Fungal diseases move around via spores, and spores spread in a variety of ways. Sometimes, there’s nothing you can do about the spread. Insects can bring spores with them, or spores can be spread by the elements. Spores traveling on the wind arrive no matter what you do. During a downpour, spores can be splashed up onto trees from the soil, although mulching provides a partial remedy, as it offers a barrier. Other times, though, spore spread is entirely within your control. Spores can spread through improper irrigation, on gardening tools, and from your own body to susceptible trees. In these instances, you can prevent spore spread. Indeed, prevention is generally the answer to tree fungal issues. Disinfect tools, avoid contact with plants on wet days, and don’t over-water. Understanding which species are most at risk, and learning to identify some of the most common types of tree fungus can help minimize any potential problems. The fungus behind it is spread by elm-bark beetles. Signs that an elm tree has it show up in the foliage. The leaves can curl, drop, wilt and turn yellow. Growing resistant cultivars is the best option as treatment is difficult. For identification, look for wilting, browning out of season (spring or early summer), and leaf drop. Remove infected trees, especially if you are growing multiple oaks together, since the fungus spreads through intertwined root systems. No fungicide kills this. Your only option is prevention. The best step to take is growing a tree not susceptible to it, like arborvitae (Thuja spp.) or birch (Betula spp.).
Perennials like tall garden phlox (Phlox paniculata) commonly get it, but trees get it too. It’s not fatal, but, once a plant gets it, its appearance is spoiled until its leaves drop. To prevent it, space plants properly (promoting air circulation) and practice sound irrigation policies. Fortunately, reddish-brown spots precede the holes, so, if you’re paying attention, you won’t be fooled. By mid-summer, the leaves turn yellow and drop. One reason to take this fungus seriously is that it puts your tree under stress, and insects and other plant diseases can take advantage of the stress to infest the tree. Cherry trees (Prunus) are especially vulnerable. Helpfully, several fungicides can be used as treatment. It takes the form of a black film covering the leaves. Scale insects are ultimately responsible for the presence of sooty mold. Control these insects with neem oil, and you won’t have trouble with this tree fungus. Like many fungi, it’s especially active in spring. It’s harbored in winter by leaves you allowed to stay on the ground from last year. Raking up those leaves and taking them elsewhere is the simple solution. Trees stressed for too long by this disease become susceptible to insect infestations. Dogwood (Cornus spp.) is one of the popular trees that’s highly susceptible to this fungus, which is fatal. Although the presence of Armillaria is sometimes indicated by mushrooms, don’t rely on mushrooms as an indicator. Look, instead, for browning or yellowing of leaves, wilting leaves, leaf drop, and stunted growth. Control root rot through prevention:
When watering, direct irrigation at ground level and keep any spray off trunk and foliage Apply water at dripline, not up against trunk Avoid over-watering Ensure proper drainage
Or avoid the problem altogether by planting water-loving trees like pussy willow (Salix discolor).
