To me, citrus fruit suggests the promise of something exciting, joyful, fresh. Maybe it's the mix of sweet and sour, or the palette of colours in which these fruits present themselves to us. Maybe it's even the light of the long, sunny days they seem to evoke.

Whatever feelings these fruits stir in you, they’re in danger. An insect-borne bacterial disease called Huanglongbing (HLB) is threatening the world’s citrus trees, and the plantations affected by it have lost more than 60% of their harvest. International unity between governments and researchers is essential to combatting this threat, one of many that are being exacerbated by climate change.

August 12 marked the 75th anniversary of the signing of the Geneva Conventions, essential in defining how to treat both military and civilian populations in the event of war. Bombings such as the one carried out by Israel last week on a school in Gaza bring these conventions face to face with their practical utility.

And now that the Olympic Games are over, what psychological challenges do athletes who have spent years preparing for this event face?

Claudia Lorenzo Rubiera

Editor, Madrid

Plant disease could spell apocalypse for citrus fruits

Raphael Morillon, Cirad; Barbara Hufnagel, Cirad; Patrick Ollitrault, Cirad; Virginie Ravigné, Cirad

A disease known as Huanglongbing (HLB) is devastating citrus orchards in many countries, causing huge losses in citrus production.

Gaza war: 75 years after signing of the Geneva Conventions, Israel’s deadly attack on a Palestinian school shows their limitations

Lawrence Hill-Cawthorne, University of Bristol

The Geneva Conventions, are supposed to protect civilians in war. Israel and Hamas appear to have forgotten this.

Mental health after the Olympics: why so many athletes struggle to adapt to normal life after big competitions

Juan González-Hernández, Universidad de Granada

26.4% of elite athletes experience serious mental health problems after retirement.

Teenagers give their tips to fight doomscrolling

Anne Cordier, Université de Lorraine

Platforms are doing everything in their power to keep us hooked to their dopamine-generating features. How can we keep control of our digital time? Teenagers have their own strategies.

‘To be or to be?’ Why this fundamental concept is so difficult for learners of Spanish

Zeina Alhmoud, Universidad Nebrija

Spanish has two ways of saying “be”, which forces language learners to see the world in a whole new way.

How ‘woke’ marketing lets fast fashion brands get away with environmental and labour abuses

Mariko Takedomi Karlsson, Lund University

Fashion can be a useful vehicle for political messages – until someone asks who makes the clothing.

France’s second-ballot system may seem chaotic, but here’s how it benefits voters

Henry Milner, Université de Montréal

Under France’s second-ballot system, French voters can vote with their hearts in the first round, knowing they’ll be able to vote in the second round with their heads — in other words, strategically.