Powdery Mildew Tree Disease
Powdery mildew is a common disease that appears as a white powdery substance on the leaf surface. It attacks all kinds of trees. Trees most commonly affected by powdery mildew are linden, crabapple, catalpa and chokecherry, but almost any tree or shrub can get powdery mildew. Ash rust is a fungal infection that can cause premature defoliation.
Powdery mildew is a tree fungus that coats leaves blocking the process of photosynthesis. Every year trees and shrubs rely on photosynthesis to create food for new leaf growth. When this process is interrupted by powdery mildew the food reserves aren’t replenished and the tree/shrub’s growth will be stunted which can affect overall health. The stress caused by powdery mildew also makes the tree more susceptible to other diseases and insect infestations.
Sooty Mold Tree Disease
Common meyer lemon diseases fall into several basic categories. Viral diseases, like citrus tristeza, may also be deadly to other citrus trees. Mold growth, like sooty mold, covers the plants leaves, fruit and stems, damaging fruit. Rot, like foot rot, harms the lemon’s roots. Fungal infections, like greasy spot, may leave the lemons inedible. Bacterial diseases, like citrus blast, may spread by wind. Some citrus diseases are such severe risks to an entire crop that certain states quarantine infected trees or destroy them altogether.
Sooty mold is a fungus, which causes the blackening of the leaves of citrus trees.
The mold forms on the leaves as a result of honeydew secretions from insects such as whiteflies, aphids and mealybugs. Insect control is the most effective way to prevent the incidence of this disease. To control the insects and prevent the secretion of their honeydew discharge, spray the tree with bug buster insecticide. When spraying the tree ensure that both the top and undersides of the leaves are adequately sprayed. A second treatment spray may be required about 10 to 14 days later depending on the severity of the insect infestation.
Verticillium Wilt Tree Disease
Planting a tree is an action full of hope. We hope that our tree will grow and flourish, living out its life – which will certainly be decades, and perhaps even a hundred years or more – free of problems that threaten it. This is usually true, trees are remarkably tough, and most grow and survive without problems. But some don’t. Sometimes it is a major outbreak, like dutch elm disease, that decimates a much-loved tree. Most often it is a lower-level disease that picks away at a particular type of tree, like the verticillium wilt that is spreading through maple trees these days. Other diseases look dramatic but do very little harm.
So for gardeners, it helps to have some knowledge of diseases, to encourage the good, and separate the bad from the merely ugly. An earlier blog on diseases of maples has been a popular resource for our readers, so to continue giving that basic information, this time we are going to look at the diseases that pine trees may suffer from, which one’s matter, and what to do about them. Plum trees are susceptible to quite a few pests and diseases, and require regular maintenance. Fertilizing the fruit trees and spraying them with fungicides and pesticides is necessary to promote strong, vigorous growth. Some of the most common plum tree diseases that are caused by fungal infections are black knot, brown rot, powdery mildew, verticillium wilt, perennial canker and plum pockets. The bacterial diseases affecting plums are crown gall, bacterial spot and shot-hole. Plum tree diseases like plum pox virus and plum rust are caused by pests like aphids.
Leaf Spot Tree Disease
Decidious trees, those that lose their leaves seasonally, can develop leaf spot diseases. These tree diseases debilitate trees and shrubs by interrupting photosynthesis, the process by which plants creates food and energy. Some of the most common diseases observed in our forests are those of foliage, including broadleaves on hardwoods and needles on conifers. Leaves are green tissues that are more susceptible to attack by pathogens than are the woody parts of a tree, and the effects of foliage diseases are often very noticeable because of their dramatic appearance. Most leaf diseases are relatively harmless, causing little if any long term damage, and disappear when leaves are shed in the fall.
However, there are some pathogens which infect leaf tissues, but are then able to spread into other parts of a tree causing serious disease and even tree death. Leaf diseases tend to be weather dependent and are often most severe in years with cool wet springs. Look for leaf spots (lesions), discoloration of foliage, and early leaf drop (defoliation).The most common – and least important – problems can be seen on the leaves. There are a variety of leaf diseases found in maple trees that vary in intensity from year to year and from place to place. These usually show up as different kinds of spots on the leaves. They are usually seen in mid to late summer and none of these diseases are life-threatening.