For lab this week we were asked to examine individual soybean plants and look for insects present as well as insect damage that had occurred during the growing season. I had two soybean plants, one that was physiologically mature and ready to harvest and another that was at R6 with full seed pod (shown above). With the beans being at different growth stages, i was able to look at damaged plants on both green plant tissue and dead tissue. A couple pictures of what i found are posted below.
Stink Bug damage where feeding had occurred in the uppermost bean in this pod.
Although this picture doesn't show it to well, there is a stink bug nymph just in front of my index finger.
From what i saw in lab, if i had two fields with these two different maturities i would be sampling the R6 field. From the picture i posted above you can see the damage that the stink bug had done to the bean in the pod, but it is to late to solve that problem in a mature bean plant. If you are sampling in the younger of the two beans you may be able to save some yield at that point. To go along with that i found a nymph on my younger plant so there must have been adults present in the field. Both my old and young soybeans plants showed some damage from Bean Leaf Beetle, possible grasshopper and Stink bugs. If i had 30 plant samples that showed all the same type of damage from the 3 insects listed above, i believe there would be enough pressure to treat the R6 field with an insecticide. My concern with that statement is the maturity of the field, if my plant was slightly behind on a field basis then it may be to late to see any benefit from treating, so it is somewhat hard to call with just two plants.
Once we had completed our evaluation of the bean plants we were asked to do some quick estimates of percent defoliation on 60 soybean leaves that were spread across the lab tables. I will comment more on this next week as we have not received any results yet, just did the guessing part.
Do you know for sure that the damaged seed was the result of stink bug feeding? This type of damage can also be caused by drought conditions as well as soybean aphid feeding? Hint: Look for feeding scars/sites.
ReplyDeleteGreat use of your cell phone!
What did you use to base your treatment recommendation on? When treating so late in the season, you need to be aware of preharvest intervals and associated insecticide residues. Would that be the case here?
Nice picture showing percent defoliation. I was going to hand out a similar image, but I wanted to students to experience defoliation ratings without the use of such aids.