Question: We are having a big problem with a cactus wren. It is digging into our saguaro and throwing the guts of the cactus all over the sidewalk. Any suggestions on how to get rid of it or, at least, apply something to make it stop?
Answer: This is a very common question. Cactus wrens and other desert birds that make their nest in saguaros do so by removing bits of the outer tissue to make their nesting holes. This does no harm to the cactus and is a vital part of the Sonoran desert ecosystem.
Blocking up the holes will create conditions favorable for infection to form that can kill the plant. Your saguaro provides nesting sites and food for a host of native animals and is a key part of our desert.
Q. I recently planted some asparagus roots. Do you have any suggestions about care of the plants until they are mature enough to produce?
A. Asparagus is a perennial vegetable requiring good drainage and full sun. Plant one-year crowns in late winter. Medium-to-rich soil, with a pH of 6.0 to 6.7, will boost asparagus success. Higher phosphorus and potassium and other organic matter is needed in establishing your crop.
Annually add nitrogen and top-dress with a mulch for moisture retention. Deep watering weekly during the summer is also warranted. For additional ideas on maximizing your crop of asparagus, go to the Arizona Master Gardener Manual site: http://ag.arizona.edu/pubs/garden/mg/vegetable/asparagus.html
Q. How I do I get rid of mites or gnats in my houseplants? I have changed to a higher grade of potting soil and sprayed with two different brands of pest control for fruit and vegetable plants.
A. Fungus gnats are small mosquito-looking insects that are found in homes with houseplants that are usually getting too much water. Fungus gnats feed on algae, fungi and organic matter in the plant medium. If you religiously allow your plants soil to dry between watering, you will lose the fungus gnats, which are harmless but annoying.
Q. We have several mature native paloverdes with a rotting-type appearance in the limbs. The trees seem otherwise healthy, but we are concerned.
A: This kind of damage is common in paloverdes and other desert trees that are receiving too much water. Excessive growth from over-watering leads to soft wood and weaker tissue. Branch junctions with included bark can become sites where rot can set in. Desert trees use water very efficiently and will grow too quickly if given too much water.
Established trees should receive only supplemental water during the hottest months to reduce stress. Excessive pruning can open the canopy to sun scorch, which can permanently damage the tree’s fragile photosynthetic tissue.
“The whole idea of planting desert trees in the landscape is to conserve water,” says Scott McMahon, an arborist at the Desert Botanical Garden.
E-mail your garden questions to email@example.com.