Author
|
Submitted to: Internet Web Page
Publication Type: Popular Publication Publication Acceptance Date: 1/23/2007 Publication Date: 1/23/2007 Citation: Chen, W. 2007. White Mold of Chickpea. Internet Web Page. Interpretive Summary: White mold of chickpea in the United States is described. The various disease symptoms in different parts of the US is reviewed. The known pathogen species and disease cycle are described. Also discussed are management practices controlling white mold of chickpea. Technical Abstract: White mold of chickpea can occur at either seedling stage or at flowering and pod filling stages. At seedling stage, the disease occurs at the base of the stem causing symptoms like collar rot. Often white mycelial growth around the stem on soil surface is visible. Affected plants wilt and die. Black sclerotia in various shape and sizes form on dead or dying chickpea stems right above or below the soil line. However, in the Pacific Northwest and the northern Great Plains, the disease is more common at the flowering and pod filling stage. Infection starts at upper stem or on senescent flowers. Infected stems become pale in colour like bleaching, and the symptom spreading both upward and downward along the stems. Under heavy canopy and humid conditions, white puff mycelial growth becomes conspicuous, and black irregular-shaped sclerotia may form and are visible on the stems. The plant parts above the infection wilt and die. Disease infected fields show appearance of chlorotic and dying branches or whole plants scattered in the field. The disease is caused by Sclerotinia sclerotiorum in the Pacific Northwest and the Great Plains. But both S. sclerotiorum and S. minor are reported to cause white mold of chickpea in Arizona. In all cases, the pathogens produce black and irregularly shaped fruiting bodies of sclerotia that survive adverse conditions, and the sclerotia can either germinate directly or produce apothecia and ascospores that can be spread by wind, land on plant parts and initiate new infection. All the pathogens survive adverse conditions or between crop seasons as the black sclerotia in soil or from infested seed lots. Sclerotia can germinate directly by means of mycelium in the soil and infect chickpea stems. Sclerotia can also germinate by means of apothecia bearing ascospores in asci. Ascospores are blown and spread by wind and land on stems or flowers to initiate new infection. Long-term rotations with non-host crops like cereal crops when possible will reduce the inoculum (sclerotia) density. |
