a’ 
} 4 
Black walnut tree in early September, 
severely defoliated by the anthracnose 
fungus disease. Many of the nuts 
fell prematurely; kernels in the re- 
maining nuts were poorly filled. 
shriveled kernels. Badly infected trees 
grow little, and are greatly weakened 
and more vulnerable to winter injury. 
ControlThe disease can be con- 
trolled by four applications of a 
fungicide spray each year. Start the 
treatment when the walnut leaves ap- 
proach 12 inches in length, and apply 
at 2-week intervals. Do not wait for 
spots to appear before spraying or seri- 
ous damage will have been done. Trees 
ranging from 15 to 25 feet tall will need 
5 to 10 gallons of spray apiece in each 
application. Commercial spraying serv- 
ices may be required to properly spray 
trees of this height. 
Zineb is the most effective fungicide 
against anthracnose, but maneb and 
low-lime bordeaux also give good con- 
trol. For zineb and maneb sprays, 
mix 10 tablespoons or 2 ounces of zineb 
or maneb with 5 gallons of water. For 
low-lime bordeaux spray, mix 1 cup of 
lime and 114 cups of copper sulfate 
with 10 gallons of water. 
Bunch Disease 
Symptoms and Damage.—Bunch 
disease stunts the growth of black 
6 
walnut trees and lowers nut produc- 
tion. The cause of the disease and 
means of spread and infection are 
unknown. 
Infected trees develop bushy, broom- 
like shoots on branches in midsummer, 
and also upright, suckerlike shoots on 
trunks and main branches. Some 
shoots die back during late summer, 
but others are killed during the winter. 
In addition, leaflets narrow, curl, and 
turn yellow. 
Control_—Preventing healthy trees 
from becoming infected is the only 
known method of control. This is 
done by cutting out and destroying all 
diseased trees as soon as the bunchy 
growth is seen. The disease also at- 
tacks butternut, heartnut, pecan, and 
hickories. If infected, these trees must 
also be removed. 
INSECT PESTS 
The most serious insect pests of 
black walnut trees are the walnut lace 
bug, curculios, walnut husk maggot, 
walnut caterpillar, and fall webworm. 
These pests and measures to control 
them are outlined below. 
Broomlike growth on the trunk and 
main branches is characteristic of 
bunch disease of black walnut. 
