Questions on: Gladiolus
Ron Smith, Horticulturist, NDSU Extension Service
A: Your comment makes good sense -- after three years, who can keep all those corms straight?
Q: I have a beautiful poinsettia plant that I transplanted to my garden this spring. It looks great now, but I am wondering how I can bring it back in the house. Will it bloom for Christmas? Also, do gladiolas have to be lifted in the fall? (Wahpeton, N.D.)
A: Basically, cut your poinsettia back to the height you want, bring it inside and give it long nights. And yes, lift the glads after a frost has blackened them.
Q: What chemical product can be used to control weeds and thrips in a plot of gladiolas? I prefer to garden organically, but I am also having problems with weeds in a plot of sweet corn. (Lake Benton, Minn.)
A: You'll have a tough time controlling thrips in your glads organically. I have never been successful. You can try insecticidal soap if there are no predatory insects present. Otherwise, use Orthene (a contact/systemic) to control them.
I would suggest presprouting the weed seed and killing off the seedlings with Roundup. Or, you may want to try solarizing the area by covering it with heavy clear plastic for about two weeks prior to planting. The weeds will sprout and stay soft, with some drying. Those that don't are easily rogued out when the plastic is removed. Plant your sweet corn close. Hand cultivate while canopy is open (usually until July 4th or so) then let them go. The corn will form a dense enough canopy so that the weeds beneath it will be weak enough to be noncompetitive. Otherwise, there are many herbicides that can be used in sweet corn.
Q. Enjoy your column in the Green Sheet of the Aberdeen American News.
Enclosed is a clipping of a gladiolus stem. Nearly all my flowers got buds, but then would sort of dry up. If these had a disease on them will this hurt the bulb? What can I do? Thank you. (Hosmer, S.D.)
A. Your glads had typical thrip symptom damage. After the first fall frost blackens the tops, bring in the corms and dust with sulfur during the storage period. Next spring, follow a rigorous spray program for their control with Orthene, Malathion or Sevin. Their feeding activity causes discoloration of flowers, foliage, and in most cases keeps the buds from opening. Try also to plant the glads in another location next year. Crop rotation helps keep insect and disease problems to a tolerable level.
Q: Your Garrison reader is not the only one whose glads lost their color. The first time it happened to me, an elderly lady told me, "That 's a sign to get new bulbs." I've never kept track of how many years it takes for the color loss to happen, but it does happen. It would be interesting to see what would happen if one would take them to another garden (or area) to see if they would still all bloom yellow. It's too late for me to try it, because I refused to dig mine at all this fall. Because of the discoloration, I decided to run another test to see if they can withstand a North Dakota winter in the ground. Spring will tell. (E-mail reference, Gardner, N.D.)
A: It would be nice to know what causes this to occur with glads. I think it might be genetic flare-up known as a chimera, specifically a periclinal (parallel to the surface) of the original flower tissue. Unfortunately, I cannot nail down any reference that will say that glads are affected this way. There is also a chance this could be a virus that is causing this, but my skeptical mind has a hard time accepting that happening on such a wholesale basis. I'll be interested in learning of your "research" results.
Q: Regarding this question about gladiolus changing colors, I don't know if this is true, but Mom used to say that if you stored different colors gladiolus corms together, they would eventually all become the same color. And of course, I never doubted mom. (E-mail reference, Fargo, N.D.)
A: Smart man -- and if you are really smart, don't ever doubt your wife either! However, that still doesn't explain why or how the change takes place, so I am still stumped! But thanks for responding, and who knows if there isn't some science behind what your mom says?
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