Monitoring Procedures and Form for Weighted Nematode Ratings
The ratings and calculations will help to determine the weighted nematode rating (WNR), expressed as a percentage
for your field.
Weighted root rating classes table
||Percent of root system
How to sample:
- Divide the field into representative blocks
- Select 1 sample of 15 to 20 root systems in a random pattern from as broad of a representation of each block
as possible. Remove as much of the root system as possible with a root lifter (for example, carrot or beet
lifter) keeping side roots intact.
- Gently wash or shake the soil from the roots.
- To sort the root systems into weighted ratings (0, 1, 3, 5, 7) use the diagram above and silhouette the root
system against the sky or a white board and evaluate for gall severity.
- Use the weighted root rating table below to record the number of roots in each weighted rating category and
to calculate the WNR.