Herbicide Interactions withColletotrichum gloeosporioidesf. sp.malvaea Bioherbicide for Round-leaved Mallow (Malva pusilla) Control

Abstract

Colletotrichum gloeosporioidesf. sp.malvae(C.g.m.) was evaluated under greenhouse conditions for round-leaved mallow control in combination with the following herbicides: bromoxynil plus MCPA (1:1), diclofop, imazethapyr, metribuzin, sethoxydim, and 2,4-DB. Treatments consisted of C.g.m. and herbicide applied alone, tank mixed, and C.g.m. applied 48 h before, and 1, 24, and 72 h after herbicide. Split applications with bromoxynil plus MCPA, imazethapyr, metribuzin, (C.g.m. before or after) and sethoxydim (C.g.m. before) enhanced round-leaved mallow control over C.g.m. applied alone. However, diclofop or 2,4-DB tank mixed or applied in a split application with C.g.m. did not improve round-leaved mallow control over C.g.m. applied alone. Bromoxynil plus MCPA, metribuzin, 2,4-DB, and imazethapyr may be tank mixed with C.g.m. without significantly reducing round-leaved mallow control, unlike sethoxydim or diclofop which inhibited C.g.m. development. Dew period did not influence the effectiveness of bromoxynil plus MCPA applied 30 h before C.g.m., but round-leaved mallow control increased with increasing dew period for metribuzin applied 30 h before C.g.m.

Effects of selected pesticides and adjuvants on germination and vegetative growth of Phomopsis amaranthicola, a biocontrol agent for Amaranthus spp.

“…Imazethapyr at 0.01, 0.1, 0.5, 1 and 2 times the recommended rate affected spore germination of C. gloeosporioides f. sp. malvae , although germination remained above 50% of the control at all concentrations (Grant et al. , 1990b).…”

“…malvae to sethoxydim had a more adverse effect on spore germination than on growth. At 0.5 times the recommended field rate, spore germination dropped to 0%, whereas mycelial development was inhibited only at the recommended rate and not at 0.01, 0.1 and 0.5 times the field rate (Grant et al. , 1990b).…”

“…Metribuzin also did not affect spore germination of C. gloeosporioides f. sp. malvae at concentrations up to 2X HR but caused the mycelial colour to change (Grant et al. , 1990b).…”

“…Compatibility of herbicides with fungal biological control agents has been examined to some extent (Khalil et al. , 1985; Grant et al. , 1990a,b; Poprawski & Majchrowicz, 1995; Rayachhetry & Elliott, 1997; Wyss & Müller‐Schärer, 2001).…”

Innovative Applications of Microbial Agents for Biological Weed Control

“…Experiments with split applications of several herbicides with C gloeosporioides f.sp. malvae resulted in enhance efficacy when compared to the application of the mycoherbicide alone (Grant et al, 1990b). More than 50% of the herbicides applied at 0.1 to 2 times the recommended rate did not interfere with the growth of the mycoherbicide (Grant et al, 1990a).…”