The influence of timing the application of nitrogen fertilizer on early blight (Alternaria solani).

Background: Field experiments were carried out in 2016 and 2017 to study the influence of timing the application of nitrogen fertilizer (N-fertilizer) on the susceptibility of potatoes to early blight. We hypothesized that potatoes that receive N-fertilizer as split applications or a one-time application at emergence will have a higher N content and be less susceptible to early blight than those that receive N-fertilizer as a one-time application before planting. N-fertilizer was applied either as a one-time application before planting or at emergence and as split applications.
Results: Potatoes that did not receive N-fertilizer were more susceptible to early blight [high area under the disease progress curve (AUDPC)] than those that did receive N-fertilizer (low AUDPC). The timing of N-fertilizer application had a significant effect on the susceptibility of potatoes to early blight. Potatoes that received the entire quantity of N-fertilizer at emergence or as split applications had higher N contents and were less susceptible to early blight than those that received the entire quantity of N-fertilizer before planting. Potatoes that did not receive N-fertilizer had a markedly lower starch yield than potatoes that received N-fertilizer. Potatoes that received the entire quantity of N-fertilizer before planting had a lower starch yield than potatoes that received the entire quantity of N-fertilizer at emergence or as split applications.
Conclusion: N-fertilizer applied as a one-time application at emergence or as a split application was the best treatment to ensure both high N content and lower attack of early blight, which confirms our hypothesis. © 2018 Society of Chemical Industry.
(© 2018 Society of Chemical Industry.)