Resistance tests in vegetable crop varieties

Resistance to pests and diseases is an important objective in many vegetable crop breeding programs. Resistance is an alternative for chemical crop protection and normally results in less residues in your dish, less damage to the natural environment, and less costs for the application. Seed companies are developing many new resistant varieties.

About the test

DUS tests

Naktuinbouw uses information about resistance in new variety descriptions. An official variety description is a legal requirement for listing.

Some information in the official variety description must be checked in official tests. More explanation about resistance in DUS research and official variety description can be found on our webpage “How to tell us about resistance?“ (to be published soon).

We do these tests preferably by ourselves. We perform hundreds of resistance tests on new varieties of lettuce,  spinach, tomato, tomato rootstock, pepper, cucumber, gherkin, melon, French bean, vegetable peas and various types of cabbages. The tests are performed in accordance with internationally agreed protocols of CPVO and UPOV.

Third party tests

The same tests that we do for DUS research,  are also offered to third parties. Our independent position and our transparent, accessible procedures are contributing to mutual trust between companies that meet each other in the market place, and we make new variety applications possible for all, also for companies that cannot perform resistance tests.

Look here at the list of Resistance tests that we can perform for you for a fixed tariff. We can also develop new resistance tests on request, in any crop.

You can also perform resistance tests yourself, using the reference- isolates that we use for official variety descriptions. The delivery of most of these reference-isolates is subject to special conditions. Check out the Isolates validated for resistance testing .

We also perform resistance  tests with differential varieties, with the purpose of determining the race identity of a given isolate of a pathogen. We have fixed prices for downy mildew in lettuce and spinach, and for clubroot in Brassica oleracea.

Requirements for submission

A sample of 100 seeds is requested for each resistance test. We use a minimum of twenty plants per test. This is the minimum for evaluation of uniformity in seed propagated crops. We ask for more seeds because we sometimes need to repeat the test. Also, we take into account that some seeds will not germinate.

For isolate determinations, we need a fresh spore sample or sporulating material. It may be helpful to tell us the name of the variety from which the isolate was taken.


Requests for resistance tests and race determinations are normally processed within six months. Sometimes it will take a year. When a test is urgent, we try to adapt our planning.

Delivery of reference-isolates is normally possible within a week.


To all services and products of the Variety Testing department the terms and conditions of Naktuinbouw apply.

See list with rates (part 9).