Plants "Scream" When Stressed, Scientists Discover

The quiet field you're standing in right now might actually be filled with conversation you just can't hear.

Scientists at Tel Aviv University have discovered that plants emit ultrasonic sounds when they're stressed, producing faint pops and clicks similar to bubble wrap snapping. These sounds are as loud as normal conversation at 60 to 65 decibels, but they occur at frequencies far beyond human hearing.

The research team recorded tomato and tobacco plants using special microphones in both soundproof chambers and greenhouses. They stressed the plants in two ways: withholding water for several days and cutting their stems.

The results were startling. Stressed plants produced 30 to 50 sounds per hour at irregular intervals, while healthy plants stayed mostly silent.

"When tomatoes are not stressed at all, they are very quiet," says lead researcher Lilach Hadany, an evolutionary biologist at Tel Aviv University. The team trained a machine learning system that could actually distinguish between sounds from dehydrated plants versus physically damaged ones.

Even more fascinating: plants experiencing water stress began making sounds before showing any visible signs of wilting. The sounds peaked after about five days without water, then declined as the plants dried out completely.

The researchers tested other species too, including corn, wheat, grape, and cactus plants. They all emit sounds when stressed.

Scientists believe the sounds may result from cavitation, a process where air bubbles form and burst inside the plant's vascular system. But here's where it gets really interesting: these sounds could be carrying important information to other organisms.

The Ripple Effect

This discovery opens up an entirely new understanding of how nature communicates. Moths deciding where to lay eggs might listen to plant stress signals. Animals choosing what to eat could use the sounds to pick healthier plants.

Other plants might be eavesdropping too. Previous research shows that plants increase sugar levels in their nectar when they detect pollinators nearby, and sound can actually alter plant gene expression.

"If other plants have information about stress before it actually occurs, they could prepare," Hadany explains. The implications go beyond just understanding nature better.

Farmers could soon use acoustic monitoring to track crop hydration levels in real time, catching drought stress before it becomes visible. This could dramatically improve irrigation efficiency and reduce water waste in agriculture.

"Now that we know that plants do emit sounds, the next question is, 'who might be listening?'" says Hadany. Her team is currently investigating how other organisms, both animals and plants, respond to these sounds in completely natural environments.

The world around us has been having conversations all along, and we're only just learning to tune in.