<em>Foreboding</em> means predicting or announcing that something bad is about to happen. Taking the answers one by one, you can see how they relate to the same ominous idea:
a "strange blight" and "evil maladies" refer to a destructive condition which no-body can explain;
an "evil spell" means that it is interpreted as a magical curse;
the "shadow of death" is a metaphor meaning that death is coming to the crops or cattle (depending on the original text excerpt).
