Pests And Diseases That Attack The Magnolia Leaf
There are many diseases and pests attacking the magnolia leaf, belonging to the majestic 80 feet tall magnolia tree. These gigantic trees can even reach a width of up to 40 feet if environmental elements do not destroy them first.
Magnolia trees are most commonly used to either shade homes or fill up a large open space in landscaping. They produce breathtaking creamy white colored flowers that fill the air up with a sweet, romantic aroma. The magnolia leaf is glossy green with a reddish-brown fuzz found on the underside. In the late fall, fuzzy brown cones will ripen and then winter brings the tree bright red seeds attached to each individual leaf.
Algal leaf spots, weevils, wax scale, sooty mold and powdery mildew are all common magnolia leaf diseases and pests, none of which are generally fatal but they can cause quite unsightly foliage.
Sooty Mold
The magnolia leaf becomes covered in a black fuzzy fungus. The fungus grows due to honeydew that is secreted by mealybugs, aphids, white flies and scale insects. To remove this mold you need to use soapy water to wash the affected foliage. Then you will want to apply a fungicide to kill the fungus as well as an insecticide to destroy the insects.
Powdery Mildew
Powdery mildew can affect the magnolia leaf during extended periods of humidity. Small gray or white spots grow and then merge together to create a coating over the leaf. If the case is severe enough, the stem and leaf can become stunted or distorted. You should apply a fungicide that is specifically designed for powdery mildew.
Algal Leaf Spot
This is a type of parasite that will first appear as a circular green spec with edges that are wavy and then as spores develop, they turn red. If a non-parasitic fungus happens to colonize with the algal then the specs turn gray instead of red. In this particular tree, the parasite attacks both the magnolia leaf and its twig. The best defense for this disease is good hygiene. Be sure to remove any infected leaves, rake and burn them. Do not set lawn sprinklers too close to the tree and prune any overhanging trees to help with evaporation. Apply a hydrated lime and copper sulfate mixture every other week.
Weevils
Yellow weevils will not affect the health of a well established tree but they are quite unsightly. Adult weevils will over-winter among magnolia leaf litter and then emerge in the spring to feed on the underside of leaves and buds. Tiny holes found in the leaves are a good indicator of an infestation. In June, their larvae feed on the leaf, leaving a scorched, brown appearance. For an organic control you should remove the leaf litter so that you eliminate their winter habitat or for a chemical option, you can apply acephate or carbaryl if 10 percent or more of the leaves appear as though they are damaged.
Wax Scale
A female magnolia wax scale can grow to have a diameter of half an inch and will range from pink to orange to brown in color and be armored with a white wax. They will over-winter on the youngest twigs, appearing as a gray nymph and then reach maturity around July. Damaged twigs will be swollen and purple. The scale will secrete honeydew that will attract black mold to attack each magnolia leaf, one at a time growing on the infected twig. You should offer your tree ladybugs for organic management as they will feed on the wax scale and leave your magnolia tree healthy and pest free.