CHICAGO — In this edition of Weekend Gardening, Tim Joyce dives into the mailbag to answer viewer questions about insects that eat rose leaves and how to properly use vinegar to get rid of pesky weeds.
Viewer email no. 1: Bugs eating Cathy's rose leaves
Kathy from DeKalb wrote to say that something is eating her rose leaves and she wanted to know if there is anything she can do to stop that.
Aphids are tiny, soft-bodied insects that normally feed on roses by boring holes into the plants and sucking the sweet sap, but the curled, browned leaves are probably the result of that, and they're not seen here.
Thrips — These are small winged insects that usually target rose flowers, especially the base of rose blossoms.
So, you're probably screwed again. Spider mites also love roses, but their attacks often cause the leaves to turn brown and curl. So no good.
So, what we're left with are caterpillars, specifically sawfly larvae, also known as rose slugs.
These green caterpillars nibble at the undersides of leaves, leaving tan spots and sometimes making the leaves look like bones, so this is probably the bad guy eating your rose bushes.
Luckily, there are some common solutions for these pests: Kill them with a strong stream of water from a hose or spray the plants with a mixture of neem oil, water, and a little dish soap. If they're caterpillars, in particular, you can remove them and rely on beneficial garden insects or natural enemies, like parasitic wasps or predatory beetles, to take care of them.
It helps if you regularly check the undersides of your rose bushes' leaves to repel invaders before they have a chance to fully develop, and clean up any garden debris under problem plants to ensure eggs don't lie dormant over winter and plague you next season.
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Viewer Email No. 2: Mary asks: How do I properly mix horticultural vinegar to kill weeds?
Viewer Mary wrote in that she brought gardening vinegar, which is stronger than kitchen vinegar, and would like to know how to make a solution to kill weeds, but doesn't know how to dilute the vinegar.
We get a lot of emails about how to use vinegar to kill weeds, but the good news is that you're already doing the first part right by purchasing horticultural vinegar.
Vinegar is quite watery, so mix 1 cup salt with 1 ounce of dish soap and apply the vinegar mixture to the plant.
Transfer the mixture into a clean plastic spray bottle and begin spraying.
Focus on the leaves, not the ground.
You may need to repeat this several times, every few days, over the next few weeks. This is not a magic pill, so keep your expectations low.
This solution works best for most young weeds, but for established weeds with taproots, like dandelions and thistles, you may be able to get away with simply pulling them out.
Viewer Email #3: Rick gives helpful tips about ivy growing on Chicago buildings
Viewer Rick Rose, who liked a story published earlier this month about ivy growing on buildings, said he wanted to point out that the study was done in a relatively warm climate with relatively new bricks, so it might not be entirely applicable to Chicagoland, where a lot of the brick around here is the older, softer variety.
Most importantly, moisture-induced freeze/thaw cycles are at work here, which can cause cracks to form and grow in masonry and road surfaces.
But for Rick of Rogers Park, it proved to be a costly lesson: The north side of his brick building doesn't get enough sunlight in the winter to dry it out during the day, so moisture built up and caused considerable damage to his home.
So, to paraphrase Rick, take Ivy's research with a pinch of salt.
If you have any gardening questions, we'd love to hear from you. Email us at the address below with a picture of your area and the plant you're having trouble with.
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