Plant Parasite Nematodes

Plant parasite nematodes can attack food crops such as corn.

Nematodes are microscopic roundworms that live in soil. Although most species prey on animals or insects for food, more than 4,300 species eat plant roots or shoots. The most common plant parasite nematodes found in home gardens or food crops are root knot nematodes or bean root nematodes. Plant parasite nematodes can be difficult to treat.

Symptoms

Plants affected by nematodes show symptoms above the ground and in their roots. The first noticeable above ground symptoms are plants withering, turning yellow, having stunted growth, not producing as much fruit or vegetables as usual, producing malformed fruit or vegetables and prematurely aging. When uprooted, the plant's roots often are deformed and covered with round swellings called galls or root knots.

Diagnosis

Unfortunately, symptoms of nematodes are similar to other problems, such as plant diseases or poor soil conditions. In corn, nematodes symptoms are similar to damage caused by herbicides. Symptoms such as withering or growing far smaller than expected also occur in cases of too little or too much water or other environment-produced causes, according to the University of Maryland Extension. The only way to diagnose nematodes positively is to send soil samples for examination to local agricultural department services or to universities with agricultural programs.

Treatment

The most effective nematode treatment is to keep the ground in which infected plants were growing in fallow for about two years. This starves out the nematodes. Destroy all infected plants so the nematodes do not have anything to feed on. In future, rotate crops so that nematodes that are used to one vegetable cannot thrive if a grain is planted there. During times when the sun is strong, quickly heating the soil can kill nematodes in its upper layers, according to the University of Missouri. Place a transparent sheet of polyethylene film on the affected area to super-heat the soil to temperatures between 98 and 126 degrees Fahrenheit.

Prevention

Nematodes can transfer from infected soil to uninfected soil from dirty garden tools. Be sure to always sterilize garden tools with 10 percent of bleach in the water. Many vegetables and fruits affected by nematodes come in nematode-resistant varieties. Weeding also eliminates places where nematodes can reside.

References

• North Carolina State University: Plant Parasitic Nematodes: Classifications and Descriptions; 2002
• University of Maryland Extension: Introduction to Plant-Parasitic Nematode Biology and Management; S. Sardanelli; April, 2010
• University of Missouri Extension: Managing Nematodes in Gardens; Melissa Goellner Mitchum; 2010
• University of Illinois Extension: More Details on Corn Nematodes; Terry Niblack; May 15, 2003

Resources

• University of Tennessee: Nematode Control in the Home Garden; Charles Hadden, et al.
• University of Nebraska-Lincoln: Nematodes in General
• US Department of Agriculture: Extracting Nematodes from Soil Samples