Wendy from Dupont writes
Every year, I battle the dreaded cottonwood fluff, followed by millions of tiny cottonwood spouts. The tree is in a protected area behind my home, so I can't cut it.
Most pre emergents will not prevent tree seeds from sprouting. Casoron 4G Herbicide while safe to use around established Cottonwood trees, does not state that it would stop the cottonwood seeds specifically from sprouting, just annual weeds.
SureGuard SC is a potential option as its a post and pre emergent herbicide for use around established trees and plantations. Per the product label, the manufacturer states the following information:
"IMPORTANT: When applied as directed, poplars (Populus balsamifera, P. niger and P. tremuloides), hybrid poplars (P. sp. x sp.), and cottonwoods (P. deltoids and P. trichocarpa) have shown tolerance to this product. However, this product is a very active herbicide. Exercise responsible judgment and caution until familiarity is gained with this product. Test this product on a small number of plants to determine if this product can be used safely on a widespread basis. Do not apply this product over the top unless trees are more than one year old."
You can often reduce cottonwood fluff by making a cottonwood tree seedless through annual treatment with an herbicide containing ethephon, like Florel Plant Growth Regulator.
PGR herbicides are growth inhibiting, and they will prevent the seeds from forming when sprayed at the appropriate time of year. Getting a head start on treating your cottonwood tree with a growth hormone early in the spring is best and a full coverage spray of the fruit and tree is needed to prevent the seeds from dropping. You would not be able to spray a systemic application at the roots and have it impact the seed at the top.
Answer last updated on: 09/20/2022
