Reducing the risk of onion bacterial diseases: A review of cultural management strategies

Abstract

Onion (Allium cepa L.) bacterial diseases can cause catastrophic crop losses. Chemical and biological control products are not curative and have mixed or limited efficacy at preventing onion bacterial diseases. Cultural management strategies, such as appropriate irrigation and nitrogen (N) management practices, can reduce the risk for bacterial infection and disease progression. This review synthesizes available literature on cultural management strategies to mitigate onion bacterial diseases and identifies knowledge gaps, promising strategies, and limitations. This synthesis revealed that high N fertilizer application rates, the use of overhead irrigation, and late‐season irrigation or rainfall, especially during field curing, can increase bacterial disease pressure. These factors contribute to conducive conditions for bacteria to colonize the foliage and neck of onion plants. Other in‐season strategies, such as reducing the total amount of irrigation or adjusting application rates of nutrients other than N, have not limited losses to bacterial bulb rots while maintaining desired yields. At the end of the growing season, appropriate timing of lifting bulbs (undercutting to sever the roots) and other practices that speed field curing can reduce the risk of bacterial bulb rots. However, it is less clear if topping (removing foliage) before or after curing influences bacterial bulb rots. Conflicting results reported for some cultural management strategies indicate that local conditions, such as climate and soil types, must be considered for optimizing practices to manage onion bacterial diseases. Advancing our scientific understanding and grower awareness of strategies that reduce onion bacterial diseases is a cost‐effective opportunity to avoid losses.

Complete Issue

“…Losses of more than 50% of production due to onion bacterial diseases have been documented under conditions that favor disease development. Given the value of this production, the magnitude of the threat, and the lack of a curative chemical control option, an integrated approach is needed that emphasizes multiple preventative cultural management strategies to reduce the risk posed by onion bacterial diseases, as highlighted in a recent review article in Agronomy Journal (Belo et al, 2023).…”

Cultural Management Strategies to Reduce the Risk of Onion Bacterial Diseases

“…Losses of more than 50% of production due to onion bacterial diseases have been documented under conditions that favor disease development. Given the value of this production, the magnitude of the threat, and the lack of a curative chemical control option, an integrated approach is needed that emphasizes multiple preventative cultural management strategies to reduce the risk posed by onion bacterial diseases, as highlighted in a recent review article in Agronomy Journal (Belo et al., 2023).…”

“…Local strains of Burkholderia gladioli pv. allicola (causal agent of slippery skin) and Pantoea agglomerans (causal agent of center rot and bacterial leaf blight) were applied to onions in inoculated plots at approximately 5 and 50% tops down to increase bacterial disease pressure (Belo et al., 2021, 2023).…”

Thiosulfinate tolerance gene clusters are common features ofBurkholderiaonion pathogens

“…Onion ( Allium cepa L.) production industry, valued at US $1 billion is a major contributor to the USA economy (Belo et al, 2023). Bacterial pathogens can infect onions at different stages of production from seedling to storage posing a serious challenge to growers (Mark et al, 2002; Zhao et al, 2022).…”

“…Bacterial pathogens can infect onions at different stages of production from seedling to storage posing a serious challenge to growers (Mark et al, 2002; Zhao et al, 2022). Upon conducive environmental conditions, bacterial pathogens can cause more than 50% losses in production (Belo et al, 2023). Members in the Burkholderia genus are historically associated with onion disease with its first report dating back to 1940s (Burkholder, 1942).…”