There are a few guys out there thinking that with the cooler nights, SOYBEAN APHIDS will be leaving their fields so they don’t need to spray those fields that recently reached threshold. If aphids are staying at threshold levels 3 or 4 days after the initial assessment, you still need to spray. Only those fields that are dropping in numbers or have reached into the R6 stage and are no where close to threshold can be considered safe from having to be sprayed for aphids. The cool night temps do not guarantee the aphids will leave to look for buckthorn yet. Triggers from plant quality may also determine whether they stay or go elsewhere.
HOWEVER other insects are starting to be a problem. IP and seed fields need tending to still. BEAN LEAF BEETLE adults are showing up in high numbers at a few of our sites in both Lambton and Elgin Counties. Fields in other counties could also be at risk. Scout fields to determine beetle presence and look at pods for feeding. I like to pluck about 50 pods randomly in the field, grabbing pods from the top 3rd of the plant without taking the smallest/youngest ones. If 10% of the pods collected (or in this case 5 pods) have feeding scars and holes on the surface, AND the beetles are still active in the field, a spray is required in IP or seed fields if the crop is not reached the middle of R6. Preharvest intervals come into play if you get any deeper into the R6 stage of soys. Look for clipped pods on the ground as well as this should also be included in your assessment. If significant clipping is taking place and beetles are still active in the field, spray is required.
STINK BUGS have also made an appearance at threshold levels in a field in Chatham Kent. Very high numbers were reported by Joe Tomecek and after some discussion it was obvious the field needed to be sprayed. Again, only IP and seed soybean fields are at risk, as stink bugs impact quality by piercing the soybean pod, scaring the seed itself. Control may be warranted in IP food grade and seed soybeans if an average of one stink bug per foot of row or 0.2 bugs per sweep are found during the late R5/early R6 stage of soybeans.