Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 11/5/2013
Publication Date: 5/5/2014
Citation: Hartman, G.L. 2014. Phoma glycinicola (Red Leaf Blotch): A threat to soybean production in the USA. In: Liu, Dongyou, editor. Manual of Security Sensitive Microbes and Toxins. Boca Raton, Florida, CRC Press. p. 801-806. Interpretive Summary:
Technical Abstract: Red leaf blotch of soybean [Glycine max (L.) Merr.] is the common name for the disease caused by the fungal pathogen Phoma glycinicola Gruyter & Boerema. Other names for red leaf blotch inlcude Dactuliophora leaf spot, Pyrenochaeta leaf blotch, and Pyrenochaeta leaf spot. The disease was first reported in Africa in 1957, and is currently a threat to production in central and southern African countries where it is endemic. Phoma glycinicola is a culturable, soilborne fungus. It is known to infect soybean and Neonotonia wightii (Arnott) Lackey, a perennial legume that inhabits the woodlands and grasslands of southern Africa. The fungus is likely to have other hosts, and was shown experimentally to infect many other legumes. The fungus is known to occur in Cameroon, Ethiopia, Malawi, Nigeria, Republic of Congo, Rwanda, Uganda, Zambia and Zimbabwe. There was one report of the the fungus occuring in samples collected in Bolivia in 1982. Other reports have not corroborated this find. The pathogen has not been reported in the USA. Most of the published literature about red leaf blotch are from studies completed in Zambia and Zimbabwe, where yield losses of up to 50% were reported. Statistics on yield losses from other affected areas generally are not available. If the fungus/disease were found in the USA, it may become economically important, because of its potential to cause significant yield losses and the importance of the soybean crop to the agro-industry in the USA. The soybean production area in the USA has increased from 6.1 million hectares planted in 1950 to 30.6 million hectares planted in 2012 with an estimated worth of $35.8 billion in 2011. If the fungus became widespread in the USA and severe epidemics follow, the states that produce the most soybeans may suffer the highest economic losses.