Case study of agricultural adaptation for the climate change impact on crop diseases in Taiwan – integrated management of Welsh onion Phytophthora blight induced by heavy rainfall

Climate change has led to a significant increase in the frequency of extreme weather events.
In Taiwan, the frequency of heavy rainfall has increased significantly, and has caused various crop diseases; most of them were caused by Phytophthora spp.
In recent years, Phytophthora blight of Welsh onion caused by P. nicotianae resulted in severe yield loss after heavy rainfall in Taiwan.
The causal pathogens could cause stem rot and/or leaf blight.
Pathogens from suckers and in field soil are the most important inoculum sources.
Several fungicides and low-risk materials with control potential had been screened by pot cultivation tests in the greenhouse.
Field trial results show that the regular application of phosphite weeks before the rainy season or the precise application of fungicides before and during the rainy season could significantly reduce the disease severity of Welsh onion Phytophthora blight.
Furthermore, applying healthy suckers plus chemicals usage mentioned above could greatly reduce disease severity and reduce the yield loss of Welsh onion caused by the disease.

XXXI International Horticultural Congress (IHC2022): International Symposium on Sustainable Control of Pests and Diseases

J.-H. Huang, C.-Y. Yuan

Allium fistulosum, Phytophthora nicotianae, Oomycetes, flooding, leaf blight, stem rot, root rot, integrated control

https://doi.org/10.17660/ActaHortic.2023.1378.32