Signs of lack of water or excess heat?

[to be chafoin]

While the heat wave has just arrived by icic, I open this thread to exchange to distinguish the signs of lack of water or excess heat and perhaps to find remedies to make ...
And to start what is called the black ass disease that has just arrived on a lot of my tomatoes.

By consulting my book I read: "apical necrosis: sign of lack of calcium caused by saline stress, water moderately and regularly.". I did not water at all so the question is: is it really this lack of water that causes this "disorder of physiological origin"?

[Ahmed]

In your case and since you never watered, you do not have too much to ask yourself a question: you bring water ...

[Did67]

This article seems to show that this can be more complex:

http://www.tous-au-potager.fr/necrose-p ... le-tomate/

[Ahmed]

I am aware of it, but in the case of our friend, the necessary step is first watering ...

[Did67]

In Gironde, it can also be soils deficient in Ca⁺⁺, all, of course, amplified by a lack of water ...

I have, despite the heat wave, piles of tomatoes without watering. Without black ass.

Varietal sensitivity also seems to me a point: I observed it at home, in 2015 perhaps, on an elongated variety as in the photo. But I do not remember which one. And it was the only one!

[Forhorse]

I do not know if this is really a cause of this disease, but I read many years ago that this disease is usually caused by water stress and that this water stress is often caused by irregular watering more than by a real lack of water.
When watering tomatoes, it should be done regularly (depending on the capacity of the soil to retain water) so potentially every day and with always the same amount of water.
For example, giving a watering can per foot every day is a good practice for watering tomatoes.
Drowning the foot one day and then no longer watering during 1 week is a bad watering practice that causes water stress.
Giving 4 or 5 a few days, then nothing for a few days is bad practice.

In my vegetable garden I have a foot that has this disease, because this foot is the victim of a mole which systematically makes a gallery underneath. As I have always watered the plant has not made any deep roots and is content to take the water that I give it on the surface, but with the galleries which drain everything, my watering does not benefit it => water stress => black ass.

[Did67]

I have the opposite experience: my tomatoes under tunnel; never again watered until 20 days ago (the soil was soaked by the winter rains and those of May, I did not put the tarp of the tunnel until the beginning of July); there, I empty an underground tank of several m3 by pumping in the middle of the tunnel (which makes 6m X 6m); I forget ; the tank is emptied; since then I have not watered; not a black ass!

[to be chafoin]

Oh, it is known for soils that can be deficient in Calcium, the Gironde?

I did not water because I did not see any worrying sign of lack of water on the leaves. My soil is clay and when I harvested my first pdt the soil was still wet. Same thing today: under the rest of hay and say the first 2 centimeters of the ground, clumps of clay fresh clay crumble by hand! I wonder if this is possible: the earth slightly wet but the plant can not extract this water for lack of suction force?

I'm starting to water now. With this clay soil, I usually use this advice: a good watering a week. In any case I could do little more: I must draw water from the watering can to a well which is at the neighbor's house at about 50m. As the water is too cold, I have to pour this water into a tank of 130 l and let it warm a little before watering. So it's handling ... besides I can not go to the garden every day. That's why the thick hay cover seemed to me a good strategy ... but I'm a little too dragged to react (deceived a little by the leaves) ...

Another sign may be lack of water and / or calcium, also visible on the fruits:

[to be chafoin]

To match the previous message ... Didier said he saw the meadow begin to suffer. Here it is again and always different from elsewhere:
not really blatant sign of drought even on the ground it goes green again.

[Did67]

Oh, it is known for soils that can be deficient in Calcium, the Gironde?

On the side of the Landes, certainly: sandy soils, sometimes blackish when they are cultivated [their local name escapes me, but I knew it; I, in my youth, plowed in Gironde Bazas], acidic, so poor in Ca ++ ...

You are not known, on this side there, for your limestones!

I hasten to specify: I do not know the vineyard side!