Foliar treatment of 2,4-dichlorophenoxyacetic acid for control of common scab in potato have beneficial effects on powdery scab control

Prior studies have shown that applications of the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) to the foliage of potato plants can reduce common scab.Here field and glasshouse trials suggest that 2,4-D foliar treatmentsmay also reduce the biologically distinct tuber disease, powdery scab. Significant correlations between suppression of common and powdery scab fromthe field trials suggested an interaction between the two diseases or possible additional broad spectrummechanisms of enhanced defence against pathogen invasion provided by 2,4-D treatment.