Planting Dates

Planting Dates

Cultivation of the Date Palm (Phoenixdactylifera) has been practiced since prehistorictimes and seems to carry an aura of mystery andromance, probably abetted by the unfamiliardesert locale of all major date-producing areas.Where it is grown extensively, the Date is often aprimary food. In the United States it is an exoticplant whose requirements restrict its growth forfruit production to very limited areas of the lowdeserts of southeastern Calif. and parts of Ariz.

The Date is a true subtropical plant, grownnowhere in the tropics. Its requirement for heatand freedom from rain or high humidities duringmost of the fruit development period are theprimary limitations. The trees will withstandtemperature down to 20° F. without injury.Below 20° F. the fronds may be badly injured orkilled, but the terminal growing point isseldom killed at temperatures as low as 8° to io°F. However, where normally grown, such lowtemperatures are due to intense radiationfrosts and are of very short duration; the bud isprotected by the insulation of the envelopingleaf-bases. Continuous cold below 20° F. wouldbe expected to be fatal. Rain and even highhumidities result in cracking and checking ofthe fruit at almost all stages of development andis the prime reason that dates are not adapted tothe South and southeastern states. If fruit is notwanted, male or female palms may be grown faroutside the range for fruit production--in thesoutheastern states wherever oranges are grown,and at latitudes to nearly 40° N. in inland valleysof the Pacific Coast.

To mature fruit, average growing tempera-tures for the period a month before bloom tofruit ripening must be at least 70° F. for the veryearliest maturing varieties to 90° F. for latevarieties. Extremely high daytime temperaturesare not essential, but do prevail in the desertregions where such average temperatures areattained.

Palms are easily grown from seed, whichshould be planted an inch deep in a good seedbed. Fruit of seedlings will be much poorer thanfrom varieties, and as Date Palms are dioecious,about half of such seedlings will be male.

Propagation of palm varieties is by 4-5-year-old offshoots—lateral growth that develop onthe base of young palms. Those near the groundwill be with roots, those above ground without.Rooted offshoots are cut from the mother palmand planted immediately in the location desired,in a site prepared well in advance by digging ahole about 3 ft. across and t ft. to 18 in. deep,filled with well firmed topsoil, which should befertile and settled at planting. Unrooted off-shoots may be planted under shade; manywill fail to root. Offshoots have their leavescut back to 3-4 ft. long and tied together.They are usually protected by wrapping withpaper or old palm fronds, especially during thefirst winter, when they are more tender to lowtemperatures. Newly planted offshoots shouldbe watered frequently, or mulched, so that thesoil near the surface does not dry out.

Natural pollination of dates is seldomsufficient to yield good crops, even when a highproportion of male palms are present. Pollina-tion is by hand. Male inflorescences are takenwhen they are just emerging from the spathe.Two or three strands of male flowers are in-serted in an inverted position into the emergingfemale inflorescence, which has just been cutback about one-third, and sometimes has hadthe inner whorl or two of female floweringstrands removed (thinning). The bunch is tied atthe distal end to retain the male strands, but thetie will need to be loosened periodically as thefruit grows. Alternatively, the male flowers maybe allowed to shed their pollen on paper; it iscollected and small balls of cotton dipped intoit. Two of these balls are inserted into the femaleinflorescence, as described above.

At flowering the female inflorescence isrelatively short and upright. It soon grows inlength rather remarkably, and the weight of thedeveloping fruit bends it over. For best resultsthe inflorescence is brought through the leafbases as it grows, until it hangs in an invertedposition below the leaves ; often the bunch stemis tied to a leaf base to prevent the weight of thefruit from breaking it. The distal bunch tie isthen removed.

About midseason or a little later an invertedcone of kraft or similar paper is often tiedaround the bunch, with the wide end open toassist air circulation. This tends to protect theripening dates from birds and rain.

Palms are planted at distances of 25-3o ft.,the former being used for a few of the smallerkinds such as ,Khadrawy'. They are not sensitiveto soil conditions, and do well in heavy-to-sandysoils of moderate depth. They are tolerant ofbrackish water and soils with relatively high saltcontent, but do better in fertile soils and goodwater. They require little nitrogen fertilization;observations on their requirement for otherfertilizer elements and micro-nutrients arelacking.

Date palms use large amounts of water,especially in the areas where they are commonlygrown. The high transpiration rate may be anadaptive feature to hold plant tissue tempera-tures down, for the temperature of the body ofthe palm is usually about the same as that of thesoil below the depth heated in the daytime.

Drought conditions will stop growth and aredetrimental to fruit development.

Pruning of date palms consists of cutting offold fronds which are beginning to die, asindicated by browning of the leaf pinnaetoward the tip of the frond. It is usually done inlate summer. Normally 8o to too mature leavesare maintained in the crown, which are enoughto mature 8 to 12 bunches of dates and stillinsure return bloom the following year. Thesharp thorns at the base of the leaves are usuallyremoved, primarily to assist in the pollinationand harvesting procedures. Besides the thinningof the fruit clusters described, bunches in excessof 8-12 are removed when or soon after theyappear, as the palm can set more fruit than itcan mature properly, and excess fruit productionin t year will drastically reduce that in the next.

Dates of commerce are all fully mature; a fewvarieties, such as `Barbee' which lose astringencyearly, can be used at earlier stages. Such useeffectively reduces the heat requirement andextends the area where they can be grown forgarden use. When they reach the full khalal(pre-ripe) stage, as indicated by the fruitturning pink, yellow, or red, they may beharvested, allowed to soften naturally and thenused. When full ripe, the tamar stage, thefruits are light to dark brown and begin towrinkle. Not all fruit on a bunch ripens at thesame time; for best quality multiple pickings aretherefore necessary. If some fruit is in the latekhalal or rutab (soft-tip) stage it may beripened off the tree by holding the fruit, wellspread out, at temperatures from 8o° to 95° F.,the higher temperatures being used for the lessmature fruit. Ripe or ripened fruit may beheld for long periods in cold storage; forseveral months at 30° to 32° F. and a year ormore at o° F. Curing temperatures for immaturefruit should not be extended beyond the timenecessary, for high temperatures accelerate theinversion of sucrose, so that the dates may be-come syrupy, and sugar crystalization takesplace later, but not if held at o° F.

Each producing area of the world hasvarieties particularly suited to it. Those foundbest in the United States are listed below. Datevarieties are divided into three classes: dry dates(see `Thoory'), semidry (see `Zahidi' and`Deglet Noor'), and soft. The latter are usuallyconsidered to have the best quality; semidryvarieties are commonest in commerce becausethey are best adapted to handling and packaging.

`Deglet Noor', a semidry type is the leadingvariety in the United States, and is the onemost often found in the market. It is relativelylate maturing (for the warmest areas) and thepalm is vigorous and large. `Zahidi' is anothersemidry variety of good quality.

`Thoory', a dry date, is seldom found in thiscountry; although favorites in the Near East,the dry dates have not become popular in theUnited States.

`Halawy', `Barhee', `Khadrawy', `Medjhooll'and `Saidy' are soft dates, which differ in size,shape and mature color, but all are of excellentquality. 'Barhee' is an early-maturing variety.The soft dates tend to pack and stick together incommercial handling, and are more subject tofruit rots, so although of higher quality than thesemidry types are generally limited to specialtyand local markets. These kinds have theirsugar primarily as glucose and fructose,whereas the sugar of the dry types is mostlysucrose. The semidry types are intermediate andthe proportion of the 2 types of sugars isaffected materially by the time of harvest andthe handling given after harvest. For the highestpercentage sucrose they should be harvested assoon as ripe and stored as soon as possible.

Growing date palms for their fruits is anexacting art; as the palms become older themany manipulations become more difficultbecause of the height of the crown. qthadrawy'is a variety which grows somewhat more slowly.There is, of course, no way to hold palms low.

Mealybugs and scale insects infest theleaves and suckers and are controlled by theusual sprays of insecticide #44 or #45 in thecooler weather and by # 15 in the growingseason Diseases

Heart rot turns the heart of the palm blackand the buds and new growth are curled andstunted. Avoid planting suckers from infectedplants. Use of fungicides is impractical.

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