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. Older foliage and weak or frail trees are more susceptible.
The first symptoms appear on the underside of mature leaves as small, round, green velvety spots, while on the upper surface of the leaves, pale yellow blotches appear.
As the disease progresses, by midsummer 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. Small leaflets may also develop spots and drop from the tree.
If the disease is severe, the nuts will ultimately turn black and will display indented spots, and the tree’s foliage will drop prematurely in late summer to early fall. Once the nut has become entirely black, it too will fall from the diseased portion of the tree.
Not only are the fruits wasted, but this condition can result in a decline of the tree’s vitality, along with a weakened resistance to infection from other diseases.
Pecan Leaf Blotch Control
The leaf blotch fungus is able to overwinter in fallen leaves. A good practice for controlling the disease is to clean up leaves before winter sets in and remove the old fallen foliage in early spring just as the frost is thawing.
Before deciding on purchasing and planting a new pecan tree, it’s a good idea to consult with your local nursery experts who may be able to guide you in buying trees that show a history of being more disease resistant.
Otherwise, those treating pecan leaf blotch commonly depends on the use of fungicides. The best recommendation is to contact your local agricultural extension agency to learn about your options before spraying your pecan trees. If you choose to treat the tree with a fungicide, it should first be sprayed after the tree has pollinated. A good way to tell whether this has happened is that the nutlet tips will have turned brown. Experts say a second spraying should take place about a month later.