Fungicide seed treatment effects on seed-borne ascochyta rabiei in chickpea

A chickpea (Cicer arietinum) seedlot, naturally infected with Ascochyta rabiei, was sorted into two lots of asymptomatic and symptomatic, based on visual symptoms observed. A laboratory assay showed 16% A. rabiei infection in asymptomatic seeds, while symptomatic seeds had 73% infection. Asymptomatic and symptomatic seeds were treated with different fungicides to determine their effects on seedling emergence from soil and on ascochyta blight development in seedlings grown in a growth chamber and in the field at Fargo and Carrington, ND, in 2006. The emergence of seedlings grown from asymptomatic seeds was significantly (P < 0.05) greater than the emergence of seedlings grown from symptomatic seeds in the growth chamber and field trials. Fungicides were able to increase plant emergence from symptomatic seeds when compared with a control in the growth chamber trials. In the growth chamber trials, the treatment with a mixture of metalaxyl + thiabendazole + ipconazole + azoxystrobin was the most effective at slowing the development of disease on plants from symptomatic seeds. This research reinforces the importance of seed health testing and fungicide seed treatments as part of an ascochyta blight management program.