TMTD (thiram). The active substance is tetramethylthiuram disulfide, and according to the new nomenclature — bis-(dimethylthiocarbamoyl)-disulfide:
A fine crystalline powder of yellowish-gray color, melting point 155-156°C. Practically insoluble in water, but soluble in most organic solvents. The compound is chemically stable, does not decompose in acidic or alkaline media. Resistant to high temperatures. Decomposes with strong oxidizers to form sulfuric acid and carbon dioxide, and in alkaline medium, reducing agents convert tetramethylthiuram disulfide into salts of dimethyl dithiocarbamic acid.
Non-volatile, therefore, when working with it, you can use dust-proof respirators.
TMTD is produced in the form of an 80% wettable powder. The preparation is stable during storage. In the form of a fine suspended powder, it creates explosive mixtures with air.
TMTD is resistant to environmental factors and belongs to persistent pesticides, which degrade in biological environments into non-toxic components over 0.2-2 years.
On plants, it remains active for 1-1.5 months after application. Due to the risk of residue accumulation in the harvest, TMTD can only be used for seed treatment and disinfection of planting material.
Seed treatment is carried out using a water suspension or with moistening immediately before sowing or in advance (several months before sowing). Seeds of leguminous crops are treated during nitrogenation at least 2 weeks before sowing.
Dosage rates for 80% preparation for treating 1 ton of cereal seeds: 1.5-2 kg, sugar beet — 5-6, legumes — 3-4, flax, sunflower — 2-3, cucumber, watermelon, melon — 4-5, tomato, cabbage — 8, onion seedlings and onion black seeds — 4-5 kg.
TMTD is effective against fungal diseases, especially for tuberous and root crops, but less effective than mercury-containing preparations, yet reliably protects seeds from fungal pathogens and root rots. In soil, on treated grain, fungicidal activity lasts up to 30 days.
TMTD is used to combat Fusarium in wheat, seed mold in corn, polypodiosis in flax, Ascochitosis in peas, root rot in sugar beet, and others.
TMTD is effective against diseases of root crops and potato tubers. Treatment of carrot seedlings is carried out before winter storage and before planting into the ground, dosage rate 6-8 kg/ton.
Dusting root crops with the preparation before storage reduces losses during storage by 1.5-2 times; repeated treatment in spring before planting reduces plant losses on the field by 1.5-4 times.
Treatment of potato tubers before planting at a rate of 2.1-2.5 kg/ton (70 liters of 3-3.5% TMTD suspension per ton) reduces damage from scab, Rhizoctonia, and Phytophthora. For controlling cabbage diseases, TMTD is applied to seedlings in greenhouses and nurseries at a rate of 1-1.5 g/m2. In higher doses, the preparation has repellent properties against mice.
TMTD is moderately toxic to warm-blooded animals and humans (LD50 for rats 400 mg/kg). It has a pronounced cumulative effect, causes dermatitis when applied to the skin, conjunctivitis when it gets into the eyes, increases sensitivity to alcohol, and in large doses, it has mutagenic and carcinogenic effects.
