UACES Facebook Herbicide Effectiveness on Poisonous Hemlock
skip to main content
Arkansas Fruit, Vegetable and Nut Update

Herbicide Effectiveness on Poisonous Hemlock

by Ryan Neal - January 28, 2019

Here is another guest post from Benton County Agent and blueberry grower Ryan Neal sharing his results from an herbicide spot spray demo on hemlock in 2018.

Hemlock growing on the side of the road

Hemlock is a problem weed we are seeing a lot more of in the county. If not controlled this invasive broadleaf can take over areas in just a couple years. This demo was an effort to show the effects of 4 different herbicides on hemlock in fencerows and roadside ditches.

Herbicides were applied to plots using a handheld gallon pump sprayer on March 16, 2018. Treatments are listed below :

  • Treatment 1*: 2,4 D at 2oz per gallon of water ($0.47/oz; $60/gal)
  • Treatment 2*: GrazonNext at 2oz/gal ($0.43/oz; $110/2 gal)
  • Treatment 3: PastureGard at 1oz/gal ($1.50/oz; $50/quart)
  • Treatment 4: Roundup at 2oz/gal ($0.31/oz; $40/gal)

*Indicates private applicator training (PAT) would be required to buy these products in the gallon size. 2.4 D could be purchased by the quart without the PAT license

 

 

Dates of photos: (left) March 16th, 2018, (middle) March 26th, 2018, and (right) March 26th, 2018.   

Photo of a field in a spot spray trial divided up into four plots separated by an orange spray painted line, a mix of green short grass and tall dead grass     Photo of a spot spray trial in the field divided up into four plots, each labeled depending on treatment and amount, with a University of Arkansas Division of Agriculture sign in the background; plots have quite a bit of plant growth in the plots     Photo of a spot spray trial in the field divided up into four plots, each labeled depending on treatment and amount, with a University of Arkansas Division of Agriculture sign in the background; some plots have more plant growth than others

 

 

 

Six weeks later, no broadleaf weeds were visible on the PastureGard plot (below) Photo of a barbed wire fence with a large bare spot underneath where herbicide had been applied surrounded by large patches of grass

 

 

 

Six weeks later, no broadleaf weeds, and only some perennial grasses were visible on the Roundup plot (below). Unlike the other herbicides in this demo, Roundup is a non-selective herbicide and targets both grasses and broadleaf plants. 

Photo of a barbed wire fence with a large bare spot underneath where herbicide had been applied surrounded by large patches of grass

 

 

 

Six weeks later, hemlock was still present although stunted on the 2,4 D plot (below)

Photo of a barbed wire fence with small patches of weed underneath where herbicide had been applied surrounded by large patches of grass

 

 

 

Six weeks later, no broadleaf weeds were visible on the GrazonNext plot (below)

Photo of a barbed wire fence with medium sized patches of weed underneath where herbicide had been applied surrounded by large patches of grass

 


In conclusion, hemlock was completely controlled in this demonstration with all herbicides except 2,4 D. 
Some other things to consider include:

Photo of a man applying herbicide using a hand sprayer to a patch of weeds growing along a fenceline
  • You would need a PAT license to purchase GrazonNext as this appears only to be available in the 2 gallon jug
  • Roundup or Generic Glyphosate would leave the ground bare in most cases so erosion could be an issue
  • PastureGard is the most expensive per ounce but does not require the PAT and can be purchased by the quart
  • All plots were sprayed in early spring when the plants were still small, if you wait until hemlock is larger then results are likely to be less successful.  Hemlock is also present in the late fall so treatment then would also be advisable.

 

Of course always follow the label on any product you choose!

Top