If Landesmann asserts a claim against Acorp and Beeco, what, if anything, will Landesmann recover?
The entire amount of Landesmann's damages, jointly and severally, from the two companies
Nothing, because neither company discharged enough pesticide to cause harm to Landesmann's cattle. 
Nothing, unless Landesmann can establish how much pesticide each plant discharged. 
One-half of Landesmann's damages from each company.