AmericanHort, HRI announce new recommended terms for disease resistance claims

AmericanHort and its research foundation, the Horticultural Research Institute (HRI), announced that they have announced an "industry-initiated movement" to begin a market-wide standardization for terms appearing on plant material being released to the market. The tags, per the announcement, will reference specific diseases and/or abiotic stresses. 

The goal, per the release, is ultimately to help customers understand different traits and characteristics - drought, cold exposure, etc. - so customers have more reasonable expectations for performance once they purchase plants. Another term they hope to clarify is resistance, as customers treat resistance and tolerance as the same. The reason they are recommending these changes now, per the release, is due to an expected influx of new plant material into the market over the next few years. 

Disease resistance and tolerance to abiotic stresses (such as drought, cold exposure, others) in plants contribute greatly to plant health and ultimately to the success of our industry. As more new plants are anticipated to be released targeting disease and/or abiotic stress management, the industry will be faced with how to best represent these traits to customers and set performance expectations. Often the terms resistance and tolerance are used interchangeably, and oftentimes resistance is mistakenly thought to equal immunity.

At the request of Industry representatives, AmericanHort led an effort to explore an industry-wide adoption of specific terms to be used in the event of a new plant release when describing disease resistance and/or tolerance to abiotic stresses to help avoid unsubstantiated and misleading claims.

Jean-Marc Versolato, Production Manager, Plant Health Department, Bailey Nurseries, participated in the process and commented, “It’s a good idea for the whole industry to use the same words to describe a plant’s response to stress and to clarify the specific pathogen or agent tested. This is useful so that the end customer understands the claim being made, and there is no ambiguity a plant’s resistance or tolerance to a stress.  It becomes a truer statement and no longer misleads the customer into thinking a plant is resistant to all sorts of problems.”

A working group made up of the research community and industry breeders advised a set of clear definitions for the terms immunity, high or intermediate resistance, susceptibility, and tolerance to be used industry-wide going forward. Disease specifics should be included on marketing claims. For example, a tag on an impatiens plant should state ‘High Resistance to Impatiens Downy Mildew’ as opposed to ‘High Resistance to Disease.’

Shannon Carmody, Plant Pathologist, Ball Horticultural Company, commented on the process, “The development of downy mildew resistant Impatiens started a conversation internally at Ball Horticultural Company about how to use accurately disease resistance language in breeding, product development, and marketing for ornamental crops. We look forward to working with other industry stakeholders to improve clarity and consistency for our customers.”

The full white paper is available on the HRI website. AmericanHort encourages all breeders and those involved in new plant introductions within environmental horticulture to follow this guidance.