Factors Influencing the Efficacy of the Potential Microbial Herbicide Alternaria alternata (Fr.) Keissler on Amaranthus retroflexus (L.)

Lawrie, J.; Down, V. M.; Greaves, M.P.

doi:10.1080/09583150029413

Cited by 22 publications

(15 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…malvae) on round-leaved mallow (Malva pusilla Sm) (Makowski, 1993). Formulation additives, including a range of biopolymers and oils, may prolong the wetness around germinating spores through lowering evaporation rate (Womack et al 1996;Lawrie et al, 2000). These additives, therefore, may enable fungal spores to withstand certain degree of wetness interruption during germination and penetration.…”

Section: Discussionmentioning

confidence: 98%

Effect of plant stage, Colletotrichum truncatum dose, and use of herbicide on control of Matricaria perforata

Graham¹,

Peng²,

Bailey³

et al. 2006

BioControl

View full text Add to dashboard Cite

Colletotrichum truncatum (Ct) was examined in a tank mix with the herbicide 2,4-D, clopyralid plus MCPA (Caurtail M Ò ), or metribuzin (Sencor Ò ) for control of scentless chamomile at 8-(younger) and 11-leaf stages (older) under controlled conditions. In initial trials, Ct at 7 Â 10 6 spores/ml (200 l/ha) reduced the fresh weight of scentless chamomile only slightly. However, its combinations with herbicides improved the efficacy variably depending on the herbicide used and stage of the weeds. Ct plus 2,4-D reduced the fresh weight by about 50% at both leaf stages of scentless chamomile when compared to untreated controls but no plants were killed. The fungus plus Curtail M consistently killed younger but not older plants, and the efficacy was substantially greater than that of the herbicide alone. The herbicide Sencor was highly effective on younger plants, and adding Ct did not achieve additional benefits. On older plants, however, Ct plus Sencor was substantially more effective than the herbicide alone, causing 76% fresh-weight reduction when compared to controls and killing 9 out of 16 older plants in four trials. Sencor applied alone reduced the fresh weight of older plants by 65%, but no plants were killed. Tested at doses ranging from 2 Â 10 6 to 20 Â 10 6 spores/ml, Ct plus Curtail M was most effective at the highest fungal inoculum dose, consistently killing younger but not older plants. In comparison, Ct at a medium dose (7 Â 10 6 spores/ml) plus Sencor killed the majority of older chamomile plants (7 out of 12), whereas the herbicide alone did not cause plant mortality. Further increasing fungal inoculum dose from this medium level did not enhance the weed control by Ct plus Sencor.

show abstract

Section: Discussionmentioning

confidence: 98%

Effect of plant stage, Colletotrichum truncatum dose, and use of herbicide on control of Matricaria perforata

Graham¹,

Peng²,

Bailey³

et al. 2006

BioControl

View full text Add to dashboard Cite

show abstract

“…retroXexus, the eVect is variable and, usually, only fully expressed under ideal conditions. That is to say, for greatest eYcacy, a high conidial concentration needs to be applie d to small plants (3 or less leaf stage) in large volumes and exposed subsequently to a very long dew period (Lawrie et al, 2000). Clearly, such requirements are not conducive to developing this organism as a microbial herbicide, although alternative formulation may improve the situation (Greaves et al, 1998).…”

Section: Discussionmentioning

confidence: 98%

Investigation of Spray Application of Microbial Herbicides Using Alternaria alternata on Amaranthus retroflexus

Lawrie¹,

Greaves²,

Down³

et al. 2002

Biocontrol Science and Technology

Self Cite

View full text Add to dashboard Cite

Inclusion of Alternaria alternata conidia in a spray formulation aVected the distribution pattern on the target. The dry weight of Amaranthus retro¯exus plants was reduced by more than 83% when A. alternata conidia (10 7 ml 2 1 ) were applied at 200 L ha 2 1 or greater and when given a 24 h dew period. At low applicatio n volumes (25 or 50 L ha 2 1 ) plant dry weight was reduced by only 29 or 54%. After 7± 8 h dew period, conidial germination on the leaf surface was 11± 19%. This increased to 62 ± 91% after 24 h dew period. Counts of conidia on leaves indicated that up to 86% of the conidia sprayed were not retained on the target plant, or did not reach it. This is reXected in lesion numbers per unit area being only 3± 5% of the calculated theoretical numbers. The results cast doubt on the suitability of A. alternata as a microbial herbicide for the control of Am. retro¯exus.

show abstract

“…In this case, eight of the 10 formulations tested increased the efficacy of the pathogen P. herbarum to cause disease on dandelion. This may have been due to the emulsion preserving the aqueous phase containing the fungal mycelium in the formulation, capturing moisture from the atmosphere or the plant surface (Lawrie et al 2000), penetrating the plant via stomata (Gauvrit & Cabanne 1993;Greaves et al 2001) or damaging the cuticle (Amsellem et al 1991;Klein et al 1995) which may assist infection, or by stimulating the growth of the fungal pathogen (Womack & Burge 1993;Abbas & Egley 1996). However, significant phytotoxicity was observed and this is the first such report associated with these previously described formulations, as prior studies have recorded little or no phytotoxic symptoms (Daigle et al 1990;Auld 1993;Womack et al 1996).…”

Section: Discussionmentioning

confidence: 98%

Oil emulsions increase efficacy ofPhoma herbarumto control dandelion but are phytotoxic

Stewart-Wade

Boland

2005

Biocontrol Science and Technology

View full text Add to dashboard Cite

Paraffinic-vegetable and vegetable oil emulsions were investigated for their ability to increase efficacy of the fungal pathogen Phoma herbarum as a bioherbicide to control dandelion (Taraxacum officinale ) under sub-optimal leaf wetness durations (LWDs) in controlled environments. Mycelia of P. herbarum (20%, v/v) were formulated in 10 oil emulsions; two based on paraffinic-vegetable (soybean) oil mixtures, and eight based on vegetable (canola, coconut and soybean) oil emulsions alone. Emulsions were applied to dandelions using an automatic track sprayer and plants were exposed to sub-optimal LWDs simulating dew periods in field conditions. An aqueous formulation of P. herbarum was included as a standard treatment and formulations without P. herbarum were included as controls. Eight of 10 oil emulsions (two paraffinic-vegetable and six vegetable) significantly increased damage ratings caused by P. herbarum compared to the standard treatment under certain sub-optimal LWDs (P 0/0.05). However, all oil emulsions caused at least some phytotoxicity when applied alone under most LWDs. Also, the high viscosity of nine oil emulsions caused mixing and application problems. These results indicate that oil emulsions increase damage ratings caused by P. herbarum on dandelion under sub-optimal LWDs, but may not be suitable formulations due to their phytotoxicity and high viscosity.

show abstract

Factors Influencing the Efficacy of the Potential Microbial Herbicide Alternaria alternata (Fr.) Keissler on Amaranthus retroflexus (L.)

Cited by 22 publications

References 10 publications

Effect of plant stage, Colletotrichum truncatum dose, and use of herbicide on control of Matricaria perforata

Effect of plant stage, Colletotrichum truncatum dose, and use of herbicide on control of Matricaria perforata

Investigation of Spray Application of Microbial Herbicides Using Alternaria alternata on Amaranthus retroflexus

Oil emulsions increase efficacy ofPhoma herbarumto control dandelion but are phytotoxic

Contact Info

Product

Resources

About