Estimating potential weed population density

Potential weed population density can be estimated in several ways. If weeds produce seeds, count the number of seed heads or pods and the number of seeds per pod or seed head on a given sample plot. This gives an estimate of the total number of seeds produced.

A more complex but accurate method is to take soil cores, sieve and wash these samples, and count the seeds in these samples. This technique is often of limited use as a research tool because it is time consuming and depends on seed identification skills.

Irrigate small areas and identify and count germinating weeds. This can be done in the fall but does not always provide a realistic indication of potential weed emergence due to the complex nature of seed dormancy. Using records from past monitoring provides an assessment of aspects such as weed species, density, seed set and location. It allows monitoring of changes over time.