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Showing posts from February, 2019

Salt Problems with Houseplants, Caliche Soils, and Get Those Bulbs in the Ground ASAP!

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Southwest Yard & Garden by Dr. Marisa Thompson
Reprints from years past. Written by Dr. Curtis Smith, retired NMSU Extension Horticulture Specialist, with additions by Dr. Marisa Thompson. 
Question from 1997: What does it mean when they say our soil is calcareous? Answer: The term calcareous refers to the abundance of calcium, or lime, in our soil. This is due to the fact that our dry environment has not resulted in the leaching of calcium and other salts from our soils. Some of these salts, such as sodium, can be toxic to plants at the level found in some New Mexico soils. Calcium, however, is not toxic, but it does alter the pH, or acidity, of the soil, making it difficult for some plants to obtain the nutrients they need. Other plants, especially those native to calcareous soils, have no problem and flourish in our soils. The main message to remember is that we do not have to add lime to our soils like they do back east. The main component of wood ash is calcium carbonate, so it’…

Controlling Perennial Weeds: Silverleaf Nightshade and Nutsedges

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Southwest Yard & Garden by Dr. Marisa Thompson with guest contributor Dr. Leslie Beck


Question: Silverleaf nightshade and nutsedge are taking over parts of my yard! Please help. Organic control options are appreciated. -Helen B., Las Cruces, NM Answer: Last week I asked NMSU Extension Weed Specialist, Dr. Leslie Beck, to explain why annual weeds like sandburs and goatheads are so difficult to control and to give us options for managing them without the use of pesticides. Visit https://nmsudesertblooms.blogspot.com/2019/02/the-early-bird-catches-weed-control-of.html to read that column. The two weeds for this week, silverleaf nightshade (Solanum elaeagnifolium) and nutsedge (Cyperus esculentus and Cyperus rotundus, aka yellow and purple nutsedge, respectively), are perennial plants, and control tactics are different than for annual weeds. Both of these perennials have modified stems that lurk below the soil surface and make control especially tricky. And both have NMSU Cooperative Exten…

The Early Bird Catches the Weed: Control of Goatheads and Sandburs

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Southwest Yard & Garden by Dr. Marisa Thompson with guest contributor Dr. Leslie Beck

Controlling Annual Weeds: Timing is Everything with Goatheads and Sandburs

Question: Can you help me battle my weeds organically? I’ve got sandspurs and goatheads. Are there soil conditions weeds hate? -Helen B., Las Cruces, NM
Answer: Ouchie, that’s a nasty duo of weedy enemies. Most readers can commiserate all too well. Sandbur is a grass of the Cenchrus genus, also commonly referred to as “stickers” or “sandspurs.” Goatheads (Tribulus terrestris), also known as “puncturevine,” have tiny yellow flowers; delicate, compound leaves; and spiny seeds that are even meaner and tougher than sandburs. Many people mistakenly call sandburs “goatheads,” and I understand why. Both have spiny seeds. Both get all tangled in your socks and shoelaces when you’re not looking. Here’s the quickest way to tell the difference: place one of each seed type on the floor and then step on them both while barefoot. They both h…

(PART 2) Don’t Jump to Conclusions when Diagnosing Tree Problems

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Southwest Yard & Garden by Dr. Marisa Thompson
Question:The Texas red oak, live oak, and pecan trees in my yard were looking bad going into the fall, as were my neighbor’s honey locust and maple. When I searched for problems online, I found different possible pests and diseases for each tree. Can you help me narrow down the possibilities? -Richard V., Hobbs, NM
Answer: This is Part II of the column on diagnosing tree problems.  Last week, we learned that water stress and weed whacker injury are the most common tree problems in our landscapes and that the rooting area necessary for large trees to survive and grow is much bigger than most folks realize. **click here for Part I** We also touched on the reasons why symptoms are rarely sufficient for conclusive diagnosis of a tree disorder. This is partly because symptoms may point to secondary or tertiary problems. Many—but not all—insect pests and pathogens are more likely to attack trees that are already stressed. Plant stressors can be …