Screening for resistance of Allium species to Sclerotium cepivorum with special reference to non‐stimulatory resistance
ABSTRACT Approximately 150 seed lots of Allium cepa and more than 30 different Allium species were tested in the greenhouse under strictly controlled conditions against Sclerotium cepivorum, the causal fungus of Allium white rot disease. The quantity and quality of the inoculum was determined using a simple and rapid test to achieve a high degree of standardization. Only the A. cepa cultivar “Sweet Sandwich’ and A. porrum, A. rotundum, A. sphaerocephalon and two further unidentified Allium species showed significantly lower disease incidence than the cultivar ‘Golden Bear’. The stimulatory effect of the root exudates on sclerotial germination was compared with that of diallyl sulphide. With the exception of A. species‘PI 249549′, extracts of all species that showed low levels of disease incidence in the greenhouse test stimulated sclerotial germination only weakly.
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ABSTRACT: The effects of leaf extracts of Brachiaria humidicola, Crotalaria paulina. Eucalyptus citriodora. and Brassica oleracea var. capitata on mycelial growth and sclerotial germination of Sclerotium cepivorum were evaluated in vitro. Water extracts of leaves had little effect on either growth or germination. However, acetone-water leaf extracts usually had the greatest inhibitory effects. Acetone-water extracts reduced mycelial growth more than sclerotial germination. Leaf extracts of E. citriodora at 1000 and 10000p.p.m. in acetone-water completely inhibited mycelial growth and sclerotial germination of S. cepivorum. Thus, this extract is potentially useful for the control of garlic white rot. and its effect will be evaluated under field conditions.ZusammenfassungUntersucht wurden die Einflüsse von Blattextrakten von Brachiaria humidicola, Crntalaria paulina, Eucalyptus citridora und Brassica oleracea var. capitata auf das Myzelwachstum und die Sklerotienbildung von Sclerotium cepivorum in vitro. Wasserextrakte der Bltter hatten kaum Einfluß, weder auf das Wachstum noch auf die Keimung. Am hufigsten hatten jedoch Aceton-Wasser Blattextrakte die größten hemmenden Effekte. Die Aceton- Wasser-Extrakte reduzierten das Myzelwachstum strker als die Sklerotienkeimung. Die Blattextrakte von E. citriodora verursachten eine völlige Hemmung des Myzelwachstums und der Sklerotienkeimung von S. cepivorum bei einer Konzentration von 1000 bzw. 10000 ppm in Aceton-Wasser. Von daher hat dieses Extrakt das Potential als Bekmpfungsmaßnahme gegen die Mehlkrankheit in Knoblauch, und dessen Effekt wird unter Freilandbedingungen beurteilt.Journal of Phytopathology 06/2008; 146(8‐9):421 - 425. · 1.00 Impact Factor
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ABSTRACT: Onions and garlic are the most popular cultivated forms of the family Alliaceae and consumed by almost every culture on earth. According to the 2001 statistics of the FAO, onions are second only to tomatoes in value of vegetable crops cultivated world wide. There are a number of pathogens attack onions and garlic throughout their developmental stages since the developmental process is important in the progression of diseases. Onions are normally propagated from seed, planted directly into the field, although onion sets and transplants are also used. Garlic has been vegetatively propagated for millennia, by planting cloves. Vegetative propagation results in additional disease management problems. This chapter covers disease management of many of the major bacterial, fungal and viral diseases of onions and garlic, with an emphasis on those diseases that have been the topic of disease management research or for which effective disease management systems have been put into practice. Short descriptions of the pathogens and symptoms are included to assist in identification of the specific diseases.
- Plant Disease - PLANT DIS. 01/1998; 82(10):1142-1146.