I don’t know how common this is in tomatoes plants.
In the research I’ve done it gets mentioned but not consistently. It also seems linked to greenhouse plants more than outdoor ones, the link being humidity.
However I wanted to include it as, just like Blossom End Rot, it has a water connection.
Growing tomatoes for the first time I tended, especially as growing in pots and grow bags, to think about watering in very simplistic terms.
Enough and the plant would live; insufficient and it would die.
And whilst that’s a principle not to ignore, I’m also learning there are more subtle connections between water and the plant’s structure and well being.
Oedema is caused by the plant taking up more water than it can use/process. If it takes up more water through its roots than it can lose through its leaves (via the process of transpiration) the cells in the leaves over fill with water. This causes little green bumps on the underside of the leaf.
This water, in excess of the leaf cell’s holding capacity, can cause the cell to burst. When this happens the cell dies, turns brown and crusty. All of which will be evident on the underside of the leaf.
Just as with Blossom End Rot this doesn’t mean the plant is doomed….
But conditions need adjusting.
High humidity decreases the rate of transpiration. So in addition to decreasing the amount of water going in at the root end, adjustments to enable more water to leave the plant as water vapour via the leaf need to be made. This can be achieved by increasing ventilation and air circulation.
One of the adjustments not to make is removing the affected leaves. Less leaves = less transpiration. Not the desired effect – some functioning cells on a leaf are better than none!
So that’s the Oedema factor – another made-for-TV sounding drama in the life of the Tomato plant.
