Black Stringy Stuff Growing Around My Plant

Disease Identification

• Armillaria root rot is a generic term referring to an infection by 11 different types of fungi. The disease is also referred to as shoestring root rot and affects about 700 different varieties of herbaceous and woody plants including trees, fruit and crops in all the temperate and tropical regions of the world. The presence of black strings around the infected plants is among the distinct characteristics of the disease.

Characteristics

• The armillaria fungi spread primarily with direct root-to-root contact between plants and with rhizomorphs. Rhizomorphs are black, shoestring-like growth structures that start to grow beneath the bark, on the roots or on the soil around the infected plants. The cord-like rhizomorphs have white cores and black outer skin and spread by branching, causing infection by penetrating healthy plant roots.

Symptoms

• Earliest signs of infection include premature yellowing and defoliation in trees. Plant growth is stunted with noticeably less vigor. Eventually there is twig and branch dieback. The symptoms can progress rapidly or slowly through the plant or tree. The lower stem or trunk of the plant starts to decay. Small plants can decline and die rapidly, while symptoms become evident more slowly on larger trees. Severe infection leads to excretion of watery fluid from the lower trunk area. Light-colored, fan-shaped fungal growth and black, stringy rhizomorphs are seen growing around the plant.

Management

• Since there are no curative fungicides for infected plants after an infection occurs, the best management strategy is to prevent the infection from occurring. Buy healthy plants from reliable sources. Keep plants healthy with timely watering, fertilization and pruning. Do not injure plants unnecessarily or damage tree trunks and roots. Weak, stressed trees and plants with poor defense systems are highly prone to infection.