Question: This past October, I planted three palo verde โdesert museumโ trees that were in 10-gallon containers. Also, a Texas mountain laurel that I previously emailed you about and a pyracantha and some lantana. We depart for the summer on April 14. I plan to set up an irrigation system. Can you advise me as to the size and number of emitters per tree, frequency of irrigation and duration of irrigation?
Answer: The number of emitters is based on the size of the tree, so if your trees are 7 to 10 feet in diameter, for example, you would use about four emitters that can deliver about 3 gallons per hour. If your trees are larger, you can add a couple more emitters every 4 or 5 feet in diameter larger. The emitters should be placed in a circular fashion at the edge of the crown of the tree or shrub. For desert species like the paloverde, watering every 14 to 21 days in the summer to a depth of 24 to 36 inches is best. In the winter, you shut off your irrigation for desert species unless we get no winter rain. The pyracantha will likely need more frequent irrigation, more like every week in the summer, and will still benefit from water every three weeks in the winter.
Question: Is my saguaro dying or dead? It is about 4 feet tall and eight years old. Professional landscapers transplanted it two years ago from its original spot facing in the same direction and only about 10 feet away. There are no drips around it and only receives water when it rains. I sure would appreciate your help to determine if I should replace it.
Answer: Your saguaro looks like it needs some water. The recommended irrigation schedule for cacti is once every 10 to 14 days in the summer and every 21 to 28 days during the spring and fall to a depth of 12 to 18 inches. Once nighttime temperatures go below 60 degrees, you can shut off the irrigation. Most cacti will survive without supplemental winter irrigation. Another recommendation, albeit too late in this case, would be to provide some shade cloth for newly transplanted cacti. Transplanting is a stressful thing for any plant, and shelter from the sun is one way to reduce that stress. Sunburned cacti turn yellow, and in extreme cases, too much sunburn can kill cacti. Your plant looks like it will survive if you can provide the irrigation, although time will tell.
Question: Yesterday I found two bees entering my single-story homeโs rafters through two small openings in the stucco and wood. Also, the bees tracked toward me after I stood nearby. Then, this evening, I found a 20-inch-long and 2-inch-wide dark spot in my ceiling. The spot is directly below the two spots where I saw the bees entering the rafters. However, I donโt hear any buzzing. Also, I went into my attic area, but couldnโt see the floor due to the insulation in the attic. What actions would you recommend I take?
Answer: If you see honeybees coming and going from a hole in your home on a regular basis, there might be a colony living inside. The sign on your ceiling makes it more suspicious, and if related, could mean the bees have been there for a while. If you continue to see bees coming and going from that area, I recommend you have a professional take a closer look. This is a job for a beekeeper or a pesticide control operator. You donโt want a bunch of bees coming after you in defense of their colony. Depending on where you live, there is likely a list of people who will inspect this situation and do any remedial work for you for a fee. If you live in Tucson, a list can be found on the Tucson Beekeepers Facebook page.
Question: Why does my plant look sick?
Answer: Two things jump out at me right away. First, this plant is too close to the building. You can see that the leaves donโt have enough room to grow to their mature size. Likely this is a problem for the roots as well. The ideal thing to do would be to move this plant to a more suitable location before the summer heat begins. Secondly, the leaves are showing signs of drought and salt damage.
The brown tips are your first clue. Salt builds up in the root zone over time because our soils and water are high in salinity, and most fertilizers are as well. The solution for this part is to give the plant extra water every few months to wash the salt out of the root zone. Put the plant on a regular irrigation schedule of deep watering every 10 to 14 days in the summer, every 21 to 28 days in the spring and fall, and none in the winter, unless we get no rain.
Make sure the watering goes 12 to 18 inches deep in the soil.
Question: A friend of mine took the attached photo while we were out walking along Kinney Road. Do you know what it is called? Oddest thing weโve seen here in Tucson so far.
Answer: The odd looking plant you found is Wootonโs locoweed, also called half-moon milk vetch (Astragalus wootonii). Itโs a Southwest desert native, and can be found from the California desert into Texas. Itโs a member of the legume family Fabaceae. According to the USDA, it is a winter annual in the Southwest deserts, and in wet winters can be a major component of the creosote bush and saguaro cactus desert, mesquite savannahs and desert grasslands. It germinates following autumn rains, and continues to grow through the winter, becoming a large, robust plant with white to pinkish-purple flowers, followed by large, inflated, single-compartment pods. Once seeds are set, it dies back. Since it remains green and actively growing over winter, it is relatively palatable, and poses a significant risk of poisoning for grazing animals.