Most of you know we have been battling Nematodes in our greens for the past 6 years. Dr. Miller from the University of Missouri found them examining a plug I sent him from a bad spot on #5 green back in 2014. I am certain we have had problems with Nematodes in our greens for many years. Nematodes attack the root system of turfgrass. Greens are extremely susceptible to damage because of the low mowing heights of the grass. Nematodes live in the soil most feed on roots from the outside and a few burrow into the root and feed from the inside. The ones that go inside the roots are the hardest to control. Anytime you have a pest that pierces or burrows into roots you can have problems with root infecting diseases also. I have been treating our greens with nematicides this entire season. I have been trying to kill one species of Nematode, Lance. The past few years Lance has been our biggest problem. Lance is the only nematode that does not have a good control option available. We can kill all other Nematodes that attack turfgrass easily. There is one nematicide that is labeled to kill Lance it is called Divanem. The problem with Divanem is it gets tied up in the thatch and organic matter of the soil so it only goes down to about one inch into the soil. One inch is not deep enough to reach Lance nematode. My thinking was if I aerate the greens to create a channel down into the soil profile I could get the nematicide down to where the Lance nematodes live. That did not work. Dr. Crow from the University of Florida told me that it will go down in the aerifying hole but will not move laterally. He also told me if I was using nematicides to control Lance I would not get very good control of Lance but would kill other nematodes. Without competition, Lance numbers will grow higher. With the higher number of Lance, the damage to the turf is greater.
I started to spot symptom near the end of June. I sent two samples off to University of Florida after July 4th weekend. By that time, the greens were starting to show problems. Both samples came back over the threshold for Lance nematodes. One week later I sent a third sample off and it came back Lance above the threshold. At that time, I was still spraying nematicides trying to kill Lance. Greens 1,4-6, 9 -12, and 14 were progressively getting worse. The week of July 13 the University of Missouri opened up their labs. They had been closed because of Covid. I sent a fourth sample to Dr. Miller to check for disease. He told me the sample I sent was full of Pythium root rot. That same green also had high levels of Lance nematodes. Root rot is a very serious root fungus. Over the years, I have sent many samples to the lab and this was the first time any disease was found. I was shocked because I have been on a preventive Pythium fungicide applications all season. The next day, we went out with a curative application for Pythium root rot. Since that time, greens have responded to the treatments. The cooler temperatures have also helped tremendously.
I decided to close #11 green last week because the front portion was so severely damaged. I believe by the end of the month we can have the green back open. We have been very busy seeding the greens that are hurt the most. 1, 9, 10 - 12 and 14. Bentgrass seed has already germinated on 10 - 12 and 14. We will continue to spot seed any area that does not take. We will also pull plugs out of our nursery to help fill in bigger areas. We will overseed the remaining 13 greens. I do this annually by mid August. We will be applying soil and foliar treatments weekly to get the greens back. We have raised the height of cut on all greens. Greens 1-9, 13, 15-18 are being mowed at .150. Greens 10-12 and 14 are being walk mowed at .180. We will continue mowing at this height through August.
So how do we keep this from happening again. Until a better nematicide comes out that can effectively kill Lance nematode, I will not be spraying for this pest. Florida deals with nematodes year round and some good work has come out using compost to naturally control nematodes. There is a fungus in the compost that attack nematodes. It is not a cure I just need to get our greens through the two hottest month of summer. There is a process where you can mix the compost with sand and it can be injected into the green profile. It is called DryJect. I will be scheduling them to come this fall. I have also found some sprayable organic soil products, we will be using to help build up our soil biology to better defend against nematode damage. Dr. Crow has a new Lance nematode trial going on now. If there is a successful product, it won't be out for 2 or 3 years. This will not help us in the short term. We will work very hard to get the greens back. I am sorry for any inconvenience this has caused the membership.
Thanks,
Ed
Lance nematodes inside a root.
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