chong

At one point in time, the plant experienced dryness, where the soil got dry, either wholely or parts of it. The thing to do is make sure that the soil is evenly moist.

I can't tell from the picture if it's in the ground or in a pot. If it's in the pot, when the soil gets dry, soak the whole pot in water for a few hours. This will allow the soil in the entire pot to absorb the water. Subsequent watering will be evenly distributed. Otherwise, there will be pockets of dry soil that will repel the water and get bypassed when you water it. While the top of the soil may appear that the soil is wet, the pockets will remain dry. Any root in that pocket will wither and die if not soaked through in time.

If it's in the ground, either water it with a drip or soaker irrigation system, or flood the plant for a half a day with slow trickle watering.