistant lines were lower when ranked. These resistant selections also had less fewer cysts per plant, heavier root dry weights and higher shoot growth scores. The parents of the most resistant lines were from two Italian ladino cultivars (Ladino Gigante Lodigiano and …

Rhoma Black Stem Disease- A Threat To Susceptible Annual Medic Pastures, M J. Barbetti

IGC Proceedings (1977-2023)

Phoma black stem disease, caused by Phoma medicaginis, is the most important fungal disease of annual Medicago spp. (medic) pastures in Western Australia. It is readily seed-borne and this provides an important inoculum source for spreading the disease into new sowings in areas free of leguminous crop residues. The disease produces dark brown to black lesions on cotyledons, leaves, petioles and stems and can cause leaf drop and petiole and stem collapse, Reductions in herbage production of up to 169!, and seed yield of up to 209!, have been recorded in grazed swards, while in ungrued swards, losses in herbage …

Effectiveness Of Acremoniu Lolli In Annual Ryegrass In Controlling Greenbug (Schizaphis Graminum Rondani) Injury, L R. Nelson, Marta R. Harrington, D Marshall

IGC Proceedings (1977-2023)

This experiment tested 3 ryegrass (Lolium multiflorum Lam.) genotypes with (E+ )° and without (E-) endophyte, to determine the effectiveness of the endophyte in reducing leaf damage caused by greenbugs (Schlzaplris granthum Rondani). Results Indicated that presence of endophyte increased resistance in only I of 3 lines tested. The apparent resistance was observed.as leaf necrosis (leaf necking, yellowing, tip die-back, and leaf death). Resistance was not observed until green bug reinfestation of 3-month-old plants. A control with E+ Kentucky 31 fescue (Festuca arundinacea Schreb.) also had reduced greenbug damage compared with E- Kentucky 31 plants. This study …

Invertebrate Pests Of Endophyte-Infected And Endophyte Free Perennial Ryegrass Swards In Northern New Zealand, R A. Prestidge, R N. Watson, E R. Thom

IGC Proceedings (1977-2023)

Plots of endophyte-infected and endophyte-free perennial ryegrass (Lollum perenne) cv. Ellett and white clover (Trifolium repens) cv, Grasslands Pitau were established in autumn 1990 by direct drilling into pastures previously sprayed with glyphosate herbicide. Plots were rotationally grazed by dairy cows. Insect pests were sampled by soil coring and extraction, and plant pathogenic nematodes by root staining and examination. Ryegrass tiller density and the proportion of ryegrass in the swards were-significantly less in November, March and May on plots sown with endophyte-free ryegrass c_ompared with endophyte-infected ryegrass. Conversely, the propo!'tion __ of white clover was greater on endophyte-free …

Invertebrate Pests Associated With Italian Ryegrass In Northern New Zealand, R A. Prestidge, R N. Watson, E R. Thom

IGC Proceedings (1977-2023)

Damage threshold levels were established for adult Argentine stem weevil (Listronotus bonariensis (Kuschel)) feeding on Italian ryegrass (Lolium multiflorum Lam;) cv, Concord seedlings in a glasshouse pot trial. Population densities of 35-70/m1 reduced seedling survival by 34% and herbage yield after 28 days growth by 35%. A field trial was established In autumn 1991 by sowing Concord in early February, in late February and in March into areas previously treated with glyphosate herbicide, Insecticide application increased ryegrass tiller density by 36% from 2339/m' (April 1991) and herbage accumulation by 43% from 1.4 t DM/ha only up to the …

Screening For Biological Control Agents Of Root Pathogens Of Pasture Legumes, R A. Skipp, F S. Hay

IGC Proceedings (1977-2023)

Fungi isolated from roots of legumes from pasture soil were applied to seeds of red clover (Trifolium pratense L.) on water agar in Petri plates in a seedling screening test designed to detect antagonism to the fungal pathogens Fusarium solani, Trichrocadium basicola and a Pythium sp. Isolates of Triclroderma koningii, T. /ramatum, a binucleate Rhizoc1011ia sp. or an unidentified basidiomycete protected seedling roots from damage by one or more of the fungal pathogens. Fungi isolated from cysts of the plant-parasitic nematode Helerodera trifolii obtained from pasture soil were tested for their ability to infect eggs of H. trifolii …

Effects Of Three Viruses On Productivity Of Annual Pasture Legume Swards, R A. C Jones

IGC Proceedings (1977-2023)

The effects of 3 non-persistently aphid-transmitted viruses on the productivity of swards of annual pasture legumes were investigated in 1988-91. Virus-host combinations studied were alfalfa mosaic virus (AMV) in burr medic (Medicago polymorplia), cucumber mosaic virus (CMV) in subterranean clover (Trifo/i111n subterra11eum) and bean yellow mosaic virus (BYMV) in subterranean clover. Swards were mown to simulate grazing, grazed or left undefoliated. Herbage (dry weight) and seed production were decreased significantly by infection with all three virus-host combinations. However, the extent of losses vnried with extent of virus spread, cultivar, site and season. Decreased seed yield resulted from both fewer and …

Burial Of Surface-Applied Lime By Earthworms In South Australian Pastures, G H. Baker, P. M.L Williams, V J. Barrett, P J. Carter

IGC Proceedings (1977-2023)

The ability of earthworms, Aporrectodea trapewides, A. caliginosa, A. rosea (Lumbricidae) and Gemascolex walkeri (Megascolecidae), to bury surface-applied lime and offset soil acidity was investigated in 2 pastures in the Mount Lofty Ranges, South Australia, In one pasture, A. trapewides increased pH by 0.8 of a unit at 4-6 cm depth. A. caliginosa also increased soil pH compared with controls, but A. rosea and G. walkeri had no influence, A. trapewides is suggested as a valuable addition to acid pastures, if not already present,

Effects Of Fungicide Seed Treatments On Germination And Establishment Of Sainfoin And Other Legumes, Nan Zhi Biao, Liu Zhao Hui, R A. Skipp

IGC Proceedings (1977-2023)

Treatment of seed with thiram or thiophanate methyl at a rate of 3 g ai/kg seed increased germination of crownvetch (Coro11illa varia L.), milkvetch (Astragalus ads11rge11s Pall.), sainfoin (011obrycl1is viciifolia Scop.) and yellow sweet clover (Melilotus officinalis (L.) Lam.) in laboratory tests. The magnitude of the increases varied with fungicide and species. The greatest increase in germination relativ!) to that of untreated seed was 115% for sainfoin dusted with thiophanate methyl. Thiophanate methyl increased field emergence of sainfoin at 4 and 8 weeks after sowing by 41% and 55% respectively, and at 8 weeks increased the dry weights of shoots …

Pastures In Crop Rotations Enhance Earthworm Populations In Southern Australia, John C. Buckerfield

IGC Proceedings (1977-2023)

The effects of crop rotations on earthworm populations in seasonally dry arable lands was assessed on long-term field trials at 2 sites with an annual rainfall of 450-500 mm, In cropping and sheep-grazing areas of southern Australia. Earthworm densities were substantially higher in rotations of cereals with a volunteer-pasture phase than under continuous cropping with cereals and grain legumes. The degree and frequency of soil disturbance associated with cropping has been shown to influence earthworm numbers: trial plots In which crops were sown with minimal cultivation, in alternate years, supported earthworm populations 2-3 times higher than those conventionally cultivated and …

Costs And Benefits Of Controlling Grasshoppers On Rangeland, E W. Huddleston, R Sanderson, L A. Torell, J H. Davis, J G. Watts

IGC Proceedings (1977-2023)

Ultra low volume (ULV) aerial application of malathion at 0.58 I/ha is the common method of rangeland grasshopper control in the USA. Aircraft often are unavailable or too expensive for treating small infestations; therefore, air-assist ground equipment was adjusted 10 apply the ULV rate from a small truck. In winds of 2.2 m/sec or greater, control with the ground equipment was equivalent to that expected from aircraft. The low spray volume, low sprayer cost and use of a small truck have increased the benefit/cost ratio. Using results from this research and site-specific estimates of control costs and forage value, the …

The Rodent Pests Of Pasture And Their Control In China, Xixian Hou, Weihui Dong, Yanlin Zhou

IGC Proceedings (1977-2023)

Rodent damage is increasingly recognised as a major problem for grasslands of China rodents damage up to an estimated 33 million ha each year, There are two reasons for rodent damage in grassland: one is overgrazing, which causes degeneration of grassland and provides good habitats for rodents; another is the ecological characteristics of rodents. A rodent control programme has been followed for years in China, and includes: (1) studies on the ecology of major rodent pests in pasture, (2) prediction of population, (3) setting up control indexes paying attention to economic benefits, (4) tightening up grassland management and developing integrated …

Stylo Host Heterogeneity For Anthracnose Management, S Chakraborty, A N. Petitt, R M. Boland, S Low Choy, D F. Cameron, J A.G Irwin, R D. Davis

IGC Proceedings (1977-2023)

Small plots of 3 different mixtures of Stylosallllles. scabra genotypes were established within background paddocks of either pure cv. Seca, or a mixture of 6 S. scabra genotypes including Seca, to study anthracnose development in the three mixtures under exogenous inoculum pressures arising from the two backgrounds. There was no difference in disease severity between the background paddocks after the first year. In the small plots, severity of nearest neighbours significantly influenced anthracnose severity on the partially resistant accession 55860 in the first year; this effect disappeared as the disease became more widespread throughout the plot in later years. Replacing …

Increased Resistance To Sclerotinia Crown And Stem Rot Of Alfalfa Through Recurrent Selection Of Surviving Plants In Inoculated Field Plots, M Kanbe, F Fujimoto, S Inami

IGC Proceedings (1977-2023)

ABSTRACT Breeding alfalfa (Medicago saliva L.) for resistance to Sclerotinia crown and stem rot (SCR; causal agent Sclerotitivia trifoliorum Eriks.), which is a serious disease in Japan, was started in 1983. Increased resistance to this disease has been examined after repeated selected of surviving plants from artificially inoculated field plots to the 5th generation. The strains selected for SCR resistance showed higher resistance than Tachiwakaba, which was the main breeding material. The effectiveness of selection judged by the survival rate of progenies was low in the early selection generations but high in the later ones, It is considered that …

Biological Control Of Alfalfa Aphids In Japan Using Coccinella Septempunctata Brucki, Keiichi Takashi

IGC Proceedings (1977-2023)

The oviposition, predation, and survival abilities of Coccinella septempuncrara bmcki Mulsanl (lady beetle), a natural enemy of alfalfa aphids (Acyrtllosyphon kondoi Shinji), increased as temperatures rose in laboratory tests. The second-instar larvae were released into cages in alfalfa (Medicago saliva L.) fields in spring 1991. One month later, alfalfa plants in the control cages without larvae showed much lower yield; however, no damage was observed in cages in which larvae had been released. There is a strong probability that alfalfa aphids can be controlled by the timely release of lady beetle larvae in the field.

Fire And Ant Interactions Mediated By Honeydew And Extrafloral Nectar In An Australian Tropical Savanna, Fernanda M. P. Oliveira, Carlos H. F Silva, Melinda L. Moir, Inara R. Leal, Alan N. Andersen

Natural Resources Research Articles

Fire is a major disturbance affecting ecosystems globally, but its impact on mutualisms has received minimal attention. Here, we use a long-term field experiment to investigate the impact of different fire regimes on globally important ant–honeydew and ant–extrafloral nectar (EFN) mutualistic interactions in an Australian tropical savanna. These interactions provide ants with a key energy source, while their plant and hemipteran hosts receive protection services. We examined ant interactions on species of Eucalyptus (lacking EFNs) and Acacia (with EFNs) in three replicate plots each of burning every 2 and 3 years early in the dry season, burning late in the …

Managing Frost Risk, Department Of Primary Industries And Regional Development, Western Australia

Grains and other field crops factsheets

Frost occurs on clear nights in early spring when the air temperature drops to 2°C or less. Crop damage from frost may occur at any stage of development but is most damaging at or around flowering.

Frost is difficult to manage, and damage will be unavoidable in some seasons. Risk management options proven to reduce frost risk include paddock zoning, crop and variety selection, time of sowing, stubble management and managing inputs. The greatest gains result from in paddock choice/zoning, crop and variety choice, and manipulating the canopy.

Red Fox, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity factsheets

This factsheet provides information on the red fox in Western Australia (WA).

The red fox (Vulpes vulpes) is a native of the northern hemisphere where it occurs throughout most of Europe, Asia, North America, and the northern coast of Africa. The red fox was first introduced to Australia (Victoria) from Britain as early as 1845 for hunting with foxhounds. Having become successfully established in Victoria by about 1870, it colonised most of mainland Australia over the next 70 years. Foxes are not found in the most northern regions of Australia, including northwest Kimberley.

In WA, the fox is a declared …

Rabbit Control: Fumigation, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity factsheets

Fumigation for rabbit control involves the introduction of poisonous gas into a warren. It is one of the best control methods to use where low numbers of rabbits live in a few widely scattered warrens. The threat to non-target animals is minimal. This factsheet should be read in conjunction with registered product labels and directions for use. Check the Department of Health, Western Australia website (health.wa.gov.au) for public health requirements for the use of phosphine fumigation.

Fumigation may be used in areas where access is limited, such as fence lines, around trees, and on riverbanks, but it may be difficult …

Feral Goat, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity factsheets

The goat (Capra hircus) was one of the first animals to be domesticated, 8 to 10 thousand years ago. Archaeological work indicates the earliest attempts at domestication were in dry hills surrounding the Mediterranean basin. The ability of goats to utilise the coarse browse of mountainous areas made them suitable for domestication, in preference to sheep. With large-scale domestication of goats throughout the world, goats escaped and established feral goat herds on most continents. Overgrazing by goats has caused severe environmental damage, worldwide.

Goats arrived in Australia with the first fleet. They were introduced to many areas by early settlers …

Rabbit Control: 1080 Versus Pindone, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity factsheets

There are two toxins available for controlling pest rabbits in Western Australia: 1080 and pindone. This factsheet provides a brief summary of the main characteristics of both vertebrate pesticides. 1080 is generally the preferred toxin for rabbit control in Western Australia (WA).

Any attempt to reduce the impact of rabbits on the productivity of any agricultural enterprise (for example, pasture, crops, tree farms, horticulture) should be undertaken as part of a pest management plan.

This strategy should be proactive rather than reactive to a problem. It should also include a long term strategy for dealing with potential rabbit damage, including …

Climate Smart Agriculture, J. David Aiken

Cornhusker Economics

There are several programs encouraging producers to reduce their carbon intensity, including United States Department of Agriculture climate-smart agriculture programs, the 2024 Nebraska Climate Action Plan, and the 2024 Nitrogen Reduction Incentive Act. The hope is that producers with lower carbon intensity (CI) scores will receive a premium for their products. Producers would be well advised to learn more about these programs, as reducing carbon intensity in agriculture seems to be an emerging agricultural policy trend that will be with us for some time to come.

Development Of Intensive Grassland Systems: From Science To Practice, D G. Mccall, G W. Sheath

IGC Proceedings (1977-2023)

Level of nnimal production from grassland is determined by the amount of pasture grown, pasture utilisation and animal conversion efficiency. The key components affecting production are pasture growth and animal conversion efficiency. These arc mainly influenced by environment, genetics and through inputs to maintain soil fertility or animal health. Systems development aims to link pasture growth and animal conversion through efficient strategies for pasture utilisation. The means of influencing pasture utilisation is through adjustments to animal feed demand, feed supply or grazing management. Stock policies that adjust the pattern and level of feed demand are of greatest significance in developing …

The Ecology Of Grazing Management, R K. Heitschmidt

IGC Proceedings (1977-2023)

The broad objective of this paper is to review the fundamental principles of grazing management as a means of assessing the inherent value of intensive and extensive grazing systems. Conceptual analyses of intensive and extensive grazing systems reveal that the fundamental differences between intensive and extensive grazing systems are related to differences in non-grazing rather than grazing tactics. Intensive grazing systems employ a wide array of non-grazing tactics in an attempt to overcome the inherent ecological constraints that limit secondary (i.e., livestock) productivity in extensively grazed systems. Moreover, analyses of the ecological or true efficiency of various agricultural production systems …

An Analysis Of The Dry Matter Intake And Rate Of Live-Weight Gain Of Growing Cattle Fed Forage Diets, J G. Buchanan-Smith

IGC Proceedings (1977-2023)

The intake and rate of live-weight gain of 500 growing steer calves fed experimental forage diets in 7 trials were compared with corresponding values predicted using the Na1ional Research Council (NRC) model (1984). The cattle were predominantly weaned calves and most of the experimental diets were alfalfa-grass silage, either unsupplemented or supplemented with various protein sources, but some diets were based on maize silage or maize grain. The feeding period evaluated in this study ranged between the first 84 and 147 days when protein accretion rate in the cattle would be relatively high. Dry matter intakes were overpredicted by the …

Management Of Extensive Pastures For Dairy Youngstock, G.E J. Fisher, D J. Roberts

IGC Proceedings (1977-2023)

The effects of low input systems on the ground cover of species and yield and chemical composition of herbage cul from extensive lowland swards was studied over 3 years. The live-weight gain of dairy heifer replacements offered grazed or conserved forage from these pastures was also assessed, The swards were sown with a mixture of grasses, wildflowers and herbs and received no inorganic fertilizers, Applications of slurry in January and February increased herbage yield by 43%, but reduced the cover of flowers and herbs. Using a 2- cut conservation system improved yield of metabolisable energy/ha in herbage by 33%, and …

Intensive Grazing Of Alfalfa By Beef Steers, M Rasnake, W R. Burris, G D. Lacefield, J Randolph, N Gay, L Davis

IGC Proceedings (1977-2023)

In the temperate region of North America, high temperature and moisture deficit cause low forage growth during the summer of most years, making it difficult to grow beef (Bos taurus), calves through summer grazing. Alfalfa (Medicago sativa), offers some potential to provide high dry matter production during summer if an effective system of grazing can be developed. The objective of this study was to test a system of intensive grazing of beef steers on alfalfa to maximise live-weight gains/ha and maintain plant population. Alfalfa was no-till seeded into a 6.5 ha field in autumn 1988 after …