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It can help, but I would highly advise planting legume crops between season. This will usually outcompete weeds, and provide aeration for the soil so that you have to till less. They will always remain shorter than the corn, so there is little chance of this outcompeting corn.

This is very good permaculture practice that will eliminate the need for pre-emergents, and nitrogen supplementation.

I do not see much issue with broadcasting a pre-emergent, but there are a few ways to avoid this all together.

My sweet corn grows and produces well with compost enriched soil and a complete, mineralized, organic fertilizer.
I use Agricola's 4-8-4:
http://www.soilminerals.com/Agricolas4-8-4_MainPage.htm
or something like this is next best:
https://www.domyown.com/dr-earth-organic-all-purpose-fertilizer-p-9485.html

Your corn appears to be suffering from a blight. This can be treated in a number of ways, but overwatering will be the main cause. Soil should be dry, fully, down to about 2 or 3 inches before watering again. Most of the time, they won't require much extra water.

This article will give you more information: https://www.gardeningknowhow.com/edible/vegetables/corn/corn-seedlings-with-blight.htm

This article will help you to grow corn: https://www.gardeningknowhow.com/edible/vegetables/corn/how-to-grow-corn.htm

It is not necessary to hand pollinate corn. That looks to have already spent its pollen awhile ago, and the flowers are now dying off, as usual.

This article will help you to care for sweet corn: https://www.gardeningknowhow.com/edible/vegetables/corn/grow-sweet-corn.htm

This looks more like a saturated soil issue. Wet soils that do not get a chance to dry out will promote root rot, which is what this appears to be the start of.

If you have any control over watering, make sure to let it dry out, thoroughly, down to about 3 inches or so between watering.

Here is an article that will help you to grow corn:

https://www.gardeningknowhow.com/edible/vegetables/corn/how-to-grow-corn.htm

Unfortunately, your photo did not come through. I am unable to assess the damage.

One thing that does come to mind is the leafroller.

Here is an article for more information:

https://www.gardeningknowhow.com/plant-problems/pests/insects/leafroller-damage-control.htm