About the Potato Atlas Archives...
The first World Potato Atlas was developed at the International Potato Center (Centro Internacional de la Papa, or CIP) in the 1980s and maintained for several years -- primarily by Robert Rhoades, Robert Hijmans, and Luisa Huaccho -- to provide country-specific information about potato production, constraints, and uses. A newer version of the atlas, providing updated and more detailed information of a limited selection of countries, was initiated in 2006.
The "atlas archives" included here are based on chapters of the original effort which so far have not been substantially updated. Although some of this information is clearly obsolete, some remains relevant, at least for historical background.
HISTORY AND OVERVIEW
Potatoes were well established in contemporary Zimbabwe by the early twentieth century. In 1911, variety trials were undertaken with recorded yields up to 11.5 tons per hectare (t/ha) (Joyce, 1988). In 1956, a breeding program was started which has since expanded to meet the country's seed requirements. Since the 1960s, only the national breeding program has been authorized to import potatoes under rigid quarantine procedures, and then only for breeding and evaluation purposes (Joyce, 1982b).
Zimbabwe's emphasis on breeding and seed production stems largely from the need to avoid the introduction of pests through imported seed potatoes that might threaten tobacco production, a very signficant cash cropfor the country (Joyce, 1988, 1982a, 1982b). Since its inception, the breeding program has produced 400 potential varieties, 70 of which have been evaluated in variety trials, and 12 of which have been distributed to commercial producers (Joyce, 1988). In 1975 CIP began supplying true seed to the national breeding program (Joyce, 1982a). Joyce (1988) reports average yields of 15 t/ha, up from six t/ha in 1970, attributed primarily to the success of the national breeding program (Joyce 1988, 1982).
GEOGRAPHY AND PRODUCTION ZONES
Potatoes are generally grown at elevations above 1,200 meters above sea level (masl).
Two ecological zones can be distinguished:
- Seed production (class AA) and breeding activities are concentrated in the eastern highlands, at elevations above 1,800 masl. Climatic data for Inyanga Experimental Station are roughly representative. Average annual precipitation is 1,120 mm, most of which falls from November to March. Mean daily maximum temperatures range from 16.0° C in July to 22.6 °C in October, with mean daily minimums from 5.5° C in July to 13.0° C in January (Joyce, 1982b).
- Ware potatoes and class A seed are mainly grown in highveld areas with elevations of 1,200-1,800 masl. Harare provides an example of climatic conditions in these areas. Mean annual rainfall is 815 millimeters (mm). Mean daily maximum temperatures range from 20.8° C in June to 27.9° C in October. Mean daily minimum temperatures vary from 6.3° C in July to 15.7° C in January (Joyce, 1982b).
PRODUCTION SYSTEMS AND CONSTRAINTS
In the eastern highland seed producing areas, one crop is produced each year. Planting occurs after the onset of the spring rains, usually in mid November, but as early as September and as late as mid-December depending on local conditions. Harvest takes place from March to July, cool temperatures and lack of rainfall permitting extended harvests (Joyce, 1982b).
In the highveld areas, three crops are grown each year. The summer crop corresponds to the single season described above for the eastern highlands, although supplementary irrigation is common where available. This crop is planted with the spring rains in early November and lifted in March/April.
Two additional crops are grown under irrigation:
- The first irrigated crop is planted before the end of the rainy season in February/March, but must be irrigated from April or May until harvest in June/July.
- Planting of the second irrigated crop takes place in the middle of the dry season in July/August, with harvest in November/December sometimes hampered by wet condition due to the onset of the rainy season (Joyce, 1982a, 1982b).
Commercial potato farming in Zimbabwe is capital intensive, with a high degree of dependence on purchased inputs. Production cost are very high, reaching $3,000/ha or more (Rhoades, 1984). As a precaution against eelworms, seed potatoes are grown in a six-year rotation, four years of weeping love grass followed by two years of a single variety of potatoes. Land preparation, including plowing, ridging, and (where necessary) liming, commonly starts a full year before planting. Shortly after the first rains, two t/ha of NPK 6:17:6 is applied in the furrows and lightly covered with soil. This is followed immediately by setting seed tubers 40 centimeters (cm) apart along rows spaced 0.9 meters. Spraying for aphids, tuber moths, and other pests begins shortly after emergence and is repeated weekly until the haulms are cut. Two ridgings are done by hand: the first when the plants are 20-25 cm tall, and the second about two weeks later. Throughout the growing season, the crop is inspected and off- type plants rogued immediately (Joyce, 1982b). Yields at Inyanga Research Station consistently exceed 50 t/ha (Joyce, 1984 and 1982a).
Ware producers in the highveld typically space plants about 30 cm along rows 90 cm apart for a density of about 37,000 plants/ha. Fertilizer rates are typically the same as in the eastern highlands, but without the top dressing. Warmer growing conditions, nearly year-round production, and the absence of isolation from other solanaceous crops increase the risk of virus infection. Spraying for blight, aphids, and tuber moths is done about once every ten days (Joyce, 1982a). Commercial yields average around 17 t/ha (Joyce, 1984 and 1982a).
Disease and Pest Constraints
Late blight (Phytophthora infestans) is a problem, particularly during the summer ware crop in the highveld. It is generally controlled by regular fungicide applications (Joyce, 1982a).
Viral diseases include PVY, PVX, PVS, and PVM. In the highveld, viral infection can reach 30 percent (Joyce, 1982b). However, the regular production and distribution of virus-free seed has reduced the level of virus infection considerably, including the virtual elimination of leaf roll (Joyce, 1982a).
Insect pests include aphids and tuber moths, although the availability of pesticides has so far limited their impact, at least on commercial production (Joyce, 1982a).
Baboons are a serious threat to potato production in Zimbabwe. Since 1973, when baboons wiped out its entire seed crop, Inyanga Station has had to post a 24-hour guard at considerable expense (Rhoades, 1984).
VARIETIES AND SEED SYSTEMS
Four varieties are grown commercially:
- Amethyst, a locally bred variety, occupying the greatest area;
- B.P.1, originally from South Africa;
- Montclare, another locally developed variety;
- Pimpernel, a yellow fleshed variety originally from Holland, grown under contract for crisp (potato chip) manufacturers.
Up-to-Date (U.K.) was evaluated in the first variety trials in 1911/1912 and in all subsequent trials. Though phased out of commercial production as of 1982, it continues to be used as a standard in variety trials. (Joyce, 1988 and 1984).
As noted above, virtually all seed tubers planted in Zimbabwe are produced in the country. After testing by the breeding program, virus-free seed tubers are distributed to certified contract farmers in the eastern highlands who carry out four bulkings (foundation seed through AA3). Seed growing areas must be completely free of other solanaceous plants, and contract farmers are restricted from growing even a small crop of ware potatoes for home consumption. AA3 seed is distributed to farmers in the highveld areas, who bulk it once to produce A1 seed for ware production (Joyce, 1982b).
CONSUMPTION, STORAGE, AND MARKETING
Even though only aggregate information is presently available, potato consumption is certainly not distributed evenly across the geographic regions or social classes of Zimbabwe. As in other African countries, consumption is concentrated among upper income city dwellers and people living in major producing areas. Many Zimbabweans enjoy the taste of potatoes, boiling them in their skins when available, but cannot regularly afford them (Rhoades, 1984). FAO (1986) estimates for Zimbabwe show a total availability of 22,000 tons of potatoes in 1984 of which 88 percent was utilized for human consumption, 7 percent for seed, and the remaining 5 percent was wasted. Per capita consumption of potatoes in 1984 was only two kilograms, about 0.2% of caloric intake (FAO, 1986).
In contrast to most developing countries, storage of seed and ware potatoes in Zimbabwe is remarkably, perhaps uniquely, unproblematic. In the eastern highlands, cool temperatures, dry soils, and isolation from viruses allow harvest of AA seed to be spread out from March to July without loss of yield or seed quality. The tubers are stored in well ventilated sheds without refrigeration, allowing rising temperatures in August and September to break dormancy. Such tubers are well-sprouted and in excellent condition for planting in November (Joyce, 1982b). With year round production, ware potatoes spend little time in storage (Joyce, 1984).
Marketing of potatoes is free from government controls other than a small tax levied on the sale of ware potatoes. Large-scale farmers belong to a marketing organization through which they sell their crop to private wholesalers. The five major wholesalers set prices once a week. Retailers sell potatoes in 15 kg paper sacks. In 1984, the going price for a 15 kg bag of first grade ware potatoes was about Z$3.50, and 30 kg of AA certified seed tubers went for Z$15.00 (Joyce, 1984). No information is available on informal distribution of seed or ware potatoes among small farmers (Joyce, 1984).
FAO 1986. Basic Data Unit, Production Account, Unpublished May 1986 Update.
Joyce, M.J., 1988. Potato Varietal Development Programme in Zimbabwe. Paper Presented at the Regional Seed Potato Workshop, Harare, Zimbabwe, 22-27 February 1988.
Joyce, M.J., 1984. Country Presentation: Zimbabwe. Country Report Presented at the Regional Post- Harvest Workshop, 18-22 June 1984, Nairobi, Kenya. International Potato Center, Region III.
Joyce, M.J., 1982a. Potato Production in Zimbabwe. In: S. Nganga (Ed.), Potato Development and Transfer of Technology in Tropical Africa. International Potato Center, Addis Ababa.
Joyce, M.J., 1982b. Some Aspects of Seed Potato Production in Zimbabwe. International Potato Course: Production, Storage, and Seed Technology. Report of Participants. International Agricultural Center, Wageningen, The Netherlands.
Rhoades, R. 1984. Notes on Potato Production in Zimbabwe. Unpublished Manuscript.
Van Buren, L., 1988. Zimbabwe: Economy. In: Africa South of the Sahara 1987, 17th edition. London: Europe.