Weed tour highlights problem areas in Green River

By Phil Fauver Staff Writer

The Skyline Cooperative Weed Management Area held their Annual Weed Tour in Green River. The Skyline Cooperative Weed Management Area Board, USU Extension, and the Green River Conservation Area Board sponsored this tour.
The weed tour started at the Green River City Hall with USU, Dennis Worwood and Ron Patterson welcoming members representing counties Carbon, Emery and Grand as well as the US Forest Service and the Utah DOT.
During this tour there were discussions and demonstrations of how to control Russian olive trees, Russian knap weed, Puncture Vine and White Top Weed control methods and options. The last place on the tour visited was the Lee Thayn melon farm to discuss weed control in melons.
The tour first moved to the Russian Olive treatment area in the Green River State Park where many Russian olive trees have been killed and removed. At this location, Worwood and Patterson discussed and demonstrated how to eradicate Russian olives trees with the cut stump treatment, the basal bark treatment, the frill cut and whole tree spraying. The herbicides mentioned for use were Roundup, 2,4-D and Triclopyr (Garlon 4).
Ron Patterson of USU Extension said his Department has been experimenting since 2005 in an effort to find the best method for killing and removing Russian olive trees. They started with the frill cut treatment that is cutting holes in the tree through the bark to the cambium layer spaced about an inch apart and placing one milliliter of herbicide in each of those holes. The diameter of the tree will determine how many holes need to be drilled. The frill cut treatment worked well in the fall of the year, and for year-round treatment.
Worwood stated with Russian olives, you have a couple of challenges you usually have more than one stem. Sometimes the stems are so close together it is difficult to get close enough to the stem to make the holes and kill the tree. The 41 percent Glyphosate herbicide is applied without dilution and can be returned to the original container.
To kill a Russian Olive tree with the basal bark treatment Triclopyr (Garlon 4) mixed with diesel fuel at a ratio of 3 to 1 is used spraying the bark all the way around a young tree. The basal bark treatment will work with trees that have a diameter of 6 inches or less.
Upon examining the areas where the Russian Olive trees were pulled out of the ground, it was found, the remaining roots rapidly started re-growing new trees.
Patterson then demonstrated the cut stump treatment, where herbicide is placed just inside the tree stump bark circle. Not only were the trees killed, but the roots died as well. In Carbon County, Russian Olives have been considered a noxious weed since 1998.
Patterson used an herbicide applicator gun to demonstrate applying herbicide to several stumps to the cambium layer beneath the bark. Patterson said this method of stump treatment has provided almost 100 percent control of Russian Olives.
He said after three years of testing, we have found the cut stump treatment to be most successful. Now we’re working on methods for controlling the re-growth, where the trees have been pulled out of the ground and the young trees are starting to grow from the remaining roots.
Dr. Dan Drost, USU Extension vegetable specialist led the group to the Lee Thayn melon farm. Their rows of watermelons and muskmelons were still in the field surrounded by weeds and grass. Lee Thayn said all of the good melons had been picked and shipped to those that sell melons.
Dr. Drost Said that we have started to develop a Utah vegetable production guide. This guide is for commercial vegetable farmers and is a guide to give them everything they need to know about growing vegetables. The guide lists chemicals used, for insect control, for disease control and weed management.
The Department of Agriculture is adding some new chapters to our guide. These chapters will include how to produce cucumbers, squashes and melons.
The guide will list all of the chemicals we have available for use in the production of vegetables. We expect this will be a great help to the growers.
When it comes to weed management in melons. There are only about six or seven different herbicides that we have available to us to control weeds and none of them are very good. Those melon plants are very sensitive to herbicide chemicals and the tiniest amount will cause the plant to die.
In this field there has been a lot of melon bed management. We have about 25 different weed species and various grasses brought in with the irrigation water. The broadleaf weeds are the ones that give the farmers are the most trouble. They are very hard to control. Next year, we plan to come to Green River and do a series of studies on weeds in melons. Lee Thayn has pretty good control of weeds in his fields. At the beginning of the growing season the field looks good and then weeds start to grow when you run irrigation water down the rows.
Some of the growers are planting winter wheat or oats in the fall where the melons grew and then the spring strip tilling before planting melons. The oats and wheat keep the soil from being eroded away by the wind.
Dr Drost discussed using strips of plastic to control the weeds by blocking sunlight from the weeds. This method can create a weed free environment where the crop is going to grow. Lee Thayn said you couldn’t irrigate under the plastic.
Another successful way of growing melons and conserving water is to use drip irrigation instead of flood irrigation.
Weeds always grow faster than vegetables and the weeds interfere with water movements through the field. They get in your way. When you’re trying to grow the crop. The weed growth can change the humidity in the field resulting in more disease pressure.
Finding ways to control weeds in a high value crop like melons is our goal.
Worwood stopped the group along the roadway to show them what the weed with the name “puncture vine” looks like. It is a warm season annual plant and grows the same time of year that melons would grow. It originated in a warm climate around the Mediterranean. The puncture vine is water efficient. To make one pound of puncture vine it takes 150 pounds of water. To make one pound of alfalfa it takes 850 pounds of water. The plant is well adapted to heat. From the time the plant germinates until it flowers is three weeks. From the time it germinates and produces viable seeds is five weeks. It is somewhat poisonous and can produce toxicity in sheep. Most animals will not graze the puncture vines. The plant is easy to kill. It is an annual. If the plant is cut off below the crown of the plant you have killed it. It can be sprayed with 2-4D or Roundup and kill it. The problem is the spiky seedpods with five sections in the fruit every section has one to four seeds. If you have this plant your goal is to stop it from going to seed. The seeds will last from five to eight years in the soil.
“Puncture vines main weed characteristic, as indicated by its common names of puncture vine or caltrop, is its spiky seedpods. (A caltrop is a metal device, used to deter passage by vehicles with pneumatic tires or the hooves of horses; it has four projecting spikes so arranged that when three of the spikes are on the ground, the fourth points upward to poke a tire or hoof.) The seeds of puncture vine are enclosed in a hard caltrop-like case that can injure livestock, people, and pets when stepped on and can even puncture bicycle tires. Another common name is “goat head.” Good soil moisture and warm temperatures are needed for germination, but after the plant is established it can tolerate dry soils due to its rapidly produced deep taproot (ipm.ucdavis.edu).”
Cory Worwood Emery County Weed Department took the group to view Russian Knapweed. Russian Knapweed is a perennial plant with a pineapple head. Knapweed can be controlled with herbicides and the plants are usually sprayed when the plant is dormant. The chemical used stays in the soil to prevent the weed from growing again. Knapweeds are all connected in a clump of roots and are poisonous to horses.
The Skyline Cooperative Weed Management Area provided a box lunch for the group and Lee Thayn donated the melons. Roger Barton a Resource Coordinator for the Utah Dept of Agriculture and Food delivered the box lunches.