nematodes in corn

Pathogen

Plant parasitic nematodes are tiny worms that cause some of the world's worst crop diseases and yield losses, and every plant has nematodes that can destroy them. For corn, at least two different types of parasitic nematodes have been found in Nebraska corn fields. Also, each species can have many species that can eat corn.

Symptoms

There are more types of symptoms caused by corn nematodes. However, diagnosis cannot be based on symptoms because most of them are general and can mimic those involved in other common problems, such as insect damage, soil compaction, nutrient deficiency and herbicide risk, among others. Some of the most common plant symptoms can range from subtle to severe and can appear as root damage, such as necrosis and malformation and stunting, chlorosis, and wilting of plant parts. Above.

 

Nematodes may be distributed throughout the field, but large populations exist in seemingly randomly distributed field patches. This distribution can reason for the development of 'hot spots' in the field (picture). In the most severe cases, the plants in the middle of these hot areas can die due to severe injury or at least sustain a significant root injury.

Epidemiology

Most plant nematodes have a hollow style on their head to pierce root tissue and feed. The style can also produce important plant enzymes in the feeding process. Styles can vary greatly in size and shape between nematode species and play an important role in nematode taxonomy.

Plant parasitic nematodes vary in the way they feed on plant roots. Some nematodes spend their entire life in the soil feeding on the roots from a single site or multiple sites as they pass through the root zone and are called ectoparasites. Some nematodes may spend most of their lives feeding under the roots and are called endoparasites. Nematodes can damage yields by competing with grains for photosynthate. In addition, the damage they cause to the roots can also prevent the plant from transporting water, even if there is sufficient soil moisture.

Differences in the species of parasitic nematode plants can also control their distribution. For example, a large species such as Longidorus spp. (needle) and Belonolaimus spp. (string) requires sand clothes for movement. Damage caused by some small nematodes can also be increased when crops are grown in sandy soils, but most nematodes are not restricted by soil type in their distribution.

Analysis

Because diseases caused by nematodes cannot be diagnosed based on plant symptoms alone, collecting samples and taking them to the laboratory for nematode analysis is necessary. Most nematode experts agree that estimating the nematode population in the soil and the root tissue is important when performing a nematode analysis. Thus, some laboratories may require the collection of individual root samples in addition to soil samples when performing nematode testing. Contact your endemic laboratory to confirm that they perform nematode testing and to obtain specific instructions regarding sample submission and associated fees. The UNL Plant and Pest Diagnostic Clinic perform nematode testing.

Administration

Nematode management in corn can be difficult due to the chronic nature of the problem. Crop rotations may or may not work as dictated by the field's distribution patterns of the nematode species. Some soil-applied nematicides are labelled for use in corn, but until recently, poor crop yields have limited their use except inside severe nematode influence. As of 2007, at least 2 agrochemical companies are testing seed treatments and expect to release them on corn soon.