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I am growing aquadulce fava bean plants and something is eating holes into the leaves. At first i thought this was caused by slugs but when i look closely i can actually see that the holes are preceded by necrotic black spots.

This must be caused by either a bacterium or by a fungus. The problem is, i don't know which one is exactly causing these spots (and eventually holes) to form. I live in the netherlands and i've sown the fava beans in autumn. All of the fava bean plants are still very young (seedlings) and the climate is very cold and wet, with the temperature averaging between 7 to 15 degrees celcius or so. I've read that the disease Ascochyta occurs in environments with prolonged wet and cool conditions and that it also develops early in the growing season. The problem is that the marks that ascochyta leaves don't have the same color as the marks that are on my plants.

It could also be botrytis fabae (chocolate spot disease). What do you guys think? Below are some photo's.

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EDIT: Here are some more pictures that show both the dark spots as the development of those spots into lesions/holes.

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  • @PolypipeWrangler the disease you mention doesn't seem to eat holes through leaves, and i don't see any black spots either. My guess is that its Cercospora leaf spot. This disease thrives at higher temperatures but can also be seen at colder wet temperatures. But i'm not 100% sure
    – Maurice
    Nov 5 '20 at 9:57
  • This resource has pictures of fava bean diseases from page 14. grdc.com.au/__data/assets/pdf_file/0030/369147/… Nov 5 '20 at 10:06
  • More photos as the spots develop please, I dont see fungal fruiting bodies inside the spots yet Nov 5 '20 at 10:08
  • It is so cold where you are - little fungal disease expected. Perhaps early symptoms of rust. Nov 5 '20 at 10:09
  • @PolypipeWrangler please see my new pictures. I think it could be Cercospora leaf spot. The disease is explained here: communities.grdc.com.au/field-crop-diseases/… What do you think?
    – Maurice
    Nov 5 '20 at 23:28

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