Five ways climate change is contributing to increased threats to plant health


That’s why the United Nations proclaimed May 12 as the International Plant Health Day to raise international awareness of how protecting plant health can help end hunger, reduce poverty, protect biodiversity and the environment, and to stimulate economic development.

On the occasion of the first International Plant Health Day, the Food and Agriculture Organization of the United Nations (FAO) reports that plant diseases and pests are increasingly prevalent due to of climate change.

Nearly 40% of food crops are destroyed each year by plant pests and diseases. The losses recorded, both in terms of yields and income, have a devastating effect on the poorest communities whose livelihoods are based on agriculture.

Plant pests and diseases know no borders. In a highly globalized and interconnected world, it is not surprising that these can travel and colonize new regions.

This spread is aggravated by climate change, which creates favorable conditions for the presence of these pests and the survival of certain plant diseases in new areas. Climate change has already contributed, for example, to widening the host range of pests and their distribution, including for the red palm weevil, the fall armyworm, the fruit fly, the desert locust and the borer ash emerald.

The increase in the number of harmful organisms constitutes a significant threat to the environment, since these, in particular invasive organisms, can lead to significant losses of biodiversity. Plant diseases are equally devastating, destroying crops and reducing farmers’ incomes.

So what are the most invasive plant diseases and how is climate change contributing to their spread?

The FAO highlights five increasingly dangerous diseases that threaten plant health:

1. Potato late blight

Late blight is a disease that attacks potatoes and tomatoes and is caused by the fungus Phytophthora infestans. In tomatoes, the disease causes lesions on leaves, petioles and stems, while potato tubers show rot up to 15 millimeters deep. The fungus adapts very easily to changing conditions and prefers warm and humid seasons. Climate change creates favorable conditions for its proliferation at different times and in different places. In Egypt, for example, increasingly hot and humid weather conditions are conducive to outbreaks of potato late blight and allow the pathogen to multiply earlier in the growing season. cultures.

2. Coffee rust

This fungal disease, also known as Hemileia vastatrix, attacks the leaves of the coffee tree. It first manifests as yellow spots and then turns into an orange-yellow powder that easily contaminates other coffee plants. Coffee leaf rust is one of the major problems in coffee production worldwide as the disease is able to adapt to different climates. Global warming appears to help reduce the pathogen’s incubation period, meaning more generations can develop in a growing season.

3. Fusarium wilt of banana

Fusarium wilt of banana is a lethal fungal disease caused by a soil fungus, Fusarium oxysporum TR4. The fungus enters the banana tree through the roots and impedes the flow of water and nutrients to the cells of the plant, causing progressive leaf destruction. The disease eventually leads to the death of the plant. High temperatures as well as extreme weather events such as cyclones, two impacts commonly linked to climate change, can increase the risk of banana wilt disease.

4. Xylella fastidiosa

Xylella fastidiosa is a bacterium transmitted by several species of sap-sucking insects, such as leafhoppers, which infect many crops of significant economic interest (vines, citrus fruits, olives, almonds, peaches, coffee and ornamental and forest plants). The bacterium prevents the host from absorbing water, which eventually causes internal drying out. Xylella occurs mainly in the Americas, southern Europe and the Near East, but it can spread beyond its current range. The resurgence of insect vector populations could lead to a significant spread of the disease.

5. Grapevine downy mildew

Downy mildew is an extremely serious fungal disease of grapevine caused by the fungus Plasmopara viticola. It can lead to considerable crop losses. The pathogen attacks the green parts of the vine, especially the leaves, and causes angular, yellowish and sometimes oily lesions located between the veins. The increase in air temperature favors the onset of the disease. Climate change is causing changes in temperatures in many regions, which increases the risk of major outbreaks of grapevine downy mildew.

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