Wednesday 17th June 2020 is UN World Desertification and Drought Day with the theme Food.Feed.Fibre. By 2030, food production will require an additional 300 million hectares of land, but the combined impact of intense land-use and rising global temperatures threaten the areas of land currently producing our food, feed and fibres.
Repeated harvesting of high input crops in areas with low rainfall and high temperatures contributes to reductions in soil quality. Plant disease exacerbates the impact on land-use for crop production. In areas with sustained, high temperatures many diseases flourish. Healthy plants grown under heat stress are more susceptible to viruses and sustained dry periods expose crops to a range of wilt diseases.
Livestock are fed with grain and crops to supplement their diet. Production of animal feed takes up 50% of all agricultural land and 33% of the planet’s freshwater resources. Land conversion for agricultural purposes often leads to biodiversity loss, high water usage and pollution. Switching to sustainable practices in animal husbandry can cut livestock emissions by up to 30%. The pressure on land to produce feed is as intense as the factors causing drought and desertification in crop cultivation.
The UN Convention to Combat Desertification UNCCD is looking to highlight land-based solutions for people and planet. This year they are focussing on the impact of the fashion industry on land use. In particular, the huge quantity of water used to produce cotton.
As a case study they have highlighted the “impact of the fashion industry on land and water in Indonesia’s West Java Province. Here, in the area prone to drought during the dry season, over a hundred textile and garment companies use over 2,500 liters of water – largely for the cotton growing – to produce one t-shirt.”
Technology, recycling and conservation of resources can help combat global desertification. The UN have made a series of short films on the issues of drought and desertification and present solutions to preserve land use.
Plant pathologists can address the impacts of drought and heat stress on desertification by exploring the ways in which high temperatures and water stress affect plant disease. We are learning how healthy plants become more susceptible to disease under elevated temperatures. The conflict of more vigorous growth balanced against the increased impact of disease. Diseases spreading in warm climates as a result of viral-vector interactions e.g. enhanced heat tolerance of viral-infected aphids.
A combination of disease surveillance and analysis of plant/pathogen molecular mechanisms provide an understanding of how high temperatures and low water availability exacerbate plant disease. We can use these tools to identify disease risks in countries growing potentially susceptible crops. Understanding the factors that lead to plant disease allow us to target genes for breeding and even gene-editing technologies. Knowing how heat and water stress impact plant disease helps us to plan for imminent disease and avoid the worst impacts to parts of the world most at risk to desertification.
Understanding plant disease dynamics is essential to managing our land resources sustainably. Combatting yield losses in our food, feed and fibre crops will decrease the amount of land required to sustain the needs of the planet. Increasing yields in areas with sufficient rainfall will protect those susceptible to drought by allowing less intensive forms of agriculture and intensification.