Q: Can I prune fruit trees now, or do I need to wait until they are dormant in January? Will you be giving fruit tree pruning classes again this year?
A: Prune fruit trees lightly with a hand pruner any time there is a problem at any time during the year. Heavy pruning that requires a saw or loppers should be done during the winter months after leaves have dropped.
Removal of limbs with loppers or a saw is easier after leaf drop when you can see the arrangement of limbs and branches and where to cut. Avoid using loppers or a saw during the summer months because of sunburn and damage to the trees by our intense sunlight.
The majority of pruning cuts for fruit trees will remove entire limbs and not leave stubs where branches are cut off. Many of the desirable pruning cuts remove vertical growth, upward or downward, which produce little to no fruit and interfere with light entering the canopy.
I will offer pruning classes for fruit trees Saturdays beginning in mid-December. Watch the newspaper or my blog for exact dates and locations.
Q: What are the yearlong fertilizer requirements for landscape plants ranging from acid-loving to desert lovers such as cacti, palms and other plants to beautify home landscapes.
A: Desert gardening and horticulture is more difficult to practice than traditional horticulture talked about on most blogs, information sheets, YouTube videos, books and other places. Most information in the media is derived from “traditional horticulture,” and these practices may or may not work in the desert.
When applying fertilizers to landscapes in desert climates and soils, consider soil improvement and irrigation beforehand. Soil improvement, where and when needed, solves many fertilizer issues.
The biggest mistake made by desert horticulturists and gardeners is a lack of soil improvement to desert soils when and where needed. Desert soil improvement solves 90 percent of the fertilizer and irrigation issues in residential landscapes, because the majority of plants grown in desert landscapes are not desert plants.
Spend more money and effort on improving the soil than buying and applying specialty fertilizers. Improving the soil and using organic surface mulches around non-desert plants reduces the need for chemical soil amendments, fertilizer applications and pesticides.
With proper soil improvement, here are my recommendations for fertilizer applications, either conventional or organic:
n Nitrogen and potassium are needed by all plants on a regular basis.
n Apply phosphorous fertilizers when planting seed, transplants from containers or bare root, rhizomes, bulbs or any plant just getting started.
n Plants grown for their flowers or fruit require at least one fertilizer application of nitrogen plus phosphorus during the growing season and applied two weeks before flowering and fruiting.
n Fertilize vegetables and annual flowers monthly and lawns every eight weeks.
n Fertilize prized landscape plants more often than ordinary landscape plants.
n Use specialty fertilizers on rare occasions for very specific reasons.
Q: I want to plant pine trees like I saw at the Hughes Center near Sands and Paradise. They have foliage near the ends of the branches and have a round shape, rather than conical or a Christmas tree shape, but I don’t know what they are.
A: They might be attractive when they’re small, but most pine trees are large when mature. They don’t fit in small or medium-sized landscapes and are not compatible (designwise) with one- or two-story homes. They might be fine for commercial landscapes and parks but not around homes on small residential lots in the desert.
I think the trees you saw were still relatively young — 20 years or less — planted too close together and not given enough water. This is why they were round in shape with needles only at the ends of the branches.
Pine tree availability at nurseries is somewhat limited compared to other parts of the country. I believe the pine tree you saw that interests you is an older Mondell or Afghan pine that becomes rounded as it matures and attains a height of 40+ feet.
Another commonly sold pine here is the Aleppo, which resembles Mondell pine in its youth. Both trees when younger are pyramidal or Christmas tree-like in shape. The Mondell becomes more rounded with age, and the Aleppo pine becomes gangly and informal in shape. The Aleppo pine can reach heights of 60 to 70 feet.
A third large pine planted here in the 1980s and making a comeback now is the Chir or long-needled pine. It is a very graceful, pyramidal pine that is less tolerant of cold winter temperatures. All three of these large pine trees should not be used in small residential landscapes, particularly with single-story homes.
So-called smaller pines may not actually be smaller when mature. The Italian stone pine, a pine tree with a rounded shape all through its life, is a slow-growing pine that may be acceptable in smaller residential landscapes for a number of years. However, it can reach 50 feet when mature. It can also provide edible pine nuts, the chef’s pignoli.
Our state tree, the single leaf piñon pine, would be a good choice for desert landscapes if you could find it. But it can be large as well — 50 feet or more — when irrigated and given time. It also produces edible pine nuts.
A pine tree popular with landscapers and architects over the years is the very distinctive Japanese black pine. It has been touted to be tolerant of alkaline soil, but it is a specimen pine with a unique shape that makes it popular in designer landscapes.
However, I have never seen a Japanese black pine perform well here in our climate and soils. You see it used further north in arid states. You don’t find many older ones around town, which may speak volumes about how well it is suited for our location.
Q: We have fruit trees planted in an area we have covered with wood mulch. We always clean up the fallen fruit. Can we leave the fallen leaves on the ground, or do they need to be cleaned up?
A: It is always a good idea to clean up fallen fruit because of pest problems. It is also very important to remove dead fruit from trees after harvesting.
I like to see fruit picked up from the orchard floor at least weekly. If you don’t, it can lead to numerous insect and vertebrate pest problems. If you are composting this fruit, either bury it in the compost pile or put it in sealed containers where pests can’t get to them.
One common insect problem with nearly all soft fruit when it’s ripe is fruit beetles. They get into decaying fruit on the orchard floor, where their populations multiply rapidly. These beetles then infest soft mature fruit hanging on the tree waiting to become tree ripened or disposed fruit laying on top of the compost pile.
If this is a problem with your fruit trees, improve orchard sanitation by picking up fallen fruit and remove old and damaged fruit hanging from the trees.
Leaves from most fruit trees are not a problem if left on the ground to decompose. That’s not true, however, in the vegetable garden and possibly other parts of the landscape. Leaves and stems will decompose much faster if they are chopped or shredded first.
If it were me, I would shred leaves and stems and leave them on the orchard floor to decompose, but not the fruit.
Bob Morris is a horticulture expert and professor emeritus at the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.