UC IPM Online UC ANR home page UC IPM home page

UC IPM Home

SKIP navigation

 

Research and IPM

Grants Programs: Projects Database

Project description

Effects of plant age at the time of root-knot nematode (Meloidogyne javanica) infection on yields. (02FE031)
Program UC IPM competitive research grants program
Principal
investigator
A.T. Ploeg, Nematology, UC Riverside
Host/habitat Melons; Vegetable Crops
Pest Root-Knot Nematode Meloidogyne spp.
Discipline Nematology
Review
panel
Applied Field Ecology
Start year (duration)  2002 (Two Years)
Objectives Determine how long a crop (melon) needs to be protected from root-knot nematodes in order to avoid severe yield loss.

Determine how damaging root-knot nematodes that occur deeper in the soil profile are.

Determine how much damage can be attributed to root-knot nematodes that infect plants later in the crop cycle.

Determine how useful it is to control root-knot nematodes post-plant, after the initial infection has occurred.

Final report Field experiments were conducted at two sites (South Coast Research and Extension Center (SCREC), Kearney Research and Extension Center (KREC) to study the effect of the age of plants at time of nematode infestation on yields and nematode reproduction. The assay crop was melon var. Durango, and nematodes were root-knot nematodes (M. javanica). The experiments had three components: inoculation of nematodes at different times after melon seeding, inoculation of nematodes at different soil depths, and eliminating nematodes at different points in time after seeding. At the harvest of the crop, yields, nematode symptoms (galling), and final nematode populations were determined. Differences between the treatments were analyzed using statistical procedures.

In summary, delaying nematode inoculation generally resulted in slightly higher yields and lower root galling, but effects on final nematode populations were generally inconsistent. Inoculating nematodes very close to the seed resulted in significant yield reductions, whereas inoculation of nematodes at greater depths generally did not result in yield losses. Similarly, nematode inoculation in the upper soil layer resulted in higher levels of root galling, and higher nematode populations at harvest. Attempts to eliminate or reduce nematodes at different points in time after seeding of the melons (with Vydate) failed, as there were no significant differences between these treatments.

It is concluded that, in order to prevent major nematode damage in melons, it is important to prevent nematode infection very early on in the crop cycle, and to eliminate the nematodes in the upper soil layer (e.g., 0-25 cm). Nonchemical alternative management strategies such as solarization or biofumigation may achieve this. Effects of such tactics on final nematode populations, however, may not be dramatic, as delayed or "deep" infestations still resulted in significant nematode populations at harvest time.

Second-year
progress
Field experiments were conducted at two sites to study the effect of the age of plants at time of nematode infestation on yields and nematode reproduction. The assay crop was melon var. Durango, nematodes were root-knot nematodes (Meloidogyne incognita/M. javanica). The experiments had three components: 1) variations in the time that nematodes were inoculated (at seeding, two, four, and six weeks after seeding); 2) variations in the depth at which nematodes were inoculated (5, 25, 50 cm below the seed), and 3) variations in the time when a nematicide (Vydate) was applied (at seeding, two, four, and six weeks after seeding).

In this second year, the melon crop at the South Coast Research and Extension Center (SCREC) was a complete failure (poor emergence, complete failure of plants to grow), and no data could be collected. We have not been able to identify the reason for this. In contrast, the trial at the second location (KREC) was very successful. The results were similar to those obtained the previous year and again showed that melon yields were higher, and root galling indices were lower when plants were allowed to grow for two, four, or six weeks before nematode inoculation.

Inoculating nematodes very close to the seed at the time of seeding resulted in a significant yield loss of about 50%, but did not result in significant yield loss when nematodes were inoculated at greater depths.

We did not observe any significant effects of the Vydate treatments on yields, galling or nematode populations.

First-year
progress
Field experiments were conducted at two sites to study the effect of the age of plants at time of nematode infestation on yields and nematode reproduction. The assay crop was melon var. Durango, nematodes were root-knot nematodes (Meloidogyne incognita/M. javanica). The experiments had three components: 1) variations in the time that nematodes were inoculated (at seeding, 2, 4, 6 weeks after seeding); 2) variations in the depth at which nematodes were inoculated (5, 25, 50 cm below the seed), and 3) variations in the time when a nematicide (Vydate) was applied (at seeding, 2, 4, 6, weeks after seeding). First year results showed that delaying nematode inoculation did not affect plant growth or nematode reproduction at one of two sites. At the second site, melon yield was lower and root galling more severe when nematodes were inoculated closer to plant seeding. Effects of inoculating nematodes at different depths were highly significant at both sites, with yields being significantly lower as nematodes were inoculated closer to the seed. When inoculated at 50 cm below the seed, nematodes did not significantly reduce crops yields at either site. Vydate treatments did not result in significant yield increase or nematode reductions at either of the two field sites.

Top of page


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright 2014 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   web template revised: December 27, 2014 Contact webmaster.