Can you suggest what to use to prevent the early defoliation of knock outs (roses) by rose slug - Organically if possible?
Last year was a great (or bad depending on how you look at it) year for rose slugs destroying rose foliage. This year we’ve already had early questions about 2010 rose slug control! Well, first, there are no systemic insecticides that I am aware of that are organic, so you’ll have to attack the rose slug itself. (Bonide’s or Bayer’s Tree and Shrub Insect Control are the systemics - 3 in 1 Rose Care usually covers them, too, but always check the label.) Even with the use of systemic insecticides, many times a backup plan may be needed if the populations are high. So here are some natural ways to help suppress rose slugs on roses: -Hose them off with a strong stream of water. -Hand pick them off / smash them. -Sprays include Captain Jack’s Deadbug Brew (Spinosad - certified organic), Insecticidal Soap, Neem, and Horticultural oil. (Bt does not work on rose slugs) NOTE: Be sure to spray the undersides of the leaves. Most of the time they will be under the leaves, and very hard to see when they are small. They typically feed at night but can be found in the morning. Remember there are a couple types of rose slugs and multiple generations as well. They do not look like slugs but more like a small caterpillar. They’re actually a sawfly.
Iris borers - By the way, we have also found the above mentioned systemics doing a great job helping fight against iris borers in iris! Yes, it needs to be applied this spring as the irises are beginning to grow.