Soybean insect pressure continues to be pretty mild, with insecticide application mostly being applied for stink bugs. Below are some comments on what to expect during the next several weeks. As corn harvest begins, don’t forget that this is the same window where insect infestations are most likely.
- Stink bugs are consistently our number one pest, and the chances of treatment-level infestations (9 or more per 25 sweeps) increase in late maturing fields. Typically, infestations begin the blossom around R5. Almost everyone is reporting that numbers are low at R3 as they are making fungicide applications. Avoid the temptation to tank mix a pyrethroid insecticide with your fungicide just because you are going across the field. Scouting is critical!
- The threat of serious soybean looper infestations appears to be low at this time. However, the risk will increase over the next several weeks. The most common caterpillar currently being reported is green cloverworm. Treatment is generally recommended between R1-R6 if defoliation exceeds 20%. However, insecticide applications can be made based on larval counts in sweep nets: 1) 19 per 25 sweeps for loopers and 2) 38 per 25 sweeps for green cloverworm.
- The corn earworm moth flight remains lower than average. There have been no reports of significant infestations in soybean. I’m hopeful we will get off easy this year, but it is critical to scout for this pest between R1-R4 when infestations generally get started. The treatment threshold is 9 larvae per 25 sweeps.
- Kudzu bugs have now been found in most counties bordering Alabama and Mississippi (see map below). These are mostly low numbers found in kudzu. At this late date, I’m expecting that any infestations in soybean will not justify treatment during 2013 (with the exception of some fields in the eastern part of Tennessee). It takes more than a few bugs to warrant an insecticide application. Our current suggested threshold is 1 immature kudzu bug per sweep (25 per 25 sweeps).
Please refer to UT’s Insect Control Recommendations for Soybean for a current list of recommended insecticides and rates.
