Maleic hydrazide is a synthetic chemical compound that regulates plant growth. It influences and modifies the natural development processes in various plants by interacting with their internal systems. This leads to controlled alterations in growth patterns, primarily for managing plant development in agricultural and horticultural settings.
What is Maleic Hydrazide
Maleic hydrazide is an organic compound with the chemical formula C₄H₄N₂O₂ and a molecular weight of 112.09 grams per mole. It appears as an odorless white crystalline solid. This synthetic substance is classified as a pyridazinone. Its chemical arrangement allows it to interact with plant physiology.
How it Regulates Plant Growth
Maleic hydrazide regulates plant growth by inhibiting cell division. This action is most effective in meristematic tissues, regions of active cell growth found in root tips, shoot tips, and buds. When absorbed by plant leaves and roots, the compound transports throughout the plant’s system. By preventing new cells from forming, maleic hydrazide suppresses overall growth, including the development of sprouts, buds, and unwanted side shoots known as suckers. This temporary inhibition allows for specific management of plant development without causing immediate cell death or widespread damage.
Common Applications
Maleic hydrazide is widely applied in agriculture, primarily for preventing sprouting in stored crops. It is commonly applied to potato, onion, and garlic crops before harvest to inhibit sprouting during extended storage. This helps maintain the quality and marketability of these vegetables.
The substance also controls sucker growth in tobacco plants, which diverts energy from leaf production to unwanted side shoots. In the United States, approximately 80-88% of maleic hydrazide use is for tobacco cultivation, with 10-18% for potatoes. It is also applied to control perennial grasses in areas like lawns, turf, and along utility rights-of-way.
Safety and Regulatory Status
Maleic hydrazide has low acute toxicity through oral, dermal, and inhalation exposure. However, it can irritate the skin and eyes, requiring precautions during handling. Some research suggests potential mutagenic and carcinogenic properties in cell cultures and animals, but no evidence of human carcinogenicity has been found.
Regulatory bodies like the U.S. Environmental Protection Agency (EPA) and the European Union (EU) oversee its use to ensure public and environmental safety. The EPA has reregistered maleic hydrazide, concluding that its use according to approved labeling does not pose unreasonable risks. Current U.S. limitations prohibit treating crops within seven days of harvest and feeding treated forage or hay to livestock.
The European Food Safety Authority (EFSA) also reviews maleic hydrazide, evaluating its uses on various crops. These reviews assess risk and may recommend modifications to residue levels. Adherence to label instructions and regulatory guidelines, including permissible levels in food, is essential for safe handling and application.