The corn could have a sulfur deficiency, but I don't think that's it. Looking at the picture, it appears the corn is growing with the squash. Squash is a heavy Mg and Zn feeder. If the pH is a little low, or either nutrient is lacking in the soil, the corn will suffer first since it is more nutrient sensitive than squash. If the growing nights have been cool, that will make it worse. If P is high, Zn will definitely be affected. It could even be all three nutrients. If I had to take a guess, I would say cool nights, Mg and Zn deficient soil coupled with competition with the squash is causing it. That would explain the stunting as well as the yellow streaking. A good soil test would tell the tale in an instant.