Proper Use of A Sweep Net
Variability between people using sweep nets can be huge. Assume four people go to the field and take 100 sweeps each. I would almost guarantee you that each will come back with 4 different counts even if the insects are perfectly uniform. There are things you can do to increase the accuracy between samplers but there will always be variability present. This is important because when sweep net thresholds were developed, they were developed by the samplers sweeping a “certain†way. If you are doing it differently than the folks who developed the thresholds you will likely have to treat more or less depending on how you are sweeping.
Here are some tips to properly use a sweep net. First, walk quickly (take big steps) between sweeps. This is important if your target is a highly mobile insect like tarnished plant bugs. If you are walking slowly and taking sweeps close together, you are likely spooking adult plant bugs that you will miss in the next sweep. Second, sweep perpendicular to the row with a flat net. Do not make huge arcs when you sweep. If you are making huge arcs and not hitting the row perpendicular to the net, you are sweeping more foliage per sweep than someone who is correctly hitting each row perpendicular. This will result in you catching more bugs than the way the threshold was designed. This will lead to more sprays than required. Third, hit the plant with some force and scoop on the upswing. Don’t bush hog the foliage but you should be getting some foliage in the net when you are done. If you are not getting some foliage in the net, you are likely not hitting the plants hard enough. This willl lead to your counts being lower than someone using the correct amount of force. Lastly, train all your summer scouts to sample the same way. If you take 10 minutes with your summer workers you can calibrate everyone in your crew to use similar methods which will increase your confidence in their counts. There will always be some variability when using a sweep net but these tips will improve your accuracy. Click this video link for a demonstration of using a sweep net correctly: Proper Use of a Sweep Net
