This is now personal. First, it was toilet paper and hand sanitizer. Later, components in automobile electronics became scarce. Supply chain disruption has now hit agriculture and by extension, food plots. Glyphosate is in short supply and prices have escalated. I have given up on trying to comprehend the causes of supply chain disruption and I am not even going to touch that aspect of the glyphosate shortage. I am going straight to weed management alternatives without glyphosate.
Glyphosate has
many use patterns in food plot management.
Two of the most common and important uses are site preparation and
preplant application to control emerged weeds on seedbeds before seeding
forages. Glyphosate can also be applied
with a specialized applicator called a weed wiper. While this is a small niche use of
glyphosate, it is a very useful tool to control tall weeds without damaging
forages. Since glyphosate has many
possible uses in food plot management, the entire weed management program needs
to be considered when planning alternatives.
A word of warning: there is not a
one-for-one replacement herbicide that can be cleanly substituted for
glyphosate. The entire weed management
system needs to be tweaked to fill the glyphosate void.
Revised mechanical weed
control strategies. Preplant tillage
using a disk harrow or power tiller can replace glyphosate for weed control on
the seedbed prior to seeding forages. This
is called stale seedbed weed control. The
objective of stale seedbed weed control is to create a weed-free seedbed before
seeding forages which gives crop seedlings a competitive jump on weeds. Multiple tillage operations may be needed to
produce a weed-free seedbed. While repeated
stale seedbed tillage is effective, it adds to the overall cost of weed control
compared to a single application of glyphosate.
Mowing or clipping tall weeds is a partial replacement
for glyphosate applied with a weed wiper.
Repeated mowing suppresses erect annual and perennial weeds. Ideally, mowing should be done when weeds
reach 12 to 18 inches in height which is normally well-above the low growing
forages. Over a three- to five-year period,
repeated mowing during summer months can deplete root reserves of perennial
weeds. This practice will help suppress their growth and reproduction. Mowing is not as effective as glyphosate in
managing perennial weeds. However, in
the absence of glyphosate mowing will keep populations perennial weeds from
increasing.
Other herbicides. Glyphosate is broad spectrum and
systemic. Glyphosate controls grasses
and broadleaf weeds; both annuals and perennials. However, there may be situations during site
preparation where grasses are not present and broadleaf weeds need to be
controlled. For site preparation broadleaf
weed control 2,4-D and/or triclopyr are substitutes for glyphosate. Understand that grasses will not be
controlled by either 2,4-D or triclopyr, but these alternative herbicides are
very effective in controlling broadleaf weeds.
Additionally, triclopyr is very useful in controlling woody broadleaf
weeds and brambles. These herbicides
will kill food plot forages if directly applied. However, 2,4-D and triclopyr have minimal
soil herbicidal properties and are ideal for site preparation.
Glufosinate is a
non-selective herbicide that has similar use patterns as glyphosate. Despite name similarity, glyphosate and
glufosinate are chemically very different.
In general terms, glufosinate is not as effective on perennial weeds as
glyphosate. Informal discussions suggest
that glufosinate may also be in short supply.
Glufosinate has not been marketed or packaged for small- or intermediate-uses,
but that may change in the future. Glufosinate
has been more costly than glyphosate and that trend will likely continue (Table
1).
Pelargonic acid
is a fatty acid, somewhat like a soap.
Pelargonic acid is a quick acting non-selective contact herbicide that
controls annual broadleaf weeds. Pelargonic
acid does not move in the vascular system of treated plants and will not
control perennial weeds. In the recent
past, many glyphosate-containing herbicide products sold in chain stores were
blended with pelargonic acid to quicken weed control response. I have many years of research experience with
pelargonic acid. While the herbicide can
effectively control annual weeds on seedbeds, it is tricky to use and achieve acceptable
performance. Pelargonic acid is a
specialized herbicide that has not been widely used in conventional agriculture
making it a costly alternative to glyphosate (Table 1).
There are
herbicides derived from plant-based products that may be promoted as
alternatives to glyphosate. These are
niche herbicides used in organic crop production. All are non-selective and quick acting, but
not systemic. Natural product herbicides
will not control perennial weeds and I never controlled grasses with these
products. Product names are numerous, nearly
impossible to track, and change rapidly as rebranded products are introduced. Active ingredients are from plant-based
sources; concentrated vinegar (greater than 20% acetic acid), citrus oil (d-limonene),
lemongrass oil, clove oil, cinnamon oil, and others. Based on many years of research experience
with these herbicides, performance of natural product herbicides was unpredictable,
and I am being kind with my assessment.
Furthermore, these herbicides are very expensive (Table 1). Therefore, Whitetail Institute does
not recommend natural product herbicides for weed control in food
plots.
Stretching
glyphosate supply. For those who
already have glyphosate, supplies can be extended by carefully matching rate
with weeds present. Refer to Table 2. Common use rates of glyphosate range from
0.5% to 2.0%. Small annual weeds can be
effectively controlled with glyphosate mixed to make a 0.5% solution. The highest rate (2%) should be reserved to
controlling woody weeds or any perennial species. For site preparation when grasses and
broadleaf weeds are present, adding 2,4-D and/or triclopyr with a low rate of
glyphosate will provide acceptable overall weed control.
Don’t forget about name brand
Roundup®. When this issue began to
develop in autumn 2021, I contacted a friend with Bayer – the current owners of
name-brand Roundup®. Name-brand Roundup®
products are formulated in the U. S.
Generic glyphosate herbicides are formulated overseas. However, supply of name-brand Roundup®
remains linked to availability of the active ingredient and inert carriers
which are manufactured overseas. Despite
the vulnerability, name brand Roundup® may be available from time to time in
the months ahead. Name-brand Roundup® is
more costly than generic glyphosate, but do not become fixated on the price difference. All glyphosate herbicides are going to be
pricey in 2022.
I highly
encourage everybody to actively shop for glyphosate beginning now. Procrastination may equate to weed control
problems. I suspect that many food
plotters purchase herbicides from common retail outlets. If these outlets do not have glyphosate, then
divert your shopping efforts to traditional agricultural suppliers. Traditional agricultural suppliers will have
glyphosate at times and perhaps you can purchase or at least reserve glyphosate
for a future purchase. Be prepared to buy
glyphosate in case-lots (two - 2 ½ gallon containers per case) – not by the
gallon. Traditional agricultural
suppliers sell products packaged for large-scale use, not homeowner or
intermediate use. Additionally, please
understand that traditional agricultural suppliers may first serve farmers and
their large-volume customers.
While preparing
for this article, I was surprised to discover that many herbicides can be
purchased on Amazon. A search last week (February
2022) indicated generic glyphosate was available on Amazon, along with
glufosinate. Triclopyr, an excellent
herbicide for site preparation weed control, can be purchased on Amazon. There may be other reputable internet-based
vendors that have glyphosate.
Going
back to 2013, there was a shortage of .22 LR ammunition. At 6:30 a.m. on every weekday, a local
department store had a large number of customers clustered around the sporting
goods section waiting for ammunition to be restocked. They cackled with glee when the heavily laden
cart carrying ammunition came clanking down the aisle. This folly was repeated daily for
months. The reasons for disruption in
.22 LR supply were vague, but there was certainly hoarding which contributed to
the chaos. My brother and I jokingly concluded
that .22 LR ammunition had become a form of currency. In 2022, glyphosate is now a form of
currency. Anybody want to swap .22 LR
ammo for a quart of Roundup?
Table 1. Comparison of non-selective herbicides for
site-preparation or stale seedbed weed control.
|
|
Volume purchased |
Product cost |
Lowest labelled rate1 |
Cost/acre2 |
|
|
|
($/gal.) |
|
|
|
Pelargonic
acid |
2.5 gal. |
$83.20 |
Mixed to 3% |
$208/A |
|
d-limonene |
5 gal. |
$66.00 |
Mixed to 16% |
$211/A |
|
20% acetic
acid |
5 gal. |
$19.80 |
Ready to use (no mixing) |
$396/A |
|
Glufosinate |
2.5 gal. |
$82.80 |
Mixed to 1.5% |
$25/A |
|
Generic glyphosate |
5 gal. |
$63.60 |
Mixed to 0.5% |
$6/A |
1For
each herbicide, the rate assumed was the lowest rate to control small weeds
based on information on the product label.
2Cost
per acre is calculated for the amount of herbicide added to a 20 gal. sprayer
to create the desired dilution.
Table
2. Dilution comparisons for
different glyphosate rates1.
|
Spray tank volume |
Amount of glyphosate2 added to spray tank |
||
|
|
0.5% rate |
1.0% rate |
2% rate |
|
|
|
|
|
|
1 gal. |
0.6 fl. oz. |
1.3 fl. oz. |
2.6 fl. oz. |
|
5 gal. |
3.2 fl. oz. |
6.5 fl. oz. |
13 fl. oz. |
|
10 gal. |
6 fl. oz. |
13 fl. oz. |
26 fl. oz. |
|
25 gal. |
15 fl. oz. |
32.5 fl. oz. |
65 fl. oz. |
|
100 gal. |
60 fl. oz. |
130 fl. oz. |
260 fl. oz. |
1Small annual
weeds can be controlled with glyphosate applied at 0.5% dilution. Perennial weeds are controlled by glyphosate
at 2.0% dilution.
