Overwatering trees can lead to trouble
Here are some questions I encountered at the Springs Preserve this week:
Q: Why is my 2-year-old paloverde dying a limb at a time?
A: Your tree could have sunk into the ground and moist soil collected against the trunk, which may have caused collar rot that plugs the tree's vascular system. Dig down to where the roots spread out and peel back the trunk's bark. If the cambium area is brown and slimy, it is collar rot. Pull the soil away from the trunk to dry out that sensitive area.
If your water doesn't drain away, roots may be in the water to cause root rot. Dig down to examine the roots. If they, too, are brown and slimy, it's root rot. Provide drainage to alleviate the problem.
As an added note, you are dealing with a drought-tolerant plant. It gets by on very little water and does fine, so stop overwatering.
Another indicator of overwatering is constant pruning. Dennis Swartzell of Horticulture Consultants eliminated three prunings a year at the University of Nevada, Las Vegas by cutting back on water.
Q: When do I fertilize my paloverde trees?
A: Never. Paloverdes are legumes that produce their own nitrogen. If plants produce pods or beans, such as mesquites and sennas, they are legumes.
Q: Why do people choose rocks over organic mulch?
A: Many people do not find mulch attractive and claim it blows around and attracts bugs. This is not true. Bob Morris of Cooperative Extension mulches with tree clippings at his orchard. He dug down to show me the rich black soil constant mulching created.
His happy trees pointed out all the beneficial effects microorganisms had done while breaking down the mulch.
Q: My xylosma is getting too big. Can I cut it way back?
A: Prune it in January or February, but that's a lot of wood to remove at one time. Remove half the growth each year for successive years until you get to the desired size, then prune often to maintain your desired size and shape. We need to use xylosma more, because it is such a beautiful shrub or small tree.
Q: When do I prune my ornamental grasses?
A: I know it's tempting to cut them back now, but they're at their peak and will continue through the winter. If you prune now, you'll look at ugly stumps until new grass emerges next March. The straw-colored grass has a beauty all its own so hold off until March. At that time, cut them back to about four inches high and in a few short weeks new grass emerges.
Q: Do we need to water deciduous trees and shrubs after they lose their leaves?
A: Yes. Our warm temperatures and winds sap moisture from the soil and leave salts behind. The added moisture refills the soil reservoir and flushes the salts away.
Q: We removed hybrid Bermuda to put in a patio. Do we need to spray the remaining sprigs with Roundup?
A: No. Covering the area with cement prevents Bermuda from restarting. Roundup can only kill plants when applied through leaves, so it can't kill the sprigs.
Q: If I use Roundup, how long before I can replant?
A: Can you wait 10 minutes? Soil deactivates it so it can't do any harm to existing plants if you spray the roots of the plants you save.
Q: When can I plant Jerusalem artichokes?
A: Now -- if you can find them -- and into spring. They are forget-me-not plants, needing only moisture and spring feedings, but they need full sun.
Q: As I plan next spring's vegetable garden, what's the best fertilizer to purchase?
A: Get a complete fertilizer containing nitrogen, phosphorous and potassium. Some brands have trace nutrients in them.
Q: We found a deep purple plant at the Springs Preserve with small pink blossoms that is beautiful. We want to know its name.
A: It's Purple Heart and it's readily available. It prefers relief from that hot afternoon sun and loves to wander around. Another rich purple plant is trailing lantana. It frosts down but bounces back next spring. It loves our hot summers, generating lots of blooms.
Q: What is the yellow stringy stuff engulfing my basil and eventually killing it? How do I get rid of it?
A: It's a parasitic plant called dodder. Destroy all dodder-infested plants before they set seeds. This tenacious parasite will engulf other plants if allowed to spread.
Linn Mills writes a garden column each Sunday. You can reach him at linn.mills@springspreserve.org or call him at 822-7754.
