My black-eyed Susans have roundish spots on the leaves. How can I prevent this?
Septoria is one of several fungal leaf spot disease possibilities. It appears as roundish spots with a lighter gray center. The easiest approach is to pull off infected leaves as soon as you spot them. Thin plants for good air circulation. Remove excess volunteers and divide crowded plants in the fall. Avoid overhead watering. A sulfur fungicide will help control infection. Like most fungicides, it does not cure current infection but works to prevent new infection.
I found black beetles with orange-yellow speckles on my Brussels sprouts, mating and laying eggs. I ripped out the Brussels sprouts and threw them away, but they're still on my kale and collards. What else can I do?
Harlequin bugs are a type of stinkbug that commonly feed on members of the mustard family (e.g. cabbage, broccoli, radishes). There are 2-3 generations each summer. Look under leaves and destroy egg masses which look like rows of tiny black and white striped barrels. Nymphs can be controlled with insecticidal soap, pyrethrum, rotenone or neem. Adults overwinter in plant debris, so it's important to remove spent plants. Use floating row cover to exclude this pest.
University of Maryland Extension's Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click "Ask Maryland's Gardening Experts" to send questions and photos.
Newly hatched, bright red and rather cute, assassin bug nymphs don't hint at the lethal chaos they will bring to insect pests in your garden. As they mature, nymphs progress through several instar stages, becoming somewhat elongate adults of varying color and pattern. There are many species of assassin bugs. A common one in Maryland is the wheelbug, dark gray with what appears to be a spoked wheel in its back. All are ambush predators known for their long proboscis (beak or mouthpart) which they stab into prey. Injecting enzymes, they liquefy their victim's insides. How satisfying to spy an assassin bug impaling a stinkbug or Japanese beetle in their grasp! Protect these predator insects by avoiding pesticides. Beware: That proboscis of theirs can leave a painful nip. In the photo, a chain of assassin bug eggs are at left. See more about assassin bugs on the HGIC website.