Difference Between Algerian and Dancy Mandarin Oranges

Q. I just bought a dwarf ‘Algerian’ and dwarf ‘Dancy’ mandarin orange. The Dancy is doing fine but the Algerian’s leaves are getting brown spots and falling. Is this a pest or disease? I don’t want it to spread!

'Algerian' mandarin (tangerine) with spots on its leaves. One person in Las Vegas growing citrus claims the secret to growing citrus here is soil drainage.

A. Our humidity is so low that I doubt it’s a disease problem. The reason for the difference in leaf brown spots could be its landscape location, adequate soil prep at the time of planting, or the genetics of the plant. The spots are most likely cultural, management; something you have done, or should be doing. Since it happened after transplanting, I’m guessing it has something to do with how it was planted, where it was planted or how the tree was irrigated.

Citrus Origin

            Both trees grow in the subtropics to tropics so make sure the tree was planted with a mixture of compost and soil in a planting hole about three feet wide and about 12 to 18 inches deep. The additions of organics in the soil should darken it. Cover this planting with a layer of woodchips to keep the wood chips rotting, full of organics and moist between irrigations. Make sure it is staked after planting in case there are strong winds.

Landscape Location

            If planting in full sun on the West or South side of a building and it’s showing signs of sun or heat stress, consider shading the tree’s canopy for the first year of growth. Shading doesn’t require shade cloth. It can be done with anything that provides some late afternoon shade. It is probably a good idea to shade the plants from the afternoon sun the first year.

Cultural

            Do not water trees daily except immediately after planting. Daily irrigations are meant only to settle the soil around the roots, not to give the tree a daily “sip” of water. Make sure it’s staked during its first season of growth. During the hot summer months, water as infrequently as every other day if two days of water is applied all at once.

            With a newly planted 5-gallon fruit tree, the tree should receive 4 to 6 gallons of water each time it’s watered. This water should be distributed through three , 2 gallon per hour emitters or four, 1 gallon per hour drip emitters under the canopy of the tree at about a foot from the trunk. As the tree gets larger over time, it needs more water applied over a lager area. Plan for it. Add additional drip emitters (not extra minutes) further from the trunk under the expanding canopy to give it this extra water. When the tree is fully grown at 20 to 25 feet, it should need about 30 gallons of water at each watering.

            Plant these trees at least three or four feet from hot walls and they should handle the reflected high temperatures okay if the soil is amended and they are watered before it gets hot. Fertilize the trees right after harvest with a citrus fertilizer. Prepare the soil with compost and make sure it has good drainage.

Dwarf Types

            Dwarf versions are grafted onto different rootstocks than the standard sized trees. This will impart a slightly different flavor to the fruit. The dwarf version of mandarin orange should get about 12 feet tall and 12 feet wide if unpruned. ‘Dancy’ mandarin oranges (sometimes called tangerines) are the most popular mandarin orange fruit in the world (sometimes called “cuties” in the supermarket). 'Algerian' mandarin oranges are noted for their winter cold hardiness.