Association between Soil Acidity and Bacterial Wilt Occurrence in Potato Production in Ethiopia

Abstract

Soil acidity is one of the main constraints to crop production worldwide. In Ethiopia, the problem of soil acidity has been increasing. Currently, more than 40% of cultivated land in the country has a soil pH < 5.5. Recently, bacterial wilt (caused by Ralstonia solanacearum) has become a serious problem, reaching epidemic levels in some of the major potato growing districts in the country. However, it is currently unknown if the current outbreak of bacterial wilt in potato production is associated with soil acidification or not. To examine the association between bacterial wilt and soil acidification, we conducted a field survey and field experiments and detected and characterised R. solanacearum strains. The study showed that 50% of potato fields were very strongly acidic (pH 4.5–5.0) and bacterial wilt incidence was higher in potato fields with low soil pH. The field experiments indicated that lime application significantly increased soil pH (p < 0.001) and reduced bacterial wilt incidence (p < 0.001). The more lime was applied, the stronger the positive effect on soil pH and the stronger the reduction in bacterial wilt incidence. Bacterial wilt incidence was on average 10.8% under 12 t/ha lime application, while it was about 40% in control plots (without lime) after 90 days. All R. solanacearum strains isolated from the symptomatic potato plants were Phylotype II. Our findings show that the current outbreak of bacterial wilt in Ethiopia is associated with soil acidification. They add to the understanding of the risk factors for bacterial wilt in potato. Aside from farm hygiene, sanitation and cultural practices, addressing soil acidification using lime needs to be considered as an additional component of an integrated package to deal with bacterial wilt in potato under acidic soil conditions.

Potato bacterial wilt in Ethiopia: history, current status, and future perspectives

“…1 ) with more emphasis in central high lands where major seed potato is being distributed to the country ( Gorfu, Woldegiorgis & Kassa, 2013 ; Abdurahman et al, 2017 ; Sharma et al, 2018 , Tessema et al, 2020 ; 2022 ). The disease transmission was slow and not a plague too many potato farms at a time, so that no one gave due attention to the pathogen and by now it becomes a serious production threat for the farming community ( Gorfu, Woldegiorgis & Kassa, 2013 ; Sharma et al, 2018 ; Tafesse et al, 2021 ). The spread of the disease to different parts of the country was traced from latently infected seed tubers and currently the pathogen is serious constraint to more than 5 million potato farmers of Ethiopia ( CSA, 2018 ; Abdurahman et al, 2017 ).…”

“…Nyawade et al (2016) pointed out incorporating suitable indeterminate legume cover crops such as Dolichs lablab in potato cropping systems enabled to minimize soil and nutrient losses due to erosion. This in turn has effect on soil acidity, which has positive association with bacterial wilt prevalence in potato fields ( Tafesse et al, 2021 ). The study by Mwaniki et al (2017) indicated that rotations involving spring onion with the locally grown cereals such as barley and wheat could be utilized in curbing bacterial wilt in Kenya.…”

“…Though potato bacterial wilt is a soil-borne disease, the spread and prevalence as well as disease outbreak could be aggravated by many biotic and abiotic factors such as poor agricultural practices, unlimited animal and human movement to farming fields, lack of knowledge on appropriate field sanitation procedures, planting pathogen infected seed year after year, weak seed quarantine rules, soil acidity, and environmental variations ( Gorfu, Woldegiorgis & Kassa, 2013 ; Tafesse et al, 2021 ; Tessema et al, 2020 ; 2022 ). It was evidenced that environmental temperature also has direct effect on the success of pathogen invasion to varying host species ( Wei et al, 2015 ).…”

Application and mechanisms of metal‐based nanoparticles in the control of bacterial and fungal crop diseases

“…is a worldwide plant disease that causes serious damage to important cash crops such as tomatoes and potatoes. 4,5 Nowadays, the means to control crop diseases caused by fungi and bacteria mainly include breeding resistant varieties, using chemical pesticides or improving field management measures. Often the breeding of resistant varieties takes a long time, while the use of chemical pesticides is effective but has caused bacterial resistance, environmental contamination, and ecological and human safety problems.…”

“…Bacterial wilt caused by the bacterium Ralstonia spp. is a worldwide plant disease that causes serious damage to important cash crops such as tomatoes and potatoes 4,5 . Nowadays, the means to control crop diseases caused by fungi and bacteria mainly include breeding resistant varieties, using chemical pesticides or improving field management measures.…”