Florida citrus growers, who represent 65 percent of all
citrus growers in the U.S.1, understand the importance
of staying ahead of weed pressures. Researchers at the
University of Florida have found that untreated weeds can
result in a yield loss of up to 33 percent, which equates
to losing almost 40 acres of trees in one season for the
average Florida grower.2
Weeds compete with trees for nutrients, water, light and
grove space and can damage the tree, impact yield and
hinder regular harvesting practices. Weeds can even
compete with target plants for uptake of insecticides and
other chemicals, making the crop more susceptible to
insects and disease.3
While cultural and mechanical practices can provide
some help in managing weed pressures, most growers
utilize herbicides to deal with major threats. Herbicides
are typically divided into two groups: post-emergent,
which attack established weeds, and pre-emergent,
which prevent germination. Post-emergent or contact
herbicides are applied directly to the visible parts of the
plant. Pre-emergent herbicides are applied directly to
the soil, where they are absorbed by emerging stems
Roy Morris, a Crop Science technical sales
representative located in Florida, counsels growers
across eight counties on best practices for dealing
with weed pressures. He recommends including a
pre-emergent herbicide spray for two reasons.
“Using a pre-emergent spray greatly reduces the
number of herbicide applications on the crop because
of the residual effect of spraying the soil instead of the
weed. When using this type of residual program, the
herbicide lasts in the soil for several months, preventing
the weeds from germinating,” said Morris.
“A contact program only kills the weeds that are in the spray
area, increasing the number of times a grower has to spray
each season,” Morris said. “A residual program, on the other
hand, greatly reduces the number of applications needed.
A reduction in the number of applications reduces spray
load, which reduces a grower’s cost and carbon footprint.”
Pre-emergent sprays also allow growers to get ahead
of the heavy ushes of weeds that occur during Florida’s
rainy season, typically from May to August. During these
rainy months, it’s often too wet to apply herbicides
directly to the weeds that thrive in wet conditions.
Utilizing a pre-emergent-residual program enables
growers to continue managing weeds, even in harsh
In his territory, Morris recommends growers use
Alion® herbicide from Crop Science. Alion is a
broad-spectrum, pre-emergent herbicide that can be
mixed with a contact herbicide for protection from
weeds that are lurking below the soil as well as weeds
that have already emerged.
“Alion has been an effective herbicide in our citrus industry,
as long as it’s applied properly,” Morris said. “You’ve got to
get it in contact with the soil, ahead of the weed germination.
If you do it right, it’s pretty impressive.”
Learn more about how a long-lasting, pre-emergent solution
like Alion can help eliminate weeds in your citrus groves.