Juglans microcarpa
Little Walnut
Juglans microcarpa, little walnut, is a small round-crowned tree with edible nuts. It is found in dry, hot regions in both part shade and sun. The nuts are the smallest of any walnut species and mostly provide food for wildlife in the area.
May be sensitive to thousand cankers disease, low CaCO3 tolerance, may be susceptible to mistletoe.
Good potential utility as an urban tree based on evaluation of 15 trees, healthy crown, 100% survival, very fast growth rate. Signs of chlorosis found on one individual. Herbivory found on one individual. Very vigorous in both the nursery and landscape, frequent basal sprouting was observed. Potential pruning may be necessary and trees may be susceptible to thousand cankers disease.
We trialed two treatments, both started in mid-January, with seed collected from 1 specimen. Half were put in 150 day cold stratification in moist perlite in plastic bag in refrigerator. The other half were sown outdoors. The refrigerated cold stratification had double the germination as the winter sowing. In future trials, outdoor sowing should be in fall. Seedlings are moderately quick growers with a nice form.