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Invert Emulsion Droplet Size and Mycoherbicidal Activity of Colletotrichum truncatum

Published online by Cambridge University Press:  12 June 2017

Grant H. Egley ,
James E. Hanks  and
C. Douglas Boyette
Grant H. Egley
Affiliation:
South. Weed Sci. Lab., Agric. Eng., Applic. Tech. Res. Unit., Stoneville, MS 38776
James E. Hanks
Affiliation:
Agric. Res. Serv., U.S. Dep. Agric., Stoneville, MS 38776
C. Douglas Boyette
Affiliation:
Agric. Res. Serv., U.S. Dep. Agric., Stoneville, MS 38776
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Abstract

When formulated and sprayed in an invert emulsion (IE), conidia of the mycoherbicide, Colletotrichum truncatum, controlled hemp sesbania in the absence of dew. To optimize hemp sesbania control, formulation droplet size influence upon the pathogen's germination and pathogenicity was investigated. Conidia germination in manually produced IE droplets decreased from 46% to 5% as droplet diameter decreased from 2700 to 900 μm. Droplet size did not affect appressoria formation. On a per conidium basis, 900-μm droplets were more pathogenic to detached hemp sesbania leaves than were 2100-μm droplets. An air-assist spray system produced droplet spectra with volume median diameters of 421 and 104 μm, respectively. The spectrum of smaller droplets covered the target better than did that of larger droplets. When applied to whole hemp sesbania plants in greenhouse trials, conidia in the smaller and larger droplet spectra gave 90 and 94% control, respectively. Sufficient conidia germinated in IE droplets of a variety of sizes to control hemp sesbania excellently.

Keywords

Hemp sesbania (Sesbania exaltata (Rydb) ex. A. W. Hill # SEBEX), Colletotrichum truncatum (Schw.) Andrus and MooreBiocontrolfungal pathogenhemp sesbaniaspray formulationair-assist sprayerSesbania exaltataSEBEX
Type
Research
Information
Weed Technology , Volume 7 , Issue 2 , June 1993 , pp. 417 - 424
Copyright
Copyright © 1993 Weed Science Society of America 

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References

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