OCSPP 850.4150: Vegetative Vigor


Non-target plants, i.e. plants in natural and semi-natural habitats within the agricultural land such as hedgerows, field borders, meadows and other small biotopes may unintentionally be exposed to plant protection products.
The EPA guideline OCSPP 850.4150 assesses the potential effects on plants following deposition of the test item on the seedlings at the 2-4 true leaf stage.

Study Design

Plant species

The plant species selected for the test should derive from different plant families to consider the taxonomic diversity and should give reliable and reproducible results. Ten plant species are chosen according to the specific properties of the test item and the intended use. There should be six dicot species of at least four families, one species of which is Glycine max (soybean) and four monocot species of at least two families, among them Zea mays (corn). One of the ten chosen species has to be a root crop such as Allium cepa (onion), Daucus carota (carrot) or Beta vulgaris (sugar beet).



Test rates

Test rates are usually determined in a range-finding pre-test. For plant protection products the rates for the pre-test are calculated based on the maximum application rate.

Course of the test

Plants are grown from seeds to the 2- to 4- true leaf stage. Sowing takes place on different dates to ensure that all species are in this stage at the application day. Then the test item is sprayed onto the seedlings. The test item concentration of each spraying solution has to be confirmed analytically before and after application. After the application, the plants are evaluated weekly for effects (phytotoxticity and shoot height) in comparison to water treated control plants for 21 days. At the test end the endpoints are measured and recorded.

Growth Conditions

The studies are performed in a growth chamber with controlled, optimized test conditions for standardised studies. The temperature is 22 °C during the light period and 18 °C during the dark period (mean 22 °C ± 10 °C) and humidity is 70% ± 25%. During the photoperiod of 16 hours light the intensity is 350 ± 50 µE/m2/s.
For special needs, more differentiated studies and research these conditions can be adapted within a wide range.


Endpoints are mortality, shoot height and shoot dry weight. If the test is conducted as multiple rate test effects on shoot height and shoot dry weight are reported as ERX (Effective Rate) for each species individually or if the test is conducted as limit test as NOER (No Observed Effect Rate). Phytotoxicity (e.g. chlorosis, necrosis, deforamtion) and growth stages (BBCH code) are recorded. If the test is conducted as multiple rate test an ERX (Effective Rate) caluation on phytotoxicity is possible.

Guidelines and Literature

  • OCSPP 850.4150 “Vegetative vigour”