HERBICIDES in FORESTRY EM 4481 Jam!!I

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HERBICIDES IN FORESTRY EM 4481 Jam!!i"y 1980 -.: --i-- - r

COOPERATIVE EXTENSION SERVICE • COLLEGE OF AGRICULTURE • WASHINGTON STATE UNIVERSITY • PULLMAN In cooperation with the United States Department of Agriculture Issued in furtherance of the Acts of May 8 and June 30, 1914, by the Washington State University Cooperative Extension Service, J. 0. Young, Director On March 1, 1979, EPA suspended all forest uses of 2,4,5-T and silvex (2,4,5-TP). Although these herbicides are suggested in this publication they must not be used unless the suspension is modified or removed. HERBICIDES IN FORESTRY* Michael Newton, Professor School of Forestry, Oregon State University

Undesirable woody and herbaceous plants are problems in strikingly in degree of control and composition of residual commercial forests and on fence lines and rights-of-way. Safe, vegetation, hence in the choice of method. dependable methods of chemical weed control have been de The Oregon Forest Practices Act has the mandatory require veloped for most forestry needs. Reforestation, in particular, ment of successful reforestation after logging. It also prescribes may depend heavily on weed control. Depending upon local certain rules regarding uses of herbicides to protect plantations. conditions and weed composition, the results sought differ Operators should familiarize themselves with these rules.

FOREST LAND BRUSH CONTROL The objective of weed or brush control on commercial forest gests a remote possibility of hitherto unknown toxicity. It is al land is to provide larger and higher quality harvests and to ways wise for the applicator to avoid unnecessary exposure to reduce the length of time required to bring the crop to ma these chemicals. It is always wise to consult the neighboring turity. The weed control job alone cannot produce a harvest, but landowners before conducting a major spray job, and to take the must be combined with cultural practices involving either seed maximum precautions to avoid trespass, despite recent evidence ing or planting, and subsequent practices which bring the crop that watershed contamination from broadcast sprays is prob to maturity. Growing trees is the ultimate objective, not killing ably a very limited problem. The benefits from wise use may brush; brush control is merely a phase of the reforestation be enormous and can be realized without adverse effects with procedure. good planning. Chemicals ALWAYS FOLLOW THE DIRECTIONS ON THE LABEL. The Virtually all brush and weed tree control on forest lands is done labels are based on the best research information available, with 2,4-D, 2,4,5-T, silvex, amitrole, glyphosate, picloram, fosa and information pertaining to safe application is required by mine, MSMA, or cacodylic acid as dormant or foliage sprays, or law. injections. Atrazine and Velpar are used for herbaceous weed Method of Application control in plantations; dalapon also is used for some perennial The methods selected for the application of herbicides in a grasses. These materials, singly or in combination, give broad brush control situation depend upon the species composition, spectrum activity on forest weed species. The 2,4-D type com proximity of crops, degree of control required and available pounds are relatively non-injurious to Douglas fir seedlings dur equipment. Method and season of application also have a ing the dormant season. Amitrole is more injurious to conifers, major influence on degree of selectivity. but has greater activity on certain 2,4-D resistant plants. Pic loram is nearly always harmful when applied directly to conifers. In general, brush in which most stems are less than two inches Satisfactory reforestation brush control can be achieved with the in diameter, and grassy weed problems inoperable with farm proper formulation of these compounds applied at the proper equipment are best treated by aircraft. Spot brush control is best season and with the right carrier. Dicamba has shown activity on suited for hand or tractor-mounted ground rigs. Weed trees some resistant species, but needs further testing for general over 1 ½ to 2 inches in diameter and conifers to be thinned are recommendations in reforestation work. Soil-active rerbicides most economically treated by injection. Some of the other are seldom suited for selective brush control in this region be methods are useful in special circumstances, but the above cause of their tendency to injure conifers, but are useful for site usually give the best results per dollar. The commonly used preparation. Fosamine and glyphosate, new products, are grown methods are described below, with special emphasis on objec inhibitors applied exclusively as late-summer foliage treatments tives, formulations, and equipment peculiar to each. to brush. Glyphosate also may be used on herbs any time coni Foliage Application: Foliage spraying is an extensively used fers are dormant. practice which, to some extent, lacks selectivity for conifers. Safety and Toxic Hazard Non-stocked brush fields which are to be converted to conifer The broadcast application of pesticides has received consider stands are sometimes better suited to foliage spraying than able attention in recent years in connection with the danger to dormant spraying. Species such as vine maple and others (Table animals and other forms of life. The known toxicity of the com 1), are not satisfactorily controlled by this method. Manzanita, mon brush-killing compounds used on forest lands is rather low, Ceanothus, and other persistent-leaved brush species, lend as in indicated in the section of this manual pertaining to the themselves to satisfactory control with foliage treatments at any properties of herbicides. In the Lake states, the same chemicals season from late dormancy until late summer. The choice of sea recommended for local use in reforestation have been used to son for these species is determined, within broader limits, by top-kill brush to promote the proliferation of sprouts for deer the availability of spray equipment and the presence or ab browse. Local studies have shown that deer degrade both sence of susceptible crop trees. Alder and salmonberry are phenoxy herbicipes and atrazine with negligible accumulation, especially sensitive to foliage sprays, but timing is critical. and no apparent harmful effects. Meat quality has not been af It is important to wait until foliage is mature for good contra,. fected by either class of herbicide as used for reforestation . Spraying of rapidly elongating stems will result in excessive Dioxin in 2,4,5-T and silvex does not appear to contribute to sprouting, except in very sensitive species. The optimum season risk. is usually midsummer in terms of target species control. There are numerous factors which the pesticide applicator must Chemical: 2,4-D, 2,4,5-T, the combination of 2,4-D and 2,4,5-T, consider. Treatment of a forest often entails the application of silvex. dicamba, picloram, amitrole, and fosamine are the herbi large amounts of chemicals over large areas. It is difficult to cides used for foliage applications. For rates of application refer delineate precisely which areas are being treated, and which areas are certain to be free of drift. Recent evidence regarding • See section on chemicals and properties for pesticide trade long-term effects of some herbicides on laboratory animals sug- names . to Tables 1 and 2. 2,4-D and/or 2,4,5-T are by far the most Effectiveness and low cost of injection will probably limit general helpful herbicides of this group. The others are used only where use of basal applications, especially in view of limitations on these fall short. Amitrole and dicamba are non-volatile and are availability of oil. very promising on some resistant species. Picloram-2,4-D mix Chemical: The low volatile ester forms of 2,4-D, 2,4,5-T, silvex, ture gives excellent control of some species. Picloram and di dicamba, or picloram singly or in combination , may be used fo r camba are highly toxic to conifers when applied directly, but basal spraying. 2,4,5-T, or the combination bf 2,4-D and seedl ings planted 6 or more months after treatment are norm 2,4,5-T, is generally used when mixed brush species are in ally unaffected. Water is almost always used as a carrier. volved; dicamba is excellent where residues will not harm Application: The choice of whether to spray foliage from the conifers, as is the new ester fo rm ul ation cf piclor:::::-""' -,,-..J ~ - " c .,.. air or with ground equipment depends upon the size of the job Silvex is most effective on bigleaf maple between March and and the equipment available. For most spot spray jobs, ground October, but 2,4,5-T may be more effective at other seasons. equipment is the most satisfactory. With ground equipment, it is Application: Herbicides for basal sprays are always applied necessary to completely cover the foliage of the brush being with oil as a carrier, using either diesel or stove oil. Rates of 10 treated. It is generally necessary to apply 100 gallons per acre or more pounds active ingredient of the herbicide to each 100 or more of the spray solution to get adequate coverage. Aerial gallons of oil are used (10 + aehg). For successful results with application involves 5 to 10 gallons per acre. Whi le the ground basal sprays, the stem must be soaked and thoroughly covered equipment lends itself very well to small jobs, the labor re throughout the treatment area. The results from basal treat quirement is excessive on jobs of more than a few acres and ments do not become immediately apparent. Often the tree will aerial application is preferred. On large jobs, aerial spraying be leaf out and die back one or two years before finally dying. comes a much more inexpensive way to apply herbicides. The Spring appli cations may produce best top-kill, wh il e summer lower dosages and volumes applied by aircraft may not produce and fall sprays may give better sprout control. Winter treatments quite as complete results as a soaking ground spray, but should may require a higher volume of spray with higher concentration prove adequate for most forestry purposes. as well. Foliage treatments for most deciduous species should be when the plants are in full leaf. Season of application is important. Modified Basal Application: This method of application is a Best results with fol iage sprays of phenoxys, amitrole, picloram combination of the foliage and basal methods of application. or dicamba are · achieved in late June to early August. Fosamine It is wasteful of chemical, but quite effective, especially on should be applied only in August and September. Treatment ea rly in summer results in excessive sprouting . blackberries. Foliage treatment may be used with reasonable selectivity after Chemical: The same chemical mixtures that are effective in conifers have completed terminal elongation. Maximum selec basal method of applicatio n. tivity is observed with 2,4,5-T after August 1, and fosamine after Application: The spray mi xture is 6 pounds of th e acid equiv September 1 . alent of the hormone chemicals in 1O to 15 gallons of diesel _ oil, plus enough water to make 100 gallons of total spray; for Dormant Application: Applications are made during the season hard-to-kill brush , straight oil carrier should .be used . Proper when buds are beginning to swell, but have not actually opened. application requires careful wetting of the stem at the base, and This season is now used extensively in areas where Douglas at least 2/3 to 4/5 of the foliage of the plant. The application fir or true firs are established and require release from brush is made during the growing season. High volumes of oil and which is susceptible at this season. In all cases, except where chem ical may prove excessively odorous for settled areas. the brush species retain green foliage during the winter months, oil is used for the herbicide carrier. Emulsions may be as effec Cut Surface Application: In the frill treatment, the trunk of the tive on the persistent-leaved brush. Pines are sensitive to tree is hacked or frilled at intervals around the trunk at a con dormant sprays, after the end of January. venient level. The frills are made by using an axe to cut over Chemicals: Essentially always phenoxy herbicides and prin lapping notches. The cuts are made through the bark, with the cipally 2,4,5-T, are applied in low volumes by helicopter or chips remaining connected to the tree. The cut frill can be with mist blowers. Other types of ground apparatus are not treated any time during the year, but the cut section should be well adapted to the requirements of this type of treatment; treated with the concentrated amine-formulated herbicide imme even the mist blower may not provide adequate coverage. diately after the frill is completed. Few species require complete Oil shortages will place serious restrictions on this practice. frilling. Spaced axe cuts with ¼ teaspoon (¼ teaspoon is about There are no known substitutes for oil. Except for vine maple, equal to one milliliter [ml.] or cubic centimeter [cc.] of herbicide however, most species can be treated in summer. Vine maple per cut) are usually adequate. is sensitive to 2,4,5-T only during March-April. The new fosa Girdles are made with an axe or a girdling machine. If an axe mine is also effective on vine maple in September, and may is used, cut the girdle at the lowest height convenient to the offer an effective substitute for the dormant spray. A new regis axeman. Make a double hack and remove the chip, forming a tration for a non-emulsifiable combination of picloram and band completely surrounding the tree. Apply the chemical, 2,4,5-T should be used during the dormant season only, and in mixed as for a basal spray, directly to this fresh cut with a oil carrier. low-pressure knapsack sprayer, or with a paint brush. This is very time-consuming and is less effective than proper basal Basal Application: This method of application is generally used treatment in terms of sprout control. This procedure has been where selective treatment of plants is desirable. It is also a much publicized, but is not now recommended in view of mod means of extending spraying time for brush control, since basal ern alternatives. applications are effective from March to October. With basal Season is important in cut-surface applications .. Certain herbi treatments, the spray is mixed with oil and applied to the lower cides including 2,4-D amine act most effectively during the 8 to 10 inches of a tree trunk or brush stem, soaking the trunk upward phase of sap movement, and others including MSMA liberally to the ground line. Even larger hardwood trees with cacodylic and picloram are best when sap is "moving down" in thick bark are usually controlled effectively by basal treatments. the fall. Season also affects root reserves of food for recovery. 4 Stumps may be treated with either of two methods. One method Injection of conifers is probably the lowest cost method of is essentially the same as for basal treatment. The only differ thinning. Total kill is not required, and minimal dosages will · ence is that the tree top is removed and the stump is treated permit good development of untreated trees . Heavy dosages, to prevent regrowth and resprouting. Research with bigleaf particularly of picloram, offer danger of "flashback" damage to maple and Oregon white oak indicates that best results require untreated trees. Organic arsenicals, cacodylic acid, and MSMA that the stump be thoroughly soaked around the ground line appear to offer considerable protection from bark beetles in with the spray solution at any time after cutting, but preferably trees killed by the herbicide. MSMA is the more effective for before regrowth of sprouts. Far less costly is the application of killing effects on the trees, and is generally recommended; it is undiluted herbicide to the perimeter of the freshly-cut stump most effective in fall and early winter. surface. A teaspoonful is adequate for almost any stump when Brush control for reforestation-special considerations uniformly distributed around the perimeter of the live wood in a thin line. Stumps thus treated may sprout weakly in the second Brush is not the only problem likely to be prevalent in brushy year if treated during the growing season or fall. Spring stump areas scheduled for reforestation. Brush is fine habitat for ani treatment has not been as successful. A delay between cutting mals that feed on tree seedlings. Mo~eover, in heavy stands of and treatment of even an hour may reduce effectiveness. brush, dead or alive, there is substantial shade to weaken trees, and considerable debris capable of falling and crushing Chemical: 2,4-0 or 2,4,5-T amines, picloram, dicamba, MSMA, small planted seedlings. An ordinary effort to establish trees in or cacodylic acid used singly or in combination, are most effec such circumstances will surely result in failure. tive and easiest to apply for the frill and girdle method. Esters Trees used for reforestation in the brush need to be substantially will not work well. Do not mix cacodylic acid or amitrole with larger than those used for Christmas trees and old field plant amines or other salts of 2,4-D, 2,4,5-T, silvex, or picloram. ings. They should also be repellent treated, or, preferably, of a These chemicals are used undiluted. species unpalatable to animals. Finally, the seedlings should be able to persist in shade. If Douglas-fir is used, it must be recog Application: When using the hormone chemicals such as 2,4-0, nized that it is attractive to animals, and cannot tolerate heavy 2,4,5-T or picloram the cut area or injection should be treated shade. Douglas-fir seedlings should be a minimum of 24" tall with the undiluted chemical as purchased. Use 1/s to ¼ tea for such areas; 30H is preferable. Normal two or three-year-old spoon (= 1 ml.) of the· chemical for each cut. When using un nursery seedlings are inadequate, because of rabbit damage diluted chemical, it is always necessary to use amine or other and inability to stand up under litterfall. salt formulations. Use of diluted mixtures may be more time con suming and less effective. Addition of a small amount of water Perhaps better suited than Douglas-fir is grand fir for areas of may be necessary in freezing weather to reduce vicosity; the less than 60" rainfall, and western hemlock in the moister salt concentration will prevent freezing. Phenoxy herbicides areas. Both species are quite unattractive to animals even with should be used during late spring and early summer; MSMA out repellents, and are capable of tolerating a substantial degree and cacodylic acid should be used only during fall and winter, of re-encroachment by brush. Seedlings 1O" -24" are adequate except on conifers. Picloram may be used any of these seasons in size. Markets are improving rapidly for timber of these spe in mixture with 2,4-0. cies, and they may well prove economically more attractive than Douglas-fir, for which planting success may be uncertain. Application may be done with various types of tree injectors, Experience is showing that two applications of herbicide or even or with a hatchet and squeeze bottle. Tree injectors are tools more, may be necessary for full establishment of plantations. designed to place chemicals into trees without frilling, girdling, These should be scheduled so that most species are controlled or felling. The injector is jabbed into the tree at regular inter immediately before planting. After planting, a spring dormant vals at a convenient height and at an angle of approxmately spray is a good means of prolonging relief from brush with a 60 degrees with the ground. On one type, a lever at the up minimum of damage to conifers. The spring dormant sprays are per end of the injector is tripped and a solution is discharged damaging to some pines, however, and release of these should into the injector hole. The object is to inject the chemical di be done during late summer. In general, the pjnes are poor bets rectly into the live tissue of the tree. An automatic injector in brushfields, and this will seldom be a consideration. hatchet recently developed at Oregon State University should make this a very useful and low-cost method, particularly since Special registration for forestry modern chemicals often do not require injection at the base of Herbicides should carry on their labels specific recommenda the tree. tions for a particular use. Forests are not included under non The "hack and squirt" method is slower than the injector, and is crop labeling according to recent interpretation of labeling laws. less precise in metering of chemicals. It offers the advantage of Herbicide dealers and distributors are required under the Fed lower investment cost for small jobs. It is not certain that results eral Pesticide Control Act of 1972 to insure that their products are comparable to those of injectors, but differences would not are properly labeled, and sold only for purposes described on be great in any event. the label. The major herbicides registered for forestry use in Oregon are listed in Table 3 with a rating of effectiveness on Cut spacing is important. As a rule, hardwoods require closer some important forest species. spacing than conifers. Alder, a moderately sensitive species, should still be injected at no more than 4 inches between cut General use formulations centers. Douglas fir, on the other hand, will be controlled by a Some herbicides are registered for general woody species con single injection (1 cc) of MSMA in stems up to 12 inches cir trol for such areas as pastures, fencelines and ditchbanks. cumference (4 inches diameter). It is always a good idea to Some are non-selective, such as the dicamba, amitrole and pic decrease spacing on larger trees, hence a 10-inch Douglas fir loram formulations; others are non-selective only at certain may receive five injections of MSMA to achieve results compar times, such as glyphosate, 2,4-0 brushkiller and other phenoxy able to one injection in a 4-inch tree. Hardwoods more than 12 formulations. These materials may be useful for site preparation inches in diameter should not have more than an inch of un or stand cleanup. Many of these products have been used tradi broken bark between injections. Rots entering injection points tionally on forest lands, but prospective users are warned to hasten demise of many hardwoods, especially alder. verify current label status and interpretation before proceeding. 5 Table 1. Chemical Brush control Recommendations for Spot Spray Treatment and Tree Injection 1

Lbs. active chemical per100 gallons of Expected Name Chemical1 solution Carrier control How applied

Alder, Red (Alnus rubra) 2,4 -D 2# Water Excellent Foliage spray Picloram & 2,4-D 1 gal. Water Exce llent Dicamba & 2,4-D 1# + 2# Water Excel lent 2,4,5-T 16# Oil Good to Basal treatme nt excellent May-July 2,4-D amine Undiluted None Good lnjection-3" be Picloram + 2,4-D Undiluted Water Good twee n centers, Cacodylic acid 5.7#/gal. None Excel lent Aug. -Dec . only Picloram pellets None Excellent Sp ring Ash, Oregon (Fraxinus latifolia) 2,4-D & 2,4,5-T 4# Water3 Fair Fo li age spray Cacodylic acid 5.7# /gal. None Good Injection in sum mer-fall Blackberry Good to Foliage spray Himalaya (Rubus procerus) Amitrole T or * 4# (2 gals.) excellent July-Aug . 2,4,5-T* 4# Water Foliag e sp ray Ju ly-Aug . Glyphosate ½ gal. Sept. -Oct. 2,4,5-T or silvex 8# Oil Excellent Basal Pic!oram + 2,4- D 1 gal. Water Good to Foliage spray excellent Aug .-Sept. Evergreen (Rubus laciniatus) 2,4,5-T* 4# Water Fair to good Foli ag e sp ray July-Aug. Glyphosate ½ gal. Excellent Sept. -Oct. Picloram + 2,4-D 1 gal. Water Good Fo liage spray 6 # Oil Excellent Basal-Sept. Trailing (Rubus vitifolius) 2,4,5-T + 2,4-D* 2# + 2# Water Good Foli ag e sp ra y Ju ly-Aug . Picloram + 2,4-D 1 gal. Water Good Foliage spray Salmonberry (Rubus spectabilis) Amitrole T 4# Water Excellent Foliage spray July-Aug. Glyphosate ½ gal. 2,4,5-T 4# Water Good Fol iage spray Picloram + 2,4 ,5-T 1 gal. Water Good Foliage spray Fosamine 4# September Broom, Scotch (Cytisus scoparius) 2,4-D 2# Water Excellent Foliage spray April-July Cascara, buckthorn (Rhamnus purshiana) 2,4-D & 2,4,5-T 4# Water1 Fair Foliage spray Amitrole T 4# (2 gals.) Water Good Foliage spray Glyphosate ½ gal. Late summer Cacodylic acid 5.7#/gal. MSMA 6.0#/gal. None Good Injection Ceanothus2 Mountain Whitethorn (Ceanothus Foliage spray cordulatus) 2,4,5-T 2-4# Water' Fair i Retreat sprouts Blue blossom (Ceanothus thyrsiflorus) 2,4,5-T 2# Water Fair i Foliage spray Retreat sprouts Snowbrush (Ceanothus velutinus) 2,4,5-T 2# Water' Fair to Foliage spray good Deerbrush (Ceanothus integerrimus) 2,4-D 2# Water Excellent Foliage spray Ceanothus sp. 2,4,5-T 10# Oil Excellent Basal treatment Cherry Bitter (Prunus emarginata) 2,4-D & 2,4,5-T 4# Water' Fair to Foliage spray excellent July Picloram + 2,4-D 1 gal. Water Good to Foliage spray excellent Dicamba & 2,4-D 1# +2# Water Excellent Foliage spray 2,4-D amine Undiluted None Excellent Injection or frill June-Aug. Cacodylic acid Undiluted None Excellent Injection or frill Aug.-Dec.

6 Lbs. active chemical per 100 " gallons of Expected Name Chemica11 solution Carrier control How applied

Chokecherry (Prunus virginiana) 2,4-D & 2,4,5-T 4# Water' Fair to Foliage spray good 2,4,5-T 12# Oil Good to Basal treatment excellent 2,4-D amine Undiluted None Excellent Injection or frill June-Aug. Chinkapin (Castanopsis sp.) 2,4,5-T 4# Water' Very poor Foliage spray Picloram + 2,4-D 1 gal. Water Good Foliage spray 2,4-D amine Undiluted None Good Frill treatment Coffeeberry (Rhamnus Californica) 2,4-D 4# Water• Poor Foliage spray Picloram + 2,4-D 1 gal. Water Good Foliage spray Cottonwood (Populus trichocarpa) 2,4-D & 2,4,5-T 4# Water Fair Foliage spray Dicamba & 2,4-D 1# + 2# Water Excellent Foliage spray 2,4-D amine Undiluted None Good Frill treatment or injection Currants & Gooseberries (Ribes sp.) 2,4-D & 2,4,5-T 2# Water Good to Foliage spray excellent Douglas fir (Pseudotsuga Menziesii) Picloram + 2,4-D 2 gal. Water Good Roadside spray Dicamba & 2,4-D 1# + 2# Water Good Roadside spray Cacodylic acid 5.7# /gal. None Good Injection (thinning) MSMA 6.0#/gal. None Excellent Injection (thinning) Picloram + 2,4,-D Undiluted None Excellent Injection (thinning) Fall-winter Elder, Red (Sambucus callicarpa) Amitrole T or 2# (1 gal.) Water Good to Foliage spray 2,4-D & 2,4,5-T 2# Water excellent Foliage spray Dicamba & 2,4-D 1# + 2# Water Excellent Foliage spray Glyphosate ½ gal. Late summer Picloram + 2,4-D 1 gal. Water Foliage spray 2,4,5-T 12# Oil Good to Basal treatment excellent Gorse (Ulex Europeaus) 2,4,5-T 4# Water Excellent Foliage spray. Best Picloram & 2,4-D 2 gal. Water Excellent on younger plants. Diuron 40# /acre Water Excellent Soil sterilant Hazel (Corylus cornuta var. Californica) 2-4-D & 2-4,5-T* 2# Water Fair to good Foliage spray Juniper (Juniperus occidentalis) Urab or fenuron 10#, Granules Good Granules around Picloram Pellets None Good base fall and winter Lodgepole pine (Pinus contorta) Cacodylic acid 5.7#/gal. None Excellent lnjection-1 cut MSMA 6.0#/gal. per 5" circumfer- ence Madrone (Arbutus menziesii) Cacodylic acid 5.7#/gal. None Poor - fair Injection 2,4,5-T 10# Oil Excellent Basal treatment Picloram Pellets None Excellent Spring treatment* Manzanita• Hairy (Arctostaphylos columbiana) 2,4-D 2# Water• Good Foliage spray Hoary (Arctostaphylos canescens) 2,4-D 2# Water Good Foliage spray Pine (Arctostaphylos parryana) 2,4-D 2# Water1 Good Foliage spray Whiteleaf (Arctostaphylos viscida} 2,4-D 2# Water Good Foliage spray Greenleaf (Arctostaphylos patula) 2,4-D 2# Water Poor to fair Retreatment of sprouts necessary; foliage spray Howell's (Arctostaphylos hispidula) 2,4-D 2# Water Good Foliage spray Maple Bigleaf (Acer macrophyllum) 2,4,5-T* 4# Water Fair Foliage spray. Lar- Silvex* ger trees difficult to Picloram + 2,4-D 1 gal. Water Fair control; retreating of sprouts necessary. Amitrole T* 4# Water Fair to good Foliage spray Dicamba & 2,4-D 1# + 2# Water Fair to good Foliage spray Silvex 12# Oil Excellent Basal treatment 2,4,5-T 12# Oil Excellent Basal treatment on small stems 7 Lbs. active chemical per 100 gallons of Expected Name Chemical1 solution Carrier control How applied

MSMA 6.0#/gal. None Excellent Injection; trees up to 16" di~metAr Aug.-Dec. Picloram Pellets None Good Pellets around base in sp ri ng * Picloram Undiluted None Excellent Frill or injection Vine (Acer circinatum) 2,4,5-T* 4# Water' Fair Foliage spray. Re- treatment of sprouts necessary. Glyphosate ½ gal. Water Late summer Picloram + 2,4-D 1 gal. Water Good Foliage spray Dicamba & 2,4-D 1# +2# Water Good Foliage spray 2,4,5-Tor Silvex 12# Oil Good to Basal treatment. excellent Oak Oregon (Quercus garryana) 2,4,5-T 12# Oil Excellent Basal treatment Amitrole T* 4# Water Good to Foliage spray Picloram + 2,4-D 1 gal. Water excellent Foliage spray Cacodylic acid 5.7#/gal. None Fair Injection 2,4-D amine Undiluted None Excellent Frill California (Quercus kello~gii) Amitrole T 4# Water Good Foliage spray Canyon Live (Quercus chrysolepis) 2,4-D 4# Water' Fair to good Foliage spray. Re - treatment may be necessary. Poison Oak (Rhus diversiloba) Amitrole T* 4# Water Good Foliage spray. Cool, late evening in July best. Ammate 1 # /gal. Water Fair Foliage spray. Re- treat sprouts. 2,4-D, 2,4,5-T or Sllvex 4# Water Fair Foliage spray. Re- Picloram + 2,4-D 1 gal. Water Fair treat sprouts. Picloram 2# Water Good Foliage spray Silvex 12# Oil Excellent Basal-Summer Ponderosa Pine (Pinus ponderosa) Cacodylic acid 5.7#/gal. None Excellent, Injection . One cut MSMA 6.0#/gal. None especially in per 5" circumfer- winter ence. Has some beetle repellancy. Wider spacing gives good kill of trees. Picloram + 2,4-D 1 gal. Water Excellent Foliage spray Rhododendron (Rhododendron macrophyllum) 2,4,5-T 16# Oil Poor Basal spray Salal (Gaultheria shallon) 2,4,5-T 4# Water' Poor Foliage spray. Re- treatment necessary. Picloram 2# Water Good One summer spray Picloram + 2,4-D 2 gal. Water Fair Foliage spray Salmonberry (Rubus spectabilis) 2,4,5-T 4# Water Good Foliage spray Amitrole T 4# Water Excellent Foliage spray Dicamba & 2,4-D* 1# +2# Water Fair to good Foliage spray Picloram + 2,4,5-T 1# + 4# Water Excellent Foliage spray Fosamine 4# Water Excellent Foliage spray Aug- ust-September Serviceberry (Amelanchier sp.) 2,4-D* 2# Water' Poor to fair Foliage spray. Sev- eral treatments required.

8 Lbs. active chemical per 100 gallons of Expected Name Chemical 1 solution Carrier control How applied

Snowberry (Symphoricarpos albus) 2,4-0 & 2,4,5-T* 4# Water9 Poor Foliage spray. Sev- eral treatments required. Sweetbriar Rose (Rosa eglanterla) 2,4-0 & 2,4,5-T* 4# Water9 Good / Foliage spray. Picloram + 2,4-0 1 gal. Water Good Good initial kill, some retreatment on sprouts. Tanoak1 (Llthocarpus sp.) 2,4-0* 4# Water9 Poor Foliage spray. Sev- 2,4,5-T* 4# Water9 Fair eral treatments required. Thimbleberry (Rubus parviflorous) 2,4-0 & 2,4,5-T* 4# Water Poor to good Foliage spray. Re- Picloram + 2,4-0 1 gal. Water Good treatment may be required. Oicamba & 2,4-0 1# +2# Water Fair to good Foliage spray Willow (Salix sp.) 2,4-0 2# Water Good Foliage spray. May need to retreat sprouts. 2,4,5-T 12-16# 011 Good Basal treatment.

* One pound MSMA per 100 gallons spray should improve effectiveness. Check label for current registration; some labels ,:nay spec ify that this treatment should be used in areas where conifers are less than four feet tall because of potential injury through root up take. 1 Herbicides listed in these recommendations generally have broadly inclusive labels, in terms of effectiveness at concentrations given. Concentrations and dosages suggested here are not necessarily listed on product labels for each species. The recommendations here are based on the best experience available, and do not exceed rates recommended for various uses on the labels. Deviations from specific labels are primarily to include species other than those for which product data were available at the time of issuance for the latest labels. New regulations regarding use and current label coverage should o~ consulted before purchasing a particular product. 2 Based on results in southwestern Oregon. • Addition of 2%-5% oil gives best results, as an emulsion.

Table 2. Chemical Brush Control Recommendations for Area Spraying Using Ground Equipment With a Boom, or Aircraft1

Active Chemical/ Gallons Expected Name Chemical' acre spray/acre Carrier control Remarks2

Alder, red (Alnus rubra) 2,4-0 or 2# 10 Water* Good Foliage spray. Best on 2,4-0 + trees less than ten 2,4,5-T years old. 2,4-0 2# 10 Oil Good Dormant spray. Aprll and early May. 2,4,5-T 2# 10 Oil Good Dormant spray Fosamine 4# 10 Water Good September Oicamba 1# +2# 10 Water Good Foliage spray. Site & 2,4-0 prep only. Picloram & 10 Water Good Foliage spray. Highly 2 gals. 2,4-0 injurious to conifers. Picloram & ½ gal. 10 Oil Excellent Site prep only. 2,4,5-T Glyphosate ½ gal. 10 Water Good Sept. 15 to Oct. 1O Broom, Scotch (Cystisus scoparius) 2,4-0 2# 5-10 Water Excellent Foliage spray. Will reproduce from seed; some sprouting. 2,4-0 2# 5-10 Oil Excellent Dormant spray. Will reproduce from seed; little sprouting. Ceanothus spp. 2,4,5-T 2# 5-10 Water* Good Foliage spray or dor- or mant. Some sprouts 2,4-0 + but not adverse to re- 2,4,5-T forestation.

9 Lb. actual Chemical/ Gallons Expected Name Chemical1 acre spray/acre Carrier control Remarks'

Elderberry (Sambucus sp.) Amitrole-T 1½# 10 Water Excellent See Salmonberry. Dicamba & 1# +2# 10 Water Good Foliage spray 2,4·0 Picloram + 2 gals. 10 Water Excellent Foliage spray 2,4-D Glyphosate ¼-½ gal. 10 Water Excellent Sept. foliage spray Gorse {Ulex europeaus) 2,4,5-T 2# 10 Water* Fair Foliage spray. 10 Water Good Good enough control Picloram & } 2 gals. 2,4-D for reforestation but not eradication. Picloram + 2,4,5-T probably more effective. Madrone (Arbutus sp.) 2,4,5-T 2# 10 Water* Good Associated species may prove difficu lt to cbntrol. Manzanitas (Arctostaphylos sp.) 2,4-D 2# 5-10 Water* Good Associated species may prove difficult to control. Maple, Bigleaf (Acer macrophyllum) Amitrole T 4# (2 10 Water Fair Foliage spray. Better gals.) controlled with basal Picloram + 2 gals. 10 Water Fair or frill treatments on 2,4-D large trees. Silvex 2-3# 10 Oil or water Fair Foliar Dormant or foliar Glyphosate ½-1 gal. 10 Water Good Sept. foliar Maple, vine (Acer circinatum) 2,4,5-T 2# 5-10 Oil Good Stem spray, pre-bud bursting. Retreatment necessary on sprouts if eradication desired, but seldom necessary for conifer release. Silvex 2-3# 10 Oil or water Fair to Use as substitute for good 2,4,5-T, as dormant or Picloram + 2 gals. 10 Water Fair foliage treatment 2,4-D Picloram + 1# + 4# 10 Oil Good Excellent for site 2,4,5-T preparation. Dicamba & 1# +2# 10 Water Good Foliage spray 2,4-D Fosamine 3-5 # 10 Water Excellent Sept. foliage spray (Site prep or release.) Glyphosate ¼-½ gal. 10 Water Excellent Sept. foliage spray (Site prep or release.) Poison Oak (Rhus diversiloba) 2,4,5-T 2# 5-10 Water* Fair Foliage spray. Retreat- ment needed. Silvex may be better. Amitrole T 4# 10 Water Fair to Foliage spray. Some good retreatment may be needed. Picloram + 1 gal. 10 Water Fair to Foliage spray. Some 2,4-D good retreatment may be needed. Salmonberry (Rubus sp.) Amitrole T 1½(¾ 10 Water Good Foliage spray in late gal.) July-Aug. Treatment Picloram + 2 gal. 10 Water Good may favor other spe- 2,4-D cies. Picloram + 1# + 4# 10 Oil Good Site prep only. 2,4,5-T Fosamine 3-4 # 10 Water Excellent Sept. foliage spray Glyphosate ¼ gal. 10 Water Excellent Sept. foliage spray

10 Lb . actual Chemical/ Gallons Expected Name Chemical1 acre spray/acre Carrier control Remarks2

Willow (Salix sp.) 2,4-0 2# 5-10 Water* Fairto Foliage spray. Retreat- good ment of sprouts nee- essary. Oicamba& 1# +2# 10 Water Fair to Fo!iage spray 2,4-0 good Picloram + 2 gals. 10 Water Good Foliage spray 2,4-D

* Ten percent oil in carrier. 1 Several products may be available that contain active ingredients being recommended. Before purchasing, it is vital that the user in sures that proposed uses comply with label restrictions. This is especially true for chemicals specifically being used for growing trees as a crop. 1 In most cases, where injury to Douglas-fir, hemlock or true firs is to be avoided, spraying with aircraft during the late end of the dormant season is to be preferred. Dosages remain the same, but oil is used as carrier. Do not attempt with amitrole T or dicamba. Pines are sensitive to 2,4-D and 2,4,5-T between March and early June, in general.

Restricted use formulations move brush on gentle topography. This should be done when Picloram and 2,4,5-T have been designated as " restricted " in soil is very dry to minimize damage. Partial scarification, com Oregon. All users must be certified in order to purchase or apply bined with chemicals, often offers the advantages of both pro product containing these ingredients as of 1977. cedures. In any event, soil disturbance should be kept to a minimum, and the operator should anticipate that scarification Machine clearing may set up a seedbed for an entirely new weed problem that There are circumstances in which scarifiation with a bulldozer can compromise results. Follow-up weed control is often is feasible. Toothed or conventional blades may be used to re- needed.

11 GRASS CONTROL FOR PLANTATION ESTABLISHMENT

The practice of planting coniferous trees on fields supporting safely, 5 pounds per acre is the maximum allowed by the label. heavy stands of grass in western Oregon is usually beset by Combinations of chemicals, such as dalapon-triazine mixtures, difficulty with plantation survival. A moderately dense stand of are sometimes more effective than triazines alone (Table 4). grass in an open field in western Oregon can be expected to Atrazine alone or in combination with 2,4-D has produced the remove virtually all available moisture in the surface 12" by most consistently good results . Some herbicides in mixture with the end of June. The removal of a heavy stand ,of grass will atrazine show promise for control of some atraz irit 1~::,1~"' ' .. make available to the seedlings much of the water which would weeds. Dalapon and 2,4-D are among the most promising ; both be lost to transpiration by the grass. Tillage may be used but can cause injury if used improperly. Velpar is a new product requires that terrain be negotiable by mechanized equipment. with forestry registration in Oregon . It is selective on many coni Herbicides may be used with the advantage that a single treat fers and produces excellent control of some atrazine-resistant ment gives complete weed control the first season, and may weeds. It should be applied in at least 20 gallons per acre for give partial weed control during subsequent seasons. The same best results . Glyphosate also will provide complete and selec principles pertain to Christmas trees or reforestation. With tive control of many resistant weeds. At present, mixtures can be Christmas trees, however, some additional considerations are applied according to the rates of individual components regis involved which are discussed in the next section. tered for use in forestry. Some products are registered for pre planting application only. Table 3 summarizes current recom Chemicals mendations for both reforestation and Christmas trees . The most effective chemicals for this use have been the tri azines (simazine and atrazine). The triazine-type chemicals Methods of Application provide relatively good weed control for an extended period at The method of application should provide even coverage of rates of 3 to 8 pounds per acre of the 80% commercial product. herbicide for uniform weed control in the vicinity of planted Although the higher rates have been used successfully and seedlings. Tractor mounted sprayers equipped to spray a strip

Table 3. Effectiveness of major forestry-registered herbicides on crop and weed species during seasons of optimum usage

Herbicide Ami Atra Dala- Gly- Fosa- Pic Species trole zine pon phosate mine loram Silvex 2,4-D 2,4,5-T VelparR Asulam Conifers Pines R 1-R 1-R 1-R s I-R S-1 I R R Douglas-fir R 1-R R R s 1-R 1-R 1-R R R True firs 1-R 1-R R R s 1-R S-1 I R R Hemlock 1-R 1-R I I s 1-R 1-R I-R ? R Woody Weed Spp. Alder R I I s R 1-S 8-1 Bigleaf maple I I I 1-R I R 1-R Blackberries s s s s s R s Cascara I s s I I I Ceanothus spp. A s s Cherry s s s s s Chinkapin R I I ElderbP.rry s s I s R I Hazel I s s I I I I Madrone R R R I I s Manzanita spp. R R R s I s s Poison oak s I I s s R I Salmon berry s s s I 1-S R I Snowberry s R R Tanoak R I I Thimbleberry R s I I R I I Vine maple I s s 1-S s R s Willow spp. 1-S R-S R-S Herbs- Annual grasses s s s s R R R R R s A Perennial grasses s 8-R S-1 s 1-R A R R R s R Bracken fern I I R s I I R A A I s Broad leaved herbs s I R s A S-1 S-R s 1-S S-1 R Sword fern A A R I R R R R R R A

R = Resistant to highest rates. I = Intermediate or variable; highest rates effective. S = Sensitive; killed by medium or lower rates. 12 of herbicide down the plantation row have been used with some Planting Techniques Concurrent with Herbicide Treatment success. When following this practice, it is quite important that In any plantation, but particularly on difficult sites, one should a wide enough strip be sprayed on each side of the planted select choicest quality planting stock of large vigorous seed row so that lateral roots do not draw down moisture supply lings. Machine planting and hand planting each have their too rapidly. In most situations, a strip at least 4 feet wide should advantages, but probably the benefits to be derived from ma be adequate for some habitat improvement for seedlings. chine planting are more striking when coupled with the use of herbicides. It is even possible that an ingenious operator can The treatment of spots up to 3 feet in diameter has not generally rig spray application equipment right on his planting machine proven very satisfactory. It is generally agreed, that the most so that the whole job is accomplished in on~ operation. effective method of weed control for plantation establishment is broadcast application. While the initial cost may be some The removal of all grass in the vicinity of the planted trees ex what greater in terms of money spent on chemicals, the poses the soil to the direct rays of the sun, resulting in surface net result in terms of cost per established tree should be some temperatures high enough to cause extensive mortality in young what lower with this method. Treatment costs for most herbicide Douglas fir and true fir seedlings. On many south and southwest applications represent a relatively small proportion of the total exposures and on flat land in valley bottoms, the soil surface plantation establishment costs. The greater the number of seed temperature may be responsible for just as much mortality as lings that can be established on a treated site, tne smaller the drought damage. In cases where heat damage may occur, unit cost per established seedling, hence the advantages are something must be done to protect the seedling from direct greatest for broadcast treatments. contact with the hot soil at the ground surface. This may be done with protective materials placed immediately around the Hand application equipment or aircraft will be the only type of root collar, or with stakes or shingles or similar types of mate equipment suitable for application on rough terrain. Airplan·e rials, which will shade the seedlings at the ground line. Ponder application has produced good results at low cost, even on osa and lodgepole pine seedlings are more heat tolerant than moderately rough terrain. It is estimated that 15% more chem other commonly used forest species; large seedlings of any ical is needed for aerial treatments than when ground rigs are . species are more heat-resistant than small trees, but any used to compensate for evaporation of fine droplets and loss of seedling must be given tender care in order to capitalize on dust. weed control.

Table 4. Chemical recommendations for plantation establishment, in pounds herbicide product per acre as aerial spray.

Pounds or quarts of herbicide product-season

Gly- Conifer Rainfall Dominant Pron- Preplant phos- planted zone-inches weed type Atrazine Simazine amide Amizine* 2,4-D* ate** Dalapon* Velpar®

Douglas-fir 50 + Perennial grass- 5 -April 2-4 fall 6-8 -Feb. Up to 4 4-6 1 ½-3 Grand fir broadleaf mix (D .fir & spruce) Noble fir 25-50 Annual 5 -March 2-4 fall 5-8 -Feb. 2 1 ½-3 Spruces grass, (Up to 1 broad leaf for true firs) Perennial 4 -March 2 4-8 grass, broad leaf Less than All 5 -fall 5 - fall 1-1 ½ 25 High elev. Low elev. All 5 -Feb. 2 1½-3 All other so+ All 5 5-8 Less than 50 All 5 5 - fall 5-8

* Up to 4# /A. 2,4-0 may be used over Douglas-fir seedlings without damage during the dormant season . Whenever using dalapon use a surfactant for optimum results . When applying 0alapon over conifers it must be mixed with atrazine, with addition of 2,4 -D optional. Do not use surfactant. Other mixtures registered as 11 /1 /77 were : Amizine (a mixture of am itrole and simazine) , and dalapon + 2,4-D, both restricted to preplant applications. Verify label for adaptability of these rates to local soil and weeds . * * Glyphosate is selective on conifers during the entire period that trees show firmly prominent buds. Non-selective during the grow ing season. Glyphosate does not produce residual control when used alone.