Background:

Sunscald in soybeans happens during repeated overcast conditions followed by days of sunlight and high heat. Soybeans with Sunscald damage typically shows a brown to rusty look to the leaves. It is typically seen on the top trifoliate where the leaflet has turned over. Unlike a disease, this is not scattered throughout the entire plant and is very easy to identify. You might see some spider mites on Sunscalded soybeans, but other than that, it should not affect yield loss. 

 

Sources:

Sun Scald in Soybeans