Unveiling tiny threats - managing nematodes in crops

By Blake Jackson

The recent state horticulture meeting held in Hershey offered valuable insights into various aspects of farming, catering to operations of all sizes. Over three days, experts from across the country delivered presentations on fruit, vegetable, and flower production, alongside discussions on marketing and wildlife management.

Among the diverse topics covered, nematodes took center stage in a talk attended by many farmers eager to enhance their understanding of this often-overlooked pest in vegetable production. According to George Byrd, a retired professor of entomology from Michigan State University, nematodes, though mostly microscopic, play a significant role in agriculture, both beneficial and harmful.

Beneficial nematodes residing in the soil contribute to plant health by feeding on bacteria, fungi, and other nematodes. Soil management practices like cover cropping can encourage populations of these beneficial nematodes. However, Byrd emphasized the importance of careful cover crop selection, as not all cover crops have an equal effect on nematode populations.

Certain nematodes dwell both outside and inside a plant's roots. Examples include root-knot nematodes, which are internal root pests causing small, round growths on roots. Root lesion nematodes also feed internally in plant roots but do not settle in the roots like their counterparts.

Other nematodes, such as dagger and needle nematodes, live outside plant roots and can spread diseases like tomato and corky ringspot as they feed on different plants. While these nematodes may not move great distances in heavy soils, they can still contribute to disease spread within a crop.

Surveys conducted in Pennsylvania high tunnels revealed that about one-third of them contained harmful nematode populations. For farmers facing declining crop performance in high tunnels, it is crucial to consider nematode populations as a potential cause.

Measuring nematode populations requires a carefully collected soil sample sent to a specialized nematode analysis lab, such as the one established at Penn State.

Nematode management poses challenges due to limitations on traditional soil fumigation methods. Preventative measures, such as using nematode-free transplants and implementing strict equipment sanitation practices, are essential. Cover cropping and well-planned crop rotations can also help contain nematode populations.

The use of nematode-resistant varieties is recommended, although options may be limited. Releasing beneficial nematodes and exploring newer bionematicides are potential strategies, but careful consideration and collaboration with industry representatives are advised.

Anaerobic soil disinfestation, under research by experts like Francesco Di Gioia at Penn State, presents another option, particularly for tunnel cultivation. As farmers navigate the complexities of nematode management, a holistic approach involving prevention, careful planning, and strategic interventions emerges as a key strategy to ensure sustainable and thriving agriculture.

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