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Asian rust Assure II herbicide Bacterial pustule Charcoal Rot Downy mildew Genetic mutation Oxygen starvation

Plant: Soybean (Glycine max) (Fabaceae) Back to List
Disease/Disorder: Charcoal rot
Causal agent: Macrophomina phaseolina (fungus)
Signs: Many survival structures of the fungus called "microsclerotia" can be seen "peppered" in the stems as with the second row of images.
Symptoms: Stem infection discolores the vascular and pith tissues so that when the stem is split, black streaks can be seen as in the first row of images.
Total image number: 8

Plant: Soybean (Glycine max) (Fabaceae) Back to List
Disease/Disorder: herbicide injury
Causal agent: something, possibly a solvent, in the herbicide “Assure II”
Signs:
Symptoms: Progression of symptoms from bleaching, reddening, then browning in blotchy to broad areas on the leaves.
See information from the University of Missouri at http://www.psu.missouri.edu/soydoc/files/weed/lipidsyn.htm
and the University of Wisconsin at
http://128.104.239.6/uw_weeds/herbinjkey/ModeOfAction/ACCase.htm
Total image number: 4

Plant: Soybean (Glycine max) (Fabaceae) Back to List
Disease/Disorder: acute oxygen starvation
Causal agent: Saturated soil/heat
Signs:
Symptoms: The death of these seedling plants was caused by a unique combination of
plant growth stage, saturated soil, and high heat causing a rapid death of the
below ground portion of the stem and root system.
The image of the field shows two different varieties. The variety on the left grew faster
and was not nearly as injured as the variety on the right which grew at a slower pace.
Total image number: 5

Plant: Soybean (Glycine max) (Fabaceae) Back to List
Disease/Disorder: Bacterial pustule
Causal agent: Xanthomonas axonopodis pv. glycines (bacterium)
Signs: bacterial streaming
Symptoms: Spots range in size from small flecks to larger necrotic areas.
The center of the spots have a raised pustule on the lower leaf surface
which can appear similar to structures seen with Asian soybean rust.
Total image number: 10

Plant: Soybean (Glycine max) (Fabaceae) Back to List
Disease/Disorder: Asian soybean rust
Causal agent: Phakopsora pachyrhizi (fungus)
Signs: urediniospores
Symptoms: Spots are mostly small flecks.
The center of the spots have a raised area usually on the lower surface of the leaves which can appear similar to structures seen with Bacterial pustule.
Total image number: 11