106 J. Aqua . Plan Manage. 50: 2012.
J. Aqua . Plan Manage. 50: 106-111
Mechanical and chemical con ol o he
in asi e co dg ass Spa ina densi lo a and
na i e plan communi y esponses in an
es ua ine sal ma sh
En iquE Ma Eos-na anjo, jEsús CaMb ollé, juan Ga Cía dE loMas, aquEl Pa a,
and susana Edondo-GóMEz*
Abs Ac
he sou h ame ican co dg ass, Spa ina densi lo a, has in-
aded a wide ange o sal ma sh a eas in sou he n spain. a
ield expe imen o examine physical and chemical con ol
o S. densi lo a, including mowing, he bicide (glyphosa e),
mowing plus he bicide combina ion, and he b eaking o
hizomes, was conduc ed in low-g adien ma sh in aded by
S. densi lo a o ind a means o con olling his in asi e spe-
cies. he g ow h pa ame e s o densi y, as well as species ich-
ness and di e si y, we e used o assess he e icacy o di e -
en ea men s in decembe 2007 and 2008. all ea men s
educed li e ille densi y o S. densi lo a a e 1 and 2 yea s o
ea men . Compa ed o he con ol, he educ ions in ille
densi y wi h hizome b eaking, mowing plus he bicide, mow-
ing, and he bicide applica ion we e 85, 65, 56, and 38% and
66, 70, 52, and 52% a e 1 and 2 yea s o ea men espec-
i ely. despi e a educ ion in S. densi lo a abundance, none o
he ea men s e adica ed his species comple ely. Howe e ,
hizome b eaking and mowing plus he bicide ea men s
p o ed o ha e he highes con ol e iciency, and plo s ea -
ed wi h hese ea men s con ained he highes alues o na-
i e species ichness and di e si y.
Key wo ds: b eaking hizomes, he bicide, in asi e species,
ma shes, mowing
In oduc Ion
he sou h ame ican co dg ass, Spa ina densi lo a b ongn.
(Poaceae), is in ading sal ma shes om sou he n Eu ope
(Figue oa and Cas ellanos 1988), no h a ica (Fennane
and Ma hez 1988), and no h ame ica (Ki elson and boyd
1997). in i s na i e sou h ame ica, S. densi lo a is a sal -ma sh
dominan o e a wide la i udinal ange and exhibi s consid-
e able mo phological a ia ion (bo olus 2006). i has been
pos ula ed ha his species was acciden ally in oduced in o
sou hwes spain by means o lumbe ade om sou h ame -
ica. in sou hwes spain, S. densi lo a has eme ged as a igo ous
in ade and ecosys em enginee ha sp eads by p oli ic seed
p oduc ion and consolida es i s s ands by clonal g ow h. i
can be a o midable compe i o ; i p oduces dense ussocks
wi h all canopies and pe sis en ly high abo e- and below-
g ound biomass (Figue oa and Cas ellanos 1988, Cas illo e
al. 2008, Ma eos-na anjo e al. 2008).
in asion by S. densi lo a is one o he mos impo an con-
se a ion p oblems a ec ing he Gul o Cadiz in he sou h-
wes e n ibe ian Peninsula because his species al e s he com-
posi ion o plan and animal communi ies, educing hei
biological di e si y (Ki elson and boyd 1997). i has become
he dominan plan species on ecen idal ma sh es o a ions
in he doñana na ional Pa k (Gallego-Fe nández and Ga cía-
no o 2007), h ea ening o sp ead o o he ma sh sys ems in
sou he n Eu ope. lea ning how o e ec i ely manage popu-
la ions o S. densi lo a is i al; hus, esea ch mus be conduc -
ed o ind me hods ha will ei he con ol o e adica e his
species, as has been al eady sugges ed o o he species o
Spa ina (an e al. 2007).
Chemical and mechanical me hods may cons i u e an
impo an ool o he con ol o S. densi lo a, as hey ha e
o o he species o Spa ina (Pa en 2004, obe s and Pul-
lin 2008). Hedge e al. (2003) explained he es ablishmen
and conside able limi a ions o a wide ange o con ol ech-
niques, including physical emo al, mowing, and he bicide,
o he managemen o nonna i e Spa ina plan s (S. al e -
ni lo a, S. anglica, and S. pa ens) in Washing on s a e. hey
indica ed ha he combina ion o mowing and he bicide
applica ion p o ided he g ea es con ol e icacy. Fo S. den-
si lo a only long- e m looding and glyphosa e applica ion
unde con olled en i onmen al condi ions ha e been s ud-
ied as con ol echniques (Ma eos-na anjo e al. 2007, 2009).
he e o e, he aims o his s udy we e o (1) e alua e he e -
ec s o di e en me hods on he con ol o S. densi lo a un-
de ield condi ions and (2) de e mine whe he hese con ol
me hods lead o enhanced plan di e si y in he long e m o
es o a ion o in aded a eas.
MA e IAl And Me hods
s udy loca ion
his expe imen was pe o med a in o Ma shes, si ua ed
on he join es ua y o he odiel and in o i e s nea he
*Fi s , second, ou h, and i h au ho s: depa amen o de biología Veg-
e al y Ecología, Facul ad de biología, uni e sidad de se illa, apa ado 1095,
41080 se illa, spain; second au ho : depa amen o de biología. Facul ad de
Ciencias del Ma y ambien ales, uni e sidad de Cádiz. io san Ped o s/n,
11510 Cádiz, spain. Co esponding au ho email: [email p o ec ed]. ecei ed
o publica ion july 7, 2011 and in e ised o m Feb ua y 7, 2012.
J. Aqua . Plan Manage. 50: 2012. 107
own o Huel a, on he a lan ic coas o sou hwes e n spain
(37°15’n, 6°58’W). he sal ma sh is subjec o a Medi e a-
nean clima e wi h oceanic in luences. Win e is we and mild
(mean empe a u e abou 11 °C in janua y) and summe is
long and d y (mean empe a u e abou 25 °C). Mean annual
ain all is 510 mm, wi h an in e annual a ia ion coe icien
o 31%. he semidiu nal ides ha e a mean ange o 2.10 m
and a mean sp ing idal ange o 2.97 m, ep esen ing 0.40 o
3.37 m abo e spanish Hyd og aphic ze o (sHz). Mean sea
le el is +1.85 m ela i e o sHz (Ma eos-na anjo e al. 2008).
o es he e icacy o he di e en me hods in he con-
ol o Spa ina and he damage o na i e plan s, we es ic ed
ou expe imen o low-g adien ma sh in aded by S. densi lo a
wi h an a ea o 0.5 ha wi h a heigh di e ence o 40 cm be-
ween i s lowe (+2.8 m sHz) and uppe (+3.2 m sHz) limi
o s udy a ea. in his loca ion, S. densi lo a sha ed habi a wi h
he na i e species Halimione po ulacoides, A h ocnemum mac-
os achyum, Sa coco nia pe ennis, and Salico nia amosissima. [a
de ailed examina ion o he physicochemical p ope ies o
he s udy si e is gi en in able 1.]
en i onmen al measu emen s
En i onmen al soil cha ac e is ics we e analysed. Measu e-
men s o sedimen conduc i i y, pH (n = 15), and edox po-
en ial (n = 10) we e made in low ide on he uppe 10 cm a
he sedimen in decembe 2006. Conduc i i y o sedimen
was de e mined in he labo a o y wi h a conduc i i y me e
(C ison-522, spain) a e mixing he sedimen wi h dis illed
wa e (1:1; edondo-Gómez e al. 2007). edox po en ial
and pH o he sedimen we e ob ained wi h a po able me-
e and elec ode sys em calib a ed in he ield (C ison pH/
mV p-506, spain). soil wa e con en was de e mined om
samples aken om he uppe 10 cm o sedimen (n = 15).
samples we e weighed be o e and a e d ying a 80 C o 48
h.
expe imen al design and ea men s
in decembe 2006, nine eplica e plo s o 2.5 by 2.5 m
we e posi ioned 2 m apa in he s udy a ea, and ou ea -
men s (mowing, he bicide, mowing plus he bicide combina-
ion, and he b eaking o hizomes) and one con ol we e
andomly assigned o each plo .
Mechanical ea men s (mowing and b eaking) o plo s
we e ca ied ou by pe sonnel om he uni e si y o se ille
using a ious hand-held b ush cu e s and sho els. all mow-
ing plo s we e mown o wi hin 10 cm o he subs a e. Fo he
b eaking o hizomes ea men , he abo e-g ound po ions
o he plan s in he plo s we e emo ed and hen he below-
g ound sedimen s, hizomes, and oo s we e dissec ed in o 20
cm long sedimen s wi h sho els.
He bicide was applied homogeneously o he plo su ace
using a backpack ag icul u al sp aye (Ma abi 5-l, Goizpe
s.C., spain) wi h a hand-held wand and an adjus able b ass
nozzle a a speed o 1 m s-1 and a a p essu e o 200 kPa (250
ml o sp ay olume). he he bicide used was glyphosa e
a 7200 g a.i. ha-1 (Glialka® 36; 360 g a.i. l-1, P esma sl,
spain). in he mowing plus he bicide ea men , glyphosa e
was applied immedia ely a e 24 h o mowing a he lowes
idal le el o p o ide he necessa y ime o he bicide up ake
and ansloca ion. he chemical ea men was likewise pe -
o med a low ides, allowing 3 o 6 h o d ying ime be o e
inunda ion o 50% o he plan . Wea he condi ions we e op-
imal, wi h ai empe a u es anging be ween 12 and 15 C
and wind speeds om 0 o 5 Km h-1. also, in decembe he
applica ion pe iod coincided wi h a pe iod o neap ides and
wi h plan s d opping seeds and en e ing senescence (nie a
e al. 2005).
da a collec ion
o es ima e he con ol e icacy, ou 0.2 by 0.2 m quad-
a s we e andomly selec ed in each plo in decembe 2007
and 2008, and he numbe o li e ille s o S. densi lo a was
eco ded. na i e species ichness and plan species di e si y
we e measu ed o each ea men . species di e si y was cal-
cula ed using shannon’s index (H’; shannon and Wea e
1949) o mula
H’= −Σpi · lnpi,
whe e pi = ela i e abundance o each species di ided by he
o al numbe o species obse ed in each plo .
s a is ical analysis
s a is ical analyses we e ca ied ou using s a is ica . 6.0
(s a so inc.). da a we e analyzed using a one-way analysis
o a iance (F- es ). da a we e i s es ed o no mali y wi h
he Kolmogo o -smi no es and o homogenei y o a i-
ance wi h he b own-Fo sy he es . We used a no mal e o
dis ibu ion, so ali e ille densi y and na i e species ichness
we e ln (x) ans o med, espec i ely, o one-way analysis o
a iance. signi ican es esul s we e ollowed by ukey es s
o iden i ica ion o impo an con as s (P < 0.05).
esul s
con ol o in asi e S. densi lo a
all mechanical and chemical ea men s had signi ican
e ec s on he con ol e icacy o S. densi lo a a e 1 and 2
yea s o ea men , wi h all ea ed plo s showing lowe li e
ille densi y han con ol plo s ( able 2; Figu e 1). b eak-
ing hizome ea men eco ded he lowes ille densi y o
S. densi lo a a e 1 yea o ea men , ollowed by mowing
plus he bicide, mowing, and he bicide ea men (Figu e
1). Compa ed o he con ol, he educ ions in ille densi y
wi h hese ea men s we e 85, 65, 56, and 38% espec i ely.
Table 1. Physicochemical P oPe Ties o The Th ee conT asTing siTes om TinTo
ma shes. Values a e mean ± se o 15 ePlicaTes. excePT o edox PoTenTial (Val-
ues a e mean ± se o 5 ePlicaTes in The uPPe and lowe limiT o sTudy a ea).
Pa ame e alues
Conduc i i y (ms cm-1) 15.6 ± 0.8
pH 6.7 ± 0.1
edox po en ial (mV) 87 ± 6.3 -146 ± 19.9
soil wa e con en (%) 27 ± 0.4
108 J. Aqua . Plan Manage. 50: 2012.
Table 2. esulTs o a one-way analysis o Va iance (anoVa) o di e enT conT ol T eaTmenTs on s. densi lo a liVe Tille densiTy and sPecies ichness and naTiVe PlanT diVe siTy o T eaTed PloTs
(shannon’s index, h´) one and Two yea s a Te T eaTmenT. T eaTmenTs: c, conT ol PloT; h, he bicide; b, b eaking hizome; m, mowing; and m+h, mowing Plus he bicide combinaTion. asTe isk indicaTe
signi icanT di e ence; Tukey TesT, P < 0.05).
1s yea one way ano a d. . F P 2nd yea one way ano a d. . F P
a iable ille densi y ( ille m-2) 4 67.60 0.000 a iable ille densi y ( ille m-2) 4 37.32 0.000
ea men C H b M ea men C H b M
H 0.000* — — — H 0.000* — — —
b 0.000* 0.000* — — b 0.000* 0.025* — —
M 0.000* 0.006* 0.000* — M 0.000* 1.000 0.018* —
M+H 0.000* 0.000* 0.000* 0.616 M+H 0.000* 0.000* 0.619 0.000*
1s yea one way ano a d. . F P 2nd yea one way ano a d. . F P
a iable species ichness 4 9.59 0.000 a iable species ichness 4 8.40 0.000
ea men C H b M ea men C H b M
H 1.000 — — — H 0.998 — — —
b 0.002* 0.002* — — b 0.002* 0.004* — —
M 0.006* 0.006* 0.986 — M 0.133 0.234 0.341 —
M+H 0.007* 0.007* 0.976 1.000 M+H 0.003* 0.007* 0.999 0.473
1s yea one way ano a d. . F P 2nd yea one way ano a d. . F P
a iable na i e plan di e si y 4 13.04 0.000 a iable na i e plan di e si y 4 6.55 0.001
ea men C H b M ea men C H b M
H 0.954 — — — H 0.880 — — —
b 0.000* 0.000* — — b 0.005* 0.041* — —
M 0.011* 0.049* 0.341 — M 0.101 0.472 0.657 —
M+H 0.001* 0.004* 0.941 0.803 M+H 0.004* 0.033* 1.000 0.597
J. Aqua . Plan Manage. 50: 2012. 109
Howe e , hizome b eaking ea men showed a ille densi y
simila o mowing plus he bicide ea men a e 2 yea s o
ea men (Figu e 1). a e 2 yea s, b eaking and mowing
plus he bicide ea men s eco ded he lowes ille densi-
ies (Figu e 1), wi h pe cen age educ ions compa ed o he
con ol o 66 and 70%, espec i ely. He bicide and mowing
ea men s each showed a ille educ ion o 52% and we e
no s a is ically di e en ( able 2).
ecoloniza ion by na i e ege a ion
b eaking, mowing, and mowing plus he bicide ea men s
showed he highes na i es species ichness a e 1 yea o
ea men ( able 2; Figu e 2); howe e , di e si y alues we e
no simila o hose o he mowing ea men due o he p es-
ence o dominan species ( able 2; Figu e 3). a e 2 yea s,
hizome b eaking and mowing plus he bicide ea men s
showed he highes na i es species ichness (Figu e 2). hese
ea men s also eco ded he highes di e si y alues ( able
2; Figu e 3). Finally, species ichness and di e si y alues o
plo s ea ed wi h he bicide we e simila o he con ol plo as
a consequence o he wide co e age by S. densi lo a.
dIscussIon
ou esul s show ha b eaking hizomes and mowing plus
he bicide combina ion ea men s had he highes con ol
e icacy on li e ille densi y o S. densi lo a compa ed o he
con ol plo . Glyphosa e applica ion was he leas e icacious
ea men (in e ms o au och honous plan species coloniza-
ion), especially in some plo s whe e he co e age by S. densi-
lo a was 100% (as happened in he con ol plo ). al hough
glyphosa e did educe li e ille densi y, he shading e ec
o he la ge numbe o dead and e ec ille s o S. densi lo-
a migh accoun o he lowe p esence o o he species in
he bicide ea men plo s. his species exhibi s a phalanx
ype o g ow h cha ac e ized by he p oduc ion o dense us-
socks, which can educe ligh a soil su ace and he eby in-
hibi coloniza ion by na i e species (Cas ellanos e al. 1998).
Ma eos-na anjo e al. (2009) demons a ed ha glyphosa e
a doses as high as 7200 g a.i. ha-1 has a nega i e e ec on
he pho osyn he ic appa a us and g ow h o S. densi lo a un-
de con olled en i onmen al condi ions, so his may educe
Figu e 1. li e ille densi y in ea ed plo s a in o ma shes 1 and 2
yea s a e ea men . ea men s: C, con ol plo ; H, he bicide; b, b eaking
hizome; M, mowing; and M+H, mowing plus he bicide combina ion. Values
ep esen mean ± sE, n = 36. di e en le e s indica e means ha a e signi i-
can ly di e en om each o he (capi al le e s o i s yea and lowe case
o he second yea o ea men ; ukey es , P < 0.05).
Figu e 2. Mean species ichness in ea ed plo s a in o ma shes 1 and 2
yea s a e ea men . ea men s: C, con ol plo ; H, he bicide; b, b eaking
hizome; M, mowing; and M+H, mowing plus he bicide combina ion. Values
ep esen mean ±sE, n = 18. di e en le e s indica e means ha a e signi i-
can ly di e en om each o he (one-way anoVa, species × ea men , p <
0.05).
Figu e 3. na i e plan di e si y (shannon’s index, H´) in ea ed plo s
a in o ma shes 1 and 2 yea s a e ea men . ea men s: C, con ol plo ;
H, he bicide; b, b eaking hizome; M, mowing; and M+H, mowing plus he -
bicide combina ion. Values ep esen mean ± sE, n = 36. di e en le e s
indica e means ha a e signi ican ly di e en om each o he (capi al le -
e s o he i s yea and lowe case o he second yea o ea men ; ukey
es , P < 0.05).
110 J. Aqua . Plan Manage. 50: 2012.
i s compe i i e abili y. Howe e , Pa en (2002) ound ha
he ime be ween applica ion and idal inunda ion o e he
canopy a ec ed he e icacy o glyphosa e in he con ol o S.
al e ni lo a, and zana a e al. (2007) obse ed ha soil wa e
con en in luenced he glyphosa e e icacy in he con ol o
Eupho bia he e ophylla. hus, he e ec o en i onmen al ac-
o s such as idal in luence and soil wa e con en could al e
he e icacy o glyphosa e applica ion and pa ly explain ou
esul s. in addi ion, o inc ease he e icacy o glyphosa e ap-
plica ion, epe i ion o he ea men in subsequen seasons
is necessa y, as p e iously sugges ed o di e en Spa ina spe-
cies ( obe s and Pullin 2008) as well as o he in asi e species
o we land ecosys ems (ails ock e al. 2001).
Many s udies ha e demons a ed a iable esponses o
Spa ina o mowing, depending on he species (li and zhang
2008, obe s and Pullin 2008). acco dingly, S. al e ni lo a
showed a signi ican educ ion in he densi y wi h an o e all
mean pe cen age decline o 68%, whe eas S. anglica and S.
ownsendii showed an o e -compensa ion e ec wi h a mean
inc ease o 42.8 and 14.7%, espec i ely ( obe s and Pullin
2008). Fo S. densi lo a, we eco ded mean pe cen age educ-
ions o abou 56 and 52% a e 1 and 2 yea s o ea men ,
espec i ely. he emo al o abo e-g ound pa s by mowing
migh ha e g ea ly educed he ene gy alloca ion o i s below-
g ound s uc u es, leading o a educed eg ow h po en ial
(Ha e kamp and Ka l 1999). Mowing was pe o med only
once a he beginning o he expe imen , al hough epea ed
mowing has been shown o e ec i ely educe g ow h in o h-
e Spa ina species (li and zhang 2008). Majo e al. (2003)
showed ha mowing migh be he leas e icacious con ol
ea men o Spa ina al e ni lo a, he mos labou in ensi e,
and he mos des uc i e o he su ounding mud la . Mo e-
o e , i s e icacy inc eases wi h he equency o mowing and
he use o la ge machine y, wo aspec s ha add up o g ea -
e damage o he associa ed mud la . in addi ion, mechani-
cal con ol me hods a e cos ly and equi e highly specialized
equipmen (li and zhang 2008). he e o e, u he es ing
o epea ed mowing is needed o be e assess he con ol o
S. densi lo a wi h his me hod and asce ain whe he i cons i-
u es a easible op ion.
Finally, hizome b eaking and mowing plus he bicide
ea men s educed he densi y o S. densi lo a be ween 85 and
65% a e 1 yea o ea men , and be ween 66 and 70% a -
e 2 yea s. li and zhang (2008) obse ed simila educ ions
o S. al e ni lo a ea ed wi h hizome b eaking in he i s
season, bu g ow h had almos eco e ed o he con ol le el
by he end o he second g owing season. o he echniques
such as he use o o o- illing, has p oduced >90% e icacy o
he con ol o S. al e ni lo a du ing win e ials bu was <70%
e ec i e du ing sp ing ials (Hedge e al. 2003). in compa i-
son, obe s and Pullin (2008) ound ha he use o mow-
ing ollowed by glyphosa e applica ion dec eased he densi y
o S. al e ni lo a by 91%. in con as , he same in e en ion,
when used o con ol S. anglica, inc eased densi ies by 19%
pe plo . Majo e al. (2003) ound ha one- ime mowing
seemed o yield a mo e consis en ly uni o m applica ion o
he he bicide and was likely o p o ide an ini ial educ ion in
he plan ’s ene gy ese es be o e chemical ea men . Fu -
he mo e, in hizome b eaking and mowing plus he bicide
plo s, S. densi lo a was eplaced by a highe numbe o na i e
species han in he bicide, mowing, and con ol plo s, esul -
ing in he highes di e si y alues.
conclusIons
ou da a indica ed ha S. densi lo a has a s ong capac-
i y o esis mechanical and chemical con ol in e en ions;
a single applica ion o he a ious con ol echniques es ed
in his s udy seemed incapable o e adica ing S. densi lo a and
e u ning in aded ma shes o a p e-in asion s a e. Howe e ,
his s udy p o ides aluable in o ma ion o he managemen
o his exo ic species in he in aded habi a s. hizome b eak-
ing and mowing plus he bicide applica ion could be use ul
o he con ol o he in asion o his species; bo h ea men s
dec eased S. densi lo a biomass and a o ed an inc eased di-
e si y and na i e species ichness.
AcknowledgMen s
We a e g a e ul o an onio j. uiz ico o e ision o he
English in he manusc ip . We also hank he spanish En i-
onmen al and science and echnology Minis ies o hei
suppo (p ojec 042/2007 o ganismo au ónomo Pa ques
nacionales and p ojec C M2008-04453).
lI e A u e cI ed
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aus alis con ol and e ec s upon biodi e si y in eshwa e non idal we -
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J. Aqua . Plan Manage. 50: 111-116
Response o a ge and non a ge loa ing and
eme gen aqua ic plan s o lumioxazin
CH is oPHE . MudGE and WilliaM . HallE *
Abs Ac
he e ec s o subsu ace and olia lumioxazin {2-[7- lu-
o o-3,4-dihyd o-3-oxo-4-(2-p opynyl)-2H-1,4-benzoxazin-
6-yl]-4,5,6,7- e ahyd o-1H-isoindole-1,3(2H)-dione} ea -
men s we e e alua ed on he loa ing weeds wa e hyacin h
(Eichho nia c assipes (Ma .) solms), wa e le uce (Pis ia s a-
io es l.), and landol ia (Landol ia punc a a [G. Mey] d.H. les
and d.j. C aw o d) as well as he non a ge eme gen species
eleocha is (Eleocha is in e s inc a (Vahl) oem & j.a. schul ),
maidencane (Panicum hemi omon schul .), picke elweed (Pon-
ede ia co da a l.), and sagi a ia (Sagi a ia lanci olia l.). all
subsu ace ea men s (≥100 µg a.i. l−1) and olia applica ion
a es >143 g a.i. ha−1 p o ided comple e wa e le uce con ol.
Con e sely, bo h lumioxazin applica ion echniques p o id-
ed <30% con ol o wa e hyacin h. no inju y symp oms we e
exhibi ed by landol ia ea ed wi h olia lumioxazin applica-
ions, and in wa e , concen a ions ≥200 µg a.i. l−1 we e e-
qui ed o p o ide mo e han 50% con ol. sagi a ia was he
mos sensi i e non a ge eme gen species o subsu ace lu-
mioxazin applica ions, ollowed by maidencane, eleocha is,
and picke elweed. sagi a ia d y weigh was educed 100% a
he bicide concen a ions ≥800 µg a.i. l−1 compa ed o a 73
o 83% d y weigh educ ion in eleocha is, maidencane, and
picke elweed. Con e sely, all eme gen species we e highly
ole an o olia lumioxazin ea men s, yielding calcula ed
EC50 alues ≥1320 g a.i. ha−1 o d y weigh . esul s o his
s udy indica e di e en ial e icacy and selec i i y among loa -
ing and eme gen a ge and non a ge aqua ic plan species
when ea ed wi h lumioxazin.
Key wo ds: chemical con ol, dose esponse, EC50: E ec i e
Concen a ion 50, Eichho nia c assipes, Eleocha is in e s inc a,
Landol ia punc a a, Panicum hemi omon, Pis ia s a io es, Pon ede-
ia co da a, p o opo phy inogen oxidase inhibi o , Sagi a ia
lanci olia, selec i i y
In oduc Ion
in asi e loa ing aqua ic plan s, including wa e hyacin h
(Eichho nia c assipes (Ma .) solms) and wa e le uce (Pis-
ia s a io es l.), sp ead by ege a i e ep oduc ion, o ming
ex ensi e ee loa ing ma s ha o en in e e e wi h na i-
ga ion, hyd oelec ic gene a ion, i iga ion, and ishing as
well as lowe ing he dissol ed oxygen and pH o he wa e
(Weldon and blackbu n 1966, Ha ley e al. 1984, owens and
Madsen 1995). hey may also ha bo mosqui oes, which a e
ec o s o diseases like dengue e e , mala ia, and encepha-
li is (Holm e al. 1977). Con e sely, na i e eme gen aqua ic
plan s may p o ide a di e se and aluable ood sou ce and
habi a o animals, can imp o e wa e cla i y and quali y, e-
in o ce sho elines, and p o ec soil agains e osion om wind
and wa e ac ion (sa ino and s ein 1982, Hei meye and Vohs
1984, sma 1995, dibble e al. 1996). damage o eme gen
non a ge and na i e plan s species is a majo conside a ion
in he bicide selec ion; a o able aqua ic he bicides a e able
o selec i ely emo e unwan ed plan s while minimizing dam-
age o non a ge na i e plan s.
one o he p ima y goals o aqua ic weed managemen
is o con ol in asi e plan s while main aining a di e se na-
i e plan communi y. na i e plan densi y and di e si y ha e
been shown o inc ease when canopy- o ming exo ic plan s
*Fo me G adua e esea ch assis an and P o esso , Cen e o aqua ic
and in asi e Plan s, ins i u e o Food and ag icul u al sciences, uni e si y
o Flo ida, Po box 110610, Gaines ille, Fl 32611. Cu en add ess o i s
au ho : us a my Enginee esea ch and de elopmen Cen e , Vicksbu g,
Ms 39180. Co esponding au ho ’s E-mail: Ch is ophe . .Mudge@usace.
a my.mil. ecei ed o publica ion Feb ua y 10, 2012 and in e ised o m
june 28, 2012.
112 J. Aqua . Plan Manage. 50: 2012.
a e emo ed (Ge singe e al. 1997), and con inued p esence
o na i e ege a ion allows di e si y o in e eb a e and ish
habi a s o be main ained (dibble e al. 1996). he e o e, i
is bene icial o selec i ely emo e loa ing in asi e species o
main ain na i e ege a ion and, in u n, wildli e habi a .
in 2010, lumioxazin ecei ed FiF a-sec ion 3 egis a-
ion o con ol o subme sed, eme gen , and loa ing aqua ic
weeds in he uni ed s a es (Valen usa Co po a ion 2011).
Flumioxazin is a e y as -ac ing con ac he bicide ha in-
hibi s p o opo phy inogen oxidase (PPo; p o opo phy in
iX:oxygen oxido educ ase, EC 1.3.3.4). i inhibi s chlo o-
phyll biosyn hesis by p e en ing ans o ma ion o p o o-
po phy inogen iX in o p o opo phy in iX, a p ecu so o
heme and chlo ophyll p oduc ion (Ma inge e al. 1989,
Cobb 1992, aizawa and b own 1999). i has been e alua ed
in g eenhouse and ield s udies o con ol o hyd illa (Hy-
d illa e icilla a [l. .] oyle) and o he in asi e aqua ic spe-
cies (Mudge 2007, icha dson e al. 2008, Mudge e al. 2010).
he high cos s associa ed wi h egis e ing an he bicide
o a new ma ke (i.e., aqua ics) may be o e come by maxi-
mizing he ma ke po en ial; he e o e, one objec i e o
his esea ch was o de e mine i lumioxazin has u ili y
as a olia o a subsu ace ea men o con ol loa ing
aqua ic weeds. Eme gen non a ge aqua ic plan s could
be impac ed by lumioxazin applica ions, so he second ob-
jec i e was o quan i y he e ec s o olia and subsu ace
lumioxazin ea men s on common non a ge eme gen
aqua ic plan s.
MA e IAls And Me hods
Floa ing aqua ic plan s. Wa e hyacin h and wa e le uce.
Plan s we e collec ed om odman ese oi nea in e -
lachen, Flo ida, and es ablished in 95 l high-densi y polye h-
ylene (HdPE) anks illed wi h 80 l o ap wa e (pH 8.0) in
ap il 2006 a he uni e si y o Flo ida (Cen e o aqua ic
and in asi e Plan s) in Gaines ille, Flo ida. ap wa e was
supplemen ed wi h 1 ml o Chela ed i on Plus1 (12-0-0) and
150 mg l−1 Mi acle-G o®2 (24-8-16) e ilize p io o he bi-
cide ea men . nu ien s we e added again a 1 and 3 weeks
a e ea men . Wa e hyacin h (5 plan s pe ank) and wa e
le uce (20 plan s pe ank) we e allowed o acclima e o 3
weeks be o e ea men . his s udy was epea ed in augus
2006 on he main campus o he uni e si y o Flo ida wi h
wa e om bi en’s a m lake (pH 7.5). bo h s udies we e
comple ely andomized designs wi h 4 eplica ions ( anks)
o each ea men . all s udies we e conduc ed unde ull
sunligh .
Fo he olia ea men s, lumioxazin3 was applied o he
oliage wi h a o ced ai Co2-powe ed sp aye calib a ed o
deli e a sp ay olume o 935 l ha−1 h ough a single ee-
je ®4 80-0067 nozzle a 0, 36, 72, 143, 286, 572, and 1144 g
a.i. ha−1 plus a non-ionic su ac an 5 (0.25% / ). subsu ace
lumioxazin ea men s we e conduc ed concu en ly a each
loca ion. Flumioxazin was applied a 0, 100, 200, 400, 800,
and 1600 µg a.i. l−1 as s a ic ea men s.
all li e wa e hyacin h and wa e le uce issue was ha -
es ed 34 d a e ea men (da ), placed in a d ying o en
a 90 C o abou 1 week, and weighed. Plan d y weigh
da a we e analyzed using nonlinea eg ession (exponen-
ial decay, y = b0e−bx) wi h he P oC nlin p ocedu e (sas
ins i u e 2002), and eg ession models we e used o de e -
mine he e ec i e concen a ion 50 (EC50), which is he
concen a ion o lumioxazin equi ed o cause a 50% e-
duc ion in d y weigh compa ed o con ol plan s. because
he e we e no di e ences be ween he slopes o he eg es-
sion lines a he 95% con idence le el, da a we e pooled
o each epea ed s udy.
Landol ia. a popula ion o landol ia (Landol ia punc a a [G.
Mey] d.H. les and d.j. C aw o d) was collec ed om a pond
wi h no his o y o he bicide ea men s in alachua Coun y,
Flo ida, and cul u ed a he Cen e o aqua ic and in asi e
Plan s in 266 l ibe glass anks in a g eenhouse (ligh in en-
si y o 1200 µmol m−2 s−1). Plan s we e cul u ed in ap wa e
(pH 8.2) amended wi h Mi acle-G o (24-8-16, 150 mg l−1)
and allowed o acclima e o 2 weeks be o e ea men . a 10 g
aliquo ( esh weigh ; 1.3 ± 0.07 g d y weigh ) o landol ia was
placed in 3 l HdPE (17.1 cm diame e by 13.3 cm deep) po s
illed wi h ap wa e (pH 8.0) and Mi acle-G o. Plan s we e
allowed o acclima e in he po s o an addi ional 2 d p io
o he bicide ea men . all po s we e amended wi h Mi acle-
G o a 2 and 14 da .
he subsu ace expe imen was conduc ed in ap il and
May 2007. landol ia was ea ed wi h lumioxazin a 0, 10,
25, 50, 100, 200, 400, 800, and 1600 µg a.i. l−1 as s a ic ea -
men s. as a compa ison ea men , diqua 6 was applied as a
olia ea men a 1.1 kg a.i. ha−1 using he desc ibed me h-
ods o olia lumioxazin ea men s. his expe imen was
a andomized design wi h i e eplica es. Folia lumioxazin
ials we e conduc ed in oc obe 2005, ap il 2007, and May
2007. Flumioxazin was applied o landol ia a 0, 36, 72, 143,
286, 572, and 1144 g a.i. ha−1 plus a non-ionic su ac an (sun-
s eam; 0.25% / ) using he same me hods as desc ibed in
he wa e le uce and wa e hyacin h s udies.
due o he di icul y o emo ing la ge quan i ies o nec o -
ic o chlo o ic and dead landol ia plan s, isual es ima es o
con ol (% con ol) we e de e mined on a scale o 0 o 100%,
whe e 0 = no chlo osis o nec osis and 100 = plan dea h.
Pe cen con ol a ings we e based on non ea ed con ol
plan s. he e we e no di e ences in con ol be ween he wo
expe imen s (Fishe ’s P o ec ed lsd, p ≤ 0.05); he e o e,
he da a om he wo expe imen s we e pooled o analysis
and means we e sepa a ed using 95% con idence in e als.
Eme gen aqua ic plan s. he sensi i i y o he non a ge
eme gen aqua ic plan s eleocha is, maidencane, picke el-
weed, and sagi a ia we e simila ly e alua ed agains subsu -
ace and olia lumioxazin applica ion echniques. all plan s
we e pu chased om a local plan nu se y in augus 2006
and ap il 2007 o he subsu ace and olia s udies, espec-
i ely. wo heal hy s ems (30 o 38 cm) o each species we e
plan ed in a mix u e o 2:1 po ing media7 o mason y sand
in 3 l HdPE po s amended wi h osmoco e®8 (15-9-12) e il-
ize a a a e o 1g kg−1 soil.
he subsu ace lumioxazin expe imen was a andomized
design wi h i e eplica es ( anks). Each species was cul u ed
ou doo s unde shade clo h (70% sunligh ) o 4 weeks in 95
l HdPE anks. Wa e le el in he anks was main ained a 25
cm, and pH emained a o nea 7.5 h oughou he s udy.
Plan s we e cul u ed o 1 mon h when lumioxazin was ap-
plied a 0, 50, 100, 200, 400, 800, and 1600 µg a.i. l−1 as s a ic
J. Aqua . Plan Manage. 50: 2012. 113
ea men s. in he olia lumioxazin ial, all i e eme gen
eplica es (po s) we e placed in one 266 l ibe glass ank (72
by 82 by 45 cm) p io o ea men . Flumioxazin was applied
as a olia ea men a 0, 36, 72, 143, 286, 572, and 1144 g a.i.
ha−1 wi h a non-ionic su ac an (suns eam; 0.25% / ) us-
ing he same me hods as he loa ing plan s.
a 40 da , all li e issue om he olia and subsu ace i-
als was ha es ed a he soil line, placed in a d ying o en a 90
C o abou 1 week, and weighed. Plan d y weigh da a was
analyzed using no-linea eg ession (P oC nlin, sas ins i-
u e 2002), and EC50 alues we e de e mined o d y weigh .
da a we e pooled ac oss expe imen al uns when no s a is i-
cal di e ences be ween he slopes o eg ession lines we e
obse ed.
esul s And dIscussIon
Floa ing aqua ic plan s. Wa e hyacin h and wa e le uce. Wa-
e le uce was much mo e sensi i e o olia applica ions o
lumioxazin han wa e hyacin h, wi h EC50 alues o 69 and
1435 g a.i. ha−1, espec i ely (Figu e 1). all olia a es ≥286 g
a.i. ha−1 esul ed in comple e con ol o wa e le uce. ea -
ed wa e le uce plan s exhibi ed chlo osis and nec osis on
he lea es 3 o 5 da and de olia ion 12 o 15 da . Folia
lumioxazin a es ≥286 g a.i. ha−1 esul ed in comple e plan
decay 21 da , whe eas suble hal a es (36 o 143 g a.i. ha−1)
esul ed in eg ow h o young plan s o wa e le uce ( ame s)
om he cen al me is ema ic egion. P e ious esea ch
( icha dson e al. 2008) demons a ed lumioxazin p o ided
97% con ol o wa e le uce plan s (9 cm diame e ) wi h 34 g
a.i. ha−1 and 100% wi h highe a es. ou esea ch e alua ed
lumioxazin on la ge and mo e ma u e plan s (15+ cm diam-
e e ), which likely explains he lowe le el o lumioxazin sen-
si i i y in ou esea ch compa ed o ha o icha dson e al.
(2008). Wa e hyacin h biomass was educed by only 41% o
he non ea ed con ol a he highes olia lumioxazin a e
e alua ed (1144 g a.i. ha−1) 34 da . he p ojec ed EC50 was
1435 g a.i. ha−1 (Figu e 1), abou h ee imes he maximum
label a e. ea ed wa e hyacin h plan s exhibi ed blackening
on younge lea es only, which is simila o inju y symp oms
no ed on wa e le uce and wa e hyacin h ea ed wi h he
PPo inhibi o ca en azone-e hyl (Koschnick e al. 2004).
subsu ace lumioxazin applica ions p o ided 100% wa e
le uce con ol a concen a ions ≥100 µg a.i. l−1 (da a no
shown). in con as , lumioxazin applied o he wa e column
ailed o educe wa e hyacin h biomass by mo e han 30% o
he non ea ed con ol plan s a any a e e alua ed (da a no
shown) and con i ms ha wa e hyacin h is mo e ole an o
lumioxazin han wa e le uce. hese esul s a e simila o
hose epo ed o wa e hyacin h and wa e le uce ea ed
wi h he PPo inhibi o ca en azone-e hyl (Koschnick e al.
2004).
Landol ia. he e ec s o a subsu ace applica ion o lu-
mioxazin o landol ia (Figu e 2) show ha mos lumioxazin
ea men s caused olia bleaching wi hin 7 o 10 da , bu
none o he ea men s esul ed in comple e con ol o land-
ol ia. Each lumioxazin ea men was di e en as indica ed
by he 95% con idence in e als. landol ia colonies ea ed
a concen a ions >25 µg a.i. l−1 began o sepa a e, and oo s
became de ached om indi idual onds. Koschnick (2005)
epo ed landol ia ea ed in he da k wi h diqua unde wen
oo de achmen wi hou chlo osis. he p ima y unc ion
o oo s o plan s in he lemnaceae amily is s abiliza ion o
onds (landol 1986). diqua applied as a compa ison ea -
men esul ed in 100% con ol less han 5 da when he
he bicide was olia applied a 1.1 kg a.i. ha−1. duckweed is
ex emely sensi i e o diqua and has a ypical EC50 o 4 µg a.i.
l−1 (Pe e son e al. 1997), he cu en indus y s anda d o
duckweed con ol.
he olia applied lumioxazin landol ia s udy was con-
duc ed h ee imes; ea ed plan s we e isually simila o
con ol plan s a all a es up o 1144 g a.i. ha−1 and showed
no dose esponse, and he e o e we e no ha es ed (da a
no shown). he olia ea men s o landol ia and wa e hya-
Figu e 1. he e ec o a olia lumioxazin applica ion on he d y weigh
o wa e hyacin h and wa e le uce 34 d a e ea men . da a a e shown as
d y weigh means ± s anda d e o (n = 8). EC50 = e ec i e concen a ion 50,
concen a ion o lumioxazin (g a.i. ha−1) equi ed o educe wa e hyacin h
and wa e le uce biomass by 50%.
Figu e 2. Pe cen con ol ( isual) o landol ia 21 d a e a olia diqua
(kg a.i. ha−1) and subsu ace lumioxazin applica ion (µg a.i. l−1 a.i.). Pe cen
con ol ±95% con idence in e al (n = 10). o e lapping con idence in e al
ba s indica e no signi ican di e ence.
114 J. Aqua . Plan Manage. 50: 2012.
cin h we e unsuccess ul, and olia a es ≥286 g a.i. ha-1 we e
needed o con ol wa e le uce. hese esul s sugges ha
lumioxazin up ake is limi ed by he lea cu icle o occu s p i-
ma ily h ough oo up ake o abso p ion by he unde side
o he plan .
Fu he esea ch is needed o de e mine i lumioxazin
applied as a subsu ace ea men is as e icacious o wa e
le uce in highe pH wa e (9.0). Mudge e al. (2010) dem-
ons a ed lumioxazin in neu al pH wa e is mo e inju ious
o subme sed aqua ic plan s han when applied o high pH
(9.0) wa e .
Eme gen aqua ic plan s. Eme gen aqua ic plan s had
highly a iable sensi i i y o lumioxazin aqueous concen a-
ions up o 1600 µg a.i. l−1 (Figu e 3). sagi a ia d y weigh
was educed 100% a concen a ions ≥800 µg a.i. l−1 com-
pa ed o a 73 o 83% d y weigh educ ion in eleocha is, mai-
dencane, and picke elweed. sagi a ia was he mos sensi i e
species o a subsu ace lumioxazin ea men ollowed by
maidencane, eleocha is, and picke elweed based on calcula -
ed EC50 alues o d y weigh ( able 1). hese da a indica e
eleocha is, picke elweed, and maidencane would be inju ed
by he maximum lumioxazin concen a ion o 400 µg a.i. l−1;
howe e , eleocha is and picke elweed would likely eco e
om he ea men .
Visual inju y symp oms obse ed 2 weeks a e he subsu -
ace lumioxazin applica ion o eme gen plan s included in-
e einal chlo osis (sagi a ia and picke elweed), eddening
on lea ma gins (maidencane), and mino chlo osis (eleocha-
is). Flumioxazin and o he PPo-inhibi ing he bicides a e ab-
so bed p ima ily by plan oo s wi h some abso bance in he
shoo s when applied o he soil, bu ansloca ion is limi ed
once he bicides a e abso bed in o olia issue because o he
apid desicca ion (Fadayomi and Wa en 1977, i e and Co-
ble 1981, unland e al. 1999, senseman 2007). Po s wi hou
holes we e used in hese s udies, and ew oo s we e isible
abo e he soil line. he e o e, lumioxazin up ake occu ed
ei he h ough he unde wa e s em, subme sed lea es, o
oo s. P e ious esea ch (Fadayomi and Wa en 1977, i -
e and Coble 1981) ound li le ansloca ion o PPo-inhib-
i ing he bicides in plan s, bu he subsu ace ea men o
eme gen aqua ic plan s in his s udy sugges ed mo emen
o lumioxazin om he soil o lowe s em in o he lea es.
i ansloca ion o lumioxazin was limi ed, his he bicide
should ha e gi dled he plan a he soil line and p oduced
inju y symp oms such as nec osis o he s em and lea es wi h-
ou einal chlo osis i s appea ing in he lea es. Fe ell e
al. (2007) showed lumioxazin in combina ion wi h MsMa
(monosodium sal o Maa) esul ed in a 94% yield educ ion
when applied as a high pos -di ec ea men o 20 cm all
co on. symp omology o lumioxazin- ea ed co on includ-
ed nec o ic lesions on lea es, eddening s ems, s em gi dling,
and e en ual lodging. P e ious esea ch also ound ha as
co on ma u es, plan s become mo e ole an o lumioxazin
because o g ea e ba k de elopmen and me abolic capaci y
(Fe ell and Vencill 2003).
Folia lumioxazin ea men s we e much less inju ious o
eme gen aqua ic plan s han subsu ace ea men s (Figu e
4). Maidencane and sagi a ia would equi e olia applica-
ion a es >1884 and 1320 g a.i. ha−1, espec i ely, o educe
d y weigh by 50% based on he calcula ed EC50 alues ( able
1). an EC50 alue could no be calcula ed o d y weigh o
bo h eleocha is and picke elweed because inc eased lu-
mioxazin concen a ions esul ed in an inc ease in d y weigh
(posi i e eg ession slope). Pos eme gen applica ions o lu-
mioxazin a e gene ally ecommended o ac i ely g owing
weeds <5 cm in heigh (Valen usa Co po a ion 2009), so
he minimal olia inju y and subs an ial lack o educ ion in
biomass obse ed in his olia s udy we e p obably due o he
ad anced ma u i y o hese plan s. inju y symp oms (includ-
ing chlo o ic and nec o ic lesions on he lea es) we e simi-
la o hose desc ibed o o he PPo-inhibi ing he bicides
(Pe e son e al. 2001). ole an species ha e educed o no
symp oms, whe eas he lea es o suscep ible species apidly
desicca e and die (Pe e son e al. 2001). he limi ed inju y
symp oms exhibi ed by plan s in he olia expe imen we e
simila o plan s exposed o subsu ace ea men s.
selec i e con ol o in asi e weed species is he goal o
aqua ic weed manage s. He bicide applica o s a ge in asi e
plan s h ough he use o speci ically o mula ed he bicides,
seasonally imed he bicide applica ions, and/o p eemp i e
spo ea men s be o e weeds become a p oblem (uni e -
si y o Flo ida 2011). he na i e eme gen plan s es ed in
his s udy we e ole an o olia lumioxazin applica ions,
e idenced by no obse ed mo ali y. in con as , subsu ace
applica ions esul ed in mo e inju y o non a ge plan s, es-
pecially when ea men s we e made in low pH wa e . Flu-
mioxazin is apidly deg aded by hyd olysis, wi h an a e age
hal -li e o 4.1 d, 16.1 h, and 17.5 min a pH 5.0, 7.0, and
9.0, espec i ely (Ka agi 2003, senseman 2007). Mudge e al.
(2010) demons a ed ha wa e pH does no di ec ly in lu-
ence lumioxazin ac i i y, bu h ough an impac on aque-
ous lumioxazin deg ada ion a es, pH o he ea ed wa e
can ha e a p o ound impac on e icacy. Mesocosm and ield
ials ha e demons a ed di e ences in lumioxazin e icacy
and selec i i y when applied o wa e wi h a pH >8.0 (Mudge
2007, Mudge and Halle 2010).
Figu e 3. he e ec o lumioxazin concen a ion on he d y weigh o
he non a ge eme gen aqua ic plan s eleocha is (), maidencane (▫), pick-
e elweed (), and sagi a ia () 40 d a e ea men . da a a e shown as
ac ual d y weigh means ± s anda d e o (n = 10).
J. Aqua . Plan Manage. 50: 2012. 121
he s udy; howe e , he low dose ollowed by he high dose
ea men esul ed in an addi ional 50% dec ease in bio-
mass compa ed o he a o emen ioned ea men (Figu e 2).
hese esul s indica e addi ional penoxsulam may be applied
a highe concen a ions a ew weeks a e ini ial ea men
o inc ease con ol. he h eshold o ini ial and seconda y
ea men s will need o be u he esea ched o de e mine
he e ec i eness o high dose ollow up ea men s.
bo h lu idone ea men s we e applied a 20 µg l−1 ol-
lowed by 5 µg l−1 a 4 o 8 Wa ( able 4). al hough ini ial
and ollow up ea men s we e he same concen a ion, he
addi ional 4 wk exposu e a he highe concen a ion esul -
ed in an addi ional 87% con ol. hese da a indica e he ex-
a 4 weeks o lu idone exposu e a he highe concen a ion
a e necessa y o con ol his weed, compa ed o he empo-
a y g ow h egula ion obse ed wi h he low dose ollow up
ea men a 4 Wa .
Penoxsulam concen a ions we e 4 and 21.5 µg l−1 o he
penoxsulam 5 and 20 µg l−1 s a ic ea men s, espec i ely, 1
da ( able 5). He bicide concen a ions emained ela i ely
s able h oughou he cou se o he s udy o he 5 µg l−1
s a ic ea men , whe eas he 20 µg l−1 s a ic concen a ions
declined a a much as e a e. he sho e hal -li e o he
20 µg l−1 ea men could be a ibu ed o g ea e e icacy
o he highe dose as plan s we e con olled and desicca ed
a a much as e a e, inc easing uV ligh pene a ion in o
he wa e column and aiding he bicide deg ada ion. Flu i-
done concen a ions dec eased o <1 µg l−1 by 8 Wa o
he F20Ex4Fb5 ea men ; he e o e, expe imen al uni s in
his ea men ecei ed an addi ional 3 µg l−1 o lu idone 9
Wa o supplemen he loss o he bicide (da a no shown).
he lu idone e- ea men concen a ion was chosen based
on he hal -li e o lu idone in he CE expe imen . signi i-
can ain all occu ed in Vicksbu g h oughou he mon h o
july, which may ha e con ibu ed o he apid dilu ion o he
he bicide. Howe e , du ing his ime he P5Ex16 ea men
concen a ion (2.8 ± 0.27) was less han he F20Ex4Fb5 con-
cen a ion 4 Wa , and by 8 Wa , penoxsulam emained s a-
ble while lu idone dec eased o <1 µg l−1. he gian sal inia
ma emained in ac o he F20Ex4Fb5 ea men om 4 o
8 Wa ; hus, inc eased pho oly ic deg ada ion was unlikely o
be he cause o apid lu idone loss.
esul s om his expe imen indica e gian sal inia con-
ol can be achie ed by implemen ing mul iple applica ions
o main aining penoxsulam o lu idone concen a ions o
an ex ended pe iod o ime (>12 wk). low dose epea ap-
plica ions a e commonly used o manage hyd illa and Eu -
asian wa e mil oil (My iophyllum spica um l.) wi h lu idone
o penoxsulam (Ge singe e al. 2001, Koschnick e al. 2003).
low dose s a ic penoxsulam ea men s (P5Ex16) can esul
in 76% con ol and comple ely supp ess g ow h du ing he
exposu e pe iod. inc eased con ol can be a ained by ex-
posing plan s o highe penoxsulam concen a ions (10 o
20 µg l−1) o longe pe iods o ime (16 wk). low concen-
a ions o slow-ac ing he bicides such as penoxsulam and
lu idone may empo a ily g ow h egula e o s un gian
sal inia o se e al weeks, bu plan s will ul ima ely eco e
once concen a ions all below his h eshold. He bicides and
plan g ow h egula o s ha e been p oposed and in es iga ed
o achie e a balance o con olling in asi e aqua ic plan s
while p e en ing nega i e ecological e ec s om unchecked
g ow h o hese species (lembi and Chand 1992, ne he land
and lembi 1992, nelson 1996, 1997, 2012 o hcoming).
G ow h egula ing concen a ions o slow-ac ing he bicides
may also be bene icial o aqua ic plan managemen , includ-
ing gian sal inia. his o m o managemen may aid in p e-
en ing de elopmen o dense in es a ions and hei nega i e
e ec s, o by slowing he eco e y o a ge in asi e plan s
om o he equi ed o ms o managemen . his could in-
clude olia he bicide applica ions o s ess om biocon ol
agen s, such as he gian sal inia wee il (Cy obagous sal ini-
ae), in an in eg a ed pes managemen p og am (Mudge and
Ha ms 2012). ecen wo k has shown posi i e esponse o
in eg a ing penoxsulam ea men s and mul iple biocon ol
agen s on wa e hyacin h (Mo an 2012).
Subsu ace s. olia expe imen . a he conclusion o
he s udy (11 Wa ), all subsu ace and olia he bicide ea -
men s educed gian sal inia d y weigh 27 o 67% o he
non ea ed con ol (Figu e 3). in pa icula , penoxsulam o-
Table 4. he bicide concenT aTions measu ed om gianT salVinia T eaTed wiTh
subsu ace aPPlicaTions o Penoxsulam and lu idone aT 20 µ g l−1 in The ceT
exPe imenT.
He bicide sampling Pe iod Concen a ion
(µg a.i. l−1 ± s.E.)
Penoxsulam 1 da a26.0 ± 0.08
1 Wa 24.6 ± 0.11
2 Wa 20.0 ± 3.37
4 Wa 20.3 ± 0.74
8 Wa 13.7 ± 0.46
Flu idone 1 da 10.8 ± 0.23
1 Wa 17.0 ± 0.27
2 Wa 15.6 ± 0.20
4 Wa 12.4 ± 0.68
Table 5. he bicide concenT aTions measu ed in T eaTed waTe ollowing sub-
su ace aPPlicaTions o Penoxsulam To gianT salVinia in The single sTaTic Vs.
mulTiPle aPPlicaTion exPe imenT.
He bicide ea men asampling Pe iod Concen a ion
(µg a.i. l−1 ± s.E.)
Penoxsulam 5 µg a.i. l−1 1 da b4.0 ± 0.17
1 Wa 4.4 ± 0.16
2 Wa 3.3 ± 0.03
4 Wa 2.8 ± 0.27
8 Wa 3.7 ± 0.11
10 Wa 3.4 ± 0.25
12 Wa 2.7 ± 0.25
16 Wa 1.8 ± 0.11
Penoxsulam 20 µg a.i. l−1 1 da 21.5 ± 1.64
1 Wa 21.2 ± 1.69
2 Wa 18.3 ± 0.90
4 Wa 17.4 ± 0.73
8 Wa 11.8 ± 0.29
10 Wa 9.1 ± 0.79
12 Wa 7.3 ± 0.71
16 Wa 1.9 ± 1.85
aPenoxsulam applied as a one ime ea men and plan s exposed o 16 wk;
n = 4.
babb e ia ions: da , days a e ea men ; Wa , weeks a e ea men .

122 J. Aqua . Plan Manage. 50: 2012.
lia (24 h) plus lu idone subsu ace, penoxsulam olia (24
h), and penoxsulam olia (s a ic) educed mean plan d y
weigh o below p e ea men le el. he penoxsulam olia
(24 h) plus lu idone subsu ace ea men p o ided be -
e con ol han all penoxsulam o lu idone s and alone o
combina ion subsu ace ea men s. al hough he glyphosa e
plus diqua mix was ini ially highly e icacious, plan s began
o eco e wi hin 3 Wa and displayed no inju y symp oms
by 11 Wa . P e ious esea ch demons a ed diqua a a much
highe olia a e (1.12 kg ha−1) plus a me hyla ed seed oil
and o ganosilicone su ac an blend p o ided 100% con ol
o a single laye o gian sal inia 6 Wa (nelson e al. 2001).
he amoun o plan ma e ial and densi y o he ma in he
subsu ace e sus olia expe imen was much g ea e (i.e.,
hicke ) a he incep ion o he expe imen compa ed o he
single laye o gian sal inia ea ed in p e ious esea ch by
nelson e al. (2001). he addi ional laye s o plan ma e ial
in his s udy likely p e en ed some o he he bicide sp ay so-
lu ion om eaching he plan ma e ial below he wa e su -
ace.
Flu idone concen a ions ailed o each he a ge dose
o 20 µg l−1 and ne e exceeded 6.1 µg l−1 h oughou he
cou se o he expe imen ( able 6). he eason o he low
concen a ion, despi e he “bump” a 5 Wa is unknown.
Con e sely, penoxsulam concen a ions emained abo e 30
µg l−1 o he i s week o he s udy; howe e , concen a ions
dec eased o 22.8 µg l−1 a 2 Wa and emained ela i ely
s able h oughou he emainde o he s udy ( able 6). he
penoxsulam 59.57 g ha−1 olia a e (24 h and s a ic) was
equi alen in amoun o ac i e ing edien o a 20 µg l−1 sub-
su ace penoxsulam ea men . Pa ial mig a ion o he bicide
in o unde lying wa e was a planned e ec o he s a ic olia
ea men . al hough he heo e ical in-wa e concen a ion
o 20 µg l−1 was ne e achie ed by his s a ic olia ea men ,
some o he he bicide solu ion was abso bed by he oliage,
and he emainde eached he wa e column and was a ail-
able o up ake by he subme sed oliage. he penoxsulam
s a ic olia ea men was 12.0 µg l−1 a 1 Wa and dec eased
o 7.8 µg l−1 by 11 Wa ( able 4).
Gian sal inia ea ed wi h subsu ace o olia s a ic
penoxsulam ea men s began o exhibi simila inju y symp-
oms as ea ly as 2 Wa . Plan s ea ed wi h penoxsulam a 20
µg l−1 and 59.57 g ha−1 (s a ic) exhibi ed g ow h egula ion,
and olde issue became nec o ic h ough 6 Wa . he penox-
sulam olia (24 h) applica ion esul ed in wi ches b oom
symp oms on all new issue in addi ion o nec osis o olde
issue 2 Wa . Flu idone- ea ed plan s exhibi ed chlo osis by
1 Wa ; howe e , minimal bleaching o he oliage emained
by 4 Wa , and plan s we e symp om ee by 6 Wa . he apid
dec ease in inju y symp oms was p obably due o he low lu-
idone concen a ions in he wa e . al hough he lu idone
ea men was a ge ed a 20 µg l−1, he concen a ion was 5.9
± 0.62 o 3.2 ± 0.20 be ween 1 da and 4 Wa , espec i ely
( able 6). he dec ease in inju y symp oms and concen a-
ions p omp ed a bump ea men 5 Wa o inc ease he
dose o 20 µg l−1 in all expe imen al uni s con aining lu i-
Figu e 3. E ec o subsu ace and olia penoxsulam (P), lu idone (F),
glyphosa e (G), and diqua (d) applica ions on ma u e gian sal inia mean
d y weigh (± s.E.) 11 weeks a e ea men (Wa ). Plan s exposed o s a ic
ea men s emained o he du a ion o he expe imen , while 24 h indi-
ca es plan s we e emo ed om ea men and placed in esh wa e . Ho i-
zon al line ep esen s p e ea men biomass o gian sal inia. Means wi h
he same le e a e no signi ican acco ding o Fishe ’s p o ec ed lsd es
a p = 0.05; n = 4.
Table 6. he bicide concenT aTions measu ed ollowing sTaTic subsu ace o
olia aPPlicaTions o Penoxsulam and lu idone To maTu e gianT salVinia in
The subsu ace Vs. olia exPe imenT.
He bicide ea men sampling
Pe iod Concen a ion
(µg a.i. l−1 ± s.E.)
Flu idonea (20 µg a.i. l−1) 1 da b5.9 ± 0.62
1 Wa 5.2 ± 0.28
2 Wa 4.6 ± 0.24
4 Wa 3.2 ± 0.20
8 Wa 6.1 ± 0.53
11 Wa 4.6 ± 0.50
Penoxsulam (20 a.i. l−1) 1 da 30.3 ± 1.81
1 Wa 30.9 ± 3.55
2 Wa 22.8 ± 1.76
4 Wa 19.4 ± 4.79
8 Wa 16.2 ± 1.39
11 Wa 14.1 ± 1.32
Penoxsulam (59.57 g a.i. ha−1) 1 da 7.3 ± 0.36
1 Wa 12.0 ± 1.14
2 Wa 13.2 ± 0.78
4 Wa 14.8 ± 1.63
8 Wa 10.6 ± 0.86
11 Wa 7.8 ± 1.26
aFlu idone applied on day o ea men and eapplied 5 Wa o inc ease
concen a ion o 20 µg a.i. l−1.
babb e ia ions: da , days a e ea men ; Wa , weeks a e ea men ; n = 4.
J. Aqua . Plan Manage. 50: 2012. 123
done. he lu idone bump esul ed in an inc ease in bleach-
ing symp oms h ough he emainde o he s udy.
he subsu ace penoxsulam plus subsu ace lu idone
ea men esul ed in a a ie y o inju y symp oms h ough-
ou he cou se o he expe imen . Plan inju y symp oms in-
cluded nec osis and g ow h egula ion (1 o 2 Wa ) along
wi h minimal chlo osis and wi ches b oom. he combina ion
o glyphosa e plus diqua esul ed in as e and mo e in ense
inju y symp oms han any o he he bicide ea men in his
ial. Plan s ea ed wi h his he bicide combina ion exhib-
i ed nec osis <1 Wa . he apid ac i i y o his combina ion
was no su p ising because diqua inju es gian sal inia as ea -
ly as 1 da (nelson e al. 2001). al hough his combina ion
seemed o be highly e icacious a quickly desicca ing olde
issue, new plan g ow h was obse ed as ea ly as 3 Wa .
he single s a ic e sus mul iple applica ion s udy dem-
ons a ed penoxsulam a 20 µg l−1 educed gian sal inia
biomass 100% when plan s we e exposed o 16 wk, whe eas
plan s in his s udy we e con inuing o die and lose buoyancy
a 11 Wa . an addi ional 3 o 5 wks o exposu e should ha e
esul ed in nea comple e o comple e con ol based on he
esponse o gian sal inia o he penoxsulam in he single s a -
ic e sus mul iple applica ions s udy. his no ion is suppo ed
by p e ious esea ch, which indica ed ha als- and Pds-in-
hibi ing he bicides penoxsulam and lu idone, espec i ely,
a e ela i ely slow ac ing and equi e long exposu es (60+ d)
o e ec i ely con ol a ge species (ne he land and Ge sing-
e 1995, Koschnick e al. 2007b). he in en was o conclude
he expe imen 16 Wa , bu i was sho ened because con ol
plan s began o decline in heal h a e empe a u es we e un-
usually coole han no mal in sep embe 2010.
al hough lu idone- ea ed plan s we e minimally con-
olled in his s udy (Fig. 3), he CE and single s a ic e sus
mul iple applica ion s udies demons a ed he e ec i eness
o his p oduc (Fig. 1 and 2). Flu idone was highly e icacious
(99% con ol) when plan s we e exposed o 20 µg l−1 o a
leas 8 wk (Fig. 2). he ocus o he hi d yea o esea ch was
o ex end he exposu e ime beyond 8 wk o achie e 100%
con ol, bu lu idone concen a ions ailed o each o be
main ained a he a ge concen a ion ( able 6).
he ank mix o glyphosa e plus diqua plus wo su ac-
an s (nonionic and bu e ing agen + nonionic o gano-sili-
cone) is cu en ly one o he ecommended olia ea men s
o gian sal inia in louisiana (d. E. sande s and a. j. Pe e ,
2012, pe s. comm.). one o wo plan laye s o gian sal inia
a e con olled wi h his mix u e; howe e , mul iple le els o
plan ma e ial a e di icul o pene a e wi h a single appli-
ca ion o any olia applied he bicide o he bicide combina-
ion; he e o e, mul iple applica ions a e o en necessa y o
e ec i ely con ol o e adica e dense gian sal inia in es a-
ion (nelson e al. 2007). bo h olia penoxsulam ea men s
(s a ic and 24 h exposu e) p o ided simila con ol o he
glyphosa e plus diqua ank mix e alua ed in his s udy. he
penoxsulam 59.57 g ha−1 olia a e was equi alen o a 20 µg
l−1 subsu ace ea men i all he he bicide sp ay eached
he wa e column and ailed o come in con ac wi h he plan
canopy. in compa ison, he 24 h olia penoxsulam ea men
was designed o limi any po en ial he bicide up ake om
he wa e column. al hough he d y weigh da a e lec ed no
di e ences, many new heal hy lea es we e de eloping om
plan s exposed o 24 h, whe eas only a ew heal hy onds
we e wi nessed wi h he s a ic olia penoxsulam ea men .
because penoxsulam was s ill p esen 11Wa (7.8 ± 1.26 µg
l−1), an addi ional ew weeks o he bicide exposu e may ha e
sepa a ed hese ea men s, allowing olde plan issue in he
s a ic penoxsulam olia ea men o desicca e and allow
mo e new plan g ow h in he 24 h penoxsulam olia and
glyphosa e plus diqua ea men s. in addi ion, penoxsulam
is ecommended a 35.04 o 98.12 g ha−1 as a olia applica-
ion, which is equi alen o 2.0 o 5.6 oz p oduc a-1. Fu u e
esea ch should be conduc ed o de e mine i a highe olia
a e can p o ide g ea e e icacy as well as as e ac i i y.
P e ious esea ch has shown ha penoxsulam is an e ec-
i e he bicide when applied subsu ace o con ol hyd illa
and a iable-lea wa e mil oil (My iophyllum he e ophyllum Mi-
chx.; Koschnick e al. 2007a, Glomski and ne he land 2008).
ou da a indica e penoxsulam as a olia o subsu ace ap-
plica ion can be a iable al e na i e o he s anda d ank mix
o glyphosa e plus diqua plus wo su ac an s o con olling
a ious sized in es a ions o gian sal inia. Penoxsulam may
ha e he po en ial o p o ide imp o ed, longe - e m con ol
o e p e ious s anda d olia ea men s unde ce ain use
scena ios, pa icula ly o la ge, dense in es a ions wi h high
eco e y po en ial. subsu ace applica ions should be main-
ained o a minimum o 8 wks o p o ide accep able con ol,
bu 12+ wk o exposu e gene ally p o ided excellen con ol.
Penoxsulam applied a 5 o 20 µg l−1 unde ex ended expo-
su es, can p o ide g ow h egula ion o con ol o gian sal-
inia. along wi h le hal con ol ou comes, he abili y o use
low-dose penoxsulam o g ow h egula ion is an addi ional
use cha ac e is ic ha may complemen o he con ol ech-
niques such as biological con ol o olia applica ions whe e
o he wise e-g ow h po en ial would p eclude e ec i e man-
agemen . depending on po en ial o dilu ion o o he o ms
o dissipa ion, mul iple applica ions o bump ea men s may
be necessa y o main ain e ec i e concen a ions o penox-
sulam in he wa e column. a olia o subsu ace penox-
sulam ea men may be a bene icial ea men depending on
he locale o plan s (open wa e s. backwa e ), p esence o
non a ge plan species, o he numbe o laye s/ hickness o
he gian sal inia ma . he penoxsulam and lu idone da a
gene a ed in hese h ee expe imen s need o be u he in-
es iga ed on an ope a ional le el in ield si es in es ed wi h
gian sal inia.
sou ces o MA e IAls
1Mi acle-G o® 36-6-6, he sco ’s Company, Ma ys ille, ohio
2aquashade®, applied biochemis s, Ge man own, Wisconsin
3Galleon sC®, seP o Co po a ion, Ca mel, indiana
4sona as®, seP o Co po a ion, Ca mel, indiana
5aquaP o®, seP o Co po a ion, Ca mel, indiana
6 ewa d® landscape and aqua ic He bicide, syngen a P o essional P od-
uc s, G eensbo o, nC
7aqua-King Plus®, Win ield solu ions, llC, s . Paul, Minneso a
8 ho oughb ed®, Win ield solu ions, llC, s . Paul, Minneso a
9 eeje echnologies, Whea on, il
AcknowledgMen s
his esea ch was suppo ed by seP o Co po a ion/
aqua ic Ecosys em es o a ion Founda ion and he us a my
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