Nectarine fruit trees can flourish in the home garden with care and close observation of the symptoms of common diseases known to affect stone fruit trees. Belonging to the same cultivar group as peaches, nectarine fruit trees and orchards may experience diseases such as peach leaf curl, bacterial spot, brown rot, powdery mildew and scab.
Peach Leaf Curl Disease
The peach leaf curl disease causes the leaves to curl, turn red and pucker, according to the University of Georgia Cooperative Extension article, "Home Garden: Peaches & Nectarines." The disease can affect entire leaves or produce spots on the leaves. Other noticeable symptoms include leaves turning a powdery gray color from spores that form, according to the University of Rhode Island Greenshare Factsheet, "Peach Leaf Curl." "Shortly after this, the leaves turn yellow or brown and drop," states the Greenshare Factsheet.
Bacterial spot, another disease that can affect nectarine trees, causes "reddish-purple spots with white centers" on the leaves that fall out, leaving a holey appearance, according to the Georgia Cooperative Extension. Caused by Xanthomonas pruni, bacterial spot also will cause the nectarine tree leaves to turn yellow and fall off. The disease, too, can weaken the tree as well as reduce the fruit size, according to the article. When the nectarine fruit becomes infected, it has "small dark spots resembling open sores rather than the velvety spots characteristic of peach scab," the Georgia Cooperative Extension writes, and as the infection worsens, the nectarine fruit peel will crack.
Nectarine trees affected by brown rot end up with damaged shoots, fruit and flowers. The Georgia Cooperative Extension explains that the flowers will wilt and turn brown while the shoots may have elongated cankers on them. Brown rot "can attack the blossoms and the developing or ripening fruit and even form cankers on small twigs," according to the University of Missouri Extension in the article, "Home Fruit Production: Peach and Nectarine Culture." Symptoms of infected nectarine fruit include brown spots and fallen fruit that rots on the ground or fruit that dries up and looks "mummified" on the tree, the Georgia Cooperative Extension writes.
When nectarine trees have scab, the fruit shows "1/8-inch diameter greenish-brown to black spots" near the stem, according to the Georgia Cooperative Extension. In the Georgia Cooperative Extension "Diagnostic Guide to Common Home Orchard Diseases," researchers explain that the disease can also affect the twigs of trees, causing dark red lesions. Scab can also affect the leaves, causing "small (1/4 inch), round, and yellowish-green to yellowish-brown spots" on the leaf's underside, according to the University of Rhode Island Greenshare Factsheet "Stone Fruit Diseases: Scab."
Powdery mildew, another common nectarine tree disease, causes a white, powdery mildew on the fruit. Agriculture experts with the Tree Fruit Research and Education Center at West Virginia University in Kearneysville say the disease, caused by a fungus, can reduce fruit quality, causing loss. Just like the peach leaf curl disease, powdery mildew can cause leaves on the nectarine tree to be deformed and fall off. In addition, twigs may become stunted and buds may die, according to the WVU Tree Fruit Research and Education Center article "Powdery Mildew." Growers can use fungicide sprays to eliminate the disease, and spraying at the "petal fall stage" every 10 to 14 days "until the pit hardening stage" can help, according to the Center article.