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Dimethomorph

Publication Date: 9/95

TRADE OR OTHER NAMES

Trade names of products containing dimethomorph include Dimethomorphe, Acrobat, Forum, CME 151, and WL-127294 (1, 2).

REGULATORY STATUS

Dimethomorph is not yet registered for use in the United States (2, 6).

INTRODUCTION

Dimethomorph is a systemic fungicide which protects plants from molds, as well as killing molds on plants and preventing their spread. It is a cinnamic acid derivative and a member of the morpholine chemical family. It is a mixture of two isomers but only the Z isomer has fungicidal activity (1, 2). Dimethomorph is used as a wood preservative to control downy mildew on vines, and to control late blight on tomatoes and potatoes (1, 5). The EPA has classified dimethomorph as Toxicity Class III - slightly toxic. Products containing dimethomorph bear the SIGNAL WORD: CAUTION (2). It is available as a wettable powder, a dispersible concentrate, and a suspension concentrate (1, 2).

TOXICOLOGICAL EFFECTS

ACUTE TOXICITY

Dimethomorph is only slightly toxic to mammals. The LD50, the dose which kills half of the test animals who consume it, is 3900 mg/kg for rats, 5000 mg/kg for male mice, and 3700 mg/kg for female mice (2). The LD50 for rats whose skin is exposed to dimethomorph is greater than 2000 mg/kg (2, 5). The concentration of dimethomorph in air which is fatal to half of the animals tested, the LC50, is greater than 4.24 mg/l air for rats. Dimethomorph is non-irritating to rabbit eyes and skin (1). It is non-sensitizing to guinea pigs' skin (3).

CHRONIC TOXICITY

Reproductive Effects

Studies show that dimethomorph does not cause developmental toxicity (3).

Teratogenic Effects

No information currently available.

Mutagenic Effects

Dimethomorph is not mutagenic (3).

Carcinogenic Effects

Two-year studies on rats and long term studies of mice demonstrate that dimethomorph is unlikely to cause tumor development (1, 3).

Organ Toxicity

No information currently available.

Fate in Humans and Animals

No information currently available.

ECOLOGICAL EFFECTS

Effects on Birds

Dimethomorph is practically non-toxic to birds. The LD50 is 2000 mg/kg for bobwhite quail and greater than 2000 mg/kg for mallard ducks (1, 5).

Effects on Aquatic Organisms

Dimethomorph is moderately toxic to fish. The concentration in water that killed half of the animals tested, the LC50 (96 hrs), is 6.8 mg/l for rainbow trout, 18 mg/kg for carp and greater than 14 mg/l for bluegill sunfish. Dimethomorph is slightly toxic to aquatic invertebrates, algae, and bacteria (2, 3).

Effects on Plants

Dimethomorph is non-toxic to most plants (1). However, it is slightly toxic to Eucalyptus at doses of 1.2 mg/ml. A study has also shown that it may affect the cell wall of plants, potentially causing over-production of cell wall material (4).

Effects on Other Animals (Nontarget species)

Dimethomorph is non-toxic to bees at 0.1 mg/bee, the highest dose tested (1).

ENVIRONMENTAL FATE

Breakdown of Chemical in Soil and Groundwater

Dimethomorph has a low soil mobility and low leaching potential (3).

Breakdown of Chemical in Surface Water

No information currently available.

Breakdown of Chemical in Vegetation

Dimethomorph is only metabolized to a small degree in plants. In studies of crops at harvest, either no residues or residues up to 0.5 mg/kg were found (1).

PHYSICAL PROPERTIES AND GUIDELINES

Dimethomorph is a colorless or grey crystalline powder that is stable under normal temperature conditions. It is stable to hydrolysis and will remain stable up to five years in the dark. (1, 2).

Physical Properties:

Chemical Name: 4-[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)-1-oxo-2-propenyl] morpholine (1)
CAS #: 110488-70-5
Solubility: in water is greater than 50 mg/l at 20-23 degrees C (1)
Soluble in other solvents including acetone, toluene, hexane, and methanol (1)
Melting Point: 125-149 degrees C (2)

Exposure Guidelines:

ADI: 0.1 mg/kg body weight (3)
NOEL: 200 mg/kg (rat) and 450 mg/kg (dog) (1)

BASIC MANUFACTURER

American Cyanamid Company
One Cyanamid Plaza
Wayne, NJ 07470
Telephone: 201-831-2000
Emergency: 201-835-3100

Review by Basic Manufacturer:

Comments solicited: October, 1994
Comments received:

REFERENCES

  1. The Agrochemicals Handbook, Third Edition. 1994. Royal Society of Chemistry Information Systems, Unwin Brothers Ltd. Surrey, England.
  2. Meister, R.T. 1994. Farm Chemicals Handbook '94. Meister Publishing Company. Willoughby, OH.
  3. Shell Agriculture. 1994. Dimethomorph: The New protection Against Oomycete Fungi. Princeton, NJ.
  4. Kuhn, P.J., D. Pitt, S. Lee, G. Wakley, A. Shepard. 1991. Effects of Dimethomorph on the morphology and ultra structure of Phytophora in Mycology Research. Volume 95, no.3. pp.333-340.
  5. National Institute for Occupational Safety and Health (NIOSH). 1993. Registry of Toxic Effects of Chemical Substances (RTECS). NIOSH. Cincinnati, OH.
  6. American Cyanamid Co. Agricultural Research Division. 1994. Conversation with Susan McIntyre. August 31, 1994.