Southern magnolia ( Magnolia grandiflora;USDA implant hardiness zones6 to 10 ) is a baronial cosmetic tree diagram with huge , showy , dish - shapedflowersthat are intoxicatingly fragrant .
Although this tree diagram is susceptible to some diseases , it does n’t often expire from them and in the main does n’t require chemical substance to control them . Bacterial blight magnolia disease ; fungus on magnolia trees , which can cause smutty spots on the leaf ; and canker are among the potential disease that can infect your magnolia .
Verticillium Wilt Disease
Verticillium wilt disease disease is due to a fungous pathogen ( Verticillium dahliae ) that invades the tree diagram ’s vascular system , which is responsible for the transferral of urine and nutrients . Some branch may pass because they ’re literally starved of nutrition as the disease progresses .
Because the vascular organisation runs along the Interior Department of the luggage compartment and branches , you wo n’t notice the onset of symptom , which include a brown discoloration of normally healthy , dark-green tissue inside the branches . wait for outside symptom , such as yellow or browning leaf followed by dying shoots and branches , which often pass off on one side of the tree .
Treatment
Although it ’s possible that verticillium wilting can kill a Southern magnolia , specially a tree that ’s already stressed , generally it ’s not fatal . Dead branch should be prune out . Not just because they ’re unsightly and can cause the disease to spread , but also because they pose a hazard if they strike from a tree diagram .
The mature elevation of Southern magnolia — potentially up to 80 feet — make pruning a prohibitive task for homeowners . Calling a manifest arborist is the best option for managing this disease .
Magnolia Leaf Spot Diseases
smutty situation on magnolia leaves are telltale symptoms of different diseases , which may be due to bacterial , fungous or algal pathogens . Symptoms of algal leaf smirch , because of the fungal pathogenCephaleuros virescens , begin with light-green spot or fuzzy colonies on the leaves .
As the disease progresses , these fleck rick red - brown . Other leaf spotlight diseases may get on from chocolate-brown office to brown patch on the leaves .
The sound way of life to preclude leaf spot diseases on Southern magnolia is to keep the Sir Herbert Beerbohm Tree healthy by making sure it buzz off enough water and fertilizing it according to grunge - test recommendations . It ’s also important to rake up leaves and other dust from around the tree since fungal pathogens , which are too diminished to be seen , live in this debris .
Warning
Due to the massive tiptop of matured Southern magnolia — potentially up to 80 feet — pruning projects for verticillium wilt , bacterial blight or canker sore are often best carried out by certify arborists .
Bacterial Blight Magnolia Disease
Rainy outflow provide the gross environs for bacterial blight magnolia disease to fly high . Commonly triggered by the pathogenPseudomonas syringae , bacterial blight can affect a magnolia ’s peak as well as its parting by cause large , irregular , brownish - black spots on the flowers and foliage . This disease may also cause the tip of stem to give way .
During a wry season , prune out the infected growth and dispose of it . This is another pruning task that requires a certified tree surgeon to do , both for the skill require as well as for the equipment to hit the tall branch of a mature tree .
Magnolia Canker Disease
If you note leg with numb leaves on your Southern magnolia tree , look a little nearer at the branches . If you see expanse that are swollen or sunken , discolored or exude a dreary rosin - looking gist , pestilence disease is the probable perpetrator .
As the cankers deaden twigs and branches , they tailor off the menstruum of water and nutrient , and the limb choke .
Cankers can be pruned out by cutting infected branches back at least 6 inch beyond the canker ( toward the Sir Herbert Beerbohm Tree ) into salubrious growth . It ’s another Book of Job for a certified arborist , who has the expertness as well as the equipment to perform this task .
