What is causing these hostas to look diseased?

9 years ago

last modified: 9 years ago

These hostas are all in the same flower bed: eastern exposure (morning sun), ample moisture, treated for slugs, zone 6b (Northern NJ), last frost in early April. This has continued to be an issue for several years. Initially we assumed these were sunburned until we found slugs frequented the bed. However we have never seen a slug on/under a hosta. We treated for slugs but the holes continue to eat away the leaves. Is it just sunburn causing the damage? Any thoughts on the cause and other actions we should take?

Even with spotty leaves, we've found that hostas are the best plants for these beds. The beds are there so people don't walk into open-out windows at head level. If it does appear to be sun damage, then we will live with parts of them looking unsightly.

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don_in_colorado

9 years ago

I could be wrong, but it looks like they aren't being watered enough. The soil I can see in the bed looks quite dry.

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Comments (8)

Marisa
Original Author
9 years ago
Soil is very moist after several days of rain, but I'm looking up rain gauge data to see if they could use additional water. Did some gardening this morning and other parts of the yard were moist up to a foot deep.
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ken_adrian Adrian MI cold Z5
9 years ago
where are you .. z6 is about half the US ...

was there a frost a week or so back ...

we need to look beyond secondary issues... to what caused the first problem

you are looking for slugs at night.. right .... and how did you treat.. before or after rains.. etc ....

ken
Marisa
Original Author
9 years ago
last modified: 9 years ago
I'm sorry for the ambiguity, Ken! Zone 6b, northern NJ. Our last frost was in early April.

No sign of slugs on/beneath hostas, specifically, however slugs are often in the soil, day and night. Treated using pellets after rain several times last summer and this spring with no difference in appearance.

Should mention that this has been a problem year after year.
MadPlanter1 zone 5
9 years ago
Can't be sure from photos, but I have three that have expanded into full sun, and they get that kind of damage on their sunny side no matter how much water they get. On the plus side, they seem to enjoy the extra light and get bigger every year. Maybe you can try some sun tolerant hostas. Dancing Queen, Squash Casserole, Night Before Christmas and Aphrodite do ok.

I'm not at all sure about it being sun damage. Morning sun shouldn't fry hostas.
Babka NorCal 9b
9 years ago
The holes look like bug damage to me. Might be slugs, earwigs, little green. Caterpillars or some other little critter. Snail bait needs to be put out again and again and again when you can no longer see the pellets. Sluggo Plus will help with slugs and earwigs, but not the tiny little almost imperceptible little green caterpillars. Capt. Jack's Bug Brew ( Spinosad in liquid form ) sprayed on the tops and bottoms of the leaves will get those. Best plan is to discover which creature is gobbling before you treat them. Look for some fresh damage and start looking at the backsides of the leaves.

God luck sleuthing!

-Babka
tsugajunkie z5 SE WI ♱
9 years ago
I think there are multiple insect/mollusk issues and, from what you said, I doubt sun or lack of water are involved. Cutworms and slugs seem prime suspects so check at night and poke a bit in the soil to see if you can hunt them down.

tj
ken_adrian Adrian MI cold Z5
9 years ago
to be clear.. i see no sigh of disease ... per your title ...

ken