THE INFLUENCE OF BENOMYL FORMULATION ON THE RESPONSE OF CUCUMBER SEEDLINGS (CUCUMIS-SATIVUS) TO DIBUTYLUREA

Experiments were conducted in a glasshouse to evaluate the phytotoxici ty of dibutylurea (DBU), a breakdown product of benomyl, benomyl formu lations and constitutive ingredients of 'Benlate' Dry Flowable (DF) on whole cucumber (Cucumis sativus. Poinsett 76) plants. Benlate Wettabl e Powder (WP) and DF formulations did not affect the phytotoxicity of DBU. When commercially purchased (samples obtained from growers) DF an d WP formulations containing equivalent DBU concentrations were compar ed for phytotoxicity, no statistical interactions between formulations were observed. Benomyl, DBU and DF inert ingredients were tested alon e and in combination to assess their phytotoxicity. Only DBU at rates greater than 94 mg litre(-1) caused a reduction in root and shoot grow th. Also DBU applied alone or as a component of either Benlate formula tion was shown to reduce the peak-to-terminal chlorophyll a fluorescen ce ratio measured in vivo by a plant productivity fluorometer. (C) 199 8 SCI.