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Optimal rates of 2,4-dichlophenoxyacetic acid foliar application for control of common scab in potato

journal contribution
posted on 2023-05-18, 02:51 authored by Thompson, HK, Robert TeggRobert Tegg, Stephen CorkreyStephen Corkrey, Calum WilsonCalum Wilson
Applications of the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) to the foliage of potato plants can reduce common scab, a tuber disease. However, in prior research effective applications at 200 mg L−1 2,4-D resulted in phytotoxic side effects with reduced tuber yield and quality. This study showed that minimal significant threshold rates from 8.3 to 23.6 mg L−1 2,4-D reduced disease incidence in pot trials, and from 10.8 to 41.0 mg L−1 minimised disease severity in both pot and field trials. In only one pot trial, significant phytotoxicity was found with rates of 100 mg L−1 or greater, reducing mean total tuber mass per plot and 38 mg L−1 or greater, reducing mean mass per tuber. Notably, within the field trial, a more reliable plant growth system for estimation of yield, no significant impacts were observed. Disease control was associated with decreased sensitivity of tubers to thaxtomin A, the phytotoxin produced by the common scab pathogen essential for disease induction. The amount of residual 2,4-D in tubers at harvest varied with cultivar, Russet Burbank accumulating more 2,4-D than Desiree. Application rates less than 100 mg L−1 resulted in levels of 2,4-D below the Australian standard maximum residue limit. These data suggest that applications of 2,4-D at low rates could provide a commercially suitable control strategy for common scab.

Funding

Horticulture Innovation Australia

History

Publication title

Annals of Applied Biology

Volume

165

Pagination

293-302

ISSN

0003-4746

Department/School

Tasmanian Institute of Agriculture (TIA)

Publisher

Assoc Applied Biologists

Place of publication

C/O Horticulture Research Int Wellsbourne, Warwick, England, Cv35 9Ef

Rights statement

Copyright 2014 Association of Applied Biologists

Repository Status

  • Restricted

Socio-economic Objectives

Field grown vegetable crops

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    University Of Tasmania

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