Answer: Lots of things can cause brown spots on hosta leaves. If the spots are tan to brown and random, the cause is a fungal leaf spot disease. Remove severely infected leaves and try to keep water off the foliage. Spots that are brown and clustered are caused by the Four-lined plant bug. Anthracnose Leaf spots expand down leaf veins and infect the petioles. Use a handlens identify black fruiting bodies in lesion to confirm diagnosis. If there are dead areas between veins, suspect foliar nematodes.
And, if the leaves are scorched, it indicates insufficient water or too much sun.
Hope this information helps you determine just what might be causing the leaf spots on your hostas.
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