Producing Quality Oat Hay

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Broadleaf weeds Weeds with a thick stem such as Salvation Jane and Small-flowered mallow/Marshmallow (Malva parviflora) cause visual down grading and cure at a different rate to oats. Dark, unsightly patches or mouldy hot spots can result from the inclusion of broadleaf weeds. Cape weed is a particular problem as it causes yield loss and has a detrimental effect on quality by causing unsightly dark and low nutrient patches in bales. Brassica weeds and Bifora can result in unacceptable taints to the hay that will reduce livestock intake. Some weeds, such as Melilotus can impart taints to milk. Sharp, spiky weeds such as thistles can cause intake problems as well as impact on handling. 80% of cows in Japan are fed by hand and the presence of thistles is easily noticed. Annual ryegrass toxicity (ARGT) ARGT is caused by toxins produced by the bacterium Rathayibacter toxicus that infect the seed heads of ryegrass. These toxins can prove fatal if ingested by livestock. The bacterium is transferred to ryegrass seedheads by a nematode (Aguina spp.). The nematode, which only has one lifecycle each year, invades the ryegrass during the winter and in spring produces a gall that replaces a developing seed in the immature seedhead. If the bacterium is present, it quickly multiples during early spring, swamping the nematode and takes over the gall. After ryegrass flowers the bacterium begins to produce potent toxins called corynetoxins. Toxin production increases rapidly just before the grass hays-off. The toxin is very stable and persists in dry pasture or hay. Circumstances that favour development of ARGT are: • paddocks with moderate to high frequency of cropping; • poor ryegrass control in previous year often associated with herbicide resistance; • poor ryegrass control in-crop; PRODUCING QUALITY OAT HAY • ryegrass seedheads are cut or spray-topped after flowering has commenced allowing nematodes to complete its lifecycle; • successive short growing seasons; favours nematode multiplication; • spread of galls from infected areas within or surrounding the paddock; • pasture phase under grazed during spring, allowing infected ryegrass seedheads to mature and continue infection cycle. Infected seedheads usually show no visual signs of infection. Sometimes excessive bacterial growth causes the emerging seedheads to become twisted and deformed. In this case the bacterium will appear as a yellow exudate. When dry the exudate turns orange and becomes brittle and transparent. Close inspection of the spikelets will often reveal that individual seeds have been replaced by nematode galls, most of which will be colonised by the bacterium. The twist fungus (Dilophospora alopecuri) also causes ryegrass seedheads to become distorted. Twist is a plant parasitic fungus, but it needs the nematode to carry its spores into the plant. The spores quickly colonise the galls produced by nematode. Excessive infection can cause the seedhead to become deformed and ‘twisted’. The twist fungus is a useful biological control for the nematode and is now established in many areas affected by ARGT. However, symptoms of the fungus indicate the nematode is present in the paddock, and that the bacterium may also be present. Presence of significant levels of the fungus reduces but does not eliminate the risk of poisoning to stock. The fungus can be purchased from Biological and Resource Technology Pty Ltd who distribute the twist fungus under license. The orders must be received before the end of February and an order form can by downloaded from Biology and Resource Technology's website at www.argt.com.au Testing for ARGT bacterial contamination in export hay and straw is compulsory. Local hay buyers may also require test results. The reputation of Australian oat hay depends on the constant sampling and testing of export hay to minimise the likelihood of toxicity reaching animals. 57
Image 6.8 Pre seeding weed control is vital as in-crop options are limited. The Australian Quarantine Inspection Service (AQIS) has produced a set of standards for minimising the risk of corynetoxin contamination in export hay and straw. For the most up to date information on sampling protocols check the AQIS website (www.aqis.gov.au). At the time of publication the approved method of sampling for ARGT contamination while bales are in the paddock is as follows: • in the paddock, sample the greater of 12 bales or 15% of bales in the paddock; • samples should be taken from all bales on the perimeter of the paddock and then taken from bales that fall within the lines of a ‘W’ pattern across the rest of the paddock; or • samples should be taken from each bale that is produced every seventh lap of the baler and every bale in the perimeter lap; or • starting from the first bale in the paddock every ‘x’ bale should be sampled, following the path of the baler to ensure that the greater of 12 or 15% of bales are sampled; or • any similar systematic plan used for the selection of bales sampled. 58 PRODUCING QUALITY OAT HAY Two laboratories are accredited to test export hay samples for ARGT contamination. In Western Australia contact the Department of Agriculture, Immunology Laboratory, Animal Health Laboratories, 3 Baron-<strong>Hay</strong> Court South Perth, WA 6151 (08 9368 3491). In all other states of Australia contact the SARDI Crop Pathology Diagnostics Laboratory at the Plant Research Centre, Urrbrae, SA 5064, (08 8303 9668 or 9360). Processors intending to submit samples for testing should first register with the laboratories and obtain appropriate sample kits.
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Producing Quality Oat Hay
Page 3 and 4:
Acknowledgements Authors Pamela Zwe
Page 5 and 6:
The oat hay year planner Between cr
Page 7 and 8: Zadoks Stage Growth Code Activity C
Page 10 and 11: Foreword Growing Oat Hay was first
Page 12 and 13: Chapter 1 Why grow oat hay? Growing
Page 14 and 15: Table 1.1 Gross margin in dollars p
Page 16 and 17: Chapter 2 Is oat hay a viable choic
Page 18 and 19: Chapter 3 What the market wants? Do
Page 20 and 21: Hay for export Over the past five y
Page 22 and 23: Figure 3.5 Overview of the Australi
Page 24 and 25: Objective measurement and chemical
Page 26 and 27: Chapter 4 Disease of oats A wide ra
Page 28 and 29: Leaf and stem diseases - fungi Stem
Page 30 and 31: Septoria Leaf Blotch, Septoria aven
Page 32 and 33: Leaf and stem diseases - bacteria F
Page 34 and 35: Root Diseases - nematodes Nematodes
Page 36 and 37: Root Lesion Nematode, Pratylenchus
Page 38 and 39: Take-all, Gaeumannomyces graminis v
Page 40 and 41: Chapter 5 Variety selection for hay
Page 42 and 43: Swan Swan is a tall mid season vari
Page 44 and 45: Seed purchased for sowing to produc
Page 46: Table 5.4a Agronomic and hay qualit
Page 49 and 50: Herbicide residues Some herbicide r
Page 51 and 52: Higher plant populations produce hi
Page 53 and 54: Figure 6.1a Sown round and round -
Page 55 and 56: oadcast or deep banded at seeding.
Page 57: Weed control Impact on hay quality
Page 61 and 62: Insect control Oat hay crops are da
Page 63 and 64: 62 PRODUCING QUALITY OAT HAY Figure
Page 65 and 66: Ripe grain in hay is undesirable to
Page 67 and 68: Plants leaning at different angles
Page 69 and 70: Curing For every one tonne of hay b
Page 71 and 72: Figure 7.4 The impact of rainfall a
Page 73 and 74: Image 7.7 The windrow before (L) an
Page 75 and 76: Testing moisture content A moisture
Page 77 and 78: Handling can be easier if the bale
Page 80 and 81: Chapter 8 Storage and transport Hay
Page 82 and 83: Time line Spontaneous fires in stac
Page 84 and 85: side of the vehicle to the other, w
Page 86: Producing Quality Oat Hay The marke
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