Submitted to: Soybean Disease Compendium
Publication Type: Book / Chapter
Publication Acceptance Date: September 2, 2009
Publication Date: N/A
Technical Abstract: Phomopsis seed decay (PSD) can severely affect soybean seed quality and is a problem for many soybean farmers. This soybean disease can be caused by a number of different fungi in the Diaporthe/Phomopsis complex but it is primarily caused by Phomopsis longicolla T.W. Hobbs. Effects of PSD on yields in the United States from 1996 to 2007 ranged from 43,203 to 377,111 metric tons. Soybean seeds that are infected by P. longicolla have a range of symptoms from none to severe. Severely infected seeds are usually shriveled, elongated, and cracked and may have a white moldy appearance. Affected seeds usually do not germinate or are slow to germinate. Soybean pods can be infected at any time after they are formed. Diseased seeds are an important factor in the long-range dissemination of the pathogen. Use of genetic resistance is most practical and effective in controlling PSD. Different levels of PSD resistance have been identified in diverse soybean germplasm including plant introductions and cultivars. The widely used resistance sources include Arksoy, Delmar, MO/PSD-0259, OX615, PI 80837, PI 82264, PI 181550, PI 200510, PI 209908, PI 227687, PI 229358, PI 360841, and PI 417479. Updated information about PSD and genetics studies will be added to the new edition of the Compendium of Soybean Diseases.