Importance

The quality of the seedbed and the use and timing of herbicide sprays influence the level of weed infestation. Soil structural degradation reduces soil aeration and the rooting potential of the crop, allowing more vigorous weeds to establish and compete with the crop. A high weed population uses a lot of the soil moisture and nutrients otherwise available to the crop. In extreme cases, weeds can smother the crop.

Assessment

Visual assessment is the most common method and useful for small areas. The example given in Figure 19 show a cotton crop heavily infested with barnyard grass, melon and wild radish (Bayley and Brouwer, 2016). To assess the degree of weed infestation, we propose to delineate 1 m² on soil surface and count the percentage of the degree of weed infestation using Figure 20.

Figure 19
Figure 20

References

Bayley, D., Brouwer, D. 2016. Managing Weeds: AgGuide – A Practical Handbook. Department of Primary Industries. 105 p.