Heteric EO/PO block copolymers as adjuvants for herbicidal formulations

A method of enhancing the weed controlling activity of a broad spectrum herbicide comprising the administration of said broad-spectrum herbicide wherein a heteric EO/PO copolymer is used in conjunction with said broad-spectrum herbicide and said heteric EO/PO co-polymer has surface active properties, and the formula:

• Y[(EO,PO).sub.m (PO).sub.n (EO,PO).sub.m,H].sub.x
• wherein Y is the nucleus of an organic reactive hydrogen compound having x reactive hydrogen atoms and up to 6 carbon atoms, x is an integer, EO is ethylene oxide, PO is a propylene oxide hydrophobe having an oxygen/carbon ratio of not more than 0.40, (EO,PO) represents a hydrophilic heteric block having an oxygen/carbon ratio of more than 0.40, m,m' and n are numbers such that the total molecular weight of said hydrophilic heteric block is from about 660 to 11,400, the total molecular weight of said PO hydrophobe is from about 1500 to 3600 and the total molecular weight of said copolymer ranges from about 2,200 to 15,000 said copolymer being at least 30 weight percent hydrophilic with said hydrophilic heteric block comprising from about 5 to 40 weight percent of PO.