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Infectious plant diseases are caused by pathogenic organisms with amongst others fungi and viruses. Worldwide they can cause severe crop losses but also reduce the aesthetic values of landscape plants and home gardens even though chemical control measures are often applied. The goal of the Dümmen Orange breeding teams is to develop varieties being resistant to important diseases that require fewer chemical applications and that are more sustainable for both producers and customers.

Often the terms resistance and tolerance are used interchangeably, and oftentimes resistance is mistakenly thought to equal immunity. Industry representatives requested an AmericanHort - led 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. https://irpcdn.multiscreensite.com/5d757b5b/files/uploaded/TerminologyWhitePaper-AH-HRI.pdf


AmericanHort recommends the environmental horticulture industry use the terms immunity, susceptibility, and high or intermediate resistance to describe the reaction of a plant to pathogens, whereas the term tolerance should be used to describe abiotic stresses in marketing communications with customers. The definitions provided below are meant to provide clarity for claims made of newly released plant material relative to a particular disease(s) or abiotic stress(es) at the time of testing. Changes in resistance are not covered under the original claim.

Immunity is when a plant cannot be infected by a given pathogen.

Resistance is the ability to exclude, hinder, or overcome the effects of a specified pathogen; the opposite of susceptibility. Resistant varieties may exhibit some disease symptoms or damage under heavy pathogen pressure and/or highly conducive environmental conditions. Two levels of resistance are defined: high and intermediate.

  • High Resistance describes plant varieties that can be infected but restrict the growth and/or development of the specified pathogen and/or the damage it causes.
  • Intermediate Resistance describes plant varieties that restrict the growth and/or development of the specified pathogen and/or the damage it causes but may exhibit a greater range of symptoms or damage compared to highly resistant varieties. Plant varieties with intermediate resistance will show less severe symptoms or damage than susceptible plant varieties when grown under similar environmental conditions and/or disease pressure.

It is to be noted that if resistance is claimed in a plant variety it is limited to the specified biotypes, pathotypes, races or strains of the pathogen that it has been tested against.

Susceptibility is the inability of a plant to resist or restrict the invasion of a pathogen; the opposite of resistance.

Tolerance is the ability of a plant variety to endure abiotic stresses without serious consequences for growth, appearance, and yield.

Q&A on Dümmen Orange Intrinsa®

Q: What is “Intrinsa®”? 
A: Intrinsa is the label at certain Dümmen Orange varieties, which were created by using advanced predictive breeding technology to identify the desired breeding approach for improved performance and disease resistance with all the natural DNA inherent within the plant. Through Intrinsa we will create more sustainable and economically viable plants for a greener future.  

Q: Is Intrinsa marker assisted selection?
A: Intrinsa varieties are the result of combining marker assisted selection with other predictive breeding techniques that make use of big-data and image analysis solutions.  

Q: What is the impact of predictive breeding compared to traditional breeding?
A: With predictive breeding the impact is reached in multiple areas. 1) the quality of the breeding pipeline is increased because breeders select crosses that have a higher chance of high quality offspring. 2) Important traits/characteristics are selected early on in the pipeline – due to DNA based screens and computer based algorithms – leading to higher quality varieties. 3) in-vitro plant culture methods can be used to speed up the breeding process for those plants in which we identify outstanding performance. 

Q: Are these GMO’s?
A: No. We make use of the intrinsic nature of the plants to improve our commercial varieties. We identify plants that have a rare natural resistance against specific pathogens. These resistances are studied to build predictive breeding tools to introduce the resistance to our commercial portfolio. 

Q: What crops currently are available with Intrinsa genetics?
A: Our portfolio currently offers TMV resistant petunias and White Rust Resistant Chrysanthemums.

Q: How do I know which varieties are offered as Intrinsa from those that are not?
A: Look for the Intrinsa icon throughout the catalog or on the website to identify which varieties have Intrinsa genetics.

Q: Do we claim resistance for a particular region or country in the world?
A: Extensive internal and external testing is done to confirm resistance to certain pathogens. During this confirmation process, our scientists use pathogens from naturally relevant representations of the pathogens. i.e. if we are testing resistance against a specific fungus, we use multiple relevant geographic origins of this fungus. This allows us to inform our customers whether the resistance is general or against specific isolates (isolate: a relevant variation of the pathogen). Please contact your local sales rep for more information.

Q: Can other breeders use Intrinsa® varieties in their breeding program?
A: Use of patent protected Intrinsa® plant material will be subject to prior approval of Dümmen Orange in those markets, but we are open to discuss license arrangements, which would enable other breeders to use our innovations.


We claim the resistance as specified on the specific crop pages. Pathogens may evolve and can overcome resistance. Therefore, any resistance claim made reflects the status of a plant at the time of testing. Changes in resistance over time may not be covered under the original claim.

For more information, please contact Dümmen Orange at intrinsa@DummenOrange.com.