SPECIES ACCOUNTS

Pineapplesgrow in a relatively wide rangeof climates darker green, and its growth habit is also erect. Flowers and soils and are raised for home consumptionin many are lilac. Tubers are oblong, with smooth pink skins; the parts of CostaRica. The plant does not tolerate freezing eyes are deeper than those of atzimba. Unlike many or long periodsof drought,but it can grow well in partial North American and European varieties, flowering is shade.Fertilization increasesyields but is oftenunneces- abundant in both these varieties. sary in fertile volcanic soils. The plant may also be able In , as in other Central American countries, to absorbnutrients from the rainwaterthat collects in the potatoes are cultivated on less than 1% of the total crop- axils of the leavesand in the centerof the rosette. land. However, in Province, potato cultivation is The major pests are nematodes,which can cause one of the most important agricultural activities and pro- severedamage. Mealy bugs,scale insects, and mites may vides work and income for a considerable sector of the also reduceyields. Variousfungal diseasescause rotting rural population. of the leaves, base,and fruit (Hayes 1960). In 1976 it was estimated that 3,000 ha of potatoes were The fruit is high in water contentand in sugars(8 to planted, with a total production of approximately 50,000 15%).Maturity is indicatedby the outsidecolor. Experi- metric tons, of which 98% was produced in Cartago,Province. enced buyers can also detect watery or overripe pine- Most potatoes are grown on the slopes of the applesby thumping them and listening to the sound. Iraz11volcano (fig. 6.17b), between 1,400 and 3,000 m, where the climate is cool and humid with only a brief (2-4 months) dry season. Other potato areas are found in Food and Agriculture Organization(FAO). 1978. Pro- Province, in , and on the slopes of the duction yearbook,1977. Rome: FAO. Thrrialba volcano. The concentration of potato culti- Hayes,W. B. 1960. Fruit growing in India. 3d ~. Al- vation in a relatively small area of the Central Valley is lahabad:Kitabistan. due to climatic and soil factors as well as to tradition and LeOn,J. 1%8. Fundamentosbotanicos de los cultivos the proximity of markets in the metropolitan area of San tropicales.San Jose:lnstituto lnteramericanode Cien- Jose. cias Agricolas de la OEA. Growing seasons depend not only upon climate, but Padilla, V. 1973. Bromeliads.New York: Crown. also upon altitude. The east-facing slopes of the Irazu volcano, around , and the Thrrialba volcano, are Potatoes (Papas) influenced by the Atlantic and are generally wetter. South- and west-facing slopes of the Irazu volcano M. T. Jackson (Llano Grande, 1ierra Blanca, Cot, ) and Thepotato (Solanumtuberosum) is a memberof the fam- other areas of the Central Valley are influenced by the Solanaceae,as are tomato, pepper,eggplant, and to- Pacific climatic regime and have a dry season from Jan- Unlike other solanaceouscrops, potatoes re- uary to April. sexuallyand asexually,although at present Between 1,400 m and 2,000 m (Cartago to Potrero Cerrado), planting is done in May and the crop matures .The life of in approximately 3.5 months. From Potrero Cerrado tl;} potato plant begins with the Initiation of a San Juan de Chicua (2,000 m to 2,800 m) the main on a stolon of the mother plant. The tuber is an seasonis from April to October, with the crop harvested J. , much enlarged and modified as a food after 4 months. Above 2,800 m, the duration of the ., with minute scalelike leaves and buds or growing cycle is approximately 5 to 6 months, owing to ," Stolons are underground stems that can become lower temperatures and lower light intensity caused by " -they reach the surface of the soil. Thbers almost continuous cloud cover. However, the presence of as swellings between the terminal bud and the clouds, and consequently humidity, allows the crop to be expanding internode of the stolon. Potato planted here as early as February or March. .The typical inflo- Much of potato cultivation is on steep slopes, and is a terminal cyme, borne on a peduncle of consequently mechanization is used only for land prepa- depending upon the variety. ration before planting where this is possible. Oxen are Rica two varieties are commonly grown, at- commonly utilized for planting, as well as hand labor. rosita, although the former represents about Distances between rows are generally 70-80 cm, but potatoes produced. Atzimba has large light distances between plants vary depending upon whether the crop is for seed production or ware production (i.e., are white (fig. 6.17a). The tubers are ob- for consumption). A distance of 30 cm is generally used ~ -,' white skins and a yellowish flesh; the to produce ware potatoes. Approximately 2 metric tons medium depth. The foliage of rosita is a of seed potatoes (size 40-60 g) are needed to plant one

103 FIGURE6.17. Solanumtuberosum. a, Flowers and leaves.b, Field in full flower. Above Cartago, Costa Rica (photos,D. H. Janzen). hectare. Seed potatoes are produced at the highest el- CostaRica two factors-dIe widespreadcultivation of evations on the Irazu volcano becauseinsect vectors of dIis one variety and local climatic conditions-have con- virus diseases,as well as wilt-causing bacteria,are less tributed to dIe selection of physiological races of dIe prevalentthere. padIogendIat overcomedIe geneticresistance of dIe va- Potatoesare grown on ridges to give sufficient room riety. Conditions on manyparts of dIe Irazu volcano are for the newtubers and to leavea layerof soil abovethem. ideal for sporulationof dIe fungus,and weeklyfungicide Sucha layer helps to preventgreen tubers and infection sprayingis necessary.Early blight, causedby Alternaria by various pathogens.Planting depthsvary accordingto solani (Ell. andG. Martin) Sor., is of lessimportance and area, variety, and growing season.Fertilizers and soil is controlled by dIe samefungicides as late blight. Stem insecticidesand fungicides are applied in the bottom of c~r, causedby Rhizoctoniasolani Kuhn, is presentin the furrow at planting. Thbers are then placed in the manysoils becauseit is easilydisseminated on tubers. It furrow and covered with soil to form a small ridge. A causesconsiderable damage to emergingsprouts when layer of loose soil is addedto the ridge when plants are dIe soil is cold and wet. 20-40 cm high. Weedgrowth is also controlled by ridg- Two important bacterialdiseases of potato-bacterial ing, carried out by hand or with a ridging implement wilt, causedby Pseudomonassolanacearum E. F. Smidt, pulled by oxen. and blackleg, causedby Erwinia carotovoravar. atro- The potato is subject to many diseasesand pests in septica (Van Hall) Dye-are found in Costa Rica. The Costa Rica, and without the efficient use of fungicides former is found below 2,220 m and can persistin dIe soil and insecticidesit is i~possible to cultivate potatoessuc- for manyyears. Only rotations,including pasturegrass- cessfully.The major fungal disease,late blight, is caused es, and dIe use of healdIy seedreduce dIe severity of by Phytophthorainfestans (Mont.) De Bary. Atzimba was attack. Blackleg is a serious problem at altitudes over originally bred in Mexico for resistanceto late blight. In 2,500 m. It is carried on dIe surfaceof dIe seedtuber and

104 SPECIES ACCOUNTS causesa g~neral yellowing and wilting of the plant creasesas leaves develop on the main stem; the max- througha rotting of the stems,which eventuallymay pass imum numberproduced coincides with plant anthesis. to the tubers. llllers become independentfrom the parent stem once There are many virus diseasesof the potato, of which they developthree leavesand four or five roots of their PLRV (potato leafroll virus), PYX, PVY, and PVS are own. With sufficient sun and water and proper tem- the most important. Virusesare especiallyimportant in perature,the capacity to tiller dependson nitrogen and seedproduction, since they causea degenerationof po- phosphorusconcentrations in the soil. Active tillering, tato varieties-that is, a reduction in vigor, cropping importantto crop yields, requiresmore than 3.5% nitro- capacity,and diseaseresistance over a period of time if gen and more than 0.25% phosphorusin the soil. tubersfrom a diseasedcrop areused as seedfor the next. At anthesisone flower is borneon eachspikelet, devel- PLRV is prevalentin CostaRica, and it is estimatedthat oping laterally from the mainpanicle. An optimumtem- 95% of all potatoes are infected with the virus. It is perature for pollination and fertilization is 31-320 C. transmittedby aphids,principally the greenpeach aphid, Fertilizationsuccess is high if thereis sufficientmoisture; Myzuspersicae Sulzer, and consequentlyseed tubers are if a drought or low temperaturesoccur during this time, producedin isolated areas,generally at the highestalti- crop yields can be severelyreduced. tudes,where insect vectors are uncommon. PLRV can The rice grain is rather invariant in size, unlike grains causeyield reductions of up to 90%. In combination, of wheatand barley, in that the inner and outer ',glumes PVY and PYX can also causesevere yield reductions. containing the developing grain do not expandbeyond A numberof insect pests are common in all potato- the size of glume, which assumesmaximum size approx- producingareas. The most importantare the two species imately five days before anthesis.Thus rice yields are of tubermoth, Phthorimaeaopernlella Zeller and Scrobi- muchmore closelyrelated to numbersof tillers, panicles, balpopsissolanivora Povolni. These insects attack both and spikeletsthan to individual grain size. the foliage and the developingtubers. Phthorimaealar- Details on the origin of rice, the basic food plant of vae often burrow throughthe stemsto the tubers, but it SoutheastAsia, remainmore obscurethan for othergrain is more common for the female to lay her eggs on ex- crops in spite of its agricultural importance.It definitely posedtubers, as with Scrobibalpopsis.The damagedone existed as early as 5000 or 3500B.C. in Thailand, but its by both moths is considerable,rendering tubers un- origins could date back much farther. From China, rice marketable. was introducedto Japanand to Europeduring the second Riceand beans are the staplefoods in CostaRica, and '--, .". ..Because of century B.C. Rice was broughtto the New World soon after the SpanishConquest. costs, it remainsexpensIve and is not a Oryza sativa, the primary speciesused in world rice the diet of the rural poor, despiteits high production,is grown principally in the provincesof Gua- value. Mostpotatoes are sold fresh at harvest,as nacasteand on the Pacific side of CostaRica. warepotato storagefacilities in the country. In the 1950sGuanacaste Province produced more than portion of the crop is processed,mainly to 50% of the country's rice. However, there were often chips and frozen french fries. severe drought years in that province. During those researchin CostaRica is concernedwith de- times, imports of rice were necessary,causing price in- virus-resistantvarieties, produc- creases.In the 1960srice productionextended southward seedpotatoes, and adaptingpotatoes to hot, along the Pacific Coastat siteswhere conditions allowed With the developmentof adaptedvari- the production of dry rice. (Only about 10% of rice pro- genetic resistanceto various pests and dis- ducedin CostaRica comesfrom paddy or wetland meth- potato has the potential to become a more ods of production). By 1968Puntarenas Province, south the diet of a larger proportion of of GuanacasteProvince, produced50% of CostaRica's Ricanpopulation. rice. Although in CostaRica rice is secondonly to coffee productionin terms of areaunder cultivation (63,000 ha versus 82,000 ha), rice is produced for domestic use rather than being an export crop. In fact, rice is often imported to Costa Rica to supplementdomestic pro- 6.18), the secondmost important crop grown " "- ~ .-. duction. Most use rice and beans, either sepa- .At genninationa seminal root forms, rately or combined in a dish called gallo pinto, at every secondaryroot developmentoccurs at stem meal. Breakfastusually is gallo pinto; lunch and supper tillers begin fonning after the plant has consistof beansand rice served separately,along with or five leaves.The number of tillers in- fried plantainsand possiblya piece of meat or a vegeta-

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