Tomato Leaf Curl: Fusarium Wilt or Water Stress?

Top leaves curling on tomatoes; rest OK.

Two Possibilities

1. Fusarium wilt: Affects heirlooms. Resistant varieties labeled 'F' or 'VF'. Plant wilts completely in days; black plugs in stem block water.
2. Water stress (likely): Tomatoes need huge water; wilt fast in heat. Increase water, remove low suckers.

Test

If wilt: plant collapses in days → remove, dispose, rotate crop.

If water: perks up with irrigation.

Expert insight provided by Melissa.