Certain substituted 4-benzoyl-3,5-dioxotetrahydropyrans and thiopyrans

The method of controlling undesirable vegetation comprising applying to the area where control is desired, an herbicidally effective amount of a compound having the formula ##STR19## wherein X is oxygen, sulfur or sulfonyl;

• R is halogen;
• C.sub.1 -C.sub.2 alkyl;
• C.sub.1 -C.sub.2 alkoxy;
• nitro;
• cyano;
• C.sub.1 -C.sub.2 haloalkyl;
• or R.sup.a SO.sub.m -- wherein m is 0 or 2 and R.sup.a is C.sub.1 -C.sub.2 alkyl;
• R.sup.1 is hydrogen or C.sub.1 -C.sub.4 alkyl;
• R.sup.2 is hydrogen or C.sub.1 -C.sub.4 alkyl;
• or
• R.sup.1 and R.sup.2 together are alkylene having 2 to 5 carbon atoms;
• R.sup.3 is hydrogen or C.sub.1 -C.sub.4 alkyl;
• R.sup.4 is hydrogen or C.sub.1 -C.sub.4 alkyl;
• or
• R.sup.3 and R.sup.4 together are alkylene having 2 to 5 carbon atoms;
• and
• R.sup.5 and R.sup.6 independently are (1) hydrogen;
• (2) halogen;
• (3) C.sub.1 -C.sub.4 alkyl;
• (4) C.sub.1 -C.sub.4 alkoxy;
• (5) trifluoromethoxy;;
• (6) cyano;
• (7) nitro;
• (8) C.sub.1 -C.sub.4 haloalkyl;
• (9) R.sup.b SO.sub.n -- wherein n is the integer 0, 1 or 2;
• and R.sup.b is (a) C.sub.1 -C.sub.4 alkyl;
• (b) C.sub.1 -C.sub.4 alkyl substituted with halogen or cyano;
• (c) phenyl;
• or (d) benzyl;
• (10) --NR.sup.c R.sup.d wherein R.sup.c and R.sup.d independently are hydrogen or C.sub.1 -C.sub.4 alkyl;
• (11) R.sup.e C(O)-- wherein R.sup.e is C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy;
• or (12) --SO.sub.2 NR.sup.c R.sup.d wherein R.sup.c and R.sup.d are as defined;
• and (13) --N(R.sup.c)C(O)R.sup.d wherein R.sup.c and R.sup.d are as defined and their salts.