Change in environment causes bud drop on Thanksgiving cactus

The beautiful flowers on a holiday cactus will quickly drop if the plant is placed near a furnace vent. (Walter Reeves for The Atlanta Journal-Constitution)
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The beautiful flowers on a holiday cactus will quickly drop if the plant is placed near a furnace vent. (Walter Reeves for The Atlanta Journal-Constitution)

Credit: Walter Reeves

Credit: Walter Reeves

Q: Do you have ideas as to why flower buds are falling off my Thanksgiving cacti? Douglas C., email

A: Typically buds fall when there is a sharp change in the plant’s environment. If you just purchased it, the trip home in your car could precipitate bud drop. A change in light levels, from dark to bright or vice versa, could be the culprit. In my experience, the most likely change is when a holiday cactus is placed in front of a furnace duct.

Q: Why are the little mandarin oranges, like Cuties or Halos, only available in winter and early spring? Louis Vaughn, Atlanta

A: Unlike with tomatoes or lettuce, which can be grown and harvested year-round, consumers are at the mercy of these delicious mandarins’ annual harvest time. “Cuties” and “Halos” are just marketing names. They are not actual varieties. Different varieties of these citrus fruits ripen at different times between November and April and are marketed as “Cuties” and “Halos.” Winter is the normal ripening period for citrus in California so that’s when you see them on grocery shelves. Sometimes, you’ll find them at other times, but it’s expensive to ship them here from south of the equator.

Q: On my property, there is a mature, healthy American elm. It seems unaffected by Dutch elm disease. Is there a registry that documents surviving elm specimens? Chip Robison, Druid Hills

A: Although American elms have been decimated by Dutch elm wilt, the species is not as close to nonexistence as American chestnut. There are still many healthy specimens growing in Georgia. There is one variety, ‘Princeton’, that seems resistant to the disease. Lacebark elm is similar in appearance and shows no susceptibility. To my knowledge, there is no elm registry, but keep up with news and research concerning this historic tree.

Q: I have been a big fan of systemic tree and shrub insect control but I read that it’s bad for bees and butterflies. I use it on azaleas and camellias with great results. Must I discontinue usage to save the butterflies? Jeanne Craft, email

A: In my opinion, and I think this is supported by research, there is very little imidacloprid translocated to flowers when the product is applied as directed (a ground drench). You could further minimize harm to pollinators by avoiding insecticide application for two weeks before blooms are present. As always, be sure you have correctly identified the pest and look for nonchemical controls before you use an insecticide.

Email Walter at georgiagardener@yahoo.com. Listen to his comments at 6:35 a.m. on “Green and Growing with Ashley Frasca” Saturday mornings on 95.5 WSB. Visit his website, www.walterreeves.com, or join his Facebook Page at bit.ly/georgiagardener, for his latest tips.