Is this what is feasting on my Knockout Roses? - Ask Extension
The leaves on all of my Knockout roses are getting "lacey" from an unknown (to me) attacker. All I can see are a few of these tiny little white bugs o...
Knowledgebase
Is this what is feasting on my Knockout Roses? #136835
Asked June 25, 2013, 7:18 PM EDT
The leaves on all of my Knockout roses are getting "lacey" from an unknown (to me) attacker. All I can see are a few of these tiny little white bugs on the underside. In a section of about 40 leaves, I can see 4 of them. Are they causing the damage? It only affects the leaves, the blooms are undamaged. I have dogs, so I'm looking for a non-toxic treatment to rid the plants of this, or whatever, pest that is attacking them.
Alexandria County Virginia
Expert Response
The insect on your rose foliage looks like a plant/leafhopper and is not responsible for the damage to the rose foliage. Most likely the damage is caused by an insect called a rose slug. Look
for these insects which resemble tiny green caterpillars but are the larvae of a
sawfly on the underside of the foliage during the growing season.
You can treat with either a systemic insecticide (a once a year
application is sufficient and is not organic) or spray, targeting the underside of the
foliage, with an insecticidal soap or horticultural oil.
Spinosad is also labeled for control. The problem with the sprays
is that you can't spray when the outside temperatures are above 85º.
An advantage of the systemic is that it gives you season-long
control. For additional information see the 'plant diagnostic' section
of our website, http://plantdiagnostics.umd.edu/level3.cfm?causeID=194
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