2001-2002 Small Grain Performance Tests
The Georgia Agricultural Experiment Station
College of Agricultural and Environmental Sciences
The University of Georgia
Research Report Number 682
July 2002

SMALL GRAIN UPDATES: Diseases

Barry M. Cunfer, Department of Plant Pathology,
Griffin Campus, Griffin, GA 30223-1797.

Mild winter temperatures resulted in early buildup of leaf rust on susceptible wheat cultivars. Severe cold in late February slowed the early onset of rust and other diseases. Leaf rust increased throughout the spring, but relatively dry weather prevented development of severe rust on cultivars with moderate to good resistance. However, in a fungicide test at Plains, leaf rust reduced yield about 35% on NK Coker 9835, a highly susceptible cultivar. Powdery mildew was prevalent on susceptible wheat but damage was minimal across the state because cultivars planted had a sufficient level of resistance. Stagonospora leaf and glume blotch was more common than in recent years, but dry weather in late April and early May reduced head infection and glume blotch was generally low. Tan spot continued to be found in Georgia and is part of a leaf spot complex with Stagonospora nodorum on wheat. Fusarium foot rot was found throughout the state and take-all was sporadic. Fusarium foot rot and tan spot contributed to poor crop development in southwest Georgia during the mild winter months. The fall and winter conditions were favorable for early season development of barley yellow dwarf. However, symptoms were often difficult to detect and losses to BYD were difficult to assess. Along with cold damage, the combination of root and leaf diseases contributed to reduced yields and test weights in wheat. Barley yellow dwarf was severe on early-planted oats resulting in some fields being abandoned. Crown rust of oats was generally low in commercial fields.

Stripe rust of wheat has been increasing in the Mississippi Valley and parts of the western U.S. due to the appearance of a new race of the fungus. Stripe rust caused minor damage but was common in a variety trial at Belle Mina, in northern Alabama. It was not found in a similar test at Calhoun in northwest Georgia. Recommended cultivars and advanced breeding lines have been assessed for stripe rust susceptibility in Arkansas and Louisiana. Stripe rust could cause losses during cool wet periods that favor the disease and if susceptible cultivars are planted.

The USDA-APHIS survey again found Georgia to be free of Karnal bunt. The disease has not been found east of northern Texas where an outbreak was detected in 2001. Karnal bunt continues to be a quarantined disease.

Table of Contents