 Hello, my name is Jan Knudel, I'm an extension entomologist for North Dakota State University. This video is about scouting for spider mites and soybeans. Spider mites are very tiny arthropod and they're found on the underside of the soybean leaf. They have piercing sucking mouth parts so they feed on the green tissue of the soybean leaf. This creates a stippling effect when you first see the spider mite symptoms. Later on the leaves may turn more of a yellow color and even go bronze when the leaf tissue starts to decrease. Spider mites are kept in control naturally with a fungal disease and also a predatory mite. The susceptible stage for soybean is from the R1 flowering stage through the R6 stage which is the full pod. Scout the field at least weekly or bi-weekly. Spider mites often move into the edge of the field first and you'll see them in stressed areas like drought or hot weather will increase the populations. Look for spider mites checking the edges first to see if you have them. For sampling you can use a white sheet of paper on a clipboard, place it underneath the plants you suspect have in spider mites and wrap the plants over the white sheet of paper. The mites will dislodge from the leaves and then wait a little bit and you'll see some mites moving around. Or you can also look for the mites by pulling up the plant and then look on the undersides of the leaves and you can also look for the symptoms which are the stippling or yellowing or even bronzing of the leaf tissue. And looking at the underside of the leaves you can look for the mites, the tiny mites using a hand lens. And then you can see if the mites are present. You can also look for the webbing just like the name spider implies, the web. And they use the web for dispersing in a field, they'll move up to the top of the plant and then bloom from plant to plant on the silk strands. The next step is to determine if the plant is at action threshold for the spider mites. So since the mites are too small to count, we use the visual symptoms as an indicator of action threshold. Look at the plant and look for the stippling in the lower leaves progressing up into the middle canopy and maybe a little bit up into the upper canopy and you would want to see maybe a little bit of yellowing in the lower leaves but no bronzing or leaf drop. And that would be considered an action threshold. So as you see, this one is obviously stippling all the way up to the top leaf. So this one would be at threshold, sample several sites in the field and several plants in the field and then work your way into the field until you find that leading edge for the spider mites. First you can just spray the edge of the field and avoid the whole field being sprayed. Some cases when it's real hot and dry, the whole field may need to be sprayed. For insecticide selection for spider mites and soybeans, you can select organophosphate insecticide. Two that are registered in soybeans are the chlorophyophosphate, lorsban and generic and dimethylate. There's one pyrethrite insecticide that is active against spider mites and that's bifenthrin. Some of the trade names include tundra, sniper, fanfare and bifenthrin. We don't recommend using other pyrethrites like asana, warrior, mastic max for example because they'll actually flare spider mite populations and increase their reproductive rate. Go back to the field and re-scout about five to seven days after treatment. The reason why is because the spider mite eggs are not controlled with insecticides. The eggs will hatch usually in about five days. Check to see if those young nymphs that hatch from the eggs are increasing in population. If so, you may need to re-treat with a second application. When you're getting close to maturity, be sure you check the labels for pre-harvest intervals. Thank you for watching this video and be sure to check the website below for more information.