Growth and development of fall- and spring-planted populations of Conyza canadensis and C. bonariensis |
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| Authors: | Anil Shrestha Katrina M Steinhauer Bradley D Hanson Marie Jasieniuk Kurt J Hembree Steven D Wright |
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| Institution: | 1. Department of Plant Science, California State University, Fresno, CA, USA;2. Department of Plant Sciences, University of California, Davis, CA, USA;3. University of California Cooperative Extension, Fresno, CA, USA;4. University of California Cooperative Extension, Tulare, CA, USA |
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| Abstract: | The growth and phenological development of spring- and fall-planted Conyza canadensis and C. bonariensis were studied in Fresno, CA, USA. A glyphosate-resistant (GR) and a glyphosate-susceptible (GS) population of each species were used. Time taken by each plant to reach the rosette, bolting, appearance of first bud, appearance of first open flower, and initial seed set were converted to growing degree days (GDDs). The fall- and spring-planted C. canadensis required similar GDDs to complete their life cycles but the GR type required fewer GDDs than the GS type. In C. bonariensis, the GDDs required to complete its life cycle differed between the fall- and spring-plantings but not between the GR and GS types. The total aboveground biomass of both fall- and spring-planted Conyzas at initial seed set was similar but the spring-planted GS C. canadensis produced more biomass than the GR type, whereas the fall-planted GS C. bonariensis produced more biomass than the GR type. Plant development based on GDD models can have global implications and help in planning for timely applications of post-emergence herbicides. |
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| Keywords: | Days after transplanting glyphosate growing degree days herbicide resistance |
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