Historic, archived document Do not assume content reflects current scientific Knowledge, policies, or practices. ACIFIC INlortH Wiest FOREST AND RANGE EXPERIMENT STATION FOREST SERVICE RESEARCH NOTE PUW=288 November 1974 REPEATED SPRAYING TO CONTROL & FOUR COASTAL BRUSH SPECIES i) sf & 2 y PSW FOREST AND RANGE EXPERIMENT STATION FEB 28 1975 STATION LIBRARY COPY R. E. Stewart, Research Forester ABST RACT Resprouting salmonberry, western thimbleberry, vine maple, and California hazel shrubs were readily controlled by a respray of 2,4,5-T applied as an early foliar treatment. A respray of amitrole-T or picloram did not appreciably inerease degree of control compared with the inittal application. KEYWORDS: Herbicides, (- brush control, silvi- cultural control, salmonberry, thimbleberry, vine maple, California hazel. REST SERVICE - US. DEPARTMENT OF AGRICULTURE - PORTLAND, OREGON Research and field experience during the past 20 years have proven herbici- dal sprays to be an effective method for controlling competing shrubs and weed trees on forest lands in the Oregon and Washington Coast Ranges. However, silvi- cultural use of herbicides is complicated and requires careful selection of chemical, dosage, and carrier. Proper selection of treatments for the variety of brush conditions found on coastal sites requires knowledge of individual species' response to herbicides to accurately predict the results of selected treatments. Information is available for single applications of herbicides on major species that compete with conifers (Krygier and Ruth 1961, Stewart 1974a, 1974b), but many species resprout and are not adequately controlled by one application. Repeated applications are often required to achieve the desired degree of control. To assess desirability of respraying, foresters must know the effects of succes- sive applications of herbicides on these species. At present, this information is available only for southwest Oregon brush species (Gratkowski 1968). The tests reported here provide the same information for four major shrub species found on forest lands in the Coast Ranges. MATERIALS AND METHODS During 1970, selected formulations of herbicides were tested as early foliar and midsummer sprays on six of the most common brush species on forest lands in the Oregon Coast Ranges (Stewart 1974b). Each herbicidal treatment was applied as a foliage spray to drip point using knapsack sprayers. Sprays were applied on 10 individual shrubs of each species in a completely randomized design. Red alder (Alnus rubra) trees less than 12 feet (3.6 meters) high proved highly sus- ceptible to herbicides and were readily killed with one application; salal (Gaultherta shallon) was resistant to all herbicides tested. The remaining four species, salmonberry (Rubus spectabilis), western thimbleberry (Rubus parviflorus), ~ vine maple (Acer ctrecinatum), and California hazel (Corylus cornuta var. californica) were intermediate in response. Surviving shrubs of these species sprouted from stems and roots the following year. In May 1972, resprouting shrubs in the original plots were again sprayed with the same formulations of herbicides. Only the most effective treatments from the 1970 tests were included in the respray treatments. These tests were designed to determine the cumulative degree of control resulting from repeated early foliar applications of herbicides. Herbicides! used were: Herbicide Formulation 2,4,5-T [(2,4,5-trichlorophenoxy) acetic acid] Propylene glycol butyl ether ester Silvex [2-(2,4,5-trichlorophenoxy) propionic Propylene glycol butyl acid] : ether ester Amitrole-T [a 1:1 mixture of 3-amino-s-triazole and ammonium thiocyanate] Water-soluble liquid Picloram [4-amino-3,5,6-trichloropicolinic acid] Potassium salt The herbicide 2,4,5-T was applied in a 3-percent diesel oil-in-water emulsion on salmonberry and western thimbleberry shrubs and in water on vine maple and California hazel. All other herbicides were applied in water carriers. 1/ — Test samples of 2,4,5-T, silvex, and picloram were provided by The Dow Chemical Company; Amchem Products, Inc. provided the amitrole-T. This cooperation is appreciated. Shrubs resprouting after the original early foliar and midsummer applications were resprayed during the early foliaf season when three-fourths of the leaves of all four brush species were fully developed and plants were actively growing. This period is generally regarded as optimum for applying herbicides as foliage sprays. Treatment effects were evaluated during September of 1973, 16 months after the resprays were applied. This examination indicated that all four species could be adequately controlled for site preparation or release of small conifers by two applications of the most effective herbicides. Therefore, additional resprays on the remaining live shrubs were not necessary, and the study was terminated. RESULTS AND DISCUSSION Cumulative plant kill resulting from early foliar or midsummer sprays on mature shrubs and early foliar resprays on resprouting shrubs is shown in table 1. Resprays of 2,4,5-T were very effective on most species, especially at the lower rates of application. In many cases, the second application at least doubled the number of plants killed. This agrees with previous results for southwest Oregon species that indicate resprouting shrubs are easier to kill than full-crowned mature plants (Gratkowski 1968). Table 1.--Cumulative percentage of shrubs killed by repeated sprays on mature (1970) and resprouting (1972) brush spectes Eerste Early! Conce foliar Mae umtet foliar Species and herbicide en Carrier spray, tration respray, 1970 respray, 1972 1972 tbvachgy === Percentage of shrubs killed------------ Salmonberry: 2,4,5-T 3 Emulsion 50 90 40 100 Amitrole-T 1 Water 70 70 70 - 70 3 Water 80 80 70 80 Picloram 1 Water 70 90 100 -- Western thimbleberry: 2,4,5-T 3 Emulsion 50 90 60 90 Amitrole-T 1 Water 10 20 (0) 0 3 Water 20 50 0 30 Picloram al Water 70 100 80 90 Vine maple: 2,4,5-T 1 Water 0 20 0 20 3 Water 40 80 30 80 Silvex af Water 10 30 0 50 3 Water 30 50 30 60 Picloram 1 Water 40 80 30 80 California hazel: 2,4,5-T 1 Water 20 80 10 50 3 Water 60 100 40 80 Silvex 1 Water 40 70 0 10 3 Water 10 70 20 60 Picloram it Water 80 100 70 100 eee ee——————————E————————————E—E— 1/ When 3/4 of the leaves were fully developed. Resprays of picloram, highly effective on mature plants, were justified only on vine maple. However, a respray of the less expensive herbicide 2,4,5-T produced results equivalent to that obtained with picloram. A respray of amitrole-T had little effect on western thimbleberry and did not increase control of salmonberry. Such sprays would only tend to hasten conversion of salmonberry-western thimbleberry communities to western thimble- berry. In contrast, a respray of 2,4,5-T 1 or 2 years later would virtually eliminate both species. These results show that one foliage spray of 2,4,5-T may not adequately control well-established mature salmonberry shrubs. On the other hand, small seedlings or succulent resprouting shrubs should be very sus- ceptible. Therefore, early recognition of a developing brush problem is critical if we are to reduce the need for resprays. For conifer release, the objective is to increase the amount of light reach- ing young conifers and reduce shrub competition for soil moisture and nutrients (Gratkowski 1961). It is usually necessary only to obtain a high percentage of defoliation, a fair amount of topkill, and a minimum of resprouting. For brush- field reclamation, however, a high percentage of the shrubs must be killed and resprouting must be limited. Control adequate to release well-established conifers can be obtained with one spray of 2,4,5-T on red alder less than 12 feet (3.6 meters) high, salmonberry, western thimbleberry, vine maple, and California hazel (Stewart 1974b). For releasing small conifers or for reclamation, a second spray of 2,4,5-T should produce adequate control of salmonberry, western thimbleberry, vine maple, and California hazel. A single application of picloram, a nonselective herbicide, may be adequate for site preparation or reclamation on these species. LITERATURE CITED Gratkowski, H. 1961. Use of herbicides on forest lands in southwest Oregon. USDA For. Serv. Pac. Northwest For. G Range Exp. Stn: Res= Note’ Noo 207) ici pee illus. Portland, Oreg. 1968. Repeated spraying to control southwest Oregon brush species. USDA For. Serv. Res. Pap. PNW-59, 6 p., illus. Pac. Northwest For. & Range Exp. Stn., Portland, Oreg. Krygier, James T., and Robert H. Ruth 1961. Effect of herbicides on salmonberry and on Sitka spruce and western hemlock seedlings. Weeds 9(3): 416-422, illus. StewarGe ke Ee 1974a. Budbreak sprays for site preparation and release from six coastal brush species. USDA For. Serv. Res. Pap. PNW-176, 20 p., illus. Pac. Northwest For. & Range Exp. Stn., Portland, Oreg. 1974b. Foliage sprays for site preparation and release from six coastal brush species. USDA For. Serv. Res. Pap. PNW-172, 18 p., illus. Pac. Northwest For. § Range Exp. Stn., Portland, Oreg. PESTICIDE PRECAUTIONARY STATEMENT Pesticides used improperly can be injurious to man, animals, and plants. Follow the directions and heed all precautions on the labels. Store pesticides in original containers under lock and key--out of reach of children and animals--and away from food and feed. Apply pesticides so that they do not endanger humans, livestock, crops, beneficial insects, fish, and wildlife. Do not apply pesticides when there is danger of drift, when honey bees or other pollinating insects are visiting plants, or in ways that may contaminate water or leave illegal residues. Avoid prolonged inhalation of pesticide sprays or dusts; wear protective clothing and equipment if specified on the container. If your hands become contaminated with a pesticide, do not eat or drink until you have washed. In case a pesticide is swallowed or gets in the eyes, follow the first-aid treatment given on the label, and get prompt medical attention. If a pesticide is spilled on your skin or clothing, remove clothing immediately and wash skin thoroughly. Do not clean spray equipment or dump excess spray material near ponds, streams, or wells. Because it is difficult to remove all traces of herbicides from equipment, do not use the same equipment for insecticides or fungicides that you use for herbicides. Dispose of empty pesticide containers promptly. Have them buried at a sanitary land-fill dump, or crush and bury them in a level, isolated place. NOTE: Some States have restrictions on the use of certain pesticides. Check your State and local regulations. Also, because registrations of pesticides are under constant review by the Federal Environmental Protection Agency, consult your county agricultural agent or State extension specialist to be sure the intended use is still registered. la Pastieidas Seffaly FOLLOW THE LABEL U.S. DEPARTMENT OF AGRICULTURE ee , nbc. mere | by ae EPaTe Ny) ’ ni iy" —— hal ieedolainiy 7 x -_er — ‘oe i) pes “ < ne a jeur laan ty ig ag ob oc i ‘. patna en es oak mera Serine it Ginced eR “st DT AE i wil ples i or ot tete aa ware eon Pulare vA wis ne m : tx 7 ate! ee" pat twin vir tse 3 . : a @ = mai Lgitny: vupet lire ©) _ ™ . shext er to ws, ade na c The mission of the PACIFIC NORTHWEST FOREST AND RANGE EXPERIMENT STATION is to provide the knowledge, technology, and alternatives for present and future protection, management, and use of forest, range, and related environments. Within this overall mission, the Station conducts and stimulates research to facilitate and to accelerate progress toward the following goals: 1. Providing safe and efficient technology for inventory, protection, and use of resources. 2. Development and evaluation of alternative methods and levels of resource management. 3. Achievement of optimum sustained resource produc- tivity consistent with maintaining a high quality forest environment. The area of research encompasses Oregon, Washington, Alaska, and, in some cases, California, Hawaii, the States, and the Nation. Results of the research will be made available promptly. Project headquarters are at: Fairbanks, Alaska Portland, Oregon Juneau, Alaska Olympia, Washington Bend, Oregon Seattle, Washington Corvallis, Oregon Wenatchee, Washington La Grande, Oregon Mailing address: Pacific Northwest Forest and Range Experiment Station P.O. Box 3141 Portland, Oregon 97208 GPO 991-897