Ciba-geigy Corporation

Werner F Ory

Manfred Hudetz

Elmar Kerber

N-pyridinesulfonyl-N'-pyrimidinyl- and -triazinyl-ureas of formula I ##STR1## wherein R.sub.1 is hydrogen or fluorine;

Certain 3-oxy-2-pyridyl sulfonamide intermediates

Compounds of the formula XI, wherein R, R.sub.4, R.sub.8 and R.sub.38 are as defined in claim 1, are useful as intermediates in the preparation of compounds of formula I. Mixtures of a herbicidally effective amount of a pyridylsulfonylurea of formula I, ##STR1## wherein R, R.sub.1, R.sub.2 and A are as defined in the specification and of a herbicide-antagonistically effective amount of a sulfamoylphenylurea of formula II, ##STR2## wherein R.sub.7 to R.sub.11 and A.sub.2 are as defined in the specification are very suitable for controlling weeds in crops of useful plants, especially maize and sugar cane.

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Riehen, Switzerland

Werner F Ory