Post on 24-Aug-2020
Dimethyl Disulfide (DMDS)A Methyl-Bromide Replacement Candidate
P. Robinson, R. Whitson, & T. Estes
Natural Background Concentrations
Biological1Human expired air: max. 0.6 μg/hr)Human expired air: max. 7ng/l)Poultry manure: 85 μg/kg
Anthropogenic1
Wastewater effluent (45 μg/l)
1/ low levels are maintained due to flux
• Living Organisms• Salt Water• Brackish Water• Fresh Water• Sediment• Soil• Atmosphere
Naturally Occurring in the Environment
Formation From Natural Processes
Biogenic Atmospheric Sulfur Cycle
Methionine Degradation Pathwaycheese products
Dimethylsulfoniopropianate (DMSP) Degradation Pathway
marine bacteria
DMDS: An ubiquitous natural compound
In plants •Allium spp
• pea bean
•Brassicacea spp
• mushrooms (truffle, shiitake)
In animal tissues • milk cheese • human urine
• animal by-products
In processed food• coffee bread salmon
• registered as a food additive to create a garlic-like taste
In Brassicacea:from thiomethyl glucosinolatesGlu-S
-O3SO
N
(CH2)n-S(O)x-CH3
n = 2, 3, …10x = 0, 1, 2
Glu-S
-O3SO
NN
(CH2)n-S(O)x-CH3
n = 2, 3, …10x = 0, 1, 2
Glucosinolates
CH3-SO-(CH2)n-N=C=S
Isothiocyanates
CH3-S-SO-CH3
Thiosulfinates
CH3-S-SO2-CH3 + CH3-S-S-CH3
Thiosulfonates
mirosinase
Pathways for the formation of DMDS
In Allium spp.From S-methyl-cysteine sulfoxide
S-methyl-cysteine sulfoxide
CH3-S-SO-CH3
Thiosulfinates
CH3-S-SO2-CH3 + CH3-S-S-CH3
Thiosulfonates
NH2-CH(COOH)-CH2-S(O)-CH3
alliinase
Pathways for the formation of DMDS
Ozone depleting potential (ODP) is 0
Half-life in the upper atmosphere predicted to be on the order of several hours
Part of the natural atmospheric sulfur cycle with formation of acidic sulfur products
DMDS Atmospheric Effects
Important Industrial Uses of DMDS• Agent used in hydrodesulfurization
processes in the petrochemical industry
• Coke inhibiting agent used in ethylene furnaces
• Used as an FDA registered food additive
• (Sec. 172.515 Synthetic flavoring substances and adjuvants) for flavoring use “in the minimum quantity to produce their intended effect”
DMDS physical-chemical properties
Molecular formula: C2S2H6Molecular weight: 94.201Appearance: yellow liquidOdor: garlic-like smell
DMDS physical-chemical properties
Boiling point: 109.8° CFlash point: 16° CDensity 1.0625 (20° C)Henry’s law constant: 1.21-3 (20° C)
DMDS physical-chemical properties
Koc 15-47 mL/gVapor pressure: 28.7 mm Hg (25° C)Water solubility: 3000 mg/L (25° C)
DMDS causes mitochondrial dysfunctionand activation of K-ATP channels
blocks the cytochrome oxydase (Complex IV)acts on K-ATP channels by an hyperpolarization
DMDS Mode of Action
Acute Toxicity ProfileAcute oral LD50- rats: 150 – 240 mg/kg
Acute inhalation LC50- rats: 776 - 835 ppm (2988 – 3215 mg/m3)
Acute dermal LD50- rabbits: >2000 mg/kg
Dermal irritation: Irritant (Tox. Category III)
Eye irritation: Irritant (Tox. Category III)
Dermal sensitization: Non-sensitizer
DMDS EfficacyWeed Control
DMDS EfficacyRate Response
% Control of Nutsedge in Peppers W/ DMDS Applied Alone Under LDPE, Rate Effect Vs. Methyl Bromide.Culpepper, Univ. Georgia, Tifton 2005
30
79
90100
0
10
20
30
40
50
60
70
80
90
100
DMDS 200 DMDS 400 DMDS 600 MeBr 400 (67:33)
% Nutsedge control at 34 Days After Application
Rates in Lbs/Acre
DMDS EfficacyApplication Depth
Effect of Injection Depth & Barrier Type on Weed Control
VIFLDPE
12”12”
8” 8”
DMDS @ 62 gallons/acre (79:21)
DMDS EfficacyInjection Shank Number
Nutsedge Control in Tomato, DMDS Alone, Shank Number EffectLDPE, VIF, Vs. METALIZED FILM Gilreath, Univ. Florida, Ruskin, FL 2005 Fall
0
50
100
150
200
250
300
350
400
LDPE VIF METAL
14 day plantback interval, weed control at 74 Days after application
Counts (50 ft.) area3-shank injection
4-shank injection
DMDS @ 400 lb/A
DMDS EfficacyBarrier Type
Nutsedge Control in Tomato, DMDS Alone, Barrier EffectLDPE, VIF, Vs. METALIZED FILM Gilreath, Univ. Florida, Ruskin, FL 2005 Fall
0
100
200
300
400
500
600
700
LDPE VIF METAL
14 day plantback interval, weed control at 49 Days after application
Cou
nts
(50
ft.) a
rea
UNTREATED
DMDS @ 400 lb/A
60 65 70 75 80 85 90 95 100
LDPE (w/b)
LDPE (w/w/)
VIF (b/b)
METAL Embossed (b/s)
METAL Embossed (s/b)
METAL (s/w)
METAL (s/b)
DMDS 750 (80:20)
Trial conducted by Dr. Stanley Culpepper; UGA REC; Tifton, GA. All treatments applied on 7/14/05. Squash were planted 27 days after fumigant applications. Evaluations at 47 days after Planting
DMDS on Squash, % Nutsedge Control in Tifton; GA; Fall 2005 Mulch Type Effect, DMDS Mixture With Chloropicrin
Combinations of DMDS With Chloropicrin
Effect of Rate and Combinations With Chloropicrin on Nutsedge Control (%), Culpepper. Univ. GA, Tifton, 2005
0
20
40
60
80
100
Alone + PIC @ 100lbs.
+ PIC @ 200lbs.
MeBr @ 400(67:33)
Percent Nutsedge Control @ 97 Days After Application, LDPE Barrier
DMDS @ 200 lbs. DMDS @ 400 lbs. DMDS @ 600 lbs.
The Overall Influence of These Variables on Weed Control
DMDS 79:21 @ 74 gal570 lb. DMDS: 150 PIC
UNTREATED
LDPE
% Control of Nutsedge in Peppers w/ DMDS + PICBarrier Comparisons Culpepper, Univ. Georgia, Tifton 2006
DMDS 79:21 @ 74 gal570 lb. DMDS: 150 PIC
UNTREATED
VIF
% Control of Nutsedge in Peppers w/ DMDS + PICBarrier Comparisons Culpepper, Univ. Georgia, Tifton 2006
DMDS 79:21 @ 74 gal570 lb. DMDS: 150 PIC
UNTREATED
METALIZED
% Control of Nutsedge in Peppers w/ DMDS + PICBarrier Comparisons Culpepper, Univ. Georgia, Tifton 2006
0
25
50
75
100
LDPE METALIZED VIF
UNT DMDS 75 gal (79:21) MEBR 350 (67:33)
Trial conducted by Dr. Stanley Culpepper; UGA REC; Tifton, GA. All treatments applied on 2/22/06. Holes were punched in mulch 15 days after application and peppers were planted 3 days later.
% Control of Nutsedge at 72 days after application
Impact of Mulch Types on Nutsedge Control of the Untreated,MeBr &DMDS Treatments; Tifton; GA; Spring 2006
DMDSCrop Safety
Excellent Crop Safety
Plant back in 7-21 day
0
10
20
30
40
50
60
70
LDPE METALIZED VIF
UNT DMDS 75 gal (79:21) MEBR 350 (67:33)
Number of Fruit/Plot: Harvests 1 & 2 combined
Trial conducted by Dr. Stanley Culpepper; UGA REC; Tifton, GA. All treatments applied on 2/22/06. Holes were punched in mulch 15 days after application and peppers were planted 3 days later.
Impact of Mulch Types on Marketable Pepper Yields of the Untreated, MeBr &DMDS Treatments; Tifton; GA; Spring 2006
0
5
10
15
20
25
LDPE METALIZED VIF
UNT DMDS 75 gal (79:21) MEBR 350 (67:33)
Pounds of Fruit/Plot: Harvests 1& 2 combined
Trial conducted by Dr. Stanley Culpepper; UGA REC; Tifton, GA. All treatments applied on 2/22/06. Holes were punched in mulch 15 days after application and peppers were planted 3 days later.
Impact of Mulch Types on Marketable Pepper Yields of the Untreated, MeBr &DMDS Treatments; Tifton; GA; Spring 2006
Drip Vs Shank Effect
0
5
10
15
20
25
UntreatedControl
DMDS @ 400lbs - Drip
Pic @ 200 lbs- drip
DMDS + Pic @ 200+200 -
Drip
MB + Pic(67:33) @ 350
lbs - shank
70 DAA
WEED BIOMASS (Kg/PLOT)
DMDS Drip Application Efficacy in Strawberry, Weed Biomass
San Luis Obispo, CA 2005 Pacific Ag GroupApplication: 11/10/05. Harvest From: Jan to May
Effect on Additional Weed Species
DMDS – TomatoPacific Ag Group, Arroyo Grande, CA - 2005 (Weed Counts/row)
0 20 40 60 80Weed Control - 34 Days After Application
DMDS 400 -Drip
DMDS 600 - Drip
Weed Control (counts/row)
Purslane Corn Spurry Lambsquarters Annual Bluegrass Nutsedge
DMDS – TomatoPacific Ag Group, Arroyo Grande, CA - 2005 (Weed Counts/row)
0 20 40 60
Weed Control - 34 Days After Application
DMDS 400 -Drip
DMDS 600 - Drip
DMDS + Pic 200 +200 - Drip
DMDS + Pic 400 +200 - Drip
DMDS + Pic 600 +200 - Drip
Purslane Corn Spurry Lambsquarters Annual Bluegrass Nutsedge
DMDS alone & w/PIC
DMDS – TomatoPacific Ag Group, Arroyo Grande, CA - 2005 (Weed Counts/row)
0 15 30 45 60 75
Weed Control - 34 Days After Application
DMDS + Pic 200 +200 - Drip
DMDS + Pic 400 +200 - Drip
DMDS + Pic 600 +200 - Drip
DMDS + Pic 400 +200 Shank
DMDS + Pic 600 +200 Shank
Purslane Corn Spurry Lambsquarters Annual Bluegrass Nutsedge
DMDS alone & w/PIC,
Shank vs. drip
DMDS EfficacySoil Borne Pathogens
Tomatoes, Drip ApplicationPacific Ag Group – Greenfield, CA - 2004
0
2
4
6
8
10
Scle
rotin
ia #
/plo
t
Untreated DMDS @200 lbs.
DMDS @400 lbs.
DMDS @600 lbs.
Inline @ 20Gal/A
MethylBromide
@ 350 lbs.
Sclerotinia Rot (Scleotinia sclerotiorum )
Rated at harvest (119 days after application).
Tomatoes, Drip ApplicationPacific Ag Group – Greenfield, CA - 2004
0
2
4
6
8
10
0-10
sca
le
Untreated DMDS @200 lbs.
DMDS @400 lbs.
DMDS @600 lbs.
Inline @ 20Gal/A
MethylBromide @
350 lbs.
Corky Root (Pyrenochaeta lycopersici )
Succulent Beans & Disease Incidence France, 2003
05
10152025
30354045
50
% in
fect
ed p
lant
s
Untreated DMDS @ 267 lbs. DMDS @ 535 lbs. Methyl Bromide @446 lbs.
Rhizoctonia solani
DMDS – Tomato Verticillium WiltPacific Ag Group, Arroyo Grande, CA - 2005
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Num
ber p
er P
lot
Verticillium Wilt Infected Plants - 125 days after application
Untreated Control DMDS 400 - Drip DMDS 600 Drip Chloropicrin 200 - Drip
DMDS – Tomato Verticillium WiltPacific Ag Group, Arroyo Grande, CA - 2005
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Num
ber p
er P
lot
Verticillium Wilt Infected Plants - 125 days after application
Untreated Control DMDS + Pic 200 + 200 Drip DMDS + Pic 400 + 200 Drip
DMDS + Pic 600 + 200 Drip Chloropicrin 200 - Drip
IRIS – Plants with Fusarium WiltPacific Ag Group, Nipomo, CA - 2005
0
5
10
15
20
25
30
Num
ber/P
lot
121 Days After Application
Untreated Control MB + Pic fb Vapam VapamChloropicrin @ 200 lbs DMDS + Pic @ 400 + 200 DMDS + Pic @ 600 + 200
DMDS EfficacySoil Borne Pathogens
Sclerotinia Rot
Rhizoctonia
Verticillium Wilt
Fusarium Wilt
Pythium?
DMDS EfficacyNematodes
Soil Borne Pest Control in Tomatoes Shank Application on 3-mar, 2004
Pliant High Barrier Mulch (Black)J. Gilreath, Univ. FL Bradenton
0
1
2
3
4
Nem
atod
es/1
00cc
of s
oil
7-Jun
Number of Stunt Nematodes (Tylenchorhynchus sp. )
Untreated
DMDS @ 200 lb/A
DMDS @ 400 lb/A
DMDS @ 600 lb/A
Midas @ 300 lb/A
Midas is methyl iodide:chloropicrin (67:33)
Root Gall Severity in Tomato (0-10 Scale)
0
2
4
6
8
10
Alone + PIC @ 100
<---B
est -
Wor
st---
>
Untreated DMDS 150 DMDS 300DMDS 450 DMDS 600 Telone C35 @ 26 GPAMeBr 400 (67:33)
Meloidogyne sp.
J. Noling, Univ. of Florida @ Lake Alfred, FL 2005, fall
DMDS – TomatoPacific Ag Group, Arroyo Grande, CA - 2005
0
50
100
150
200
250
Num
ber
per
Cub
ic
Cen
timet
er
Stubby Root Nematode - 67 DAT - Compared to UTC
Untreated Control DMDS 400 - Drip DMDS 600 DripDMDS + Pic 200 + 200 Drip DMDS + Pic 400 + 200 Drip DMDS + Pic 600 + 200 DripDMDS + Pic 400 + 200 Shank DMDS + Pic 600 + 200 Shank Chloropicrin 200 - DripVapam - 75 gal - Drip Inline 20.5 gal - Drip Midas + Pic 120 + 240 -Drip
Paratrichodorus sp.
DMDS – TomatoPacific Ag Group, Arroyo Grande, CA - 2005
05
101520253035
Num
ber p
er C
ubic
C
entim
eter
Root Lesion Nematode - 67 DAT
Untreated Control DMDS 400 - Drip DMDS 600 DripDMDS + Pic 200 + 200 Drip DMDS + Pic 400 + 200 Drip DMDS + Pic 600 + 200 DripDMDS + Pic 400 + 200 Shank DMDS + Pic 600 + 200 Shank Chloropicrin 200 - DripVapam - 75 gal - Drip Inline 20.5 gal - Drip Midas + Pic 120 + 240 -Drip
Pratylenchus spp.
DMDS Efficacy Against Citrus Nematode Application Via Buried Drip at 8” Depth. Radewald, CA-2006.
0
500
1000
1500
2000
2500
3000
3500
4000
6"depth 10"depth 18"depth
Untreated DMDS @ 141 lb/A-no barrierDMDS @ 290 lb/A-no barrier DMDS @ 290 lb/A-w/LDPEDMDS @ 581 lb/A-no barrier DMDS @ 581 lb/A-w/LDPE
Number of nematodes recovered from bags buried at each depth
DMDS EfficacyNematodesStunt
Root Knot
Stubby
Lesion
Cyst?
DMDS Registration
Submission for an EUP programAugust, 2006Currently in science review
Submission for Section 3 registration1st quarter, 2007
DMDSDMDS effective in shank and drip applications (pure and 95% EC formulations)
On nematodes (200/400 kg.ha-1)On fungi (400/600 kg.ha-1)On weeds (600 kg.ha-1)
Soil diffusion is very goodEffectiveness is higher using VIF or equivalent filmsDMDS in combination with chloropicrin demonstrates excellent results, lower rates
DMDS is a viable candidate for replacement for Methyl Bromide
Thank you!