Submitted by: agcomm,  Thu Dec  4 10:39:01 1997


Hortiscope
 
Ron Smith, Extension Horticulturist
North Dakota State University
 
Q.I had a question about black knot on Canadian Red Cherry  
  trees. You suggested prune: prune them at the base. You were  
  absolutely right; no matter what we've tried, the black        
  knot comes back. The trees are coming out.
          
  The trees were twelve in number, planted for an accent color  
  around a circular flower bed at a cemetery. I don't know what  
  we can put in place of the red cherry.            
 
  Thank you for continuing to answer our questions.
  (Litchville,N.D.)          
 
A.Thank you for writing and the nice comments concerning my  
  advice.              
 
  There are a couple of crabapples you may want to consider as
  replacement. One is Prairifire, gets about 15 to 20 feet high,
  has purple foliage when new, red-pink flowers, and dark red
  fruit. Another is Red Barron, which has a more columnar shape,
  with the same basic flower, fruit and foliage character. Both
  are disease resistant.          
 
         
Q.I, like so many others, enjoy reading your articles, but
  somehow haven't seen my problem. I have a hoya plant that is
  quite large and old, but it never has any flowers. I      
  have given slips from it that do have flowers. I give it
  Miracle-Gro and try to take good care of it, but no
  flowers. Does it need a different fertilizer or could it be
  too old? It didn't bloom even when I first got it. I would
  appreciate any information you can give me. (Hitchcock, S.D.)
         
A.Hoya needs about four hours of direct sunlight and high
  potassium fertilization in order to flower. I am willing to
  bet that your friends who are successful are providing either
  or both of these conditions.
          
  Try moving it to a south-facing window and provide
  supplemental light of a Gro'-Lux quality. 
         
         
Q.I am enclosing leaves from a black-eyed Susan which I planted
  this spring. It bloomed nicely after planting and I picked
  several blossoms, but as the summer progressed the leaves
  started drying up from the bottom of the plant and the entire
  plant eventually died.  I have another plant which is still
  blossoming, but has a few dried leaves on the lower stems. I
  would appreciate any suggestions you may have for treatment.
  (Dilworth, Minn.)          
 
A.From the appearance of the leaves you sent, it appears as if
  the plants received a double-whammy of botrytis blight and
  excessive salt burn from either the soil not draining      
  properly or excessive application of nutrients.
          
  To control botrytis, avoid splashing water on the foliage.
  Daconil 2787 also helps to control the disease.           
 
         
Q.Was wondering if you can tell me what kind of a vine this is.
  It turns red and is climbing in my trees. Will it kill the
  trees? Thank you. (Willow Lake, S.D.)          
 
A.The vine is Virginia creeper, or woodbine. Allowed to grow
  unchecked, it could kill off a tree eventually by
  out-competing it for light especially, but also for water and
  nutrients.                    
 
 
Q.How do shrub roses do in our area? Have you had any experience
  with Robin Hood? Is the care required less than for tea roses,
  and are there any drawbacks to growing them?  (Eureka, S.D.)
         
A.In general, shrub roses are quite winter-hardy and adaptable to
  our area, not needing the fuss of the teas and floribundas. I
  have no experience with Robin Hood, but my references tell me
  it is completely hardy. Enjoy.
                                 ###
NDSU Agriculture Communication
Source: Ron Smith (701) 231-8161
Editor: Barry Brissman (701) 231-7866