Roses still not doing well

Asked July 11, 2017, 12:36 PM EDT

1)I have 4 rose bushes and had asked for advice about 1 month ago. Applied spinosad as advised, then some copper fungicide. These pictures show the latest - with white stringy fibers on them. What do you suggest I do? 2) Also I have many cosmos plants and want to share the seeds with neighbor. When should she plant them and can she put them in regular soil first, or do they need to go in pots? Thanks so much.

Allegany County Maryland shrubs roses cosmos

1 Response

Roses are difficult to grow in our area as they are susceptible to disease and some pest issues such as black spot, powdery mildew, rose rosette, and rose slugs. You did not mention what type of roses you have. Knockout roses are susceptible to the same issues as hybrid tea roses.

The photo on the left shows planthoppers on the stem. They are sucking insects but cause little damage. You can leave them be or hose off with a forceful stream of water. No control is necessary. See our website http://extension.umd.edu/hgic/planthoppers-flowers

Middle photo shows old damage from rose slugs. Monitor your plants for signs of these pests. http://extension.umd.edu/hgic/rose-slugs-shrubs

Right photo shows planthoppers and we notice some black spots on the stem. We cannot say what the black spots are for sure. Prune back to healthy tissue on the stem. Monitor the health of the plants.

You may want to look at our rose publication for general information and care http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/non_HGIC_FS/EB164.pd...
http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG108_Pruning_roses.... and view the website of the American Rose Society
http://www.rose.org/rose-care-articles/

You can plant the cosmos seed this fall directly in the ground in a well drained soil. Mark the area and look for growth in the spring after the last frost. Or you can store the seed and plant in the spring after the last frost.
mh