The Latest Methods for Preventing and Treating Root Rot in Dendrobium Orchids

Dendrobium root rot is also called nematode disease. Nematodes parasitize the roots of Dendrobium, causing root rot, poor growth of the above-ground leaves, leaf chlorosis and yellowing, and even plant wilting. Nematode damage creates a large number of wounds and also causes infection by other soil-borne pathogens, leading to plant disease and accelerating plant death.

Causes of Dendrobium Root Rot

Nematodes generally overwinter as eggs, larvae and adults in diseased plant residues or cultivation substrate. They are generally transmitted through nematode-infested soil, irrigation water and human contact during handling. They invade through wounds caused during transplanting in early spring, and the disease is more severe under high temperature and high humidity.

Dendrobium root rot mostly occurs in cultivation beds that use moss as the growing substrate. Nematodes exist in a dormant state in dry moss plants. After watering, the moss absorbs water and swells, and the nematodes change from a dormant to an active state, thereby harming the Dendrobium. On affected plants, white curved lines form on the stems and leaves, and the nematodes can be clearly seen under a microscope. The damage to Dendrobium is relatively severe.

Symptoms of Dendrobium Root Rot

If the leaves of a mature Dendrobium plant lose color, become bluish, shrunken and wilted, or the leaf tips scorch and wither, or new shoots are slow to emerge and growth is abnormally slow, then root rot may be occurring. During inspection, if ring-shaped or elongated ring-shaped brown spots appear on the rhizome, root tips or other parts, and the spots show obvious water-soaked rotting with slight white or brown attachments, then Dendrobium root rot can be confirmed. If the brown spots are squeezed forcefully, water will spurt out.

Prevention and Treatment Methods for Dendrobium Root Rot

Because most fungicides can only be transported upward and do not have bidirectional transport, spraying chemicals to prevent and treat root rot is not very effective. Root drenching must be used to be effective. Commonly used methods are drenching the roots with Dexon 600 times dilution or triadimefon (Yunda Puling) 600 times dilution. Other agents can also include 70% Kameitong 600 times dilution and “Lvbang 98” 1000 times dilution for root drenching.

1. When using bark and moss plants as substrate, they must be soaked in water for 1 week before use.

2. For wild seedlings, the stems and moss plants on the roots should be carefully removed and burned.

3. Apply nematicides: such as aldicarb, ethoprophos, cadusafos, etc. Apply the dosage according to the instructions.