Bearss lime (Citrus aurantifolia)

‘Moorpark’ apricot

I would like a tree care schedule for the following: Asian pear, navel orange, Fuji apple, `Ruby Red’ grapefruit, `Black Jack’ fig, `Kadota’ fig, lemon, tangerine, sweet lime, avocado, peach, nectarine, plum, loquat, `Valencia’ orange, `Minneola’ tangelo, `Owari’ Satsuma mandarin.
>Bob Bowman, Sylmar
Taking care of any type of tree, shrub or other woody plant entails five horticultural tasks: pruning, fertilization, mulching, irrigation and pest control. Let’s examine each of these for the fruit trees you have listed.
Pruning: Evergreen fruit trees such as citrus (orange, grapefruit, tangelo, tangerine/mandarin, lemon, lime), avocado and loquat are pruned minimally, if at all.
Citrus trees develop dense interior growth which results in shaded shoots and twigs that die and need to be removed. With the exception of lemons, which need to be kept in bounds, citrus trees develop a symmetrical dome and do not require shaping.
You need only remove branches (one of each pair) that rub against each other, suckers from the trunk, and water sprouts — rank vertical growth that sprouts from branches.
Pruning of evergreen fruit trees, which are usually tropical, should be done during spring or summer since winter pruning would force new growth that could be killed in a frost.
Each type of deciduous fruit tree (fig, pear, apple, peach, nectarine and plum) has its own pruning requirement.
Since fig produces on the current season’s growth, you can cut it back after leaf drop in the winter without jeopardizing the coming year’s crop. Peaches and nectarines (fuzzless peaches) are pruned more radically than any tree because of their astonishing shoot growth, with as much as 75 percent of the previous year’s growth cut back in winter.
Apple and pear (pome fruits in the rose family) are different since they produce fruit on spurs, slow-growing stems that elongate by a mere fraction of an inch per year and bear fruit for many years. Thus, annual winter pruning should be cautious, avoiding removal of spur-laden branches.
Plums produce fruit on shoots (like the peach) and on spurs (like the apple).
Fertilization: Mature deciduous fruit trees should receive 1 pound of actual nitrogen per year, while mature citrus and avocados should receive 1 1/2 pounds of actual nitrogen annually.
One pound of actual nitrogen is contained in a little more than 2 pounds of urea, 7 pounds of Best Turf Supreme (a popular lawn fertilizer that is 16 percent nitrogen), 35 pounds of rabbit manure, or 70 pounds of cow manure.
Some people apply all of their fruit tree fertilizer in the winter and let it soak in with the rain, while others divide the annual dosage into several equal applications throughout the growing season.
With deciduous fruit trees, it is advisable to leave some of the annual fertilizer allotment in reserve and to apply it following harvest.
Irrigation: Trees growing in sandy soil need to be soaked every 10 to 15 days, while trees growing in soil that has clay in it should be soaked every 15 to 20 days.
Build a basin that slopes away from the trunk of the tree, is 3 to 6 inches deep, and extends to the drip line or canopy perimeter. If water is allowed to stand around the trunk, crown (where trunk meets roots) rot may develop.
Mulching: Mulch benefits a tree in many ways. It keeps roots cool, minimizing stress to the tree in hot weather. It prevents growth of weeds and, as it decomposes, fertilizes as well. A 2-inch layer of mulch should be put down 6 inches away from the trunk out to the drip line.
Pest control: In the Valley, most of the trees on your list are pest-free. Citrus and peach/nectarine are the exceptions.
Citrus are plagued by a host of insect pests, most of which are brought into the trees by ants. By slathering a sticky preparation such as Tanglefoot on a piece of cardboard wrapped around the tree trunk, you can prevent ants from climbing into your tree with their pesty cargo (aphids, mealybugs, scales).
Leafminers, which make tunnels in citrus leaves, should be treated with Spinosad, an organic pesticide. Peach/nectarine is afflicted with a foliage-deforming fungus and should be sprayed with copper or lime sulfur following leaf drop in autumn and just before bud break in late winter.
Grape, kiwi issues
Lately, several readers have expressed frustration about trying to grow grapes, especially the `Thompson Seedless’ variety. Either the crop is small or the vines are plagued with fungus. Another reader has asked about growing kiwi fruit in the Valley.
If anyone has grown grapes or kiwis successfully, please let me know how you do it so I can share your success with the readers of this column.
Tip of the week
The `Black Jack’ fig mentioned by reader Bob Bowman is a dwarf variety that is recommended for container growing.
In general, it is advisable to plant dwarf or semi-dwarf fruit trees for their ease of harvest and moderate water requirements.
Most popular tree fruit varieties are now grown on semi-dwarfing rootstocks.