A mature magnolia tree in full heyday dictation tending from every quarter . The large , clean efflorescence of southerly magnolia ( Magnolia grandiflora ) that scent the spring zephyr with their bouquet have become symbolic of courteous Southern living . When one of these – or any magnolia species – tree develops a coating of fly ball - covered black mold , however , its knockout is promptly forgotten . Magnolia lovers will be glad to hear that this disfiguring term is treatable .
Causes
Magnolia trees suffer attacks of graduated table insect before they develop black mold . Up to 1/2 inch across , the flabby - corporate scale worm provender on magnolia throughout the Eastern United States , say Penn State University Extension ’s program helper Katherine Mazzey and extension factor Michael Masiuk . overwinter as larvae on old twigs , they make grow syringe - similar backtalk tube to suck fluids from the foliage . After feeding , the insect excrete a sticky , mellifluous waste product called honeydew that coats the tree ’s leave , arm and trunks . Black stamp overrun the trees to fertilize on the honeydew .
Features
Black mold — officially known as sooty mold — is a fungus compose of microscopical train of thought . In bombastic number , the threads produce seeable opprobrious dapple . In very large numbers , they cover wide sphere of honeydew with a charcoal grey finishing . In some instances , sooty cast will pare off affected plant in tissue - like plane , say North Carolina University Extension entomologist Steven D. Frank and fellow .
Considerations
Like all sugar - rich meaning , honeydew attract its ploughshare of insects , including fly front , ants , and wasp . Magnolia tree surface with honeydew may at the same time draw black modeling and flies , giving the unplesant impression that the fly sheet are feed on the fungus . They are n’t .
Effects
Because sinister mold fertilize on honeydew , it does n’t instantly damage magnolia trees . It may , however , cause lowly damage by cover the leaf and blocking out light necessary for photosynthesis . Because the scale insects have already damage the leaves , the magnolias may become weak and suffer from branch dieback .
Control
Keeping contraband mold and flies away from magnolia trees is a matter of manage the scale insect that produce honeydew . handle scale , however , requires patience . It may be a multi - year undertaking . Using insecticide is in effect only when the larva are crawling in search of leaves to give on . eating insect produce a protective waxy substance , note NCSU ’s Frank and colleagues .
Horticultural oils , dormant oils , and insecticidal grievous bodily harm and nebulizer treat scale . Horticultural oils suffocate larvae overwintering on the trees . torpid oils treat scale between late winter and summer , depending on diversity . Their manufacturing business provide counsel on temperature restrictions and plant sensitiveness .
Insecticidal soaps ask lineal impinging with the louse . Imadacloprid is a systemic insect powder . Applied to the grunge around a magnolia , it enters the origin system and broadcast to the leaves . Insects assimilate it die . Applying it several week before the larvae set about transmigrate may optimise its effects .
