"What's making holes in my hosta leaves?"
by Fred Davis, MG, Hill Gardens of Maine, Palermo (To view other previous articles, click Archives)
Welcome through Our Garden Gate! Listen to this recent question from a Minnesota visitor to our web site: "What can you do when you have little holes in your hosta leaves? And also what eats the whole root and kills the plants?"
Actually, this is one of the most frequently-asked questions I hear, so I thought our readers and visitors might like to share in my response.
Holes in hosta leaves are most often produced by slugs, grasshoppers and certain caterpillar-like insects. Some types of leaf-cutter bees also take almost perfectly-round sections right out of the middle of leaves. Considering you're in Minnesota (climate and conditions not unlike ours), I'd guess yours are the result of slug or grasshopper feeding - the most common cause.
More than a few gardeners these days are leaning away from highly-toxic bug sprays - which I think is a wise course of action - and selecting equally-effective natural materials. Slug pellets are attractive to birds, small animals, household pets and small children (even cats who've lain on, or walked through, pellets later ingest poisons during their grooming process). Residues get into the soil, then into our food chain and water supplies. I don't use them...the potential consequences are too disturbing.
Slugs are physiologically acidic - powerfully acidic - and are repulsed by alkaline conditions. Oddly enough, hosta grow and perform at their maximum in alkaline soil...........so...........if the soil pH is adjusted (sweetened) to the point where hosta (and almost all other perennials as well) like it, the slugs will avoid that area. There are a couple of articles on this site that will expand on the subject: All You Need To Know About Hosta and Slugs & Snails (look in Archives for other articles).
Mice, shrews, moles, voles and gophers consider hosta crowns (roots) a particularly tasty treat, and will munch on them during any time of the year - but especially over winter, under the snow when other foods are scarce.
Cats - lots of them - can help. Tiny, furry munchers, however, multiply at prodigious rates. Once again, poisons are dangerous and can be a slow, prolonged and unpleasant death for even vermin to endure. Quick-kill traps are probably the best and most effective. Orient traps so the creature MUST approach the bait from the end....not the sides. A standard mouse trap can be baited with something like half-cashews (salted...they love salty food) and placed between two bricks to prevent side-access. (if they come in from the side, they're apt to be caught by a foot or leg, then suffer for hours before perishing from terror or exhaustion.)
As you might expect, I prefer a more humane approach. Today, a wide variety of live traps are on the market and, since these little creatures adapt quickly, they can be lured into no-pain traps and you can transport them into a more wild location away from your garden. A mile would work... but not around other dwellings. Be very cautious, however, because almost all have fleas (that could be carrying disease) and could possibly carry rabies. Up close they're "cute" but don't be tempted to directly handle them.
By the way, both vermin and slugs are apt to be present in HUGE numbers - even if you don't see them. Get yourself ready for an extended battle.
Nibblers and browsers can be discouraged as well (deer, woodchucks and rabbits relish the fresh, crispy hosta leaves). A very effective deterrent is detailed in the article "Repelling The Rascals" on the web site.
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