Dithiopyr is a chemical used as an preemergent herbicide used to prevent crabgrass seeds from sprouting in the spring. Dithiopyr may alter microtubule

Microtubule

Microtubules are a component of the cytoskeleton. These rope-like polymers of tubulin can grow as long as 25 micrometers and are highly dynamic. The outer diameter of microtubule is about 25 nm. Microtubules are important for maintaining cell structure, providing platforms for intracellular...

 polymerization and stability by "interacting with microtubule associated proteins and/or microtubule organizing centers rather than interaction directly with tubulin."

It is an ingredient in many products including Dimension (herbicide) (a brand name) from Monsanto

Monsanto

The Monsanto Company is a US-based multinational agricultural biotechnology corporation. It is the world's leading producer of the herbicide glyphosate, marketed in the "Roundup" brand of herbicides, and in other brands...

.