Seeing red – in autumn leaves and in misdiagnoses

**Existential dread – the botanical version**. (Thanks to Tommy Siegel’s creative talents)

While the onset of autumnal leaf color change reminds us that winter is coming, there are many other reasons why leaves turn red. Knowing why and how leaves turn red is key in accurate diagnosis.

**Once near-freezing temperatures occur, leaves seem to turn red overnight.**

These are examples of leaf reddening misdiagnosed as phosphorus deficiency:

**The leaf reddening in all of these photos of “phosphorous deficient plants” is actually due to water stress.**

These leaves are not phosphorus deficient, either.

**Leaf reddening here is due to solar damage (leaf scorch)**

Congratulations to accurate diagnosticians at UCANR! This is indeed phophate deficiency. Damage is not localized as in the previous images.

**Lack of sufficient phosphate causes overall leaf reddening among other symptoms.**

Here are some other underlying causes behind leaf reddening.

**This Cornus kousa (dogwood) is sitting in a perched water table. Poor soil drainage is causing anthocyanins to accumulate at the margins of the leaves.**

**Leaf reddening on a *Cornus* spp. (dogwood) suffering from anthracnose**

If you’re interested in learning more about how and why leaves turn read, be sure to download my most recent factsheet, appropriately titled “Why do leaves turn red?” ] It’s peer-reviewed and relevant to any part of the world.

Enjoy this Halloween treat!

* This article was originally published here

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