Leaves Turning Brown on Shrub Roses Planted Last Fall

(Question)

Located in Kawarthas roses get full sun all day used lots of good soil . Sprayed insecticide soap and removed brown stems of rose. Can the rose bush be saved. Did find an army or two on warm on the stems.

 

(Answer)

Hello:  Unfortunately your question doesn’t provide me with sufficient information to give you an answer with much certainty.  First, given that the Kawarthas are considered zone 4b, it would be important to plant hardy roses known to survive in your area; such roses as the ones in the Morton or Explorer series would survive 4b winters.  But many of these roses die back to their roots only to spring back to life in spring.  The majority of canes of these roses are dead and need to be pruned out in early spring.  You dead brown leaves on a dead cane may have resulted from a stem that remained alive after our milder winter only to produce leaves in spring which were killed by our later than normal cold weather of April/May.  Pruning out the branch was prudent.

Secondly, your email  suggests the presence of an army of worms (I interpreted warms to be worms).  A severe infestation of pear sawfly larvae can cause the stems and leaves of roses to look as if they have been scorched.  But I think this level of infestation is indicated by your email.  A nursery may suggest an appropriate product to treat this infestation.  In the meantime continue to examine your roses on a regular basis and remove dead stems leaves and pests as you have been doing.  I have included a webpage below that contains information about common rose pests.

http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/visual-guides/rose-problems.aspx

Also be sure the plants receive sufficient but not excessive water and sunlight.  Although they were planted last year in good soil, all  roses appreciate a good two or three inches of compost and or manure in the spring and again in the early fall.   It is not too late to do that now.  I suspect that if you have planted the appropriate rose and care for it appropriately, it will survive this season and hopefully many more.  Here is a link that discusses unexpected freezing weather.

http://www.torontomastergardeners.ca/askagardener/roses-and-freezing-temperatures/ The second discusses identifying ‘dead’ parts of your shrubs and how to safely prune them out of healthy bushes.

http://homeguides.sfgate.com/tell-rose-bush-dead-48737.html