Severity of Xanthomonas axonopodis leaf blight on eucalypt cuttings under different levels of nutrients

Abstract

Summary Bacterial leaf blight of eucalypt, caused by Xanthomonas axonopodis, occurs mainly in forest nurseries, but also affects young plants in the field. Avoidance of leaf wetness for long periods of time over the whole nursery and using drip irrigation for clonal hedges are, currently, the most effective measures for controlling bacterial leaf blight on eucalypt. However, as these techniques are very costly, alternative management measures are required. We hypothesized that the management of mineral nutrients could reduce disease severity on eucalypts. To examine this hypothesis, rooted cuttings of Eucalyptus urophylla × E. grandis were irrigated with nutrient solutions containing different concentrations of copper (Cu), boron (Bo), potassium (K), calcium (Ca) and nitrogen (N) before inoculation with X. axonopodis 30 days after starting the nutrient solution treatments. Concentration of K higher than that recommended, commonly used in miniclonal hedges, reduced the severity of bacterial leaf blight. However, disease severity increased with an increasing of N/K ratio. The management of mineral nutrition solution, especially K, has great potential for integrated disease management of X. axonopodis in eucalypt nurseries.

Phosphorus, nitrogen and potassium nutrition on Calonectria leaf blight in eucalypt plants

“…In addition, lower SLA was observed at low N/K ratios. This is similar to Silva, Machado, Barros, Fonseca, and Alfenas (2018), who reported a prior to reduction of bacterial leaf spots caused by Xanthonomas axonopodis in eucalypt plants with increasing doses of K and the reduction of the N/K ratio. According to the authors, the reduction may be due to the improved stomatal control through which bacterial penetration occurs.…”

“…This is similar to Silva, Machado, Barros, Fonseca, and Alfenas (2018), who reported a prior to reduction of bacterial leaf spots caused by…”