A pesticide composition includes an active component and polyethyleneimine having a weight average molecular weight of at least about 750,000 g/mol and has improved rainfastness. The polyethyleneimine of this invention has decreased mobility in water as compared to related lower molecular weight analogs. The pesticide composition is formed using a method that includes the steps of providing the active component, providing the polyethyleneimine, and combining the active component and the polyethyleneimine to form the pesticide composition.
