Submitted to: Journal of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2007
Publication Date: 7/17/2007
Citation: Dugan, F.M., Hellier, B.C., Lupien, S.L. 2007. Pathogenic fungi in garlic seed cloves from the United States and China, and efficacy of fungicides against pathogens in garlic germplasm in Washington State.. Journal of Phytopathology. 155: 437-45.
Interpretive Summary: Garlic "seed" is actually a vegetative propagule, the cloves from garlic bulbs. In the northern hemisphere, seed cloves are planted in the fall and the crop is harvested late summer or early fall the following year. USDA-ARS At Western Regional Plant Introduction Station in Pullman Washington (part of the National Plant Germplasm System), we grow garlic to be distributed to scientists in academia and industry. We noticed problems with fungal infection of garlic and resolved to make a survey of fungal pathogens in commercially distributed garlic as well as monitoring our own stocks. We also embarked on a series of trials with fungicides labeled for garlic in Washington State. Fungi documented in the literature as pathogenic to garlic were recovered from commercially distributed seed garlic from six states in the US plus garlic originating from mainland China. Fungicides were inconsistent in effect, sometimes promoting plant health but sometimes failing to have an effect.
Technical Abstract: Commercially distributed garlic (Allium sativum) seed cloves from six states of the United States and mainland China were surveyed for the presence of fungi recorded as pathogenic to garlic in the literature. Aspergillus niger, A. ochraceus, Botrytis porri, Embellisia allii, Fusarium oxysporum f. sp. cepae, F. proliferatum, and Penicillium hirsutum, were each recovered from one or more of these commercial sources, as was F. verticillioides, not previously reported as pathogenic to garlic but here demonstrated to be a pathogen. Seed garlic distributed from public germplasm collections may also contain fungal pathogens: E. allii, F. oxysporum f. sp. cepae and/or F. proliferatum caused severe losses in 2002-2003 and 2005-2006 during germplasm regeneration and storage for the National Plant Germplasm System in Pullman, Washington. Use of fludioxonil, thiophanate methyl and/or benomyl (the latter withdrawn from the market, but used here as a standard) at label rates against E. allii and Fusarium species promoted plant health, but not when infections were located deep within tissues nor under some situations involving high disease pressure.