Looks like iron chlorosis.
Here is an older posting that talks about it. Have you had unusually wet weather and is you soil quite clayey?
Try googling iron chlorosis, you'll get lots of information on what to do about it. I have been fortunate to not have had this problem yet. With the excess of rain we have endured, I've got botyris on a few lilies instead.
Flora

Here is a link that might be useful: Yellowing asiatic liliy leaves

Thanks, Flora2b,
I read the post, and will google iron chlorosis.
Yes we had wet weather, not unusual here though. As for the soil, I think it's clayey, I am not sure.

yes, it does look like iron chlorosis.

Bagged iron supplements are often expensive. Miracid by Miracle Gro contains iron and is a quick and easy way to fix this. IF you still see problems after using it, try epsom salts for their magnesium. Not sure of the correct ratio.

Here is a link that might be useful: Miracid

Thanks buyorsell, I will try Miracid. I told my husband about epsom salts, and he was sceptical.

Epsom salts are magnesium sulfate and have been applied to plants for years.

Here is a link that might be useful: epsom salts

Thanks Buyorsell888,
Miracid turned out to be hard to find! I haven't checked Home Depot yet.
Meanwhile the lily started blooming.
Muscadet
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