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Dallas Morning News - December 8, 2016

Q.  Should I cut back my Blackfoot Daisies to the ground in the winter?  I planted them three years in a row and they never came back.  Last year I bought a BFD plant at the Master Gardeners' sale in our town and kept it on the south porch.  It survived.  Should I dig them up and winter them on the porch?  The reason I'm even thinking that is the nurseries never have them until May and then it takes a while for them to get big again.  R. L. Dallas, TX

A.  Just cut the dead off and add a thin layer of mulch. Make sure the plants have excellent drainage and the soil and roots do not stay too wet.

Q.  This was posted to a Richardson neighborhood group. Looks like Oncor is now poisoning us. My understanding is that Oncor hired this company to poison trees in Richardson . Of course, it's not just the trees... R. H. Richardson, TX
A.  Cambistat is a chemical growth regulator and I agree that it is a bad thing to apply. Growth retardants have not been studied for long term effects but it is already known that they create plant deformities that are concerning. No telling what else they do that is bad for your soil, other ornamental plants, food crops, wildlife, pets and people. Pruning tools and saws are much better choices.

Q. We are having a problem with ants and earwigs in the house. Is diatomaceous earth effective and do you recommend its use indoors?
J.F. Richardson, TX
A. Pure natural diatomaceous earth is effective on interior insect pests but there are a few points of warning. Some DE products are much purer than others. The main ones to avoid are those that contain contaminants of other pesticides. The worst are those that contain pyrethrum mixed into the DE. You probably have read that I no longer recommend the use of synthetic pyrethroids or the natural pyrethrum and pyrethrin products. These synthetic and natural products are toxic and especially bad for people with or subject to allergies. You might want to consider dusting the herb cinnamon. Ants and other indoors pests really try to avoid it. While there isn't much scientific research about why it works, some believe cinnamon's strong scent is the key. Ants communicate by smell, leaving trails of pheromones for others to follow. Introducing a fragrant spice may interfere with this communication. Black pepper seems to work in a similar way.

Q. What's your stand on spraying dormant oils to kill overwintering insects? My maintenance people recommend doing every year.
A. Oils sprayed in the dormant season are acceptable in an organic program; however, there are several “buts”. I rarely recommend them now and never use myself because they are non-selective and kill over-wintering beneficial insects as well as pests. With proper soil building and healthy plants resulting from the organic program, these killing sprays are rarely needed. If you have insect pressure serious enough to warrant dormant oil spraying, here’s more detail you need to know.
In the past, pest control oils were heavier and used only when plants were not in their growing seasons (dormant). They were called dormant oils. The old oils killed pests that overwintered on woody plants, but were too heavy to spray on plants with foliage. The term dormant oil is still used, but now generally refers to the application time rather than the product. New, lighter formulations allow use during the growing season. These products, sometimes called summer, superior, or supreme oils, can control pests from spider mites to whiteflies. These oils are safe to use around mammals, birds and reptiles but are toxic to fish. Applying oil in freezing conditions or extreme heat or during drought or periods of new growth, can injure plants. Some plants, including maples, junipers, cedars and spruce are sensitive to these oils. Be cautious if you choose to use horticultural oils and apply them only as a last resort. They will potentially damage your plants and will definitely kill beneficial insects.

Q.  How often should I be watering during the winter? My system is currently set to water 15 minutes every other day. G.P. Dallas
A.  Glad you asked. That schedule is far too much water and a very bad schedule. Step1 - turn the sprinkler system completely off and let your place dry out. I'm surprised your plants are still alive. Watering too much forces oxygen out of the soil, creates anaerobic conditions that hurt the life in the soil and make plants lazy and keeps the roots growing right at the surface of the soil rather than being deep and strong. Step 2 - with your system set on manual, push the button when the soil is starting to dry. It will cycle through all the zones and then stay off until you make the decision to push the button again. This wet-dry cycle or "pulsing" of moisture is the healthy and cost savings way to water. Folks without automatic systems should use the same concept with their hoses and other devices. How often to apply the water with this concept is up to you to determine. All sites vary due to soil type, sun or shade, slope, etc. In the cool weather of the fall and winter, it would be rare to need to irrigate any more often than twice a month at the most.


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