Will water drops on my trees burn the leaves?

This is one you sometimes hear in gardening circles – that you might burn the leaves of your plants if you water them in the heat of the day – because the drops of water act as a magnifying glass, focusing the light onto the plant and theoretically burning it. I have never observed water-droplet-shaped burns on a leaf which one would expect from this kind of behaviour. But what does the science say?

This articleref references another one behind a paywall which says that although droplets can increase light 20x at their focal points, in most of the species tested a layer of leaf trichomes hold droplets above the leaf surface, and beyond the focal point.

In another studyref “sunlit water drops on horizontal leaves without waxy hairs cannot cause sunburn regardless of solar elevation and drop shape.” – this is because “the focal region of water drops falls far below the leaf at higher solar elevations and can fall on to the leaf only at lower solar elevations, when the intensity of light from the setting sun is generally too small to cause sunburn.”

Unfortunately both papers conflict somewhat as the first says trichomes specifically hold water droplets too far away from a leaf to enable sunburn, and the second paper says only horizontal ‘hairy leaves’ can get sunburn (they found this could happen for floating fern but this plant has quite specific trichomes/hairs). In reality most bonsai trees do not have horizontal leaves, instead leaves are at a multitude of angles, and the water droplets if stuck to a leaf would probably be angled away from the midday sun. But do send me a picture if you ever see a bonsai tree burned by a water droplet!