Planting Olives

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Planting Olives

The feathery gray-green foliage and thegnarled and furrowed trunks of the Olive(Olea europa) make them a valued ornamental.The Olive is one of the hardiest of evergreenfruit trees, being able to withstand 12-15° F.with little or no damage. The tree growsvigorously in a wide range of climates, but isbest adapted to the hot, dry areas of the South-west. Some winter chilling is needed to induceflower formation; the 2 coldest winter monthsshould have average temperatures 5o° F. orbelow. At higher temperatures the trees growwell but fail to flower and fruit. The Oliveblooms very late, so that it normally escapes allfrost danger to the bloom and young fruit.Olives grow well in the Southeast, but have notborne well there; the fruit ripens too late, beingsubject to fall and winter frosts; fruit is injuredbelow 28° F.

Olives are normally propagated from cuttings,and show a remarkable ability to root fromcuttings of any size but tip cuttings. Sub-terminal cuttings, 4-5 in. long, are generallyused; remove all but the 2 terminal leaves. Hard-to-root varieties are treated with 4000 ppm(o.4%) indolebutyric acid (IBA) in 5o% alcoholfor 3o seconds; and planted in sharp sand withbottom heat. Older wood, tot in. in dia. willroot even more readily if the bottom 2 in aresoaked in a 13 ppm IBA solution for 24 hours,then buried in moist sawdust until callusedbefore planting in the cutting bed. Older andlarger branches may be planted directly in placeand will usually root. Slabs of the trunkplaced a few inches below the soil, with the barkside up, will usually send up shoots and root.Suckers are often found at the base of trees;these may be removed and planted.

Trees are sometimes produced by grafting;seeds are planted, usually after clipping the endoff; they germinate slowly. They may not beready to graft for a year. Grafting is by whip-graft or side graft. Trees are topworked by bark-grafting, usually in the spring. Trees ofthe varieties mentioned here are dwarfed some-what by grafting to certain clones.

Trees dug from the nursery row are usuallybare rooted, in which case all branches areremoved, and only a few leaves along a singlestem are left ; they are whitewashed after plant-ing. Trees in cans need only to have low water-sprout shoots removed.

Except in extremely sandy or shallow soilsthe planting hole need be only large enough totake the roots. Most varieties attain large sizeunder good conditions, and need a spacing ofabout 35 ft. for full development ; shorterdistances may be used if the trees are keptsmaller by consistent pruning.

During the first 2 years in the ground,olives are trained to 3-5-scaffold branches, wellspaced. Thereafter, pruning is normally limitedto removing unwanted growth, as it reducesyield. If the tree becomes too tall, it may betopped severely.

The Olive will grow on a wide variety of soils,including many that appear too poor for othertree species; water-logged soils should beavoided.

Olives grow and produce the best whensupplied with about as much water as otherevergreen trees. Nevertheless, they are amongthe most drought-resistant of all trees, butgrowth and fruiting will be greatly reducedwith restricted watering.

Olives are light users of nitrogen, andrespond to it only on relatively infertile soils.Even then, a pound of nitrogen per maturetree should be adequate. Potassium and borondeficiencies occasionally are seen. In the aridWest an application of 25 lbs. of potassiumsulfate should be applied; for boron apply about

lb. of borax; both treatments should lastseveral years. In the Southeast, completefertilizer applications will provide the neededpotassium; the boron applications will need tobe slightly greater, and may need to be repeatedevery year or two. For both deficiencies, yellow-ing of the leaves occurs. Potassium deficiencyleads to leaf-tip burn; boron deficiency to deathof shoot tips, and to death of the blossoms endof the fruit, a condition called Monkey-face.

The Olive flowers very profusely, the bloomdeveloping as several flowered inflorescences inthe axils of the alternate leaves. Enough maydevelop that the Olive bears more flowers thanalmost any other fruiting tree, but a highpercentage of these are normally female sterile.In any case, less than 1% set will result in aheavy crop. Cross-pollination is not usuallyneeded, but may increase set in cold springs.

Excess set results in small fruit, and increasesto alternate bearing. Spraying 20 to 28 days after full bloom with naphthaleneacetic acid, 125ppm in water containing II% light summer oil,will thin the fruit adequately in most years,although there is some danger of over-thinning,and occasionally the spray is not effective.Reducing the crop load to 3 or 4 fruits per footof shoot by hand is also effective, but verytedious.

For home use, olives will be harvested forpickling only. For this purpose, they are pickedas they turn from green to straw or pink color.A simple and effective home pickling recipe is:Soak the fruit overnight in water; replace thewater with a 2% concentrated lye solution pergal. of water, leaving it until the flesh colorchange shows that the lye has penetrated to ornearly to the pit. Replace the lye with water,leaving for 3 or 4 days, with daily or morefrequent water changes until the lye is all re-moved. Replace the last wash solution with asolution of 3 oz. of salt per gal. For storage ofmore than a few days, gradually increase thestrength of the salt solution in increments of 3oz. per gal. every other day until a final solutionof 12 oz. per gal. of water is used. Change thissolution about every 3 weeks until the olives areused. From this strong solution, remove olivesas needed and soak in fresh water for a fewhours before use.

The varieties of Olive differ primarily in sizeand oil content, which varies from lo-3o70.Small varieties are 'Mission' and `Manzanillo';large varieties are `Ascolano' and `Sevillano'.

Scales of several kinds attack Olive; 1+-2%summer oil sprays are recommended for controlin general in the summer. Peacock spot, a fun-gus disease, is controlled with Bordeaux spray(which see), 5-10-100 being sufficient strength.Shoots affected with Olive knot, a bacterialdisease, should he cut out, using care not tospread the organism with the pruning imple-ments. Verticillium wilt attacks olives; do notplant where susceptible annual crops have beengrowing, as tomatoes, potatoes, cotton andmelons. Nematodes are known to attack oliveroots.

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