Pest & Disease Library · Solutions

Blossom-End Rot in Tomato: Causes and Crop Nutrition

Blossom-end rot is a calcium-delivery disorder — not a pathogen — that sinks a dark, leathery patch on the fruit base. It follows uneven watering and rapid growth that outpace calcium movement into the fruit, common in containers and hot spells.

Common crops affected

Tomato

Why it matters

It makes fruit unmarketable, and a bad early run costs a share of the first harvest; the fix is calcium availability plus steady watering, not a fungicide.

When to act

Prevent through steady irrigation and calcium availability during rapid fruit growth.

What to look for

Water-soaked spot at the fruit base turning dark and leathery
First fruit of the season worst affected
Worse after irrigation swings and heat
Localised to fruit, not foliage

How to manage it

Keep soil moisture even; avoid nitrogen spikes.
Supply available calcium with Calcium Boost.

Recommended Vegalab program

A Vegalab calcium/biostimulant solution plus consistent watering — see Calcium Boost and the Product Finder.

Role	Product	Use
Calcium correction	Calcium Boost	Available soluble calcium to the fruit
Cell integrity	Cellular Boost	Cell integrity; drought-cracking support

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Product claims, rates, and availability vary by jurisdiction; always follow the applicable label.

Frequently asked questions

Is it contagious?

No — it’s a calcium/water disorder, so fix irrigation consistency and calcium supply rather than spraying a fungicide.