| VISIBLE ABOVE GROUND - | ROOT SYMPTOMS - |
| Stunting | Galls or Swellings |
| Chlorosis | Stubby Roots |
| Mid-day Wilting | Lesions or Dark Spots |
| Leaf Drop | Stunting |
| Small Fruit | "Dirty Roots" |
| Yellowing | |
| Curling and Twisting of Leaves and Stems | |
| Patches of Poor Growth in Field | |
| Lack of Response to Treatment For Other Problems | |
| Premature Maturity | |
| Delayed Maturity | |
| Reduced Yield | |
| "Unthriftiness" | |
This table contains above and below ground damage symptoms and signs resulting from nematode feeding and root penetration.
Persons familiar with crop damage will note that many of these symptoms and signs are not specific for nematodes but could also result from other causes, such as poor nutrition or irrigation, or other pathogens.
The point of this table then, is to illustrate that there are no specific symptoms or signs that can be relied on to diagnose a nematode problem.
Having made this point, clicking on the highlighted words in the table will lead you to pictures of plant damage in which we know the cause was nematodes.
Viewing these symptoms and signs in the field should raise suspicion of a nematode problem which can then be diagnosed through sampling.
Some of the more indicative symptoms for nematodes include mid-day wilting, patches of poor growth, and lack of response to treatment for other problems.
Because nematode feeding and movement is disruptive of plant vascular tissue, it is often difficult for plants to take up enough water on a hot day to keep from wilting. When water stress becomes less severe in the evenings, plants are able to catch up and look perfectly healthy the following morning.
Frequently, nematodes are not evenly distributed across a field resulting in patches of poor growth interspersed with healthy looking plants.
Because nematode damage resembles that caused by other problems, if efforts have been made to assure optimum levels of irrigation and fertilization and other pathogens and insects have been considered, it's a good time to sample for nematodes.
"Unthriftiness" is a symptom common to many nematology texts. I haven't been able to find it in a dictionary. Let me know if you do. It appears to be a word coined by nematologists to indicate the crop is not doing well for no particular reason.
"Dirty Roots" is a condition referring to citrus nematode. Soil sticks to a gelatinous substance which is released by citrus nematode during egg laying and is not easily removed when the roots are washed with water.
