Some vermicompost materials have been studied for their ability to suppress plant disease. However, suppression within an experimental system is not equivalent to pesticide efficacy or effectiveness against every disease.
A study on bamboo growing media and cucumber
You and colleagues in 2019 investigated worm-processed bamboo powder in a cucumber seedling system. The experiment introduced damping-off pathogens, including Pythium and Rhizoctonia, and compared the material with controls.
The abstract reports suppressive effects in the material investigated; these effects disappeared after heat sterilization. The findings suggest a role for biological characteristics within that system, but do not establish a universal disease-prevention formula for every vermicompost.
Keep the scope of conclusions intact
The base material was bamboo, the test crop was cucumber at the seedling stage, and the pathogens were identified. Changing the feedstock, crop or cultivation conditions may change the research question.
The study did not investigate insect pests. Therefore, these results should not be described as evidence of insecticidal effects of vermicompost, or attributed to HLX50 when that product was not tested in the paper.
When plants show disease symptoms
Record plant age, symptoms, their location and water conditions, then seek an appropriate diagnosis. Changing fertilizer or increasing its rate does not replace identifying the cause.
Assessing a material for disease suppression requires a test with a specific pathogen and appropriate controls. Observing less disease in one garden is insufficient to prove an input's effectiveness.
Read more: Applying vermicompost: define the objective, read the label and monitor plants; Water-retentive soil with good structure: assessing vermicompost effects.