Help Me!

[Miss Kay]

Please help me figure out what's happening to my tomatoes. Here's the background.. We are in zone 9 near the mexican border. I started these from seed and set the plants out the first of March. They are heritage tomatoes and two different kinds meant for the heat. They have been growing and doing great. It never rains here (well at least it hasn't in nearly a year) so we irrigate from a shallow well once a week. Last week we saw record heat even for here with it hitting 100 or near every day plus the wind. By the weekend they were looking like they were ready for a drink so we irrigated the row and let it soak in good. Then Sunday the cold front came through and dropped the temps down to the 50's. I didn't see them again until yesterday and all of a sudden this yellow appeared. Nothing like I have ever seen. The leaves are not wilted, the plant still looks healthy, it looks as if someone painted the inside tips and stems with yellow. Yellow usually starts at the edges of the leaf, not at the base. Have you ever seen this? I wonder with the drought if the shallow well had some salt since we are so close to the gulf. What can I expect now?

[chickenista]

It looks like iron deficiency to me.
The grow tips are pale yellow etc.. older leaves are fine.
"Iron (Fe)
Under normal soil conditions, Fe deficiency is not likely to occur unless the soil is low in “available” Fe or above 7.0 in pH. Iron deficiency symptoms (light green to yellow leaves occurring on emerging leaves) occur when the plant is under stress from lack of adequate moisture, during periods of rapid plant growth, or changing light conditions. Normally with time, these deficient-looking leaves will eventually develop a normal green color. "
But also soil with a hig acidity can do it as well.
You should check your levels adn adjust soil accordingly and plan for a long term treatment.

It best corrected with foliar feeding.

[Miss Kay]

Thank you so much. That must be it. It only happened after that hot windy week followed by quick growth after the water soaking. We have high ph here so I know it is not acid. I'll try to get some iron on them this weekend.