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Caltrans is divided into 12 geographic districts, and vegetation management (VM), plays an important role in each. District 4, which encompasses the Bay Area, is subdivided into four regions, and Bill Nantt is the landscape specialist for the East Bay and Delta regions, as well as a portion of Sacramento County that runs into the Sacramento River Delta.
Landscape specialists like Nantt are licensed pest control advisers whose main responsibility is writing and implementing annual district vegetation management plans — comprised of herbicide applications, mowing or other mechanical methods, as well as other integrated vegetation management techniques to control vegetation. Once submitted, the plans are subject to review by various state and county boards, as well as other interested public entities. This process invites plenty of plan feedback, especially in Nantt’s district, putting him and his counterparts in the spotlight in terms of managing public perception of herbicide applications.
Multiple influencers directly impact how each district’s plan is developed. Most notably, in 1992, Caltrans implemented an internal Environmental Impact Report (EIR). The report included several vegetation management guidelines, such as the department’s goal to reduce its use of pesticides by rates of 50 percent by 2000 and 80 percent by 2012.
“The EIR required us to adopt a more integrated vegetation management approach,” Nantt says. “It also moved us toward using herbicides whose recommended doses were in ounces per acre as opposed to pounds.”
In addition to the organization-wide EIR requirements, Nantt must take into account several state and federal injunctions in planning, including restrictions around using certain products because of the presence of endangered species, or nearby water sources. Because of this, all herbicide applications are thoroughly documented, along with applicator training records to promote proper herbicide use.
Caltrans also maintains an approved herbicide list for use with all applications. To be included on the list, the herbicide must first be approved by the Environmental Protection Agency (EPA), but then also meet all California EPA guidelines.
Applicator training is crucial to compliance, so each crew member receives at least 10 to 12 hours of training annually. In the Bay Area alone, Caltrans employs approximately 75 spray applicators, plus another 50 support personnel.
In rural areas, Caltrans’ proximity with adjacent agriculture also is taken into account. “In these instances, we plan accordingly to only affect target vegetation along our rights-of-way,” Nantt says.
Nantt and his crews also maintain a lot of landscaped areas, which includes intersections around off-ramps, areas along many freeways and also very large urban landscaped areas — locations where weed control must be balanced with public safety.
Complex Factors Impact VM Planning
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“The EIR required us to adopt a more integrated vegetation management approach,” Nantt says. “It also moved us toward using herbicides whose recommended doses were in ounces per acre as opposed to pounds.”
In addition to the organization-wide EIR requirements, Nantt must take into account several state and federal injunctions in planning, including restrictions around using certain products because of the presence of endangered species, or nearby water sources. Because of this, all herbicide applications are thoroughly documented, along with applicator training records to promote proper herbicide use.
Caltrans also maintains an approved herbicide list for use with all applications. To be included on the list, the herbicide must first be approved by the Environmental Protection Agency (EPA), but then also meet all California EPA guidelines.
Applicator training is crucial to compliance, so each crew member receives at least 10 to 12 hours of training annually. In the Bay Area alone, Caltrans employs approximately 75 spray applicators, plus another 50 support personnel.
In rural areas, Caltrans’ proximity with adjacent agriculture also is taken into account. “In these instances, we plan accordingly to only affect target vegetation along our rights-of-way,” Nantt says.
Nantt and his crews also maintain a lot of landscaped areas, which includes intersections around off-ramps, areas along many freeways and also very large urban landscaped areas — locations where weed control must be balanced with public safety.
Targeting Tough Woody Species
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“Milestone VM Plus wasn’t being used here previously, but now we’re transitioning to using it more because of its versatility,” he says. “We like to use it in basal bark, cut-stump or foliar applications and have great success on woody plant species. We also appreciate that it releases grasses so we don’t have large areas for invasives like yellow starthistle or stinkwort to take hold.”
On larger plants like tree-of-heaven, Nantt uses a basal bark application of Milestone VM Plus mixed with a quart of crop oil concentrate per gallon of spray solution. “We’ll also use that rate and method on smaller woody species while dormant,” Nantt says. “On species like poison oak, brooms and acacia growing in clumps six feet or less, we apply Milestone VM Plus at 2 percent mixed with 1 percent crop oil concentrate per gallon during the growing season.”
Control rates of these species have been excellent at 80 percent to 85 percent; however, Nantt points out that another important benefit has been changing the perception of applicators. “It’s important the applicators believe a product isn't wasting their time,” he says. “In the past, they just didn't bother going after these species with herbicide; they chose the never-ending battle of manual control."
Bareground Treatments for Wildfire Safety
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For bareground treatment of fixed objects like guardrails and signage, Caltrans uses either GoalTender® herbicide at 2 quarts per acre, or Accord® XRT II at varying rates, depending on the time of year. In spring, 2 quarts per acre is used. “GoalTender is great for areas where we are working around agriculture, because of its agriculture label,” Nantt says. “In fact, many adjacent farmers are using it themselves to keep weeds down.”
Caltrans has also employed hardscape solutions around guardrails such as weed barriers and extended concrete paving for treatments to reduce the need for herbicide applications.
Continuum® System Provides Benefits
Caltrans does the majority of its own herbicide tank-mixing, but recently started using Continuum Prescription Control & Container Management System from Dow AgroSciences. “When we switched from Roundup® to Accord XRT II last year, it started a transition to the Continuum system,” Nantt says. “We also wanted to get away from triple-rinsing herbicide containers, which takes time, consumes storage space and presents recycling issues. With Continuum, we set aside empty containers to ship back when we’re ready, and get full ones in return — eliminating container concerns.”Currently, Caltrans only receives Accord XRT II via the Continuum system, but is looking at adding other herbicides, such as Radar, once current inventory is used. “It’s a great system, and we’d like to push as many of our herbicides through it as possible,” Nantt says.
As a Caltrans’ landscape specialist, Nantt manages not only the undesirable plants and brush that attempt to creep onto the Bay Area’s roadsides, but also the desirable vegetation such as landscaping around off-ramps and in urban areas, and grasses along roadsides. Combining good planning with properly trained staff and flexible herbicide products, he can continue to improve Caltrans’ ever-evolving roadway system.
®™Accord, Continuum, Dimension, GoalTender, Milestone and Milestone VM Plus are trademarks of Dow AgroSciences LLC.
®Roundup is a registered trademark of Monsanto Technology LLC.
State restrictions on the sale and use of Accord XRT II, Dimension, and Milestone VM Plus apply. Consult the label before purchase or use for full details.
When treating areas in and around roadside or utility rights-of-way that are or will be grazed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details.
Always read and follow label directions.