Iowa Commercial Pesticide Appl: Right-of-Way (Category 6) Latest Update 100% Pass

Iowa Commercial Pesticide Appl: Right-of-Way (Category 6) Latest Update 100% Pass Who's Responsible? An applicator is responsible for any damage to private or public property resulting from careless application or misuse of herbicides What are roadside management objectives? The current goal of many roadside management programs is to 1) control only those plants listed as noxious weeds or 2) plants that interfere with the vision of motorists, 3) inhibit the flow of water through drainage ditches, 4) pose a fire hazard, or 5) interfere with activities of humans in other manners. Spot treatments of problem areas, rather than broadcast applications, are commonly used along roadsides. What management techniques do counties use to maintain prairie vegetation on roadsides? Counties integrate several different management techniques to maintain a strong, healthy plant community. Techniques include 1) spot spraying perennial weeds, 2) mowing of annual & biennial weeds to control seed production, and 3) periodic burning to recycle nutrients & increase plant diversity. What are the most commonly used herbicides for roadside use? The most commonly used herbicides for roadsides are postemergence chemicals that selectively control herbaceous, broadleaf plants without injuring grasses What types of herbicides are registered for use in rights-of-way? The majority of these products are either growth regulator herbicides or ALS-inhibiting herbicides. These herbicides are classified according to their mode of action, or how they kill plants. List some common growth regulator herbicides Growth regulator herbicides include the 1) phenoxy products (2,4-D; 2,4-DP; and MCPP), 2) dicamba (Banvel), 3) triclopyr (Garlon), 4) picloram (Tordon) and 5) clopyralid (Stinger). To broaden the spectrum of control, these herbicides are often tank-mixed or formulated as products that contain more than one active ingredient (e.g., Crossbow is a combination of 2,4-D and triclopyr. The specific combination used should be based on weeds present, rather than indiscriminately adding herbicides to the spray tank. What are some characteristics of growth regulator herbicides? Most of these herbicides are rapidly degraded in the soil; thus, they provide little residual control. Only weeds that are established at the time of application will be controlled. All of the growth regulator herbicides are translocated within the plant, making them effective for both annual & perennial weeds. List some common ALS-inhibiting herbicides ALS is an enzyme involved in the synthesis of specific amino acids in plants. 1) Sulfrometuron (Oust) and 2) chlorsulfuron (Telar) are the most common ALS-inhibitors used on roadsides for broadleaf control. Certain perennial grasses, including tall fescue & smooth brome, have a relatively low tolerance to these chemicals & may be injured under certain conditions, follow label rates carefully. Plateau (Imazapic) and Journey (Imazapic & glyphosate) are other ALS-inhibitors; Plateau is unique in that it is safe to use on native grass & wildflower plantings. What are the best times for applications? Generally , herbicides are most effective when applied to actively growing plants, applications should be avoided during hot, dry periods of midsummer. ANNUAL weeds, such as velvetleaf & pigweed, are easiest to control early in the spring while they are still small. Musk thistle, common mullen, & other BIENNIALS should be treated in the fall or early spring while they are still in the rosette stage. Biennials become fairly tolerant to most herbicides once the flower stalk begins to elongate. Optimum control of PERENNIALS, such as Canada thistle & field bindweed, can often be achieved with applications made while the plant is in early bloom. Two applications of a herbicide may be required to provide effective control of some perennials. Why should you be especially careful treating roadsides with selective herbicides? The ability of the phenoxy & other selective herbicides to selectively control broadleaf weeds in grass areas makes them especially useful along roadsides. However, the herbicides can cause severe injury to nearby nontarget plants if applied carelessly. Precautions must be taken to prevent physical drift or volatilization from carrying the herbicide off the target site. List some application techniques used for woody vegetation control (BASICS) 1) Foliar sprays; 2) Basal bark applications; 3) Frill and cut-surface applications; 4) Soil applications; 5) Short-term total vegetation control; 6) Long-term total vegetation control List some application techniques used for woody vegetation control The technique used should be selected after evaluating the species to be controlled, the site of application, & the susceptibility of nearby desirable plants to the herbicide. Foliar sprays should be made when leaves are fully expanded in the spring until fall color develops, avoid application in midsummer. Many growth regulator herbicides are effective against woody species. KRENITE is an alternative to the growth regulators for foliar application, little effect will be seen year of application, no leaves next year, total coverage of plant important. Basal bark applications are generally effective on woody species up to 6 inches in diameter. Can treat throughout year, avoid applications when wet. This technique reduces the amount of carrier required & greatly reduces the risk of drift. Frill and cut-surface applications have the same advantages as basal bark applications, but are effective on larger trees (larger than 6 inches in diameter), water based, best within a few hours of cutting. Soil applications - pelleted formulations often used, measure accurately, HYVAR and SPIKE are the most common, are persistent & will remain active in soil for months, PICLORAM (Tordon) is highly water soluble & is not readily bound to soil particles, runoff, all formulations, except RTU, are restricted-use pesticides. List other application techniques used for woody vegetation control Short-term total vegetation control - nonselective herbicides are often used to eliminate the need for trimming around signs, light poles & guard rails, the characteristics of these chemicals vary widely - select the herbicide that best fits the need of a specific situation, PARAQUAT (Gramoxone Extra) thorough coverage required, Paraquat does not translocate, most perennials will quickly resume growth, is rapidly inactivated in soil & will not provide any residual control, is restricted-use pesticide; GLYPHOSATE (Roundup Ultra/Touchdown) is similar to paraquat in that it will provide complete burndown of all vegetation with no residual control, Glyphosate is translocated within plants & will effectively control many perennial plants. VELAR or ARSENAL can be used in areas where it is desirable to prevent plants from quickly invading the treated area, combine the characteristics of a nonselective burndown herbicide & a preemergence herbicide, length of control varies, normally 1 to 6 months. Long-term total vegetation control - soil sterilants, often used in storage yards, parking lots, along pipelines, and in other areas where it is desirable to completely eliminate plant growth, they should not be used in areas susceptible to erosion, if before rain chemical can be eliminated by removing the first inch of soil, alternative mix activated charcoal into soil (3 pounds per 1,000 square feet of soil), trench & block tree roots When and how should growth regulators be used? Growth regulators may be used on turf areas to reduce the grass height, suppress seedhead development, or reduce mowing requirements. Best results are obtained with early spring applications made following greening of the sod; growth regulators may reduce the competitiveness of a turf stand, thus allowing weeds to become a more serious problem. Explain the Integrated Roadside Vegetation Management program The object of IRVM is to establish & maintain a safe, stable, low-maintenance roadside that is healthy & attractive for humans & wildlife. Stability is attained by the use of native vegetation, county roadside managers (CRM) mimic the durable, diverse prairie plant community that existed in Iowa for thousands of years, alongwith the use of native & non-native grasses & wildflowers, CRMs are integrating several different vegetation management techniques, in addition to traditional use of herbicides & mowing, CRMs also employ nontraditional methods to invigorate & sustain the vegetative cover. Burning is one such method. During the early spring CRMs will select several sites to conduct a planned or prescribed burn, it will retard the growth of many invading weeds & invigorate the existing prairie plants. Other important factors of IRVM are low maintenance & adjacent landowner cooperation. How can you use IRVM to manage a patch of noxious weeds that dominate a site? Integrating several vegetation management techniques, such as frequent mowing followed by a spot herbicide application in the fall, a spring burn followed by several mowings, or three spot herbicide applications 30 days apart followed by a spring burn, may be necessary to obtain weed control, a follow-up reseeding of desirable vegetation will be necessary to establish a stable vegetative cover. Explain some ways to prevent damage to nontarget plants The majority of problems encountered in right-of-way spraying involve the phenoxy or similar herbicides, they are injurious to plants at extremely low rates; the two principle mechanisms by which a herbicide moves off-target are drift & volatilization, herbicides may also move off-target in runoff water or be carried away with eroded sediment. Explain what drift is and what factors are responsible for problems encountered Drift is the physical movement of spray droplets from the target site. The two primary factors that effect the amount of drift are: spray droplet size & the wind speed; Wind: problems at 5 mph, spraying should stop when wind exceeds 10 mph; Droplet size: as droplet size decreases , the distance a droplet will travel off-target increases; select a nozzle that produces an appropriate range of droplet sizes; as spray pressure is increased, the range of droplet sizes produced will shift towards smaller droplets, operate the sprayer at a relatively low pressure; also drift retardants can reduce the formation of small droplets, an invert emulsion is a thick mixture of oil & water that has the consistency of mayonnaise, specialized spray equip required. Explain what volatilization is and what factors are responsible for problems encountered Volatilization, also known as vapor drift, is due to evaporation of the herbicide after it impinges on the soil or plant. Herbicides that have a high vapor pressure are susceptible to vapor drift whenever temperatures exceed 85F; herbicides that are prone to volatilization include the phenoxy herbicides & dicamba; available as ester ( more effective, more volatile) or amine products; Dicamba (Banvel) is especially prone to volatilization, Clarity & Vanquish contain the diglycolamine (DGA) salt of dicamba (they have a lower vapor pressure than Banvel); soybeans are particularly sensitive to dicamba. Explain what herbicide runoff is and what factors are responsible for problems encountered Herbicides also may move from the treated area in surface water runoff or in sediment; the potential for herbicide loss is determined by many factors, including rainfall events, amount of herbicide applied, & soil absorption characteristics of the herbicides; herbicides are most vulnerable to runoff during the first rainfall event after application; nonselective herbicides with a long soil residual should not be used in areas prone to runoff; hard rain, problems; no vegetation, problems; herbicides with low soil adsorption & high water solubilities (e.g., Tordon) can move from treated areas in surface runoff in the absence of soil erosion, don't use in sloped areas. Summary of roadside management A combination of cultural, mechanical, & chemical weed control practices often will provide the best results. Effect of spray droplet size on drift Droplet diameter: 10 um travels 7,480 ft; 100 um travels 77 ft Triclopyr Triclopyr is less persistent than picloram; Crossbow, a premix of triclopyr & 2,4-D, is cleared for use in pastures; Pathfinder ll is formulated for basal-bark & cut-surface treatments. Picloram Picloram (Tordon) is persistent & mobile in soil; all are restricted-use except Tordon RTU (a mix of Picloram & 2,4-D designed for cut-surfaces) Glyphosate Roundup Pro is for noncropland & forestry use; Accord is for use in forestry & utility right-of-ways; Rodeo is for aquatic use. Dicamba Vanquish is less volatile than Banvel, reducing the risk of off-target movement, soybeans are very sensitive to Dicamba. Imazapyr Arsenal & Stalker are intended for general noncropland use, whereas Contain is registered for farmstead noncropland use. Stalker is cleared for basal-bark & cut -surface treatments. Fosamine Krenite is applied in late summer to woody species & prevents leafing out next spring. Complete coverage of tree is required for a total kill. Tebuthiuron Spike is available as a wettable powder or a pellet formulation for direct application to soil. Tebuthiuron is persistent; do not apply in the vicinity of desirable trees.