Tuesday, August 2, 2016
August 2, 2016
We are battling nasty little creatures named parasitic nematodes.
Parasitic nematodes are microscopic worm like organisms that feed on roots – either by living outside the root and inserting a stylet into the root to feed, or living inside the root and feeding from within. High populations will slowly injure and kill the roots, causing the entire plant to die.
Populations are dependent on soil conditions, providing there is a host plant. During the warmer months, when the soils are warm, populations naturally increase. In the shoulder seasons, populations decline somewhat. If there is a winter with a long soil freeze, populations can decrease dramatically.
In the warmer months, as the plant comes under stress and nematode populations increase, symptoms begin to appear as off color, weak, thinning turf. There are other pests and diseases that cause similar symptoms, so testing has to be done to determine what is causing the damage, and if it is from nematodes.
We noticed symptoms last year on some greens and since then have been testing and going to war with them.
It’s not easy. There are few insecticides labeled for use against nematodes, and some will suppress certain species but not others. So while it is possible to suppress one type, that leaves the door open for the population of another type to explode since it has no competition. Also, when a nematode is killed, it leaves a hole in the root where it had been feeding that becomes an open wound for fungus, bacteria, etc to enter the root and cause even more or worse damage.
We are using a “new product” that has been used in the ornamental industry for many years to control mites, but was given a supplemental label just recently for nematodes. It’s a good product, yet is not very mobile in the soil which makes it safe for groundwater, but harder for us to move down into the root zone. In other words, it can get tied up above the root zone if not watered in immediately with enough water to get it to the roots.
When we have applied this product, we have used rain gauges to measure the amount of irrigation we have used, and by comparing the irrigation amounts to the rise or fall in populations after treatment, we’ve been fairly able to determine the right amount of irrigation we need to use to get it to the nematodes. And of course, each green needs different amounts of irrigation because of the different soil types and different depths of roots. It really becomes involved.
To prevent fungus, etc from damaging the roots, we add a fungicide specific to certain fungi that attack roots.
As with any product, there is never a complete kill. There is suppression. Our goal is to keep the populations in check throughout the year and not let them build up to the point that they cause damage. It easier said than done, but as of now, we are keeping populations in check after a serious rise in populations occurred in late June.
We are not the only course battling nematodes. Many courses in the area are doing the same, as are the top courses in the world. None of us has it easy.
And by the way, the ten inch main that feeds 6 holes had a break in it Sunday afternoon and the section needs replaced…we are limping along best we can, turning it on as we need it despite the leak, and then turning it off. As of now the parts are being shipped in. Hopefully by Wednesday we will have it back together.
Rosanna Dana Dana had it right-