a guide to the recognition and understanding of ramularia and other ...

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42 PHYSIOLOGICAL LEAF SPOTS Physiological leaf spots on spring barley variety Chariot Combination of ramularia leaf spot and physiological leaf spots
PHYSIOLOGICAL LEAF SPOTS AND POLLEN SCORCH 43 Physiological leaf spots and pollen scorch A common name sometimes used to describe unknown leaf spots is "pollen scorch". Pollen can be associated with leaf spots, but this would be expected since many physiological leaf spots and ramularia leaf spots occur on the top leaves after flowering, when pollen is likely to be seen on affected leaves. Although there is little evidence to suggest that pollen on the leaf surface is a direct cause of these leaf spots, extensive leaf scorch can be associated with pollen on the leaf surface, particularly following wet spells of weather when pollen sticks to the leaves. In these situations, the growth of saprophytic fungi, bacteria and yeasts (microflora) on the leaf surface use pollen as an additional food source growing rapidly on the leaf surface. These microflora may cause leaves to die-back earlier than normal. Leaf surfaces are however complex environments for a wide range of mircroflora. Some of these are known to prevent infection from known plant diseases whilst others may enhance disease. Plant defence mechanisms can also respond to the presence of some of these leaf surface microflora causing localised leaf death in response to a potential attack by them. The application of fungicides will influence the leaf surface microflora populations and different varieties will also have different populations of leaf surface organisms.
Page 1: A GUIDE TO THE RECOGNITION AND UNDE
Page 4 and 5: 2 Contents RAMULARIA Distribution C
Page 6 and 7: 4 RAMULARIA LEAF SPOT DISTRIBUTION
Page 8 and 9: 6 RAMULARIA LEAF SPOT DISTRIBUTION
Page 10 and 11: 8 Early stages SYMPTOMS What are th
Page 12 and 13: 10 SYMPTOMS Pepper spot symptom of
Page 14 and 15: 12 Later stage SYMPTOMS The rectang
Page 16 and 17: 14 SYMPTOMS Extensive ramularia lea
Page 18 and 19: 16 SYMPTOMS Ramularia leaf spot sym
Page 20 and 21: 18 SYMPTOMS Ramularia leaf spot sym
Page 22 and 23: 20 SYMPTOM APPEARANCE When do sympt
Page 24 and 25: 22 LIFECYCLE Disease lifecycle The
Page 26 and 27: 24 LIFECYCLE Spore dispersal Leaf w
Page 28 and 29: 26 LIFECYCLE Infection of barley by
Page 30 and 31: 28 LIFECYCLE Ramularia collo cygni
Page 32 and 33: 30 Ramularia Ramularia concentratio
Page 34 and 35: 32 CONTROL MEASURES Foliar fungicid
Page 36 and 37: 34 Fungicide choice CONTROL MEASURE
Page 38 and 39: 36 Physiological leaf spots Physiol
Page 40 and 41: 38 PHYSIOLOGICAL LEAF SPOTS Advance
Page 42 and 43: 40 PHYSIOLOGICAL LEAF SPOTS Physiol
Page 46 and 47: 44 PHYSIOLOGICAL LEAF SPOTS Physiol
Page 48 and 49: 46 Control of physiological leaf sp
Page 50 and 51: 48 PHYSIOLOGICAL LEAF SPOTS Magnesi
Page 52 and 53: 50 FUNGAL DISEASES CAUSING SYMPTOMS
Page 54 and 55: 52 FUNGAL DISEASES CAUSING SYMPTOMS
Page 56 and 57: 54 Septoria nodorum FUNGAL DISEASES
Page 58 and 59: 56 REFERENCES AND FURTHER READING R
Page 60 and 61: 58 ACKNOWLEDGEMENTS Acknowledgement
Page 62: The Chemical Company

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