Nematode Control from Shank- and Drip-applied Fumigant Alternatives to Methyl Bromide

Abstract

<jats:p>Field studies were conducted to evaluate potential alternatives to methyl bromide (MBr) for the control of plant parasitic nematodes in shallow-rooted, bedded cropping systems such as strawberry and in perennial nursery cropping systems in central California. Chloropicrin (Pic), 1,3-dichloropropene (1,3-D or Telone), combinations of 1,3-D + Pic, iodomethane (IM) + Pic, propargyl bromide (PBr), and metam sodium (MS) were compared with untreated controls and industry standard MBr/Pic treatments. Materials were applied by both shank-injection and drip-application, except MS and PBr, which were applied only by drip. The efficacy on citrus nematode (<jats:italic>Tylenchulus semipenetrans</jats:italic> Cobb) and/or root-knot nematode (<jats:italic>Meloidogyne</jats:italic> spp. Chitwood) control was investigated in three trials conducted on soils ranging from sandy loam to silty clay loam. All treatments controlled nematodes near the injection point (center of bed and moderate depths) comparable to MBr/Pic. Drip-applied Pic provided somewhat less control than MBr/Pic at the shoulder of the bed when delivered in 25 mm of water and MS provided no control at the bed shoulder. IM + Pic, both shank-injected and drip-applied, provided nematode control to a depth of 150 cm comparable to MBr/Pic. Telone EC applied to a dry field in 75 mm water did not control nematodes well at either 90- or 150-cm depths, whereas PBr controlled nematodes as effectively as MBr/Pic at the 90-cm depth, but not at the 150-cm depth. Propargyl bromide at 67 kg·ha<jats:sup>−1</jats:sup> was effective at killing the nematodes up to 30 cm deep in a strawberry plant bed. The dosage exposure values (within 96 h after fumigation) observed for greater than 99% control of nematodes were much lower for PBr (≈1 mg·L<jats:sup>−1</jats:sup>·h) than those for 1,3-D + Pic (17 mg·L<jats:sup>−1</jats:sup>·h when applied at 61:35 1,3-D:Pic mass ratio), Pic alone (10 mg·L<jats:sup>−1</jats:sup>·h), and IM + Pic (19 mg·L<jats:sup>−1</jats:sup>·h when applied at 50:50 mass ratio). Drip application technology showed promise for effective alternatives to MBr/Pic. Consistent delivery of an effective dosage of a material throughout the target soil profile is necessary for consideration as an acceptable alternative to MBr for high-value crops.</jats:p>

Properties of Soil Fumigants and Their Fate in the Environment

“…McKenry and Thomason (1976) determined the dosage in soil where fumigant concentration in soil aqueous phase was used and converted from measured gaseous concentration based on Henry's law constant. Other reported values (Schneider et al, 2008;Wang et al, 2004) used directly soil gaseous fumigant concentration integrated with time.…”

“…Products with a mixture of 1,3-D and CP (e.g., Telone C17, Telone C35) are often used. These products offer satisfactory pest control in many field tests (Schneider et al, 2008). An emulsified formulation of 1,3-D is InLine (61% 1,3-D, 33% CP, and 6% inert ingredient), which has commonly been applied through drip irrigation systems in strawberry fields in coastal areas of California.…”

“…Dichloropropene concentration (mg/l air) in the soil gaseous phase of a silty loam soil after drip fumigation with InLine (top) and shank injection with Telone C35 (bottom) at 325 l/ha at 30 cm depth (source:Schneider et al, 2008).…”

Evaluation of new chemical and biological nematicides for managing Meloidogyne javanica in tomato production and associated double‐crops in Florida

“…In tomato production in Florida, and most other fruits and vegetables produced, growers are still heavily reliant on the use of soil fumigants. Following the phase‐out of methyl bromide, conventional growers often use 1,3‐dichloropropene or metam, usually combined with chloropicrin to improve disease control . Until recently, the only non‐fumigant nematicide available to vegetable growers in Florida was oxamyl, a carbamate insecticide/nematicide, but it is now a restricted use pesticide.…”

Subsurface drip application of alternative fumigants to methyl bromide for controlling nematodes in replanted grapevines

“…was similar between drip and shank fumigation with both 1,3‐D/Cp and Im/Cp 23. The drip fumigation dosage exposure values were 17 mg L −1 h −1 of 1,3‐D/Cp and 19 mg L −1 h −1 of Im/Cp for more than 99% nematode control 24…”