Special Rose Growing Posts

Post from: Wayne Myers CR Chair         Posted:3/27/2017

Effects of the 2017 Winter

FROST DAMAGE:

Mid-March brought the Deep South some very unusual frosty weather.  North of St. Augustine, only one mile from the marsh and within four miles of the ocean, I had light frost March 15th and 16th.  On the 17th  as I write this, I don’t see new damage on the emerging foliage, but after a freeze, we must wait for a while to evaluate the damage.

If very cold-sensitive plants such as crotons and hibiscus show wilted foliage, your roses have probably been damaged.  New, tender, actively-growing foliage and buds are the most vulnerable.  Some new foliage and buds may shrivel/blacken & die.  Depending on the amount of damage and dieback, you may have to re-prune .  However, don’t re-prune until you can estimate the extent of the damage.

Once you’re sure, finger prune the dried, dead new growth.  Cut just above the highest bud eye to check the pith inside the cane.  The center pith of damaged canes will be brown.  If you  find brown pith, cut back further to the next lower bud eye until you find clean, white pith.  You might find that new growth has wilted or died back to the bud eye, but the cane wasn’t damaged.

In inland Florida, or further north in Alabama or Georgia, you may find brown pith much further down the canes that you would normally prune your roses, especially those on fortuniana rootstock.  You face a trade-off–leave a damaged cane in place that may die back later and certainly will not perform as well as an undamaged cane, or prune severely, hoping that the weather is still mild enough for the plant to recover from severe pruning.

Damage may vary widely by classes–teas, noisettes, then chinas are most vulnerable.  In previous years, even though they did not appear to be damaged, when I trimmed later in the year I found brown centers in canes of noisettes, teas, and rosa gigantea.

Wayne

 

What’s Wrong With My Rose?

By: Gaye Hammond Master Rosarian – Houston Rose Society

Not too long ago I had the great good fortune to attend a lecture presented by Dr. Ed Bush, Associate Professor of Ornamental Horticulture at Louisiana State University titled “What’s Wrong with My Rose?”   According to Dr. Bush, most of the time a rose will send visible signals that something is wrong.  Rose gardeners know to look for disease symptoms like blackspot and powdery mildew and damage caused by insects, but plant changes caused by nutrient deficiencies can be subtle and may go unnoticed in the early stages.  The chart below provides a quick reference to helping diagnose nutrient imbalances in roses.

 

If your roses display symptoms from this chart, I would encourage you to send a soil sample to Texas A&M’s Soil, Water and Forage Laboratory for confirmation before taking remedial action to rectify any nutrient imbalance.  A soil test will not only identify nutrient deficiencies – it will also identify any nutrient levels that are too high as well as make recommendations for bringing the soil nutrient profile back into balance. Soil tests are inexpensive and the results are usually received within a week.  Forms and instructions for submitting a soil sample are available online at http://soiltesting.tamu.edu.

For those residing outside of Texas, contact your local Extension Service or Master Gardener Association for forms/instructions on submitting soil samples.

Figure 1 Yellowing between leaf veins can be caused by magnesium and manganese deficiencies.  Photo courtesy of Dr. Ed Bush, Louisiana State University

WHAT’S WRONG WITH MY ROSE?

The highlighted cells in this chart represent the suspected deficient element (nutrient).  Abbreviations for the elements (nutrients) included in the chart are:

“N”                  Nitrogen                                               “Cu”                Copper

“P”                   Phosphorous                                        “Zn”                Zinc

“K”                  Potassium                                            “B”                  Boron

“Mg”                Magnesium                                          “Mo”               Molybdenum

“Fe”                 Iron                                                      “Mn”               Manganese

 

Symptom Suspected Deficient Element (Nutrient) Over Fertilization

 

N P K Mg Fe Cu Zn B Mo Mn  Over Fertilization
Yellowing of younger leaves          XX XX
Yellowing of middle leaves                  XX  
Yellowing of older leaves  XX    XX  XX      XX      
Yellowing between veins        XX            XX
Old leaves drop  XX                  
Leaf curls over        XX            
Leaf curls under      XX      XX          XXXXX
Leaf tips burn (younger leaves)                XX    
Leaf tips burn (older leaves)                    
Young leaves wrinkle and curl      XX        XX  XX  XX  
Dead areas in the leaves      XX  XX  XX    XX      XX
Leaf growth stunted  XX XX                 
Dark green / purplish leaves and stems    XX                
Pale green leaf color  XX                XX  
Leaf spotting              XX      
Spindly plant  XX                  
Soft stems  XX    XX              
Hard / brittle stems    XX XX               
Growing tips die      XX          XX    
Stunted root growth    XX                
Wilting            XX        

 

Chart courtesy of Dr. Ed Bush, Louisiana State University