Most turf managers in the North think that nematodes are only a problem in the warmer climates of the southern tier of states. While it is true that most severe nematode damage occurs on southern turf, there are a certain amount of nematodes always present in all soils. The parasitic nematodes continually feed on the roots of the turf but they only do measurable damage when their numbers reach a certain level. That rarely occurs in northern soils, but there are sufficient numbers of the nematodes present in most instances to cause a certain amount of weakening of the plant. They add to the plant’s other stress factors such as heat, low height of cut, compaction, soil borne fungi, drought, etc. This weakening of the plant without causing apparent damage symptoms is frequently referred to as subclinical damage.
Nematodes are microscopic worms that feed on the roots by inserting a tiny needle-like tube called a stylet through the epidermis of the root and into a cell. There, the nematode proceeds to suck out the sap from the cell. If enough of the nematodes are present, they can cause severe damage like they do in the warmer climates and the damage can be identified as being caused by nematodes. Even if there is no apparent damage to the plant on the surface, the holes that are opened up in the epidermis of the roots tend to serve as entryways into the plant for many soil borne pathogens. It is these soil borne pathogens that are responsible for the real damage to the plant and we never even stop to consider how they gained access into the roots.
In recent years, researchers have been able to identify nematode damage further and further north, particularly on cool season turf grown on sand. Dr. Bruce Branham at the University of Illinois identified three different cases of nematode damage in the past year. Two were on sand-based greens and one was on a sand-based bluegrass athletic field. However for every case of nematode damage that can be identified there are undoubtedly many more cases of subclinical damage that are never identified. We tend to attribute this type of damage to other stress factors such as heat, drought, compaction, low fertility, poor quality of water, etc.
Of course nematodes can be suppressed by the use of highly toxic chemicals such as Nemacur. These chemicals are dangerous to both plants and people and they are costly. Chemicals are usually applied after the nematodes have been identified and the damage can begin. A better solution is the regular use of Nature Safe to help prevent the problem from occurring before the damage is done. Our tests in Florida showed that Nature Safe suppressed nematodes even better than the toxic control chemicals. The reason for this suppression seems to be that the soil microbes that consume the energy in Nature Safe actually give off gases that are toxic to nematodes and some of the other pathogens in the soil. The net result is that the nematode populations are reduced and the turf is much stronger and healthier.
In Florida, on the warm season turf, we used heavier rates of Nature Safe than you would be likely to use on cool season turf, but the nematode problems were also much worse than you would be likely to find on the cool season turf. It stands to reason that the lighter rates normally used on cool season turf would likely suppress the lower populations of nematodes normally found there. Perhaps this suppression of the nematodes, the subclinical damage they cause and the resulting soil borne diseases, is one of the big reasons why Nature Safe fertilized turf is able to withstand the summer stress factors so much better than synthetically fertilized turf. It may also help to explain why Nature Safe fertilized turf typically has a much better root system than synthetically fertilized turf. Remember that every stress factor that can be removed from the turf in the summer time helps it withstand the other stress factors that we cannot control such as heat, traffic, etc. University research that illustrates Nature Safe’s suppression of parasitic nematodes is available on our web site.