My beautiful Jack Frost brunneras are being attacked by something chewing perfectly round holes in the upper leaves. I've used slug pellets, egg shells, and Neem oil, but the number of holes keep increasing. We've had very dry weather until yesterday, so I haven't seen earwigs. What else should I be looking for, and what else should I consider in preventing further damage?
Holes in Jack Frost brunnera
If the holes are perfectly round, it could be leafcutter bees. If so, they are beneficial and I'd leave them alone. They are only active for a brief period of time (they use the leaf cuttings to build nests) and once those are built they'll leave your plants alone and there's no long-term damage.
How big are the holes? If small then it may be flea beetles. Leafcutter bees make fairly large holes.
The holes vary in size between 1/8 and 3/8 inch. A few are a little more oval, but the majority are round. None are at the edges of the leaves; they're all in the middle. I thought leaf-cutter bees tended to chew along the perimeters.
Can you post some pictures? Leafcutter bees do tend to chew along the perimeters, although I've seen some holes in the middle of leaves too. Usually those are in addition to the perimeter holes though, not instead of. The holes sound on the big side to be flea beetles.
Flea beetle damage: http://www.google.com/search?tbm=isch&hl=en&source=hp&biw=1439&bih=665&q=flea+beetle+damage&gbv=2&oq=flea+beetle+damage&aq=f&aqi=g10&aql=&gs_l=img.3..0l10.274.3257.0.32220.127.116.11.18.104.22.168.746.2j5.7.0...0.0.9LKM9wQbEko
Leafcutter bees: http://www.google.com/search?tbm=isch&hl=en&source=hp&biw=1439&bih=665&q=flea+beetle+damage&gbv=2&oq=flea+beetle+damage&aq=f&aqi=g10&aql=&gs_l=img.3..0l10.274.3257.0.3222.214.171.124.126.96.36.199.746.2j5.7.0...0.0.9LKM9wQbEko#hl=en&gbv=2&tbm=isch&sa=X&ei=BcDLT9bkC4fO2wXzgtDZCw&ved=0CAQQBSgA&q=leaf+cutter+bee+damage&spell=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=bcfcaa549a6ae13a&biw=1439&bih=665
Here are some photos of the leaf damage. Some of the holes have been chewed further out and are now irregular. It seems as if every day brings new damage. I see nothing under the leaves or at night at the base of the plants, such as slugs. In fact the leaves underneath look much better than the ones on top.
You can definitely rule out the leafcutter bees, their holes are always perfectly circular and these definitely aren't.
So what could it be? I'm tempted to cut the plants down to basal shoots and start from scratch.
I wouldn't do something that drastic. Plants' leaves are rarely going to look perfect, and while it would be nice if you could figure out what's doing this and get rid of it, it doesn't look like it's about to kill the plant so I definitely wouldn't do something that extreme. Plus if you do that and it regrows new leaves, chances are whatever the pest is will still be around and will chew some holes in the new leaves too.
OK. Good point. I've doused the soil with a systemic, clipped off the worst of the leaves, and will see what happens. I've only seen this on the brunnera...no other plants...and can't imagine what is causing the damage. Very frustrating.
My brunnera leaves have holes that look exactly the same as those in your photos. Has your plant recovered? Any recommendations based on your experience?
Try going out at night with a flashlight.
Many pests hide in the soil or under the leaves at night.
Haven't been back here since long before Christmas, so I'm sorry I didn't see your question and respond. My brunnera never truly recovered from the leaf-hole onslaught. But when we finally got some cold weather and the leaves turned black and shriveled up, I cut them all off. Then I sprinkled slug bait everywhere and mulched the plants with about 2" of finely ground, dried leaves. I'll wait to see what happens in the spring. We've had another strange winter--not nearly as warm as last year--so I hope that whatever caused the holes has now been permanently popsicled.