Ascochyta Blight of Chickpea: Wild Pest Wednesday

Ascochyta blight (Ascochyta rabiei) is the most problematic disease of chickpea. This species of Ascochyta is specific to chickpea and is much more aggressive than it's cousins that infect dry pea and lentil (Ascochyta pisi and Ascochyta lentis, respectively).

First signs of Ascochyta blight show up as gray areas, that will quickly turn to brown lesions with dark borders (photo above). As this disease progresses dark rings within the lesions will begin to appear, arranged in concentric circles that give this disease it's most diagnostic characteristic. Wet cool weather (59 to 77 F) favor the development of this disease, while hot dry weather can stop the progression of the disease in it's tracks.

Management of Ascochyta starts with picking a moderately resistant variety. Furthermore, making sure the field you're planting hasn't had chickpeas on it in the last three years. Testing your seed for seed-borne Ascochyta is also critical. Infection levels on seed should be less than 1%, and an effective seed treatment like Obvius or Obvius Plus is essential. Once this disease is established, it can be extremely difficult to manage. Fungicides are also necessary and should be applied at or before flowering regardless if disease is present. Most Ascochyta in Montana and North Dakota is resistant to group 11 fungicides which leaves us with group 7 and group 3 like Priaxor and Provysol. There are also protectant fungicides like chlorothalonil that can be utilized, but we recommend they be used as a tank-mix partner with the aforementioned (7 & 3) FRAC groups. Rotate Provysol at 3 fl oz with Priaxor at 6 fl oz as disease persists.