Native Witch Hazel
Hi -- This looks like leaf scorch. It can be caused by drought conditions or other problems that impair water uptake. http://plantclinic.cornell.edu/factsheets/physiologicalleafscorch.pdf
The native witchhazel (Hamamelis virginiana) prefers moist soil and does dont tolerate very dry situations.
New plants typically need about 12-18 months for their root systems to establish into the native soil and may need supplemental watering during this time period.
You can check your soil moisture by using a garden tool or screwdriver to dig down to about six inches. If the soil feels warm and dry, you need to water. If it is cool/moist, it is fine. Here is some information on watering new plantings.
A light layer of mulch (no more than 2-3" deep and placed about 6 inches away from the main trunk) can help to maintain soil moisture.