Knowledgebase

Problem on leaves of my high-bush cranberry shrub #798644

Asked June 29, 2022, 4:44 PM EDT

The shrub seems healthy early in the year and was covered in blooms in the spring, but now (and also last year) the leaves have lots of light colored speckles, which on some leaves become darker brown and some have holes. On the underside of the leaves there are also tiny black speckles. Is this an insect infestation? Is it mostly unsightly, or is it going to kill the shrub eventually? (And, is there anything I can do about it?) I mostly garden organically...

Hennepin County Minnesota

Expert Response

 The present damage may be caused by four lined plant bug. Fourlined plant bug nymphs are small with developing wings. When they first hatch, they are bright red and have black wing pads and black dots on their abdomen. As the grow, nymphs are reddish orange, and the wing pads are larger with a light colored stripe on each. Fourlined plant bugs adults are greenish yellow with four black stripes running down the wings. They are about ¼ - 1/3 inch long.  Fourlined plant bug feeding usually only affects the appearance of plants. Insecticidal soap can be effective against fourlined plant bug nymph nymphs (less so against adults). Pyrethrins can also be effective. Both products must directly contact the insects to kill them. Neither product has any residual activity so repeat treatments may be needed. Insecticidal soap and pyrethrin are generally low risk to beneficial insects. https://extension.umn.edu/yard-and-garden-insects/four-lined-plant-bugs Viburnum beetle is an emerging problem for viburnum growers. Please look out for this beetle in the future. https://www.mda.state.mn.us/plants-insects/viburnum-leaf-beetle https://blog-yard-garden news.extension.umn.edu/2019/07/viburnum-leaf-beetles-now-in-minnesota.html

Pat Mack Replied June 29, 2022, 6:04 PM EDT

Loading ...