The influence of nitrogen and calcium fertilizers on septoria late blight and yield of celery.

Tesfaendrias, M.T., Truman, C., Gossen, B.D., McKeown, A.W., and McDonald, M.R. (2014). "The influence of nitrogen and calcium fertilizers on septoria late blight and yield of celery.", Canadian Journal of Plant Science, 94(8), pp. 1391-1399.

Abstract

Late blight (Septoria apiicola) reduces both yield and quality of fresh market and processing celery. Field trials were conducted over 4 site-years to evaluate the effect of nitrogen (N) rate and foliar calcium (Ca) fertilization on the development of late blight and yield on celery grown on muck soils, which have a high organic matter (OM) content. A treatment with the protectant fungicide chlorothalonil was included to determine if fertilizer could replace fungicide application in celery production. There was a cultivar×site-year interaction for each of the disease and yield variables. Repeated application of chlorothalonil fungicide reduced late blight and generally increased plant height, weight and marketable yield. The rate of N applied had a small effect on late blight, which varied among site-years. Area under the disease progress curve decreased with increasing rate of N at both sites in 2008. Similarly, an increasing rate of N resulted in an increase in yield in one of four site-years. Application of Ca did not affect late blight severity and increased yield in only 1 site-year. There was a negative correlation between late blight severity and yield. Tissue N concentrations varied among the treatments at sites with a relatively low OM content, but not at the high OM sites. The treatments had no effect on Ca tissue concentrations. Application of N and Ca alone did not adequately control late blight, but there was a slight reduction in late blight severity with increasing rates of N. Application of both N and Ca can improve yield and also contribute indirectly to improved late blight management in combination with fungicides and other integrated crop management practices.

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