Leaf blotch of pecans is a fungal disease caused by Mycosphaerella dendroides. A pecan tree afflicted with leaf blotch is generally a fairly minor concern unless the tree is infected with other diseases. Even so, treating pecan leaf blotch is an important step to maintaining the overall health of the tree. The following pecan leaf blotch info discusses the symptoms of the disease and pecan leaf blotch control.
Pecan Leaf Blotch Info
A minor foliage disease, leaf blotch of pecans occurs throughout the pecan growing region. Symptoms of a pecan tree with leaf blotch first appear in June and July, and primarily affect less than healthy trees. The first symptoms appear on the underside of mature leaves as small, olive green, velvety spots while on the upper surface of the leaves, pale yellow blotches appear.
As the disease progresses, by mid-summer, black raised dots can be seen in the leaf spots. This is a result of wind and rain whisking away the fungal spores. The spotting then runs together to form larger shiny, black blotches.
If the disease is severe, premature defoliation occurs in the late summer to early fall, which results in overall reduced tree vigor along with a vulnerability to infection from other diseases.
Pecan Leaf Blotch Control
Leaf blotch overwinters in fallen leaves. To control the disease, clean up leaves prior to winter or remove the old fallen foliage in early spring just as the frost is thawing.
Otherwise, treating pecan leaf blotch relies on the use of fungicides. Two application of fungicide should be applied. The first application should occur after pollination when the tips of the nutlets have turned brown and the second fungicide spray should be made about 3-4 weeks later.