Dodder is a serious parasitic weed in the crops in which it is a problem (particularly citrus). Alternaria destruens is the active ingredient in a registered bioherbicide for control of dodder species. In greenhouse studies, the treatments applied to citrus parasitized with field dodder were a nontreated control; oil at 7.5% v/v in water; ammonium sulfate at 0.125% w/v in water; glyphosate at 0.02 kg ae/L; A. destruens at 1.8 × 10¹⁰ spores/L; A. destruens (1.8 × 10¹⁰ spores/L) oil at 7.5% v/v in water; and a mixture of A. destruens (1.8 × 10¹⁰ spores/L) oil at 7.5% v/v in water glyphosate at 0.02 kg ae/L ammonium sulfate 0.125% w/v (the mixture treatment). The highest disease or damage severity rating out of all treatments, measured as the area under the disease or damage progress curve (AUDPC), was obtained for the mixture treatment. By 35 d after treatment, all field dodder plants that received the mixture treatment were dead but the host plant, citrus, was not. These results indicate the feasibility of integrating glyphosate, ammonium sulfate, and A. destruens to manage dodder.

Nomenclature: Glyphosate; ammonium sulfate; field dodder, Cuscuta pentagona Engelm. CVCPE; citrus, Citrus spp. ‘Smooth Flat Seville’; Alternaria destruens L. Simmons, sp. nov.