Although often profiled along with other lawn and garden diseases, nematodes are actually very small worms. Apparently they are not very well understood, but that is not because they are rare. They are actually everywhere.
Nematodes are the most numerous multi-cellular animals on earth. A handful of soil will contain thousands of the microscopic worms, many of them parasites of insects, plants or animals. Free-living species are abundant, including nematodes that feed on bacteria, fungi, and other nematodes, yet the vast majority of species encountered are poorly understood biologically (University of Nebraska-Lincoln).
Although organic gardeners may occasionally try to use nematodes as a sort of non-toxic DIY pest-control system, there are several distinct problems with this approach.
First, many varieties of nematodes feed on plant roots, making them dangerous to introduce into a healthy lawn and garden environment. One example is the root knot nematode, which feeds on many common fruit and vegetable types. Second, nematodes are dangerous because they are too small to identify easily; therefore, once your lawn or garden is obviously suffering, it's going to require some professional help to identify what the problem is. Third, management of nematodes is notoriously difficult. In the end, after explaining complicated measures that can be taken to mitigate the harmful effects of a nematode infestation, the University of California Agriculture and Natural Resources recommends focusing on prevention.
To invest in preventative measures that will keep your lawn and garden safe from harmful nematodes, be sure to consult with a pest control professional today.