I sent off a nematode assay 3 weeks post treatment. The report came back high again. This morning, at the advice of Clemson researchers, we are making a second application to attempt to knock down the population. On the positive side, if you look at my last post where the bear removed the cup on #3 green, you can see some beautiful white roots. Nematode populations peak when root systems are at their healthiest state.
Here is an interesting response from Brad Shaver, PhD with Helena Chemical Co:
Interesting about the stubby root nematodes. Have you had those in the past? I remember the lance but not the stubby root species.
Lance isn’t all that surprising. They are hard to control. Nothing does great on them. Lance aren’t even on the indemnify label. I’m not sure how well Nemacur even is. Lance are endo-parasitic and will go in and out of the root, which is part of what makes them hard to control. Similar to root-knot except root-knot will generally stay in the top of the profile where they come into contact with more active ingredient whereas lace can be found anywhere in the root zone.
As far as having more now than you did a month ago; several things are probably happening here.
1. We always see a spike in populations in the spring and fall. As temps warm up and the grass starts growing so do the roots – aka food source. There was almost certainly some initial reduction in the population which, combined with the better growing conditions, led to even more roots.
2. What you might be seeing is a rebound effect. This was commonly reported for Nemacur.
3. But probably what you are seeing is just the inherent and ridiculous amount of variability in nematode populations. In my research I was taking 3-4 nematode samples per 60 square foot plot. Every month. Even with ag labeled nematicides as positive controls I was not able to see a statistical reduction in nematode counts. Sometimes the counts would be higher, sometimes lower and sometimes the same. Samples taken on the same day from the same plot, just a few feet apart, would often be drastically different.