Skip to main content
ARS Home » Midwest Area » Wooster, Ohio » Application Technology Research » Research » Publications at this Location » Publication #425445
Research Project: Climate-smart, Adaptive, and Resilient Production and Pest Management Practices for Nursery, Greenhouse, and Protected Culture Crops

Location: Application Technology Research

Title: An on-farm method to assess viability of horticultural microbial inoculants

Author
item Testen, Anna
item Moodispaw, Margaret

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Many growers use beneficial microbes, known as microbial biopesticides, in their fight against insect and disease pests. These beneficial microbes need to be alive to combat pests, but growers do not have an easy method to determine if their biopesticides are alive and if alive, how many? We developed a low cost, easy to use method for growers to assess if their biopesticides are alive and determine the concentration of living microbes. This technique requires easily obtained products such as bottled water, a quarter teaspoon, a 1 mL syringe. Commercially available dehydrated agar products replace microbial food on Petri dishes that would require laboratory equipment to produce. The alternative plating method developed in this study produces results that correlate strongly with lab based microbial quantification approaches. This allows growers to quickly and inexpensively assess their beneficial microbial biopesticide products, improving use of these products and saving money from products that may be unnecessarily thrown away.

Technical Abstract: Microbial biopesticides are widely used in specialty crop production in controlled environment agriculture. Growers may question the viability of these microbially-based products if they have been stored improperly or their efficacy is declining. In order to develop a method for growers to assess microbial biopesticide viability on-farm, we first compared the efficacy of traditional dilution plating approaches on agar media to those on dehydrated agar products. These methods were highly comparable for fungal and bacterial active ingredients and could even detect decreases in microbial populations following exposure to a heat stress event. A dilution method using bottles of drinking water and dehydrated agar products was developed and found to be highly comparable to traditional dilution plating for both bacterial and fungal products.