Question

Many crops such as tomatoes and corn are now routinely genetically manipulated to become more resistant to disease and herbicides. what is one disadvantage of this genetic resistance?

Answer 1

The genes may be transferred to weeds during pollution. 

Answer 2

As the crop of tomatoes and corn get genetically resistant to diseases and pest attacks, the other crops which grow along with the main crop specifically the weeds get destroyed. This is so because the pest that earlier attacked the tomatoes and corn now only have weeds and other unwanted plants that can be attacked and fed upon. This may disturb the micro ecosystem with in the agricultural field.