Defoliant

A method for effecting leaf abscission in plants which comprises treating plants with a mixture comprising

• (A) thidiazuron or thidiazuron and diuron and
• (B) one or more PPO inhibitors of the formula (I)
• W—V (I),
• for effecting leaf abscission of plants,
• where the symbols in the formula (I) have the meanings:
• and
• or
• and
• or
• and
• R1 is hydrogen or halogen;
• R2 is halogen, alkyl, alkoxy, haloalkoxy or haloalkyl;
• R3 is hydrogen, alkyl, haloalkyl, alkoxy, haloalkoxy, alkyl-S(O)n—, dialkylamino, alkylamino, amino or halogen;
• R4 is hydrogen, alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, formyl, alkyl-CO— or amino;
• R5 is hydrogen, halogen, alkyl, haloalkyl or nitro;
• R6 is hydrogen, alkyl or haloalkyl;
• R7 is hydrogen, alkyl or haloalkyl;
• R8 is hydrogen, alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl or haloalkynyl;
• R9 is hydrogen, alkyl, halogen, alkoxy, haloalkyl, haloalkoxy, alkoxycarbonyl, haloalkoxycarbonyl or amino;
• R10is hydrogen, alkyl, halogen, alkoxy, haloalkyl, haloalkoxy, alkoxycarbonyl, haloalkoxycarbonyl or amino;
• R11 is hydrogen or alkyl;
• R12 is hydrogen, alkyl or halogen;
• R13 is hydrogen, halogen, alkyl, haloalkyl, alkoxy, haloalkoxy, cyano, nitro, amino, alkylamino, dialkylamino, alkoxycarbonyl, —(C═O)NH2, —(C═S)NH2, hydroxyl, acyloxy, substituted phenyl, substituted phenoxy, substituted benzyl or substituted benzyloxy;
• R14 is hydrogen, alkyl, haloalkyl, alkoxyalkyl, haloalkoxyalkyl, alkenyl, haloalkoxyalkenyl, alkynyl, haloalkynyl, alkoxy, haloalkoxy, haloalkenyloxy, alkynyloxy, haloalkynyloxy, halogen, —O—COR15, —OH, —S(O)nR15, —COR17, —CONR18R19, —CO2R20, —(CR6R7)n—CO2R20, —CR21═CR22CO2R20, —CN, —CR11(X1R23) (X2R24), —NR11—(CR6R7)n—CO2R20, —O—(CR6R7)n—CO2R20, —S(O)n—CR21═CR22—C(O)NR16R17, —(CR6R7)nCONR16R17, —(CR6R7)n—CO2R20, —NO2, —NR16R17, —NR24SO2R15 or —NR23COR15;
• R15 is hydrogen, M, alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl or halogen;
• R16 is hydrogen, alkyl, aloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl or halogen;
• R17 is hydrogen, OH, OM, alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, alkoxyalkyl or haloalkoxyalkyl;
• R18 is hydrogen, alkyl, alkoxy, alkenyl, haloalkenyl, alkynyl or haloalkynyl;
• R19 is hydrogen, alkyl, alkoxy or
• R18 and R19 together with the nitrogen atom form a 5-, 6- or 7-membered ring which may be interrupted by oxygen or sulfur;
• R20 is hydrogen, M, alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, alkoxyalkyl, haloalkoxyalkyl or —(CR6R7)n—CO2R15;
• R21 is hydrogen, alkyl, halogen or CN,
• R22 is hydrogen, alkyl, halogen or CN;
• R23 is hydrogen or alkyl;
• R24 is hydrogen, alkyl or
• R23 and R24 together are a substituted or else unsubstituted 5-, 6 or 7-membered cyclic acetal or thioacetal;
• R25 is hydrogen, alkyl, alkoxy, alkenyl, haloalkenyl, alkynyl, haloalkynyl, carbamoyl or thiocarbamoyl;
• M is an alkali metal, alkaline earth metal or ammonium ion;
• X1 is identical or different and is C-R5 or N;
• X2 is identical or different and is CR2R6, O, —S(O)n— or NR25;
• Y1 is O or S;
• Y2 is O or S;
• n, are 0, 1 or 2;
• U1 is O, S(O)n, NR23 or CR9R10.
• U2 is S(O)n, CR9R10 or C═O;
• T is CR2R6, NH or NR2.