Weed control ornamentals

Additional reasons to manage weeds in ornamental plants and conifer trees include fire protection, frost protection, rodent and disease mitigation, nutrient management, and aesthetics. Uncontrolled weeds and brush become serious fire hazards in the fall or early spring when herbaceous weeds are dry. Plantations of conifers have been lost because weeds were not controlled and fires started. Fires are less destructive when herbaceous vegetation is controlled. 

Development of weed resistance to triazine herbicides has necessitated alternative weed control strategies. Rotation of triazines with other herbicides and combining triazines with other chemistries has been effective in ornamentals and Christmas tree plantations (Van Himme, 1989). Supplemental treatments in Christmas trees have been effective, using directed sprays of phenoxy herbicides or glyphosate before resistant weeds mature and produce seeds. Weed resistance from triazines is not a problem in most forest settings where the herbicide is applied only once or twice in a rotation, since 1 or 2 years of herbaceous weed control normally ensures survival and eventual dominance by conifers. When the conifer canopy closes, virtually all herbaceous vegetation is shaded out for some decades hence resistant weeds, if present, fail to survive from one generation to the next. 

Bing, A. (1974). Weed control on ornamentals. Proc. Northeast. Weed Sci. Soc., 28 357-360. 

Bingham, S.W. (1968). Economic evaluation for weed control in field-lined woody ornamental nursery crops. Proc. Am. Society Hort. Sci., 92 704-712. 

Robinson, D.W. and J.C. Kelly (1989). Further information on the tolerance of woody ornamentals to simazine. Proc. Br. Weed Control... 

Ryan, G.F. (1968). Weed control in ornamentals. Wash. Agric. Exp. Stn. Bull., 707. 

Besides corn, sorghum and grapes, chlorotriazines have been applied mainly in citrus, in pip-fruits, in ornamental and berry bushes and in the field of general weed control. Selective behaviour can, of course, also be observed on the part of certain weeds ... 

OTHER COMMENTS used in the manufacture of fire retardant compositions for flame-proofing textiles and paper products used in flameproofing wood used to treat cigarette paper so as to reduce the hazard of tumor formation from tobacco smoke used as soil treat-ment/for weed control/on apples, pears, fruit trees and ornamental trees. 

Uses Preemergence or postemergence herbicide used to control many perennial and annual grasses and broad-leaved weeds in ornamental trees and shrubs, forestry, fruits and vegetables. 

Diphenyl ethers are both systemic and contact herbicides and are used for the selective control of annual broad-leaved weeds and grasses in a variety of crops (such as soybeans, maize, rice, wheat, barley, peanuts, cotton, onions and ornamental trees) under different application scenarios. This class of herbicides contains a diphenyl ether moiety as the core substructure. Acifluorfen, bifnox, chlomethoxyfen, chlorni-trofen, fluoroglycofen-ethyl and fomesafen, etc., are representative compounds of the diphenyl ether herbicides (Figure 1). 

Simazine is widely used for preemergence control in field-grown nursery stock in North America. Selective use in container nurseries also has been demonstrated (Ahrens, 1972 Fretz, 1974 Wadsworth, 1975 Bing, 1983). It is less widely used in container-grown nursery production because of potential leaching (Elmore et al., 1976), but is especially effective when applied in the fall or winter to control winter annual weeds in containers. Simazine currently is registered in the United States for 50 species of woody ornamental nursery stock and Christmas trees. Tables 18.1 and 18.2 list selected species of conifers and deciduous ornamental plants, respectively, and their observed tolerance to simazine at rates of 2.2-3.3kg/ha. Information for these tables was obtained from personal observations and the literature, including those references by Ries et al. (1959) Ahrens (1961) Ticknor (1972) and Schubert et al. (1986). 

Uses pre-emergence, early post-emergence or soil-incorporated herbicide to control most annual grasses and many annual broadleaf weeds in beans, corn, cotton, milo, peanuts, peas, soybeans, sunflower, and certain woody ornamentals. 

Uses herbicide for pre-emergence control of annual broadleaf weeds and grasses in cotton, beans, barley, rice, soybeans, alliums, vines, ornamentals and orchards of fruit and nut trees also to control suckers on tobacco. 

Uses herbicide for pre-emergence control of annual grasses and some broadleaf weeds in cotton, sweet potatoes, tomatoes, vegetables, capsicums, okra, soybeans, groundnuts, tobacco, pome fruit, stone fruit, citrus fruit, bush fruit, strawberries, forestry nurseries, and ornamental plants, shrubs, and trees. 

Chemical Name 3-(4-chlorophenyl)-l-methoxy-l-methylurea Af,-(4-chlorophenyl)-Ar-methoxy-Ar-methylurea Uses herbicide for pre- or post-emergence control of annual broadleaf weeds and annual grasses in asparagus, berry fruit, cereals, maize, field beans, vines, leeks, onions, potatoes, herbs, lucerne, flowers, ornamental shrubs and trees, etc. 

Chemical Name l-butyl-3-(3,4-dichlorophenyl)-l-methylurea N-butyl-N (3,4-dichloro-phenyl)-iV-methylurea Uses pre-emergence herbicide to control grasses and broadleaf weeds in peas, beans, lucerne, garlic, beets, cereals, strawberries, ornamentals and forestry. 

Chemical Name 4-(dipropylamino)-3,5-dinitrobenzene-sulfonamide 3,5-dinitro-lV, A -dipropylsulfanilamide Uses herbicide for pre-emergence control of many annual grasses and broadleaf weeds in cotton, fruit trees, vines, nut trees, soybeans, groundnuts, oilseed rape, sunflowers, lucerne, peas, sweet potatoes, mint, ornamentals and also used in noncrop areas. 

Synonym Albrass, Bexton, CIPA, CP 31393, Niticid, Propachlore, Prolex, Ramrod, Satecid Chemical Name 2-chloro-AL(l-methylethyl)-Af-phenylacetamide 2-chloro-V-isopropyl-acetanilide Uses selective pre-emergence herbicide to control most annual grasses and some broadleaf weeds in brassicas, corn, cotton, flax, leeks, maize, milo, onions, peas, roses, ornamental trees and shrubs, soybeans, and sugar cane. 

Dazomet is used for preplant control of soil fungi, nematodes, bacteria, germinating weeds, soil insects in seedbeds for tobacco, nurseries, greenhouses, substrates for potted plants, turf, ornamentals, and vegetables. Its oral LD50 in rats is 640 mg/kg. 

Pendimethalin is used as a selective herbicide to control broadleaf weeds and grassy weed species in cereals, onions, garlic, corn, sorghum, rice, soy beans, peanuts, brassicas, carrots, celery, peas, potatoes, cotton, pome fruits, stone fruits, citrus, lettuce, tobacco, and tomatoes. It is also used on noncrop areas and on residential lawns and ornamentals. 

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