Chemical Nematicides for Control of Plant-Parasitic Nematodes in Georgia Vegetable Crops

*Consult your county Extension agent or the Georgia Pest Management Handbook for recommendations on application rates and preplant intervals.

Telone II

The nematicidal properties of Telone II were discovered in 1943, but its commercial application to control root diseases caused by nematodes increased much later, when other fumigants such as ethylene dibromide and
methyl bromide were taken off the market. Indeed, Telone II became more popular for nematode control after methyl bromide began to be phased out in 2005 and vegetable producers had to apply alternatives. Telone II has been demonstrated nationally and globally to increase crop yields in nematode-infested fields at ranges relatively comparable to methyl bromide. Currently, it is the most commonly used fumigant in plasticulture and bare ground production systems in the Southeastern U.S. With the limited use of Telone II in the near future due to potential environmental concerns, there will be few alternatives available to control nematodes of economic importance. This will have a considerable impact on Georgia’s vegetable production.

Chloropicrin

Chloropicrin has been used as preplant soil fumigant for control of nematodes and soilborne diseases in various crops since 1919 in the U.S. It is manufactured in liquid form with a moderate vapor pressure and it disperses quickly through soil when applied below the soil surface under a tarp. The nematicidal effect of chloropicrin is not the primary reason for its application, as it also has fungicidal, insecticidal, and herbicidal activity,making it a broad-spectrum biocide. Chloropicrin is often used in combination with 1,3-D to fumigate soil, and formulations of chloropicrin that include 1,3-D (e.g., Telone C-17 and Telone C-35) increase the nematicidal effect of chloropicrin. Such mixtures control both nematodes and other pathogens better than either product alone.

Vapam

Vapam (a methyl isothiocyanate generator) is a liquid product that has a slow nematicidal effect compared with Telone II. This product can be applied by drenching, spraying, or injection procedures. Vapam lacks consistent performance in the control of nematodes, therefore growers do not extensively use it as a single management option. However, research suggests that effective control of root-knot nematodes can be achieved when Vapam is combined with nonfumigant nematicides. This nematicide also has some toxicity effect on weeds at higher rates.

Paladin

Paladin has been recently marketed in the U.S. as a soil fumigant to control nematodes, weeds, and soilborne plant pathogens. As an emulsified compound, Paladin may be broadcast, drenched, or drip-applied prior to planting for control of soilborne pests in vegetables crops including tomatoes, cucurbits, squash, peppers, eggplants, and melons.

Nonfumigant nematicides

Nonfumigant nematicides are nonvolatile toxic chemicals that can be applied prior to planting, at planting, or after planting through soil drenching, drip irrigation, or spraying onto the crop foliage to reduce population densities of nematodes and protect crops from damage. These products are grouped into two categories: contact (killing nematodes in soil by direct exposure) or systemic (killing nematodes while they feed from plant roots) nematicides. When applied to the soil, nonfumigant compounds are dispersed by movement in soil water. In contrast to fumigant nematicides, the efficacy of nonfumigants does not depend on soil temperature. A major drawback of these compounds is that their efficacy is generally less than that of fumigants such as Telone II for nematode control. Quick leaching of the active ingredients of nonfumigants, particularly in sandy soils, may also reduce their effectiveness. The removal of many older nonfumigant nematicides from the market due to toxicity and environmental concerns has encouraged the development of a new generation of chemical compounds that address these concerns and offer effective nematode management. A few nonfumigant nematicides are commercially available for use in vegetable crops (Table 3).

Table 3. Chemical nonfumigant nematicides currently available for use in vegetable production.*

*Consult your county Extension agent or the Georgia Pest Management Handbook for recommendations for application rates and preplant intervals. For a complete list of appropriate crops, please consult the label.

**This nematicide has not yet been registered for use at the time of publication of this note (December 2018).

Vydate

Vydate® is a carbamate (a pesticide derived from carbamic acid) that has nematicidal and insecticidal properties against plant-parasitic nematodes and soil insects. Vydate is a systemic nematicide (any compound that can be taken up by the plant through roots, leaves or both, and is effective against nematodes inside the plant), and is used in liquid form, as the granular form is no longer labeled in the U.S. due to concerns regarding its consumption by birds. This nematicide may be applied before planting, at planting, and after planting through soil drench, in-furrow, drip injection, broadcast, or foliar spray. Vydate is effective against nematodes in carrots, cucumbers, tomatoes, eggplants, squash, peppers, watermelon, and cantaloupes.

Nimitz

Nimitz® is a systemic fluoroalkenyl compound that recently received U.S. Environmental Protection Agency (EPA) registration for use in vegetable crops. In vegetable production systems, Nimitz has received much interest as a methyl bromide alternative in part because it causes mortality of target nematodes within 24 to 48 hours of product application. This nematicide controls several types of plant-parasitic nematodes (e.g., root-knot, stubby root, sting, lesion, and needle nematodes) resulting in improved fruit quality and yield of several vegetable crops, including cucumbers, eggplants, tomatoes, and peppers. Nimitz can be broadcast or applied through drip irrigation seven days before seeding or transplanting vegetables. Nimitz has shown the greatest efficacy in the control of plant-parasitic nematodes when used preplant. When applied on plant foliage,the active ingredient of Nimitz moves from the application point down into the roots, where it might affect parasitic nematodes. To prevent phytotoxicity and subsequent crop losses, foliar application of Nimitz is not recommended.

Velum Prime

Velum Prime® is manufactured as a liquid formulation and is one of the few available nonfumigant nematicides with systemic properties labeled for control of multiple species of plant-parasitic nematodes in the Southern U.S. This nematicide can be broadcast or applied through soil drench and drip irrigation at planting of vegetables.Velum Prime is registered for vegetable crops including potatoes and sweet potatoes; cucurbit vegetables such as cucumbers, pickling cucumbers, squash, watermelons, and cantaloupes; fruiting vegetables such as tomatoes, eggplants, okra, and peppers; and brassica vegetables such as cabbage and broccoli.

Mocap

Mocap® is a granular (15G) or liquid (EC) systemic insecticide/nematicide containing ethoprophos, which is used to reduce plant-parasitic nematode damage in some vegetable crops, including potatoes, sweet potatoes,cucumbers, corn (sweet and field), and cabbage. The nematicidal activity of Mocap can be achieved before or at planting by band or broadcast application.

Movento

Movento® is currently registered as a liquid formulation with potential to control both plant-parasitic nematodes and insect pests. It can be applied as a soil or plant foliage spray or through chemigation. Once applied on the plant foliage, the systemic activity of the product will allow it to penetrate the leaf surface and translocate down within plant tissues toward the roots, where most parasitic species of nematodes feed. This nematicide has shown some beneficial activity when used against root-knot nematodes in carrots and sweet potatoes.

Counter

Counter® 20G is a granular systemic insecticide and nematicide that is registered for the control of plant-parasitic nematodes in sweet corn. This nematicide can be applied in-furrow or banded at planting using the Lock’n Load handling system because of its high toxicity.

Fluazaindolizine

Fluazaindolizine is a new effective and selective nematicide for the control of nematodes, but it has not yet
been registered for use in the U.S. Over several years, fluazaindolizine has been tested in the U.S. in field
trials against nematodes including root-knot nematodes, and it has shown good nematicidal effect when used at planting. If registered, this chemical could be a promising product to control nematodes in vegetable crops, and because it does not affect beneficial organisms in the soil, it could be considered for integrated pest management programs of specialty crops.

Important considerations to get the most benefits from nematicides:

• Know the present type of plant-parasitic nematodes and their population densities in soil.

• Know the application rate, application depth, and time intervals before planting. This information can be found on nematicide label directions and should be followed carefully before applying nematicides.

• Know how to calibrate a nematicide applicator to correctly deliver the recommended rate.

• Know the environmental and soil conditions (soil temperature, soil moisture, rainfall, and wind speed) before applying nematicides. Nematicides should not be used if heavy rainfall is forecast to occur within 48-72 hours.

Summary

Soil fumigants alone or in combination with nonfumigant nematicides can provide vegetable growers effective and reliable control options for plant-parasitic nematodes, profitable yield and product quality, and increased profits. Treating soil with fumigant nematicides has been very beneficial to vegetable growers in Georgia, but environmental concerns may restrict the broad usage of these products. Telone II has been an important nematode management tool for the field production of many vegetable crops. Vegetable growers will have very limited options if soil fumigants, in particular Telone II, are no longer available. The development of new effective and environmentally safe nonfumigant nematicides has reduced the dependency on fumigant nematicides, but the application of fumigants still has great value for growers in Georgia.

References:

Lembright, H. W. (1990). Soil Fumigation: Principles and Application Technology. Journal of Nematology, 22(4S), 632-644.

Taylor, A. L. (2003). Nematocides and nematicides ̶ a history. Nematropica, 33, 225-232.

Chitwood, D. J. (2003). Nematicides. In Encyclopedia of Agrochemicals. Pp. 1104-1115. Wiley, New York. https://doi.com/10.1002/047126363X.agr171

Chen, Z., Chen, S., & Dickson, D. (2004). Nematology: Nematode management and utilization. Wallingford, UK, CABI Publishing.

Oka, Y., Shuker, S., & Tkachi, N. (2009). Nematicidal efficacy of MCW-2, a new nematicide of the fluoroalkenyl group, against the root-knot nematode Meloidogyne javanica. Pest Management Science, 65, 1082-1089.

Wright, D. J. (1981). Nematicides: mode of action and new approaches to chemical control, Pp. 421-449, In Zuckerman, B. M., & Rohde, R. A., (Eds). Plant-parasitic nematodes. London and New York, Academic Press.

Zasada, I. A., Halbrendt, J. M., Kokalis-Burelle, N., LaMondia, J., McKenry, M. V., & Noling, J. W. (2010). Managing nematodes without methyl bromide. Annual Review of Phytopathology, 48, 311-28.