Resistance to diseases and pests is an important breeding goal in many vegetable crops. Vegetable seed companies are therefore developing many new resistant varieties. Naktuinbouw can test resistances through a biotest.

About the test

Testing for DUS

Naktuinbouw uses information on resistance when describing new varieties. An official variety description is legally required for admission of a variety and is always based on a test by an independent body. More information on resistance in relation to DUS testing and official variety description can be found in the Frequently Asked Questions on this page below.

We prefer to do these tests ourselves. Every year we perform hundreds of tests on newly registered varieties of lettuce, spinach, tomato, tomato rootstock, pepper, cucumber, gherkin, melon, French bean, pea, and various types of cabbage. These testings are performed according to internationally established protocols of CPVO and UPOV.

Testing for third parties

The tests, which we perform for DUS testing, we can also perform for third parties. Through our independent position and our transparent and accessible way of working, we strengthen mutual trust between companies that encounter each other in the market and we ensure that anyone can register varieties including companies that cannot test for resistance themselves.

Below you can find an overview of resistance tests that we can perform for you at a fixed fee. In addition, we can develop new resistance tests at your request in all possible crops including ornamental crops.

You can also perform your own resistance tests using the reference isolates we use for the official variety description. Delivery of these reference isolates is subject to special conditions. Below you can find the list of isolates: validated for resistance testing. 

We also determine new isolates. For this, we have fixed fees for downy mildew in lettuce and spinach and for clubroot in Brassica oleracea.

Overview resistance tests List of isolates: validated for resistance testing.

Frequently asked questions (FAQ)

As a rule, resistance is reported on the Technical Questionnaire (TQ) that accompanies the application.

  • Chapter 5 and 7.3.1 ask, among other things, about resistances in some crops, and testing for resistance is mandatory when there is no option to fill in 'not tested' is. For clarity: resistance is never mandatory for Plant Breeders' Rights or listing, only the test may be mandatory.
  • Under chapter 7.1 you can report resistances for which no protocol has been established. It should be possible to check these resistances in an official test, and therefore the test protocol should be shared with us. This allows us to apply for an additional characteristic at the CPVO.
  • At the bottom of chapter 7.3.1 you can also report other resistances that do not appear in the applicable guideline.

If the application is very similar to an existing variety, but different because of the new characteristic, we have to apply for permission to use an additional characteristic at the CPVO. A similar procedure should be followed for National listing and Plant Breeders’ Rights.

The requirements for any characteristic are described in UPOV TGP/5/10. For resistance characteristics, both the disease and the resistance must be well documented, and the testing must be possible for an official body or possibly under the auspices of an official body.

We would like to receive the necessary background information on the new resistance characteristic from the applicant. We can keep that information confidential. We also study other information on the subject. Based on this, we assess the feasibility of the test. The costs and risks of the test should be proportional to the importance of the resistance in the DUS test. The test methodology should be suitable for establishing uniformity.

Then, the CPVO assesses whether the characteristic meets the requirements in the UPOV TGP/5/10. Although they use the same criteria as our own assessment, the outcome is still not always predictable, because the CPVO will also put a weight on the prospects for harmonisation of testing between member states.

After accepting a resistance as an additional characteristic, we will perform the resistance test and include the result in the variety description.

Additional characteristics are not automatically added to the current CPVO protocol for variety description. Such a final addition to the protocol does not depend on one application but depends on the state of the art in breeding.

If the test by an official body is not feasible, permission may be sought from the CPVO for a blind test at the applicant's premises or elsewhere, and visual assessment of the test by an official body.

The answer is no. Only the notification under chapter 5 and sometimes in chapter 7.3.1 is mandatory. Otherwise, you are free not to report a resistance.

If a resistance is not mandatory, it may still be useful to report it to us. The more we know about a variety, the better we can protect it from possible infringement. We can also conduct our testing more efficiently. Moreover, we are in a better position to make timely regulatory adjustments to new breeding issues.

There may be good reasons for this, for example because only one harmonised testing protocol is used in registration, while the interpretation of the results may differ for different climate zones. Nevertheless, we obviously always continue to strive for agreement.

We check all mandatory resistance characteristics by means of an official test. Additional characteristics are also checked by us. We also check all information we need when selecting comparing varieties, and for distinguishing the new application from the best comparing variety. Other information is not checked or randomly checked. We aim to perform official resistance testing before the start of the first growth cycle.

If there appears to be full correlation between a resistance test (biotest) and a marker test on a resistance gene, we may sometimes use a marker test. Naktuinbouw is strictly following the CPVO protocol in this respect. A biotest and marker test are in some cases both described in the CPVO protocol. We compare the result of our marker test with the TQ data, which must be based on a biotest. In case of contradictions between the marker test and biotest, we still perform a biotest. In such cases, the biotest will prevail, for obvious reasons.

Should there be any contradiction with the statement on the TQ, Naktuinbouw will inform the applicant immediately. This will affect the choice of comparative varieties for the second field trial. Should this also necessitate a third trial, this will affect the total costs of the testing.

The answer is yes. We recommend this in the case of new resistances (i.e., resistances that have not previously been used in the DUS test). Such advance notification allows us to make all the necessary preparations, for example the application of an additional characteristic at the CPVO. This is necessary to include the resistance characteristic in the official variety description.

The answer is yes. The sooner the better. This can be done by letter or e-mail and will be treated no differently from a report on the TQ. At least, if time still allows it. For reports under chapter 7.2, we will check whether we have sufficient information on the testing methodology. Some resistances are not included in the guideline but are known to us. Other resistances are new to us.

The answer is yes. Better late than never. We can include your information in our internal plant variety database. This leads to better protection of your plant variety.

You can find the fee per resistance test here.

To apply for resistance tests, please send us an e-mail.

We can process most applications for resistance tests or determinations within 6 to 12 months. If a test is urgent, we will try to adjust the test schedule.

Yes, a sample of one hundred seeds is required for each resistance test of a seed propagated crop. In our testings, we use at least twenty plants per test. This number is the prescribed minimum for assessing uniformity of seed propagated crops. We request more seeds because of repetitive tests that are required in some cases. We also take disappointing germination rates always into account.

For vegetatively propagated varieties, we use a comparable number of plants.