Absorption and Translocation of Herbicides - American Chemical

Chapter 8

Absorption and Translocation of Herbicides Effect of Environment, Adjuvants, and Inorganic Salts 1

2

Gene D. Wills and C. G. McWhorter

Downloaded by CORNELL UNIV on October 11, 2016 | http://pubs.acs.org Publication Date: June 24, 1988 | doi: 10.1021/bk-1988-0371.ch008

1Delta Branch, Mississippi Agricultural and Forestry Experiment Station, Stoneville, MS 38776 2Agricultural Research Service, U.S. Department of Agriculture, Stoneville, MS 38776 Absorption and translocation of herbicides can be s i g n i f i c a n t l y increased when adjuvants are added to f o l i a r applied spray mixtures. The l e v e l of increased control from adjuvants i s usually affected by the environmental conditions at the time of herbicide application. In most cases, herbicide absorption and translocation are greatest under environmental conditions which are most favorable for growth of the treated plant. Adjuvants added t o treatment solutions often increase absorption and translocation of f o l i a r applied herbicides, e s p e c i a l l y when plants are under stress at time of treatment. Inorganic s a l t s i n spray solutions also a f f e c t absorption, translocation and subsequent t o x i c i t y of herbicides. Many inorganic s a l t s with monovalent (+1) cations increase herbicide a c t i v i t y while some s a l t s with divalent (+2) and t r i v a l e n t (+3) cations i n h i b i t herbicide a c t i v i t y .

Activator adjuvants are almost always added to spray mixtures of herbicides applied to plant f o l i a g e (1). They serve to enhance the l e v e l of weed control obtained with herbicides. Adjuvants enhance b i o l o g i c a l a c t i v i t y of herbicides by a) increasing herbicide penetration, b) maximizing e f f i c a c y through increased phytotoxicity or s e l e c t i v i t y , and/or c) improving spray application or retention (2). Herbicide absorption and translocation are increased by activator adjuvants which include surfactants, wetting agents, penetrants, and o i l s (3). The usefulness of surfactants f o r aiding i n wetting, spreading, and s t i c k i n g of spray solutions to leaf surfaces has been noted since the turn of the century (4). A report published i n 1890 on the use of surfactants showed that an a r s e n i c a l i n s e c t i c i d e which normally had no e f f e c t on plants caused injury to plants when soap was added to the spray solution (5). However, l i t t l e attention was given to the importance of f o l i a r penetration before the introduction of organic herbicides ( 4 ) . The use of 0

0097-6156/88/0371-0090$06.00/0 1988 American Chemical Society

Cross and Scher; Pesticide Formulations ACS Symposium Series; American Chemical Society: Washington, DC, 1988.


8.

WILLS AND McWHORTER

Absorption and Translocation ofHerbicides

surfactant to enhance h e r b i c i d a l a c t i v i t y was reported i n early research with 2,4-D [(2,4-dichlorophenoxy)acetic acid] (6). A l a t e r development involved extending the use of diuron [N*-(3,4-dichlorophenyl)-N,N-dimethylurea] from being only a s o i l applied herbicide to becoming also a s e l e c t i v e f o l i a r applied herbicide. This was accomplished by the addition of an activator surfactant to the spray solution (7). As the benefits of including surfactants i n mixtures of f o l i a r applied herbicides became widely established, researchers began to recognize that other factors were also interacting to influence the effectiveness of herbicides at the time of application (8) (9). Relative humidity was shown to a f f e c t the absorption of 2,4-D (8) and both temperature and r e l a t i v e humidity influenced the absorption and translocation of dalapon (2,2-dichloropropanoic acid) (9). As early as 1942, Harris and Hyslop (10) found that phytotoxicity of the sodium s a l t of DNOC (4,6-dinitro-o-cresol) could be increased by the addition of the inorganic s a l t , ammonium s u l f a t e , to the spray solution. Turner and Loader (11.) used ammonium s u l f a t e to increase the phytotoxicity of picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid). Szabo and Buchholz (12) found that other inorganic s a l t s could increase phytotoxicity of herbicides. These researchers increased leaf penetration of the triethanolamine s a l t of 2,4-D by adding ammonium n i t r a t e and disodium phosphate to the spray solution. We have conducted studies to determine further the e f f e c t s of environment, adjuvants and inorganic s a l t s on absorption and translocation of a number of herbicides i n various weed and crop species. Surfactants In studies where surfactant was a treatment v a r i a b l e , herbicide absorption and translocation were increased by the addition of a surfactant to the spray solution (13-16). The addition of the surfactant, nonoxynol [a-(p-nonylphenyl)-w-hyroxypoly(oxyethylene)] (9 to 10 POE), to the treatment solution frequently increased the translocation of radiolabeled C-glyphosate [N-(phosphonomethyl)glycine] applied to the leaves of cotton (Gossypium hirsutum) (13). The addition of nonoxynol also increased the penetration and translocation of dalapon in johnsongrass (Sorghum halepense) as determined by the increased control of the regrowth of shoots clipped at the s o i l l e v e l 24 h a f t e r treatment (14). Absorption and translocation of the radiolabeled herbicide, C-mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino]phenyl] acetamide methylcarbamodithioic acid} was increased by the addition of nonoxynol or ethomeen 0/15 ( o l e y l t e r t i a r y amino ethylene oxidide condensate) at 0.5% (v/v) (15). Herbicide absorption was increased when either surfactant was added to the herbicide solution and applied to soybeans (Glycine max) (Table I) and johnsongrass (Table I I ) ; whereas, nonoxynol was the most e f f e c t i v e surfactant when the two surfactants were compared on common cocklebur (Xanthium pensyIvanicum) (Table I I I ) . j. W i l l s and McWhorter (16) showed that the absorption of C-fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] 1 A


91

92

PESTICIDE FORMULATIONS: INNOVATIONS AND DEVELOPMENTS Table I. Movement of C-mefluidide i n Soybeans 72 h a f t e r Application to a 2.5-cm Area on the Center L e a f l e t of the Second T r i f o l i o l a t e of Plants 24 cm T a l l 2

14


Air Temp. (°C) 22

32

RH

Percent of applied Remaining i n Treated Leaf Absorbed 14 g 10 f 41 be 62 cd 38 e 32 cd

a C Activity Translocated From T r t . L f . 4 f 21 d 6 f

W

Adiuvant None Nonoxynol Ethomeen

100

None Nonoxynol Ethomeen

22 f 80 ab 69 be

17 ef 36 cd 55 ab

5 f 44 a 14 e

40


50 de 70 be 86 a

28 de 41 be 64 a

22 d 29 c 21 d

100


52 d 69 be 78 ab

12 f 34 cd 48 b

40 ab 35 be 30 c

40

lumbers within a column not followed by the same l e t t e r are s i g n i f i c a n t l y d i f f e r e n t at the 5% l e v e l as determined by Duncan's multiple range t e s t . SOURCE: Reproduced with permission from ref. 15. Copyright 1978 Weed Science Society of America. oxy]phenoxy]propanoic acid} by bermudagrass (Cynodon dactylon) was not affected to the same extent by the addition of either nonoxynol or o i l - s u r f a c t a n t (17% polyoxyethylene sorbitan f f j t y acid ester i n 83% mineral o i l ) (Table IV). Absorption of C-fluazifop was s i g n i f i c a n t l y increased by the addition of the o i l - s u r f a c t a n t while the r e s u l t s were inconclusive from the use of nonoxynol. Van Valkenburg (17) noted that there i s an optimum herbicide-surfactant balance for each herbicide and plant species being treated, and t h i s could account for the varied l e v e l s of herbicide absorption and translocation obtained by the use of d i f f e r e n t surfactants i n our studies. Temperature In general, an increased temperature up to 35C resulted i n increased herbicide absorption and translocation (13-16, 18-21). When C-2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] was applied to the leaves of winged elm (Ulmus alata) at 3-week i n t e r v a l s throughout the growing season, analysis of the data indicated that d a i l y temperature i n the range of 24 to 40°C enhanced absorption and translocation of the r a d i o l a b e l when compared to applications made at d a i l y temperature i n the range of 11 to 34°C (18). Studies in environmentally controlled growth chambers showed similar temperature e f f e c t s (13-16, 19-21). Absorption of C-acifluorfen {5-[2-chloro-4-(trifluoromethyDphenoxy]-2-nitrobenzoic acid} applied to showy crotalaria (Crotalaria spectabilis) was approximately f o u r - f o l d greater at 27 and 35°C than at 18°C


8. WILLS AND McWHORTER


Table I I . Movement of C-mef£uidide i n Johnsongrass 72 h a f t e r Application to a 2.5-cm Area on the Third Leaf of Plants 70 cm T a l l

RH

(°c)

W

Adjuvant None Nonoxynol Ethomeen

100


45 ef 49 de 56 d

9 cde 11 bed 10 cd

36 de 38 d 46 c

40


14 h i 52 de 37 f g

8 de 13 be 10 cd

6 8 39 cd 27 e

100


70 c 91 a 81 b

15 ab 9 cd 18 a

55 b 82 a 63 b


22

32

40

Percent of applied Remaining i n Treated Leaf Absorbed 7 i 4 e 19 h 9 cd 30 g 12 bed

14 a C Activity Translocated From T r t . L f . 3 g 10 f g 18 f

Air Temp.

lumbers within a column not followed by the same l e t t e r are s i g n i f i c a n t l y d i f f e r e n t at the 5% l e v e l as determined by Duncan's multiple range t e s t . SOURCE: Reproduced with permission from ref. 15. Copyright 1978 Weed Science Society of America. temperature (19). When C-sethoxydim {2-[l-(ethoxyimino) butyl]-5-[2-(ethy1thio)propyl]-3-hydroxy-2-eyelohexen-1-one} was applied to leaves of bermudagrass, absorption was the greatest (70%) at 35°C and least (33%) at 18°C (Table V) (20). Translocation was s i m i l a r l y affected with 17% of the applied r a d i o a c t i v i t y being translocated at 35°C and only 8% being translocated at 18°C. When C-glyphosate was applied to cotton leaves, absorption was 43 and 36% at 32° and 22°C, respectively (13). Translocation of glyphosate was not affected by differences in a i r temperature at the time of treatment. There was ^^2- to 3-fold increase i n the absorption and translocation of C-fluazifop i n bermudagrass maintained at 35°C as compared to bermudagrass maintained at 18°C a i r temperature during the f i r s t 48 h after application (Table IVj^(16). There was approximately a 2-fold increase i n absorption of C-mefluidide i n soybeans, common cocklebur, and johnsongrass as temperature was increased from 22 to 35° and a s i m i l a r increase i n translocation i n soybeans and johnsongrass only, between the two temperatures (Tables I, I I , I I I ) ^ 5 ) . Absorption of C-glyphosate i n johnsongrass nearly doubled and translocation was increased as temperature increased from 24 to 35°C (Table VI) ( 2 1 ) ^ However, i n soybeans, both absorption and translocation of C-glyphosate significantly decreased as temperature increased from 24 to 35°C (Table VII). Furthermore, when dalapon was applied without surfactant to johnsongrass, both penetration and translocation of the herbicide decreased as temperature was increased from 16 to 38°C (14). a


93

PESTICIDE FORMULATIONS: INNOVATIONS AND DEVELOPMENTS

94

Table I I I . Movement of C-mgfluidide i n Common Cocklebur 72 h a f t e r Application to a 2.5-cm Area on the Second Alternate Leaf of Plants 22 cm T a l l Air Temp.

(°c)

22


32

RH w 40

Adjuvant None Nonoxynol Ethomeen

100

None Nonoxynol Ethomeen None Nonoxynol Ethomeen None Nonoxynol Ethomeen

40

100

Percent of applied Remaining i n Treated Leaf Absorbed 10 f 6 d 37 c 17 be 25 de 11 cd 31 56 54 22 35 28 56 78 55

cd b b e c de b a b

13 18 16 11 16 14 38 23 38

cd be c cd c c a b a

3

C Activity Translocated From T r t . L f . 4 f 20 c 14 de 18 38 38 13 23 10 18 55 17

cd b b de c ef cd a cde

lumbers within a column not followed by the same l e t t e r are s i g n i f i c a n t l y d i f f e r e n t at the 5% l e v e l as determined by Duncan's multiple range t e s t . SOURCE: Reproduced with permission from ref. 15. Copyright 1978 Weed Science Society of America. Relative Humidity Absorption and translocation of herbicides were increased by increases i n r e l a t i v e humidity (RH) during the f i r s t 24 to 96 h a f t e r application ( i l j ^ 15, 16, 19, 21). There was consistently greater movement of C-radiolabeled herbicides into and within plants when treatments ygre applied at 95 to 100% RH than at 35 to 45% RH. Absorption of C-acifluorfen into showy c r o t a l a r i a was 3 to 4 times greater at 100 than at 40% RH (19). Absorption and translocation were influenced by RH when glyphosate wag applied to cotton (12). Absorption and translocation of C-glyphosate increased 3 to 6 f o l d at 100% JU^compared to that at 40% RH. The e f f e c t of RH on the movement of C-fluazifop into and throughout bermudagrass was not as great as with other herbicide-plant combinations, but i n general absorption and translocation was greater at l(j)g than at 40% RH (Table IV) (16). Where C-mefluidide was applied to johnsongrass, common cocklebur, and soybeans, absorption and translocation increased 5 to 6 f o l d i n johnsongrass, about 3 f o l d i n common cocklebur and less than 2 f o l d i n soybeans as RH increased from 40 to 100% (Tables I I , i n l a n d I, respectively) (15). Translocation was often greater when C-glyphosate was applied to johnsongrass and soybeans at 100 than at 45% RH (21). S o i l Moisture Both absorption and translocation of herbicides were increased when s o i l moisture was maintained at or near f i e l d


often

8.

WILLS AND McWHORTER


Jable IV. E f f e c t of Environment on the D i s t r i b u t i o n of C-fluazifop i n Bermudagrass 48 h after Treatment


Air Temp. (°C) 18

35

RH (%) 40

Adjuvant None Nonoxynol Oil-Surfactant

14 a Percent of applied C Activity Remaining i n Translocated Absorbed Treated t. Lf. 17 i 10 h Leaf From7T rgh 2 h 8 h 10 i 21 cdefg 41 d 62 fg

100

None Nonoxynol Oil-Surfactant

28 h 18 i 67 ef

14 gh 8 h 43 cd

14 efgh 10 fgh 24 bede

40


63 fg 74 de 92 abc

29 e 12 h 77 a

32 be 62 a 15 defgh

100


87 be 95 ab 98 a

27 e 25 efg 54 be

60 a 70 a 45 b

lumbers within a column not followed by the same l e t t e r are s i g n i f i c a n t l y d i f f e r e n t at the 5% l e v e l as determined by Dulncan's multiple range t e s t . SOURCE: Reproduced with permission from ref. 16. Copyright 1983 National Vegetable Research Station.

Tabjg V. E f f e c t of Environment on the D i s t r i b u t i o n of C-Sethoxydim i n Common Bermudagrass 12 h After Application to a Single Leaf Midway Along Shoots of Plants 15 to 20 cm T a l l Air Temp. (°C) 18

35

1A A Percent of applied X A c t i v i t y Translocated Remaining i n From T r t . L f . Treated Leaf Absorbed 6 c 27 c 33 a 8 c 43 a 35 c 1

RH (%) 40 100 40 100

56 b 70 c

39 b 40 b

17 b 30 a

lumbers within a column not followed by the same l e t t e r are s i g n i f i c a n t l y d i f f e r e n t at the 5% l e v e l as determined by Duncan's multiple range t e s t . SOURCE: Reproduced with permission from ref. 20. Copyright 1984 Weed Science Society of America.


95

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PESTICIDE FORMULATIONS: INNOVATIONS AND DEVELOPMENTS

Table VI. E f f e c t s of A i r Temperature, Relative Humidity and S o i l Moisture on the Movement^gf C-Glyphosate i n Johnsongrass 72 £ After Application. The C-Glyphosate was Applied to a 2.5-cm Area on the Third Leaf of Plants 70 cm T a l l Air Temp.

Absorption and Translocation of Herbicides - American Chemical

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