Human activities are the no. 1 contributors to globalizing plant pests

24 April 2020

International Year of Plant Health 2020If there is anything the deadly COVID-19 pandemic has taught us, it is that diseases do not know boundaries and humans are responsible for carrying and spreading diseases from person to person. This is also true for several plant pests. Humans are the leading carriers of the intercontinental spread of plant pests and diseases – a fact that was established and documented almost 300 years ago. Before you deny and vehemently protest, read on. Do you remember the cassava, yam, sweet potato, plantain or avocado you carried with you the last time you travelled, because, “I do not like those people’s food, it is not delicious!” Or that beautiful flower you brought from your Europe or Africa-wide tour? Well, it could have harboured a pest, which you inadvertently boarded the plane or bus with and helped in spreading. But this story is not to crucify you and make you feel guilty. The purpose of this story is to show you how you can put a stop to the spread of plant pests and diseases. Lava Kumar, CGIAR-IITA’s head of Germplasm Health and Virology Unit, says one way to prevent the human spread of plant pests and diseases is to declare plants at border checkpoints. “When you are travelling, a quarantine officer usually asks whether you are carrying food or not. You should declare what you are carrying so that it is inspected for pathogens. If it is safe, you will be given the green light to continue, if not, the officer will confiscate it for destruction.” However, you will be excited to know that one can carry processed food since it is usually safe from pathogens. Kumar however advises that the right and better option is to get permission before bringing plants or plant parts. “Quarantine officials will help you through the process of importing your favourite stuff” he added.  In this video, Kumar explains how humans move plant pests from one place to another, how this can be curtailed, and the international measures being implemented to curb the intercontinental spread of pests and diseases.

Pests and diseases that are foreign to a country/continent are called Exotic Introduced Pathogens (EIPs) Below is a list of some EIPs in African countries/regions in which they were first confirmed. These EIPs have caused devastating losses at country, regional and continental scale.

Cassava mealybug –  – Central Africa – 1970s
Banana bunchy top virus – DRC – the 1960s
Cassava bacterial blight – Central and West Africa – 1970s
Banana Black Sigatoka – Zambia – 1973
Asian soybean rust – Zambia – 1978
Maize chlorotic mottle virus (responsible for maize lethal necrosis) –Kenya – 2011
Banana fungal wilt caused by Fusarium oxysporum Tropical race IV (FoC TR4) – Mozambique – 2014
Papaya mealybug (Paracoccus marginatus) – Ghana – 2010
Taro blight caused by Phytophthora colocasiae – West and Central Africa – 2011
Fall armyworm (Spodoptera frugiperda) – West Africa – 2016