White spots on columbine plant means fungus needs treatment

Q. We had a columbine plant for about a year which has done fairly well up until the last couple of months. It has some limbs that have begun to die and now it has developed little white spots all over it. Please tell me what is going on and what I can do to save it. It bloomed last spring and was so pretty. BM, Albuquerque

A. From your description of “little white spots” all over it, I think there is a fungus among us. Your columbine could be suffering with powdery mildew.

The good news is powdery mildew, according to my “Organic Gardeners Handbook,” “commonly causes poor growth, but seldom kills the plant.”

It is suggested that you treat applying either a Lime-Sulfur or Bordeaux mix fungicide. I’m not sure how effective either will be this time of year, and the Bordeaux mix usually has a temperature restriction for application (never when the temps are 50 degrees or below) so consider applying early next spring, just as things start to wake up and grow. The powdery mildews had a leg up this year because of all the humid weather we had in June and July. Mildew thrives in that sort of weather. Now you’re seeing the extreme effects.

You say there are dead and dying limbs, so I’ll suggest you get a very sharp pair of scissors and snip those limbs out of the plant. If they supported the bloom from last spring, they need to be eliminated.

Next, I suggest that as the leaves fall this coming dormant period, you tidy them up and throw them away. If you are a composter, do not add those leaves to your heap as the mildew would probably thrive in a warm and humid place like that. Throw the leaves and clippings away. Remember we’ve had an extremely wet late summer and fall period so far. Any fungus is in their element right now because of the weather.

If you have the columbine wellmulched, see if you can move the mulch back to allow a bit better air flow surrounding the plant. You will want to scoot the mulch back to help protect the plant come dormancy, but for now a smidgen of better air flow could help eliminate some of the fungus spore that’s hanging about.

If you need more confirmation as to what’s affecting your plant, I’ll suggest you cut off a few snippets, place them in a zipper bag, and take them to a nursery to get a consultation.

The “fresher” the collection the better. Don’t drive around for days with the sample and expect anything to be visible. And please, keep the sample closed and contained; you don’t want to take the chance of spreading an infection. Here’s to a healthier columbine next year.

Q. I’m confused. I seem to remember that you suggest feeding pansies with a fertilizer offering more nitrogen in its mix. Reading about planting pansies with the bulbs, you tout fertilizer with more phosphorus in it. Which “rule of thumb” am I following? M.C., Albuquerque

A. You are correct that pansies will benefit from an application of a fertilizer with higher nitrogen in its mix, but that comes well into the winter months. For this initial fertilization, when you are aiming to settle in bulbs and a pansy planting, you do want to offer a fertilization that is higher in phosphorus to assist with the rooting. Four to six weeks after you’ve planted, you could offer a fertilization with a higher nitrogen content in its mix. I like to think of the nitrogen as antifreeze. The pansies utilize the nitrogen during our cold periods to continue their growing and oddly enough, blooming. They are peculiar that way.

Since you are planting anew, apply either a bulb food or work some bone meal into your work. Then weeks later, if you feel the need, offer a fertilization containing a higher nitrogen base to give your pansies a kick in the pants.

It won’t harm the bulbs and the pansies will appreciate your assistance. Happy Diggin’ In.