Rust spots on hosta

[Quiet Storm]

Hi everyone,

This is the second year I have had my 'Christmas Tree' hosta, and the second year that it has developed tiny holes in the center of the leaves late in the season. The holes have rust-colored borders (the leaves actually look like they've been spattered with rust colored paint), and the leaves eventually die. Last year it was just Christmas Tree that developed this malady; this year Abiqua Drinking Gourd and a few others have it as well. Drinking Gourd is in the same bed as Christmas Tree, but the others are in different parts of my garden. I will try to post a photo tomorrow, but in the meantime, does this sound familiar to anyone?

Thanks

[Chris_W]

Hi Gloria,

I'll be looking forward to the pictures, but it almost sounds like a fungus problem, maybe some slug or insect damage that went on to get fungus damage. If the problem appears to be spreading I would recommend removing all of the leaves this fall and throwing them away. Don't let them overwinter in the garden where fungus spores can remain and spread next year. Next summer you might consider spraying with a broad spectrum fungicide like Daconil in mid to late summer, before the spots start.

As our hostas get larger and the gardens get fuller the leaves and soil will hold more moisture and create conditions that are ripe for different fungus problems, so that's sort of what I'm thinking here. Still, I wouldn't mind checking out pictures as the second thought is insect damage. The four lined plant bug seems to be getting more and more prevalent, and they can cause little round holes that can turn brown later. These will lay eggs on the hosta leaves and return in the same general spots year after year, so if that is the case an insecticide sprayed in late spring/early summer might be better, but I would still clean up the leaves this fall after they have taken a frost.

Chris

[Quiet Storm]

Thanks Chris,

I will try to post photos tomorrow.

Take care,
G.

[ViolaAnn]

Chris, do you have a picture of the "four lined plant bug"? I don't think I've ever seen it, but it would be good to know what to look for.

Ann

[Quiet Storm]

Here are the photos, I hope. I haven't posted photos in a good while, so hopefully I've done it correctly.

This is what is left of Christmas Tree:



This is Abiqua Drinking Gourd:

[Chris_W]

Hi Gloria,

That clears it up completely. You simply have slugs. They are creating all of the holes in your hostas, plus on Christmas Tree they are eating the petioles, causing the leaves to brown badly since not enough water/nutrients are able to get up the damaged stems to the leaves.

Work on controlling the slugs and you shouldn't have this trouble next year.

Thanks for adding the pictures.

Chris

[Quiet Storm]

Thanks a million Chris. We had such a cold and wet spring/summer, that the slugs just proliferated like you wouldn't believe. They are everywhere. I just haven't been able to keep up with them. I am glad that's all this is.

Deadline has worked well for me on slugs, but it can't be purchased in MA anymore, and I haven't been able to find my stash since we had renovations done to my storage area last fall. Iron phosphate works less well for me, but I may have to use that if I can't find my Deadline

Take care,

G.

[ViolaAnn]

I've had quite good success using a 1:10 or up to 1:20 mixture of ammonia and water. I drench the base of the plants, especially just as the new shoots are emerging. I also try to remove ground covers that can harbour the slugs. But even so, in this wet year, the slugs have had a field day on some of the more susceptible plants.

[Quiet Storm]

Hi,

I had noticed that the plants with the most damage are those in the part of the garden that has a thick stand of pachysandra for groundcover. I think I even see a slug in one of the pictures I posted. I am reluctant to remove the pachysandra, as it does an excellent job of choking out weeds, so I will start early in the season with my slug control efforts.

Thanks,
G.