UACES Facebook Herbicide Effectiveness on Poisonous Hemlock
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 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. 

Photo of a road with tall hemlock growing through treeline along the side of the road on a sunny day

            

 

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)

*Inidicates 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. 

Photo of a man applying herbicide using a hand sprayer to a patch of weeds growing along a fenceline

 

 

March 16, 2018 (below)

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

 

 

March 26, 2018 (below)

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

 

 

One month later on April 16, 2018 (below)

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:

       • 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.