GARDENER'S MAILBAG: What can I use to help with clear briar?
Dear Neil: My husband and I are trying to clear property, and this briar is just awful. Round Up and diesel are not doing anything to kill it. What do you recommend?
You have smilax briar. The problem in spraying it is that it has an extensive root system, often with tubers, and not very much leaf surface to absorb the herbicides. What leaf surface there is is extremely glossy and does not absorb the weedkillers efficiently. I have had very good results using a tractor and shredder to mow dense stands of it to the ground. Very little of it returns. At that point, I have found that is easiest simply to dig out any surviving clumps using a sharpshooter spade when the ground is very moist. It sounds more difficult than it really is. I have eliminated several acres of it personally around our own home using this approach. One tractor mowing took care of probably 98 percent of it.
I’d like to fine-tune some suggestions I made recently on solarizing garden soil. Based on what I have read from the University of Florida and elsewhere after a reader’s comments, it’s better to use clear polyethylene plastic than the black plastic I recommended. It will allow the sun’s rays to penetrate to the soil. Things I had read years ago suggested the black film would trap heat. If you’re interested in their full details, do a quick Web search for “University of Florida Gardening Solutions Soil Solarization.” Many other universities have additional information.
Dear Neil: I suspect that fertilizer spikes are pretty much a waste of money – that it’s just as good to poke holes 8 inches apart and fill them with fertilizer. Thoughts?
Both are wrong. The bulk of a tree’s root system spreads out evenly just beneath the surface of the soil. As such, fertilizer needs to be distributed evenly across the surface with a fertilizer spreader. It’s easiest just to do it at the same time that you’re feeding your turfgrass. The two types of plants need exactly the same type of nutrition: either very high-nitrogen or all-nitrogen plant food. Poking holes and filling them with fertilizer, using spikes or even using root-feeding rods all put way too much fertilizer in one place and none just a few inches away.
Dear Neil: Why would my Shumard red oak have leafed out perfectly this spring, been nice and green well into the summer, then started losing pieces of bark? About that same time 20 to 30 percent of the leaves started to fall. I’m concerned. What caused this?
You may have seen the several questions others have posted here over the past few months about live oaks doing similar things. Shumard red oaks and water oaks are doing it, too. The bark loss is due to damage called “radial shake.” It’s the result of the extreme cold of mid- to late February. Other species of oaks have not been hurt as commonly as live oaks, but it’s certainly been happening. You may have some limb dieback out of all this. You might want to have a certified arborist look at the tree.
Dear Neil: What is this black substance that’s coming from my crape myrtle, and what can I do to stop it?
This is a fungus called “sooty mold.” However, it’s a secondary issue and should not be your prime focus. To eliminate it, you really need to get rid of the insect that is allowing it to develop. Both crape myrtle aphids and crape myrtle bark scale insects secrete sticky honeydew residue as they feed. The honeydew drips onto all surfaces beneath the crape myrtles. To eliminate the sooty mold you must eliminate the insects. To do that you should apply the systemic insecticide Imidacloprid as a soil drench around each plant in mid-May. You can wash it off the crape myrtle trunks now with warm, soapy water and a big, soft sponge. You can power wash it off stones and other hard surfaces, but be careful not to hit your plants with the power wash spray pattern.
Dear Neil: I see many palm trees cut off and often braced with stakes. Is there still a chance of them regrowing, or are people just putting off the cost of removal?
It would appear they’re just holding out hope. However, if they’ve gone through this entire growing season without offering even one small attempt at regrowth, one could probably assume that they’ve been lost to the cold. If they have any size to them and could cause any problems were they to lean and topple, it would probably be prudent to go ahead and have them taken down rather than letting them fall.
Dear Neil: What are these eggs/insects on the trunk of my crape myrtle?
These are the crape myrtle bark scale insects I referenced earlier. Use the systemic insecticide Imidacloprid as a soil drench in mid-May to prevent them. They are a prime contributor to sooty mold. I would use a rag to rub off as many as I could quickly do now just to lower the population before winter.
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