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The Future World Food Situation and the Role of Plant Diseases1

Pinstrup-Andersen, P. 2001. The Future World Food Situation and the Role of Plant Diseases. The Plant Health Instructor.  DOI: 10.1094/PHI-I-2001-0425-01.

Dr. Per Pinstrup-Andersen 2
Director General
International Food Policy Research Institute
Washington, DC

It is an honor and a pleasure to present this lecture in memory of Glenn Anderson. Dr. Anderson's contributions to the world's wheat production are well known. Millions of small farmers and low-income consumers in South Asia and elsewhere benefitted from his work. The food supply situation I will be discussing in this paper would have been different without the successful efforts by Glenn and his teams.

The doubling of grain production and tripling of livestock production since the early 1960s has resulted in a global food supply sufficient to provide adequate energy and protein for all. However, about 820 million people lack access to sufficient food to lead healthy and productive lives and around 170 million children are seriously underweight for their age. At the close of the twentieth century, astonishing advances in agricultural productivity and human ingenuity have not yet translated into a world free of hunger and malnutrition.

What are the prospects for global food security in the twenty-first century? Will there be enough food to meet the needs of current and future generations? Can, and will, global food security be attained or will food surpluses continue to co-exist with widespread hunger and malnutrition?


Worldwide, per capita availability of food is projected to increase around 7 percent between 1993 and 2020, from about 2,700 calories per person per day in 1993 to about 2,900 calories.3 Increases in average per capita food availability are expected in all major regions. China and East Asia are projected to experience the largest increase, and West Asia and North Africa the smallest (Figure 1). The projected average availability of about 2,300 calories per person per day in Sub-Saharan Africa is just barely above the minimum required for a healthy and productive life. Since available food is not equally distributed to all, a large proportion of the region's population is likely to have access to less food than needed.

Demand for food is influenced by a number of forces, including population growth, income levels, urbanization, lifestyles, and preferences. Almost 80 million people are likely to be added to the world's population each year during the next quarter century, increasing world population by 35 percent from 5.7 billion in 1995 to 7.7 billion by 2020 ( UN 1996). More than 95 percent of the population increase is expected in developing countries, whose share of global population is projected to increase from 79 percent in 1995 to 84 percent in 2020. Over this period, the absolute population increase will be highest in Asia, but the relative increase will be greatest in Sub-Saharan Africa, where the population is expected to increase by 80 percent by 2020 in spite of the severe impact of HIV/AIDS (Figure 2).

At the same time, urbanization will contribute to changes in the types of food demanded. Much of the population increase in developing countries is expected in the cities; the developing world's urban population is projected to double over the next quarter century to 3.6 billion ( UN 1995) (Figure 3). Urbanization profoundly affects dietary and food demand patterns: the increasing opportunity cost of women's time, changes in food preferences caused by changing lifestyles, and changes in relative prices associated with rural-urban migration lead to more diversified diets with shifts from basic staples such as sorghum, millet, and maize to other cereals such as rice and wheat that require less preparation and to livestock products, fruits, vegetables, and processed foods.

People's access to food depends on income. Currently, more than 1.3 billion people are absolutely poor, with incomes of a dollar a day or less per person, while another 2 billion people are only marginally better off ( World Bank 1997a). Income growth rates have varied considerably between regions in recent years, with Sub-Saharan Africa and West Asia and North Africa struggling with negative growth rates while East Asia was experiencing annual growth rates exceeding 7 percent ( World Bank 1997b). Prospects for economic growth during the next quarter century appear favorable, with global income growth projected to average 2.7 percent per year between 1993 and 2020 (Figure 4). The projected income growth rates for developing countries as a group are almost double those for developed countries. Growth rates are projected to be lowest in Eastern Europe and the former Soviet Union. Even Sub-Saharan Africa is expected to experience positive per capita income growth between 1993 and 2020, although it will be quite low. However, unless significant and fundamental changes occur in many developing countries, disparities in income levels and growth rates both between and within countries are likely to persist, and poverty is likely to remain entrenched in South Asia and Latin America and to increase considerably in Sub-Saharan Africa.

The International Food Policy Research Institute (IFPRI) projects global demand for cereals to increase by 41 percent between 1993 and 2020 to reach 2,490 million metric tons, for meat demand to increase by 63 percent to 306 million tons, and for roots and tubers demand to increase by 40 percent to 855 million tons (Figure 5).4 

Developing countries will drive increases in world food demand. With an expected 40 percent population increase and an average annual income growth rate of 4.3 percent, developing countries are projected to account for most of the increase in global demand for cereals and meat products between 1993 and 2020 (Figure 6).

Demand for cereals for feeding livestock will increase considerably in importance in coming decades, especially in developing countries, in response to strong demand for livestock products. Between 1993 and 2020, developing countries' demand for cereals for animal feed is projected to double while demand for cereals for food for direct human consumption is projected to increase by 47 percent (Figure 7). By 2020, 24 percent of the cereal demand in developing countries will be for feed, compared with 19 percent in 1993. However, in absolute terms, the increase in cereal demand for food will be higher than for feed. In developed countries, the increase in cereal demand for feed will outstrip the increase in cereal demand for food in both absolute and relative terms.

How will the expected increases in cereal demand be met? Primarily by productivity increases; increases in cultivated area will contribute less than 20 percent of the increase in global cereal production between 1993 and 2020 (Figure 8). Most of the growth in cereal area will be concentrated in the relatively low productivity cereals in Sub-Saharan Africa. There will be some expansion in Latin America but cereal area will remain virtually stagnant in Asia. IFPRI projections show that in spite of the increasing feed demand, cereal prices will not increase in real terms over the next 20 years.

Since growth in cultivated areas is unlikely to contribute much to future production growth, the burden of meeting increased demand for cereal rests on improvements in crop yields. However, the annual increase in yields of the major cereals is projected to slow down during 1993–2020 in both developed and developing countries (Figure 9). This is worrisome given that yield growth rates were already on the decline. The two key reasons for reduced cereal yield growth rates are as follows: (1) in regions where input use is high, such as parts of Asia, farmers are approaching economically optimum yield levels, making it more difficult to sustain the same rates of yield gains; and (2) declining world cereal prices are causing farmers to switch from cereals to other, more profitable crops and are causing governments to slow their investment in agricultural research, irrigation, and other infrastructure. Efforts to reduce crop losses due to pest and diseases through resistant crop varieties, pesticides, and better cultural practices offer tremendous opportunities for increasing production.

With the projected slowdowns in area expansion and yield growth, cereal production in developing countries as a group is also forecast to slow to an annual rate of 1.5 percent during 1993–2020 compared with 2.3 percent during 1982–94. This figure is still higher, however, than the 1.0 percent annual rate of growth projected for developed countries during 1993–2020.

Food production will not keep pace with demand in developing countries and an increasing portion of the developing world's food consumption will have to be met by imports from the developed world. The proportion of cereal demand that is met through net imports is projected to rise from 9 percent in 1993 to 14 percent in 2020 (Figure 10). As a group, developing countries are projected to more than double their net imports of cereals (the difference between demand and production) between 1993 and 2020 (Figure 11). With the exception of Latin America, all major developing regions are projected to increase their net cereal imports: the quadrupling of Asia's net imports will be driven primarily by rapid income growth, while the 150 percent increase forecast for Sub-Saharan Africa will be driven primarily by its continued poor performance in food production. The United States is forecast to provide almost 60 percent of the cereal net imports of developing countries in 2020, the European Union about 16 percent, and Australia about 10 percent (Figure 12). IFPRI projections indicate that long-term trends in real food prices will be slightly falling (Figure 13).

With continued population growth, rapid income growth, and changes in lifestyles, demand for meat is projected to increase by 2.8 percent per year during 1993–2020 in developing countries and by 0.5 percent per year in developed countries. While per capita demand for cereals is projected to increase by only 8 percent, demand for meat will increase by 43 percent. The increase in per capita meat demand will be largest in China and smallest in South Asia; by 2020, Chinese per capita consumption of meat will be eight times that of South Asia (Figure 14). Meat production is expected to grow by 2.8 percent per year in developing countries during 1993–2020 (compared with 5.9 percent during 1982–94) and by 0.8 percent in developed countries (compared with 0.9 percent during 1982–94). Despite high rates of production growth, developing countries as a group are projected to increase their net meat imports 20-fold, reaching 11.5 million tons in 2020 (Figure 15). Latin America will continue to be a net exporter of meat, but Asia will switch from being a small net exporter to a large net importer.

Net imports are a reflection of the gap between production and market demand. The gap between food production and nutritional needs is likely to be even wider than that between production and demand, because many of the poor are priced out of the market, even at low food prices, and are unable to exercise their demand for needed food. The higher-income developing countries, notably those of East Asia, will be able to fill the gap between production and demand through commercial imports, but the poorer countries may be forced to allocate foreign exchange to other uses and thus might not be able to import food in needed quantities. It is the latter group of countries, including most of those in Sub-Saharan Africa and some in Asia, that will remain a challenge and require special assistance to avert widespread hunger and malnutrition.

While the above represent what we at IFPRI believe to be the most likely scenario, a number of factors that are difficult to predict will influence the future food situation. These include:

  • Increased grain price volatility;
  • Policy decisions and changes in lifestyles and incomes in China and India, the world's two most populous countries;
  • The impact of short-term weather patterns and long-term climate change;
  • Constraints imposed by water scarcity
  • Negative trends in fertilizer use;
  • Outcomes of ongoing globalization efforts, including the upcoming WTO trade negotiations;
  • Investments in agricultural research and the outcome of the current debate on the use of modern biotechnology for food and agriculture; and
  • A series of policy measures.

These factors are discussed elsewhere ( Pinstrup-Andersen, Pandya-Lorch, and Rosegrant 1997; Pinstrup-Andersen 1999) and only research and crop losses will be discussed here.


Our knowledge of global crop losses due to pests is very limited. There is consensus emerging about the need for integrated pest management (IPM), a general effort to reduce losses to pests without harmful side effects, if not about precisely how to achieve this.5 Knowledge gaps are a major constraint to advancing consensus and action. In the absence of comprehensive knowledge, disputes over costs, benefits, and the potential for harm of chemical pesticides easily become polarized.

Few governments in developing countries have systematic research and monitoring programs to generate the information needed to assess losses and their causes. Much of the data that does exist is based on a limited number of site-specific tests, often undertaken to assess the effectiveness of a particular pesticide over one season. There are also fragmentary data based on work by governments, nongovernmental organizations (NGOs), agricultural colleges, and the Consultative Group on International Agricultural Research (CGIAR). Not only is data collection limited, but there is not yet agreement on methods or models for extrapolating to regional, national, or international crop loss estimates. Many small farmers in developing countries do not maintain written records, especially if their production is primarily for their own consumption (Yudelman, Ratta, and Nygaard 1998).

Furthermore, pest infestations often coincide with climatic changes such as irregular rainfall, increased humidity, or drought, which in themselves may lower crop output. Pest outbreaks may have a devastating impact in a given year, but cause only marginal losses in other years (Yudelman, Ratta, and Nygaard 1998).

A comprehensive study of pest-induced crop losses to date was published by a team of German crop scientists in 1994, with support from the European Crop Protection Association (Orke et al. 1994). It covers eight crops that together occupy half the world's cropland, with harvests worth $300 billion in 1988–90. It does not cover some important developing country food crops, such as cassava, millet, and sorghum. The study found that pests accounted for preharvest losses of 42 percent of the potential value of output over 1988–90, with 15 percent attributable to insects and 13 percent each to weeds and pathogens. An additional 10 percent of the potential value was lost postharvest.

The breakdown of plant disease losses in monetary terms and percent by region and crop is shown in Tables 1 and 2. Losses due to plant diseases vary from 9.7 percent of the potential production (actual production plus total estimated losses) in North America to 15.7 percent in Africa. The largest losses are for rice and wheat, key developing country food crops.

Table 1—Estimated crop losses due to plant diseases by region, 1988–90


US$ in billion

Percent of potential production




Former Soviet Union



North America



Latin America









Source: Oerke et al. (1994).


Table 2—Estimated crop losses due to plant diseases by crop, 1988–90


US$ in billion

Percent of potential production













Source: Oerke et al. (1994).

These estimates should be taken only as a rough guide to the scope of the problem. Although more and better quality information is needed, these figures clearly indicate that for developing countries, losses are costly in terms of food security, foreign exchange requirements for food imports, and income losses to farmers and others whose livelihoods depend on agriculture.

Chemical pesticides have reduced crop losses in many situations, but even with a very substantial increase in pesticide use, the overall proportion of crop losses and the absolute value of these losses from pests appear to have increased over time. Despite this perverse relationship, an increase in pesticide use still appears to be profitable. Increased monoculture, reduced crop diversity and rotation, reduced tillage, and use of herbicides have all boosted yields, but have increased vulnerability to pests as well. Pests tend to develop resistance to pesticides, requiring higher use to sustain production (Oerke et al. 1994).

Inappropriate and excessive pesticide use have led to increased and unnecessary pest outbreaks and additional pest losses because of the inadvertent destruction of natural enemies of the pests, pest resistance, pest resurgence, and secondary pests. Ultimately, overuse of pesticides can reduce food production.


There is no consensus about the meaning of IPM.6 Understandings range from pesticide-free ecological agriculture to a range of efforts to use chemical pesticides more judiciously and usually as a last resort, in combination with other pest management approaches (hence the "integration"), with more careful scouting for pests and improved targeting of pesticides when they are used. There is consensus that indiscriminate, excessive, and inefficient use of pesticides exacts too high a toll in terms of human health, environmental safety, and ultimate diminishing returns to justify any short-term increases in farm income or food output.

Proponents with varying perspectives on chemicals agree that IPM must be science-based and economically viable for farmers. The emphasis is on anticipating pest problems and preventing them from reaching economically damaging levels. Strategies include:

  • Biological control, such as protecting, enhancing, and releasing pests' natural enemies, e.g., insects, nematodes, snails, or slugs;
  • Cultural practices, such as ecological landscaping to reduce field size and distance to habitats of natural enemies, erection of barriers, crop rotation, cover cropping, increased reliance on mechanical weed control, improved crop residue management, better water management, and improved pest monitoring;
  • Chemical, with less reliance on synthetics in favor of biopesticides or biochemical pesticides (pheromones, insect growth regulators, and hormones—naturally occurring chemicals that modify pest behavior and reproduction); and
  • Genetic, such as the use of naturally resistant varieties, new varieties bred for resistance, or transgenic varieties, as well as release of sterile pests to prevent reproduction.7


Public investment in agricultural research is crucial to reduce losses due to plant diseases and other pests and for achieving future food security. The private sector is unlikely to undertake much of the research needed by small farmers in developing countries because it cannot expect to recuperate sufficient economic gains to cover costs. Benefits to society from such research can be extremely large but will be obtained only if the public sector makes the research investments. Currently, low-income developing countries grossly underinvest in agricultural research aimed at solving small farmers' problems. These countries invest less than half of 1 percent of the value of their agricultural production as compared to 2 percent by higher-income countries (Figure 16) (Pardey and Alston 1996).

Continued low productivity in agriculture not only contributes to food gaps in poor countries, but also prevents attainment of the broad-based income growth and lower unit costs in food production needed to help fill the gap and improve food security by boosting both availability and affordability. While efforts to improve longer-term productivity on small-scale farms, with an emphasis on staple food crops, must be accelerated, more emphasis must also be placed on research and policy that will help farmers, communities, and governments better cope with expected increases in risks resulting from poor market integration, dysfunctional or poorly functioning markets, climatic fluctuations, and a host of other factors. All appropriate scientific tools, including bioengineering, as well as better utilization of the insights of traditional indigenous knowledge, should be mobilized to help small-scale farmers in developing countries solve the problems they are facing.

While both the international development assistance community and the governments of many low-income countries have failed to place sufficient emphasis on such agricultural research during the last 10–15 years, there are now signs that the international community and some developing country governments are recognizing the importance of expanded investment in agricultural development in general, and agricultural research in particular. Should these signs turn out to be correct, long-term food supplies and farmer incomes could expand considerably faster than what is currently projected.

IFPRI research shows that even minor increases in international assistance for agricultural research for developing countries could significantly accelerate food supplies while relatively small cuts could have very serious negative effects (Rosegrant, Agcaoili-Sombilla, and Perez 1995). Expanded financial support of both the international agricultural research system and national agricultural research systems in developing countries is urgently needed, and it is of critical importance that information based on sound scientific evidence be used to counter the great deal of misinformation that is currently pushing the governments of several developing countries to question public sector investments in research for agricultural productivity increases.


Modern science offers humankind a powerful instrument to assure food security for all. Through enhanced knowledge and better technologies for food and agriculture, science has contributed to astonishing advances in feeding the world in recent decades. If we are to produce enough food to meet increasing and changing food needs, to make more efficient use of land already under cultivation, to better manage our natural resources and reduce pre- and postharvest losses, and to improve the capacity of hungry people to grow or purchase needed food, we must put all the tools of modern science to work.

Modern agricultural biotechnology is one of the most promising developments in modern science. Used in collaboration with traditional or conventional breeding methods, it can raise crop productivity, increase resistance to pests and diseases, develop tolerance to adverse weather conditions, improve the nutritional value of some foods, and enhance the durability of products during harvesting or shipping. With reasonable biosafety regulations, this can be done with little or no risk to human health and the environment. Yet little modern agricultural biotechnology research is taking place in or for developing countries. Most such research is occurring in private firms in industrialized countries, focuses on the plants and animals produced in temperate climates, and aims to meet the needs of farmers and consumers in industrialized countries. It is essential that agricultural biotechnology research is relevant to the needs of farmers in developing countries and to conditions in those countries, and that the benefits of that research are transmitted to small-scale farmers and consumers in those countries at affordable prices. Otherwise, developing countries will not only fail to share in the benefits of agricultural biotechnology, but will be seriously hurt as industrialized countries improve their agricultural productivity.

The attitude toward risk among the nonpoor in both industrialized and developing countries is a constraint to the use of agricultural biotechnology in and for developing countries. Among people whose children are not starving, considerable resistance to agricultural biotechnology has arisen on the grounds that it poses significant new ecological risks and that it has unacceptable social and economic consequences. Although no ecological calamities have occurred, some people fear that transgenic crops will develop troublesome new weeds or threaten crop genetic diversity. Of course, any new products that pose such risks should be carefully evaluated before they are released for commercial development. But we should not forget that by raising productivity and reducing risks in food production, agricultural biotechnology will reduce the need to cultivate new lands and could therefore actually help conserve biodiversity and protect fragile ecosystems. Developing countries should be encouraged to adopt regulations that provide a reasonable measure of biosafety without crippling the transfer of new products into the field.

Public pressure in Western Europe and possibly elsewhere is likely to move governments to introduce legislation that will constrain or prohibit full use of the opportunities offered by genetic engineering and other tools of modern science for food production and processing. There is a trend in several countries toward seeing the application of science to agriculture as part of the problem rather than part of the solution. Combined with this view is a failure to appreciate the need for productivity increases in food production. While the application of modern science, including genetic engineering and other biotechnology research, to solving human health problems is applauded and encouraged, there is an increasing suspicion that the application of such scientific methods to food production and processing will compromise agricultural production systems, food safety, and the health of current and future generations. In fact, modern science methods, including molecular biology-based methods, offer tremendous opportunities for expanding food production, reducing risks in food production, improving environmental protection, and strengthening food marketing in developing countries. Should legislation constraining modern agricultural science spread within the developed countries, the consequences for long-term food supplies in developing countries could be severe, partly because of reduced exports by developed countries and partly because similar policies might be adopted in developing countries as well.

As for the social and economic consequences of biotechnology, some are concerned that large-scale and higher-income farmers will be favored because they will have earlier access to and derive greater benefits from agricultural biotechnology. These concerns are remarkably similar to those raised at the beginning of the Green Revolution. Subsequently, it became clear that the Green Revolution averted widespread starvation and helped many millions of people to escape hunger once and for all. With more pro-poor institutions and policies, many more poor people could benefit. Similarly, agricultural biotechnology can contribute to feeding many more people in a sustainable way. The new technologies, through appropriate policies, can be made accessible to small-scale farmers. Instead of rejecting the solutions offered by science, we should change policies to assure that the solutions benefit the poor.

The global community must keep its sights set on the goal of assuring food security for all. Condemning biotechnology for its potential risks without considering the alternative risks of prolonging the human misery caused by hunger, malnutrition, and child death is unwise and unethical. In a world where the consequence of inaction is death of thousands of children, we must not ignore any part of a possible solution, including agricultural biotechnology. Modern science by itself will not assure food for all, but without it the goal of food security for all and sustainable management of natural resources cannot be achieved.


 FAO (Food and Agriculture Organization of the United Nations). 1997. Data for 1961–96: FAOSTAT database , (accessed August and September).

 Orke, E. C., H. W. Dehne, F. Schonbeck, and A. Weber. 1994. Crop production and crop protection: Estimated losses in major food and cash crops. Amsterdam: Elsevier.

 Pardey, P. G., and J. M. Alston. 1996. Revamping agricultural R&D. 2020 Brief No. 24. Washington, D.C.: International Food Policy Research Institute.

 Pardey, P. G., J. Roseboom, and J. R. Anderson, eds. 1991. Agricultural research policy: International quantitative perspectives. Cambridge: Cambridge University Press.

 Pinstrup-Andersen, P., and M. J. Cohen. 1998. The world food outlook and the role of crop protection. Prepared for presentation at the 65th Annual Meeting of the American Crop Protection Association, White Sulphur Springs, West Virginia, 27–29 September.

 Pinstrup-Andersen, P., R. Pandya-Lorch, and M. W. Rosegrant. 1997. The world food situation: Recent developments, emerging issues, and long-term prospects. 2020 Vision Food Policy Report. Washington, D.C.: International Food Policy Research Institute.

 Rosegrant, M. W., M. Agcaoili-Sombilla, and N. D. Perez. 1995. Global food projections to 2020: Implications for investment. 2020 Vision for Food, Agriculture, and the Environment Discussion Paper No. 5. Washington, D.C.: International Food Policy Research Institute.

 UN (United Nations). 1995. World Urbanization Prospects: The 1994 Revisions. New York: UN.

 UN (United Nations). 1996. World Population Prospects: The 1996 Revisions. New York: UN.

 United Nations Population Division. 1998. World population prospects: The 1998 Revisions. Electronic version.

 World Bank. 1997a. 1997 World Development Indicators. Washington, D.C.: World Bank.

 World Bank. 1997b. World Development Report 1997. New York: Oxford University Press for the World Bank.

 Yudelman, M., A. Ratta, and D. Nygaard. 1998. Pest management and food production: Looking to the future, 2020 Vision for Food, Agriculture, and the Environment Discussion Paper No. 25. Washington, D.C.: International Food Policy Research Institute.


1 The Glenn Anderson Lecture presented at the joint meeting of the American Phytopathological Society and the Canadian Phytopathological Society, Montreal, Canada, August 8, 1999.

2 Director General of the International Food Policy Research Institute, 2033 K Street, N.W., Washington, D.C.  20006, U.S.A.  Tel. 202-862-5600, Fax 202-467-4439, E-mail:, Web:

3 Data from IFPRI's projections model "IMPACT."

4 All tons in this paper are metric tons.

5 The Systemwide Program of CGIAR definition of IPM: “Integrated Pest Management is an approach to enhancing crop and livestock production, based on an understanding of ecological principles, that empowers farmers to promote the health of crops and animals within a well-balanced agro-ecosystem, making full use of available technologies, especially host resistance, biological control and cultural control methods. Chemical pesticides are used only when the above measures fail to keep pests below acceptable levels, and when assessment of associated risks and benefits (considering effects on human and environmental health, as well as profitability) indicates that the benefits of their use outweigh the costs. All interventions are need-based and are applied in ways that minimize undesirable side-effects.”

6 For a variety of definitions of IPM, see the websites of the CGIAR, FAO, American Crop Protection Association, Pesticide Action Network-North America, and the New York State Extension Service's "IPMnet" -- <>, <>, <>, <>, <> -- as well as Madden and Chaplowe; Yudelman, Ratta, and Nygaard; and 1998-99 World Resources.

7 Further discussion of these strategies may be found in Pinstrup-Andersen and Cohen 1998.