CACAO GROWING CHALLENGES
More than 80% of the world’s 5 million tons of cocoa is grown in the tropical belt by small-scale farmers, and 70% of cocoa globally is grown in West Africa. A typical family-run cacao farm encompasses 1 hectare (2.5 acres) with up to 1000 trees. Infertile soils, pathogens, pests, climate changes and other problems in the world’s cocoa growing regions are threatening the future of cacao production. Millions of small-scale farmers growing cacao using old-fashioned methods are incapable of meeting the challenge.
Cacao is considered an “orphan crop” – one of the last commercial crops to undergo an agri-technical revolution. Machinery, irrigation, fertilization, soil enhancement, plant protection and research are all far behind when it comes to cacao.
Climate change is reducing the areas in West Africa that are suitable for growing cocoa. The dry season, which once was two to three months long, is now increasing to four and even five months. Cocoa trees, usually planted in the understory of tall forest shade trees, find it difficult to compete with them for water resources. The water-stressed, weakened cocoa trees fall prey to pathogens and pests. Changes in the rainy season lead to decreases in pollinator visits, which compounds the problem of low yields from the environmentally stressed and sickened trees.
PESTS AND DISEASES
The cacao tree has little resistance to diseases caused by pathogens. Indeed, the main locus of cacao production shifted out of its indigenous area in South America because of two major pathogens: Moniliophthora roreri, which causes frosty pod, and M. pernisciosa, which causes witches’ broom. Newly encountered pathogens in West Africa include Phytophthora megakarya and P. palmivora, which cause black pod disease and are responsible for the greatest overall yield losses, and Cacao Swollen-Shoot Virus, CSSV, vectored by mealybugs, which kills the entire tree within 3 to 5 years of infection,. The cacao ecosystem also serves as a habitat for a wide variety of insect pests that adversely affect production, resulting in low yields. Important insect pests of cacao include mirids, stink/shield bugs, mealybugs, stem borers, termites, and the coreid bug.
COCOA TREE NUTRITION AND SOIL FERTILITY
Long-term production of cacao and inadequate nutrient inputs has led to serious depletion of soil fertility in the cacao producing regions of the world. Adding fertilizer can substantially increase yields, but there is a large variability in response, and in some cases, no discernable yield improvement. This is because yield depends not only on available nutrients but also on a whole suite of other factors: diseases and pests, water availability, soil type, shade, pruning, pollinating insects, competition with adjacent plants for resources, and more. The causal relations between these various factors, yields and fertilizer response, as well as the requirements of cacao for different nutrients, are poorly understood due to a sparse and narrow research base. Moreover, many cacao trees in the major production areas of West Africa are old, low yielding, and sickly, and need replacing.
Inadequate pollination contributes to low pod yields, in part as a result of flower physiology and structure, and in part as a result of declining populations of pollinators. The rate of fertilization is quite low: only 1% to 5% of the total flowers. Conventional pollinators such as bees are not involved in cacao pollination because the flowers lack scent and nectar, and are physically very small. Moreover, while cacao flowers have both male and female parts, most cacao varieties are self-incompatible.
SOIL PROPERTIES AND WATER NEEDS
Cacao trees are sensitive to both drought and soil waterlogging, which is a function of the water holding capacity of the soil. In areas where there are extensive dry periods, a poor soil water holding capacity leads to water deficits, which cause large decreases in the rate of photosynthesis and lead to reduced yields. On the other hand, waterlogging during wet seasons can lead to inadequate soil aeration, prevent the initial growth and establishment of cacao seedlings, reduce pod production in mature trees, and promote soilborne fungal and fungal-like pathogens. The texture of the soil, whether sandy or clayey, has a strong influence on its ability to store and release water and nutrients.
Poverty is the daily reality for virtually all West African cocoa farmer families, who grow 70% of the world’s cocoa crop. The underlying problems that exacerbate extreme poverty – including low cocoa prices, lack of infrastructure, and no transparency and accountability as cocoa moves up the supply chain – remain unchallenged and unsolved. The extreme poverty faced by the farmers translates to many of the agronomic problems because there is no capital for timely and efficient interventions. An up-to-date and comprehensive report on this topic can be found at this link - Cocoa Barometer 2020.