Q&A: Dealing with rose black spot and sod webworm

In the Garden

Q: My roses are looking diseased and lots of leaves are falling off. Will cutting back now help to make them attractive again?

A: This wet spring has made roses highly susceptible to black spot. This is a fungus disease that begins with spotted leaves that soon turn yellow. In severe infestations most of the leaves fall off, leaving the shrub bare and unsightly.

It cant hurt to cut the rose back by a third. Hopefully that will stimulate the buds at nodes just below the cut to put out new growth. Feed your rose with a mix of alfalfa meal and organic rose food. Make sure your rose has adequate water, but use care not to wet new leaves or they will likely become infected with black spot as well.

As a precaution, spray the new growth weekly during rainy weather with environmentally friendly neem oil, available at nurseries and garden centers. If all goes well, the leaves will grow back and your rose will put on a nice display of blooms by fall.

Consider replacing your susceptible variety with a Knock Out rose. These roses are tested and only those varieties that are highly resistant ever reach the market. They lack fragrance, but they make up for it with attractive disease-free foliage and practically nonstop flowering all summer long.

Q: Ive noticed swarms of little moths hovering over my lawn and lots of small brown, dead spots are appearing. Are the two related?

A: There are a lot of possible causes for brown spots in a lawn, but the fact that youve noticed numerous moths above the lawn makes it likely that your lawn is infested with sod webworm.

The troublemakers are the offspring of the moths, -t o 1-inch-long caterpillars that hide in silken tunnels during the day and then come out at night to chew grass blades off at the base.

Just to be sure webworms are causing the damage, examine the grass. If you see silken tunnels and green frass (polite word for pelletlike bug poop) your lawn has a sod-webworm infestation.

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Q&A: Dealing with rose black spot and sod webworm