Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. 4 copes e & a2 = ¥ i ——— z fLES CLF KODE RS PO = if = Ee heey bok Z eee 2, a ————— ' UNITED STATES DEPARTMENT OF AGRICULTURE “ FOREST SERVICE : INTERMOUNTAIN FOREST & RANGE EXPERIMENT STATION OGDEN, UTAH 84401 USDA Forest Service Research Note INT-114 1970 EFFECTS OF DICAMBA AND PICLORAM ON 2 © ASAICULTUN SOME NORTHERN IDAHO SHRUBS AND TREES J, &. DefT. 0 anal ue Tele UE Ga Oe a: Fey eer ig piHONAL AEDUEE, ; Russell A. Rykerl/ , JUL 21 19/0 ABSTRACT eURRENT SERIAL DESC29S, Two recently developed herbictdes, dicanba and picloran, used alone and tn mixture with 2,4-D, gave promistyugewesults in tests on stx shrub spectes common to northern Idaho brushfields. The treatments danaged conifers, and so apparently are unsuit- - able for broadeast spraying to release established trees from shrub competttton. . Shrub species are ever present in the understory vegetation of northern Idaho forests. They are aggressive and can quickly dominate a site if the forest cover is partially or totally removed by cutting, fire, or pests. A heavy cover of shrubs makes it difficult to regenerate a forest, particularly with less tolerant species. Fven more shade-tolerant species, such as Rocky Mountain Douglas-fir [Pseudotsuga menztesit , var. glauca (Beissn.) Franco] and grand fir [Abtes grandis (Dougl.) Lindl.]--which eventually will replace shrubs--may grow slowly, lengthening the time needed for seedlings to attain harvestable size. We have used various means (e.g., machine scarification, fire, and herbicides) to + remove or to control the spread of shrubs prior to planting trees. Of these, machine scarification probably has been most successful, but is not suited to steep terrain. In steep country, we have relied on fire--sometimes preceded by herbicide application. “ Upon occasion, however, subsequent herbicide treatment has been called for because shrubs often recover rapidly during the first growing season following a burn. If a highly successful herbicide were available, it might be the only site prep- aration treatment needed on some areas. Elimination of a second treatment, such as 4 burning, would reduce reforestation costs. Herbicides also have a use in brushfields where an adequate number of trees have become established beneath the shrubs. If these areas could be chemically treated without damaging conifers, such trees could be released from excessive shrub competition. ISilviculturist, stationed in Boise, Idaho. m * iy yin cule Nc Cy Gr) pee “es P } j {i ut i y po Ore by, hy beak |) Wines Webel: ; Sete et re j ite (Wg phe * ; i ’ nm ae pal A by tf) er i" ; a f i , : JMET os Pei ei : aa ont eae SD cor icatte aioe. onde ie ee a 7 J Gi ys, | Ti hl BP tal oe : = eee NADAS, bis i eee fie ae ee 5 i, ee eae : 1 s ¢ Oe : v a io ae | by bie aera " ; oe a La EQ! eo 4 en AE. s a i Cae iy Alig at ye WAL occa ay) me rae ‘aes ) ov ay With these needs in mind, we compared the performances of picloram mixed with 2,4-D,2/ dicamba, 3/ and dicamba mixed with 2,4-D./ Two of these, dicamba and picloram, only recently have been developed for shrub control; the other, 2,4-D, has been used extensively for years. We tested the herbicides2/ on six shrub species in a northern Idaho brushfield area and on seven tree species planted in pots and grown under partly protected conditions. While they varied in their effectiveness on different species of shrubs, all damaged conifers. Consequently, we question their suitability for broad- cast spraying to release established trees. However, these herbicides should be tested further for use in reducing shrub vegetation prior to planting trees. METHOD The shrubs tested during this study were growing in brushfield areas on the St. Joe National Forest. Thirty individuals®/ of each of the following species were selected: menziesia (Menztesta ferrugtnea Sm.); mountain maple (Acer glabrun Torr.) ; ninebark [Physocarpus malvaceus (Greene) Kuntze]; oceanspray [Holodiscus discolor (Pursh) Maxim.]; redstem ceanothus (Ceanothus sangutneus Pursh); willow (Salix scoulertana Barratt). Shrubs selected ranged in height from about 2 to 12 feet. Five individual plants were assigned randomly to each of six treatments. Treatments were: No. 1, dicamba (2 pounds) 7/; No. 2, dicamba (8 pounds); No. 3, dicamba (1 pound) + 2,4-D (2 pounds); No. 4, dicamba (4 pounds) + 2,4-D (8 pounds) ; No. 5, picloram (1/2 pound) + 2,4-D (2 pounds) ; No. 6, control (no spray). Since we had used picloram successfully prior to this study, 8/we decided to stay with the application level recommended by the manufacturer. Little information was available about dicamba effects on shrubs; so we decided to try the herbicide alone and in mixture with 2,4-D at different concentrations. Using a 4-gallon hand sprayer,we applied the chemical solutions to the foliage of individual plants until dripping started. Shrub condition and height were recorded at the time of treatment in July 1966, and on two other occasions, in August 1966 and again in August 1967. 2This formulation contains 1/2 pound per gallon of 4-amino-3,5,6-trichloro- picolinic acid (picloram) and 2 pounds per gallon of 2,4-D, both in the form of triisopropanolamine salt. It is sold by Dow Chemical Company under the registered trademark ''Tordon-101.'' (Mention of trade names herein does not necessarily imply endorsement by the USDA Forest Service.) 3This formulation contains the equivalent of 4 pounds per gallon of 2-methoxy-3, 6-dichlorobenzoic acid, in the form of dimethylamine (DMA) salt. It is sold by the Velsicol Chemical Corporation under the registered trademark ''Banvel." “One pound per gallon of the DMA salt of dicamba plus 2 pounds per gallon of the DMA salt of 2,4-D. « : "This publication reports research involving pesticides. It does not contain recommendations for their use, nor does it imply that the uses discussed here have been registered. All uses of pesticides must be registered by appropriate State and/or Federal agencies before they can be recommended. An individual plant is defined for this study as having one stem or several stems if no more than 6 inches separate any one stem from others at ground line. 7amount of chemical per 100 gallons of aqueous solution. 8p. A. Ryker, Herbicides fail to insure success of a brushfield prescribed burn. UE SORES OeIVen RES NOGe ENTS 5h 7p ulus, | LOO Ol Lo} Sixty 2-year-old conifer seedlings of the following species were obtained from nearby Forest Service nurseries: Rocky Mountain Douglas-fir; Engelmann spruce (Picea engelmamnit Parry); grand fir; lodgepole pine (Pinus contorta Dougl.); ponderosa pine (Pinus ponderosa Laws.); western white pine (Pinus monticola Dougl.); western redcedar (Thuja pltcata Donn). Ten trees for each species were selected for each treatment; 10 others, the control group, were untreated. Trees were planted in pots in May 1966. They were kept in a lathhouse, except for the winter of 1966-1967 when anticipation of cold weather prompted us to move them into a greenhouse. Conditions inside the greenhouse were regulated to maintain dormancy. We treated the trees during the period July 6-11, 1966, and measured them in August 1966 and again in August 1967, recording leader elongation and plant condition. RESULTS SHRUBS We evaluated the effects of herbicides on shrub growth by means of a 5S-point rating system described by Gantz and LaningY/ (table ears For each species-herbicide combination five observations were made. Because of this low number of observations, comparisons using proportions drawn from the five response categories would give little indication of differences among species-herbicide combinations. Since the scores assigned to the rating categories increase in magnitude as the severity of the response increases, these scores were used as criteria in an analysis of variance model. The analysis revealed a highly significant species-treatment interaction. Though the analytical results agree with field evaluation and with data summaries, we cannot be sure that scores are proportional to differences in response. Consequently, the analysis may not be valid. For this reason, we derived the following information from the data summary table. Mountain maple resisted all treatments (table 1). Even the high-concentration treatment of dicamba plus 2,4-D (No. 4), which killed nearly 100 percent of the plants of other species, was ineffective against maple. Dicamba was more effective when mixed with 2,4-D than when used alone. Even the highly concentrated treatment No. 2 was little better than treatment No. 3, for which a small amount of dicamba was mixed with 2,4-D. When used alone, the low concentration of dicamba was the least effective of all treatments. Effects of the two treatments most comparable in formulation and concentration, Nos. 3 and 5, did not differ greatly among species. However, picloram (No. 5) seemed a little better for controlling ninebark, oceanspray, and redstem ceanothus than dicamba (No. 3), which was more effective on willow. The degree of reduction in shrub height also reflects differences in species susceptibility to different treatments (table 2). Live stem height was reduced most in menziesia (94 percent) and willow (90 percent). Somewhat less reduction was obtained in ninebark (85 percent), oceanspray (76 percent), and redstem ceanothus (84 percent). Mountain maple, which was little affected, showed only a 3l-percent reduction. Ren be (GanezeandaEnmRe Laning, Jr. Tordon for the control of woody rangeland species in the western United States. Down to Earth 19(3): 10-13. 1963. 3 Fis oes ap Table 1.--Mean condition values!/ for shrubs in August of the second growing season after treatment : : Treatment : Shrub : 2 : Dicamba : Dicamba : Picloram : : No species 2 Da'camba\): Dicamba, + (@l-lb;.) * (451bs..)) 2 (1/2 1b..): Mean <; treatment (23Lbse) S068 tbs s)) s5 4424 -Dm 24 =p SEND da E es 2 aGcontrol) : “ee(O2 SIDS?) a COutl DSM usec (Zab Sion) : Menziesia 3.6 4.8 5.0 5.0 5.0 4.7 1.0 Mountain maple 270 3.4 1.8 Sree 2.4 2.6 1.0 Ninebark 4.0 4.6 4.2 5.0 4.6 4.5 1.0 Ocean spray 2.6 4.4 4.4 5.0 he 46 4.2 1.0 Redstem : ceanothus 4.2 4.4 4.4 5.0 4.8 4.6 1.0 Willow 4.6 5.0 4.8 4.8 4.4 4.7 1.0 Treatment means 3.5 4.4 4.1 4.7 4.3 1.0 i ean eS 1Each treatment-species value represents the mean condition class of five plants. The condition class of each plant was evaluated as follows: Condition Value class Te aati ts (0a nate henor no errece Zi eure ac, (ule) a) kabey percent.or Less of top growth killed Si oi) tien ote OVeTo0, percent .of top igrowth? killed ADM cthis -5- ee ee ee ee - - - - Percent - - - - - - ---------- - Menziesia 29 2 0) 0 0 6 107 Mountain maple 84 37 97 46 81 69 2a. Ninebark 30 12 20 0 14 15 104 Ocean- spray 68 18 19 0 3 24 129 Redstem ceanothus 20 25 18 0 16 16 136 Willow 20 0 2 7 21 10 121 Treatment means 42 16 27 9 24 120 lIpercent of before-treatment height. CONIFERS On August 19 of the first growing season, the effects of treatments on different species varied widely. Douglas-fir appeared to be the only species resisting all treatments, except the high-concentration mixture of dicamba and 2,4-D (treatment No.4). September 8, Douglas-fir still showed little damage, but the other six species were dying. By November, even the Douglas-fir showed discoloration. In August of the second growing season, most treated plants were dead (table 3); a few lodgepole pine, Douglas- fir, and western redcedar trees were still alive, but they were in poor condition and were not growing in height. DISCUSSION AND CONCLUSIONS At the end of the first growing season (approximately 1-1/2 months after treatment), dicamba appeared to be more effective than picloram. For example, dicamba treatments apparently had killed all ninebark plants while picloram treatments had not. However, the following year, some of the ninebark plants treated with dicamba sprouted, but most of those treated with picloram died. By the end of that growing season, picloram seemed to be the better of the two herbicides for controlling ninebark. Menziesia showed little damage from any treatment during the first growing season; a few leaves died and fell from branch tips, but this was the only visible sign. How- ever, the next year, all plants died back to’the ground. Moreover, no sprouting followed treatment Nos. 3, 4, and 5. Treatments with dicamba. alone (Nos. 1 and 2) were not as effective. Because of their toxicity to the coniferous species, none of the herbicide treat- ments seems to have promise for use as a spray to release established trees from competing vegetation. eae 5 i rat a net LaNt a . tate |< aeeay gna sr ey Salamis! dn leg any me fh ~ ’ rae : - Pert Satellite iwi wp Shae pel favary female mi revit me (he E Tia has any sayitins 4 Wake na hae in Cia 7 ; Nr te, RRS RY), ATH: fy ee oe en ee an, Ya ashar Sal 1 dl b. Dea ie * te Ne, ers 4 Because of their effectiveness at relatively low concentrations, two of the treat- ments, No. 3 (1 pound dicamba plus 2 pounds 2,4-D) and No. 5 (1/2 pound picloram plus 2 pounds 2,4-D), appear to deserve further study for use in brushfield spray projects where removal of shrubs is the primary objective. Although the two herbicides were similarly effective on the species studied, picloram was more effective on ninebark, oceanspray, and redstem ceanothus, while dicamba was better on willow. ‘The choice of treatment for a specific area would depend on which species predominate and ‘on prevail- ing chemical costs. However, more experimentation is needed before we can recommend use of these herbicides on anything other than a trial basis. Table 3.--Mean condition values for conifers in August of the second growing season Treatment Tree : : > Dicamba + Dicamba <: Picloram : : No species 7 Dicambaes = Dicamba, aL Ib)) a: 14 libs) Sel 2. lbs): Mean: treatnent a(S an) 1 (U3. IyS.a)) SARA ID) so pes eal oie OES appa ID) : > (control) : @Galbser ce (8 wlbse ite 102 Sl bse) : Engelmann spruce 5.0 5.0 5.0 5.0 2 So S110 0 Grand "i j fir 5.0 550) 5.0 5.0 ‘4.9 5.0 1.0 Lodgepole pine 2.9 3.9 3.8 5.0 4.1 3.9 1.0 Ponderosa ; pine 5.0 5.0 5.0 5.0 5.0 5.0 10 Rocky Mountain Douglas-fir 3.2 ANT, 522 5.0 3.8 529 1.6 Western redcedar 4.5 4.9 4.1 5.0 4.5 4.6 160 Western white pine 50) 5.0 SAO 5.0 a0) 5.0 1.0 Treatment means 4.4 4.7 4.4 5.0 4.6 esl 1Each treatment-species value represents the mean condition class of 10 trees. The condition class of each tree was evaluated as follows: Condition Value class . No observable damage Foliage discolored and thin . Leader deformity . 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