GARDENER'S MAILBAG

Hope for oak, cactus and apple, but not photinia

By Neil Sperry | Published Wednesday, July 9, 2014

Dear Neil: I have a mushroom growth on a branch near the top of my oak tree (30 feet or so up). I’ve been told that it’s a sign of oak root rot fungus. Is there anything I should do now to treat it? I’ve been told that it will eventually kill the entire tree.

Your very best bet will be to contact a certified arborist immediately. He or she will be able to culture the mushroom to see if it presents any danger to the tree. From the photo you attached, it really looks like it’s an opportunistic saprophytic fungus (non-parasitic) that has developed from one specific branch, perhaps where there had been an injury or an old pruning wound that didn’t heal properly. A tree of that size would merit hiring a pro.

Dear Neil: I have had a Christmas cactus for six years, and it has never bloomed. I even covered it and kept it in the dark for a month one year, and still no blooms. I have others that I move indoors and outdoors year ’round (depending on freezing temperatures), and they bloom beautifully every year. Should I discard the non-blooming one? Is there any hope for it?

Like poinsettias and chrysanthemums, Christmas cacti are photoperiodic plants. That means that they measure the length of the dark period (night) to determine the proper time to flower. There is a hormone involved that is destroyed by light, hence the need to have them in total darkness for 14 hours each night. But they must have normal bright daylight the other 10 hours of the day, so covering them for a month would be very harmful, and leaving them in rooms where there was ambient light at night would prevent their flowering. Try covering it overnight each night beginning early October, but remove the blackout cover the next morning. A large cardboard box would work well. Hope that helps. Don’t discard it.

Dear Neil: Why have redtips all around town suddenly started developing black spots on their leaves and dying? I have applied the fungicide that was recommended to me, and it seems to be helping, but I’m anxious to see recovery.

You may not want to see my answer. The disease you’re talking about is Entomosporium fungal leaf spot, and it has reduced redtip photinia to an undesirable landscape plant for all parts of America, desert to rainforest – and Texas! It first shows up as maroon freckles. Then portions of the plant start to turn pale green, yellow and crispy brown. Eventually the entire plant succumbs. Fungicides offer little long-term help. Eventually you, like thousands before you, will probably decide to replace individual plants that look the worst, and at that point you’ll have to make the courageous decision not to plant another redtip right back into the void. Nellie R. Stevens hollies are probably the best large screening replacement shrub. I wish the news were better, and now the fungus seems to have moved over onto Indian hawthorns, close relatives of the photinias.

Dear Neil: I have a six-year-old Gala apple that has flourished. But I’ve had no fruit. Do I need to take it out, or should I plant another apple variety to increase its fertility?

We have one missing fact: has it bloomed? If you’re not getting blooms, you can’t have fruit. Apples often grow strongly for their first few years, establishing their canopies while they postpone flowering. If that’s the case, you don’t necessarily have to plant a second tree of a different variety. However, if you have had flowers, and if bees have been active, you might want to plant a second type of fruiting apple somewhere nearby. Check local Texas AgriLife Extension references for the best type for your locale.

Dear Neil: I’d like to plant Italian cypress trees along my back fence for privacy. How tall do they grow, and how quickly will they get to that height?

In good growing conditions, Italian cypresses grow to be 40 feet tall and 3 or 4 feet wide. While they’re attractive initially, they can become overpowering visually as they mature. Plus, they will grow at varying rates, until the tall green wall you’re expecting will look more like ranks of organ pipes. You didn’t mention how much horizontal room you have at that part of your backyard, but if you have a bit more room for the plant to grow, Little Gem southern magnolia is a lovely screening plant. It will grow to be 30 feet tall and 20 feet wide, but you can remove lower limbs so that you can work beneath it. Oakland hollies grow to be 8 to 12 feet tall and 5 feet wide. My personal favorite for years was Spartan juniper (to 15 feet tall and 4 or 5 feet wide), but it began to show a vascular disease that killed it out branch-by-branch, so it’s hard for me to recommend it now.

Have a question you’d like Neil to consider? Mail it to him in care of the Wise County Messenger, P.O. Box 149, Decatur, TX 76234 or email him at mailbag@sperrygardens.com. Neil regrets that he cannot reply to questions individually.

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