5.4a pesticides

large fields of crops all of the same type = monoculture
they tend to be susceptible to pests which feed off the crops which reduces the productivity of farming

1. pesticides (chemicals designed to kill pests)

pros
they are easily obtained
easily applicable
very effective

cons
toxic - might kill plants in the process
bio accumulation - pesticides build up in a food chain causing harm to a food source of a higher trophic level
pests mutate and resist the chemicals - more toxic pesticides have to be used