Extension Column

Cottonwoods are fast growing trees in Populus genus. These trees are hardy to zones two through nine. Cottonwood trees produce cotton every other year. They preserve their resources. There is a cottonwood fluff produced around the seed which are cotton fibers. These seeds will cover the lawn or driveway and other parts of the landscape. This can go on for two weeks or more starting late April or early May through either June or July.

Is there a way to control the cottonwood seeds? You can reduce the cottonwood seeds with an annual treatment called an ethephon-based herbicide, a fruit eliminator according to the Extension Service. These herbicides are growth inhibiting. Thus, they prevent the seeds from forming. This herbicide must be applied with care. There should be a thick coating of liquid herbicide but not an excess to cause the herbicide to drip on the ground and other plants.

Here are a few tips for applying the ethephon-based herbicide:

Once the herbicide is mixed apply, within four hours.

Do not save any unused herbicide.

Do not apply fertilizer two weeks before or after treatment.

Hire professionals to remove the tree if you cannot afford the cost of this maintenance.

Why even go through all the maintenance to control cottonwood seeds in the first place? In our drought, cottonwood seeds are highly flammable. According to the Times Union, in Schenectady, New York on June 2 a cigarette set fire to cottonwood seeds and thus, calling the fire department to come stop the fire.

There are three main species are Populus deltoids (eastern cottonwood), Populus fremontii (Fremont’s cottonwood) and the Populus nigra (black poplar). They can grow to be 80 feet tall and do well in both wet and dry environments. They grow best in moist, well-drained sandy soils. Cottonwood trees have a soft wood density and are used as a cheap type of lumber hardwood.

There are many cottonless male forms and hybrids between P. deltoides and P. nigra have been selected according to Michael Dirr, Emeritus Professor of the Department of Horticulture, University of Georgia and are as follows:

“Colmar” which is resistant to leaf diseases, yellow fall color and from the University of Illinois.

“Noreaster” averages four feet per year, hybrid, with thicker bark and canker resistance.

“Robusta” averaged four feet per year, vigorous, developed some canker 40’x 60’ by 30 to 40’.

“Red Caudina” narrow pyramidal from 50 to 70’ by 8 to 12’, large deltoid leaves with red veins and petioles. The young leaves are bronze red.