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Research Project: New Weed Management Tools from Natural Product-Based Discoveries

Location: Natural Products Utilization Research

Title: Plant growth responses of apple and pear trees to doses of glyphosate

Author
item Carvalho, Leonard - UNIVERSITY OF SANTA CATARINA
item Duke, Stephen
item Messa, Jefferson - UNIVERSITY OF SANTA CATARINA
item Regina Da Costa, Flavia - UNIVERSITY OF SANTA CATARINA
item Bianco, Silvano - UNIVERSIDADE ESTADUAL PAULISTA (UNESP)

Submitted to: Planta Daninha
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2016
Publication Date: 12/1/2016
Publication URL: http://handle.nal.usda.gov/10113/63333
Citation: Carvalho, L.B., Duke, S.O., Messa, J.R., Regina Da Costa, F., Bianco, S. 2016. Plant growth responses of apple and pear trees to doses of glyphosate. Planta Daninha. 34(4):815-822.

Interpretive Summary: The herbicide glyphosate causes plant growth stimulation at low, sub-toxic doses, especially in woody plants. This work did not find this effect in either young apple or pear trees, but found slight reductions in growth at moderate glyphosate doses, with pear being more sensitive than apple.

Technical Abstract: Glyphosate is commonly used for intra-row weed management in perennial plantations, where unintended crop exposure to this herbicide can cause growth reduction. The objective of this research was to analyze the initial plant growth behavior of young apple and pear plants exposed to glyphosate. Glyphosate was sprayed on 2-year-old ‘Gala’ apple and ‘Abbè Fetel’ pear plants at doses from 18 to 720 g per hectare of acid equivalent (ae). The plant height of neither species was not significantly reduced (less than 1%) by any glyphosate dose at 240 days after spraying, whereas the stem diameter and the dry mass of stem and leaves were reduced by 720 g ha-1 ae. The glyphosate dose required to reduce the aboveground dry mass by 50% was 162 and 148 g ha-1 ae for apple and pear, respectively. Aboveground dry mass was reduced 2% and 6% for apple and pear plants, respectively, at 720 g ha-1 ae. Hormesis was not observed in either species at doses down to 18 g ha-1 ae. Both species showed low susceptibility to glyphosate; however apple was less susceptible than pear.