The proud state tree of Texas, the pecan tree is a staple in the region. It stands the test of time and stress in part by shedding its pecan crop, and many people with a pecan tree of their own want to see it flourish. Part of this flourishing is the absence of disease. To learn more about the common pecan tree diseases that afflict the species, read our brief guide on the matter.
Scab is the first disease worth discussing due to its prevalence. Caused by the fungus Cladosporium caryigenum, this disease affects leaves and nut shells at many points during the growing process, but it’s especially harmful early in the growing season when the tree begins to bud. Visibly, scab manifests in plentiful small, dark spots on the surface of the leaves and fruit, eventually coalescing into a complete black layer as the fungus takes over. To mitigate or prevent its effects, you can coordinate with a company to apply fungicides at important points in the growing process to protect the tree’s fruit.
Downy spot, the resultant disease of the fungus Mycosphaerella caryigena, primarily attacks pecan trees’ foliage. This fungus manifests on leaves via yellow spotting, showing up first on lower branches and then ascending along the tree. As it spreads and more completely infects the tree, downy spot not only inhibits leaf growth, but also contributes to early defoliation.
Over time, defoliation compromises the future growth and fruit production of the pecan tree. One tip for limiting the spread of downy spot is to rid the ground of fallen infected leaves.
Twig dieback, caused by another fungus named Botryospaeria berengeriana, affects many Texas pecan trees, causing their limbs to die. This problem usually comes about in conjunction with other tree diseases such as scab, which weaken the tree and make it susceptible to twig dieback. One visible sign of this fungi’s invasion is the proliferation of raised black pustules among the outer branches. Usually, these branches lose around two feet to this disease, although they can lose as much as two and half feet depending on certain variables affecting the overall tree health and the mobility of the fungus. For one, water can pick up and carry the fungus from an infected area to another. When dieback occurs, removing infected limbs is of paramount importance.
Cotton Root Rot
Cotton root rot is another common pecan tree disease, one that threatens to kill the entire tree if it spreads completely. Caused by Phymatortrichum omnivorum, this fungus thrives in rainfall-heavy Texas summers and infects pecan trees when soil temperatures are high and when there’s standing water around the tree. This disease can kill a tree quickly, causing the tree to wilt around midsummer and die within a few days after wilting. This is a common and difficult-to-manage scourge on pecan trees, but it’s somewhat preventable if you reduce the pH of the soil around a healthy tree.
Many more diseases, including hypoxylon canker, rosette, vein spot, and those caused by invading nematodes, can affect pecan trees. To learn more about the threats to your trees, contact our team of certified arborists in Austin, Texas.