R O C Z N IK I G L E BO Z N A W C Z E T. X X V II, N r 4, W A R SZ A W A 1976
J A N U S Z O S T R O W S K I, A N D R E A S R E IS L E R
ON THE EFFECT OF P L A C E M E N T A N D SO IL M O ISTR U E U P O N THE H E R B IC ID A L A C T IO N OF E TH O FU M E S ATE
Institute for O rganic Industrial Chemistry, W a r s a w
Institute for Biological and Chem ical Research in Field Crops and H erbage, W ageningen
Previous studies showed that the herbicidal action of ethofumesate (2-ethoxy-2, 3-dihydro-3, 3-dimethyl-5-benzofuranyl methanesulphonate) is mainly associated with the soil. Its availability to germinating seeds and emerging shoots is of prim ary importance [6, 7]. Especially the moisture content of the surface layer of the soil could be a determining factor. Therefore some experiments were conducted in which herbicide placement and soil moisture were varied, and the phytotoxic action and leaching were studied.
M A T E R I A L S A N D M E T H O D S
A ll experiments were carried out under greenhouse conditions in the autumn and winter of 1973 at the Institute for Biological and Chemical Reasearch in Field Crops and Herbage— Wageningen.
In all experiments the 20% emulsifiable concentrate was used, and a sandy soil with 3— 4% organic matter and 7% clay (fraction < 16u).
The effect of moisture of the upper soil layer was studied in boxes (3 X 1 5X 3 0 cm) with a glass front, placed at an angle of 25° from the vertical.
These four boxes were first partly filled with untreated, moist soil (15% water). Oat seeds (5 per box) w ere then put in with the root initials downwards and more or less covered with a plastic sheet fo r separation from the follow in g soil layers. The latter w ere varied as follows:
1 cm b u f f e r l a y e r 1 cm t o p l a y e r
untreated, air-dry 4 untreated, air-dry
untreated, moist (15% water) ethofumesate 10 ppm, moist (15% water)
untreated, moist (15% water) untreated, moist (15% water)
No replicates of glass front boxes were included. Shoot and root lengths of individual plants were measured after 8 days and mean values determined.
Leaching of ethofumesate was compared to that of atrazine both in dry and moist soil, using the thick soil layer chromatography method described by G e r b e r et al. [2]. A ll plates were first filled with air-dry soil. Then half of them were wetted by infiltration until complete satura tion. A t the start of the experiment the moisture equivalent of the soil in these plates was 19 to 19.5%.
O f each herbicide 0.5 mg a.i. was pipetted in 0.2 ml water in a shalkrw furrow in the soil 2 cm from the top. The commercial product of atrazine used was a 50% wettable powder. A fte r 15 minutes 147 mm leaching water was applied (descending technique). T riticu m vulgare (spring wheat var. Orca) was used to assay for ethofumesate and Spirodela polyrhiza for atrazine in the different soil layers. Tw o replicates were included.
The effect of herbicide placement was studied by mixing various con centrations of ethofumesate in different top layers of the soil (see Fig. 1). Clay pots of 13 cm diam. without bottomholes were used. The initial moisture level was about 15%. Three replicates w ere adopted.
Fresh weight of shoots (mean values I 1nn°/n ^ 50 30 x\ 20 10 Treated 5 top soil layer
я 0 -1 cm
2 • 0—2J5cm
1 о 0 - 5 cm
2 Ц
10
7171
m Concentration of ethofumesate in the soil layerEffect of ethofumesate herbicide placem ent on response of E c h in o c h lo a c r u s -g a lli
In these pots barnyardgrass (Echinochloa crus-galli) was seded at 1.5 cm depth immediately after fillin g of the pots.
In order to exclude downwards leaching of the herbicide in this experiment, the pots were placed in moist peat. In this way, water could be supplied to the peat because of infiltration through the porious pot walls.
On the effect of placement 213
R E S U L T S A N D D IS C U S S IO N
E FFE C T OF S O IL M O ISTU R E
The results are given in Table 1. Ethofumesate reduced shoot length when incorporated into 1 cm of w et top soil, but failed to do so in a similar layer of dry soil. The results suggest that uptake of ethofumesate through emerging shoots only take place at sufficient soil moisture, possi b l y because o f the higher proportion of the herbicide available in moist soil. Apparently soil moisture is also needed as a medium to penetrate into the emerging shoot. Under field conditions one would expect a gradual range of phytotoxicity. In general, various results have been obtained with different types of herbicides [e.g. 3, 4, 11] as other adsorption and or penetration patterns might have been involved.
T a b e l a 1
TLe e ff e c t o f surface s o i l c oisture on the action of ethofumesate upon oats
D-U D-E W-U W-E
Lengths of oat shoots in cm /mean values/
10.6 j1 n . 5 8.2 3.4
Lengths o f longest root in cm /mean values/
13.1 14.8 12.3 13.4
Explanation: Top s o i l la y e r D-U = dry s o i l untreated
D-E = dry s o il treated with ethofumesate W-U = wet s o i l untreated
W-E = wet s o il treated with ethofumesate
L E A C H IN G
Table 2 gives the results of the leaching experiment with dry and moist soil. Leaching of ethofumesate was increased when the herbicide was applied to the air-dry soil, whereas that of atrazine was practically not influenced by soil at the moment of application. Movement of the w aterfront itself was slower in the wet soil after complete saturation of the dry plates.
Soil moisture could affect herbicide movement by inducing swelling of colloids and diminishing air volume which affect by-passing of water [5] and adsorption — desorption capacities [8. 9. 10]. The higher water solubility of ethofumesate as compared to that of atrazine might result
T a b e l a 2 E f f e c t o f i n i t i a l s o i l m oistu re on le a c h in g o f ethofum esate
and a tr a z in e L e ach in g dep ths /сш/ d r y s o i l w et s o i l Ethofum esate 18 18 12 12 A t r a z in e 14 16 14 16
in easier by-passing in the water phase in dry soil in this experiment. Under field conditions this phenomenon could be important for leach ing to germination zones, since the top soil layer may often fluctuate in moisture content. In deeper soil layers such fluctuations are probably less extreme.
SO IL P L A C E M E N T EFFECT ON E C H IN O C H LO A C R U S -G A L L I
Figure 1 (log. paper disp.) shows that incorporation of ethofumesate at concentrations of 6 to 8 ppm into a moist top soil layer of 1 cm already gave almost complete controlof barnyardgrass. Increase in thickness of the treated soil layer at these concentrations hardly increased phytotoxi city. This is also evident with the low er concentrations of 2 and 4 ppm where control of the barnyardgrass was incomplete.
The efficacy of soil-incorporated herbicides is determined by their interaction with soil, but the nature of herbicidal activity should also be taken into consideration. These results with ethofumesate could be interpreted by its interference with plant germination and early seedling growth. The presence of ethofumesate in deeper layer does not contribute to its direct activity, but delays to later grow th stages in which the plants are less sensitive [7]. This is in contrast to the results obtained with inhibitiors of photosynthesis [Van der Z w e e p, 12].
Probably, uptake of ethofumesate by emerging shoots is more effective than that by early root uptake. However, uptake by roots from the upper soil layer cannot be excluded, since D a w s o n [1] observed that barnyard grass develops a strong root system above the first internode.
Since in the field various factors (rainfall, water evaporation, soil type etc.) w ill determine leaching and uptake, it is clear that weed control can be rather variable, especially when the late germination of thp barnyardgrass and its moderate susceptability to ethofumesate [5, 7] are taken into account.
On the effect of placement 215
R E F E R E N C E S
[1] D a w s o n J. H.: Developm ent of barn y ard grass seedlings and their response to E P T C W eed s 11, 1963, 60.
[2] G e r b e r H. R., Z e i g l e r P., D u b a c h P.: Leaching as a tool in the e v a luation of herbicides. Proc. 10th British W eed Conf. 8, 1970, 118.
[3] G r e e n R. E. : O b r i e n S. R.: H erbicid e equilibrium in soils in relation to soil w ater content. W eed Sei. 17, 1969, 514.
[4] G r o v e r R.: Influence of soil-m oisture content on the bioactivity of picloram. W eed Sei. 18, 1970, 110.
[5] H a r t l e y G. S.: Physico-chem ical aspects of the availability of herbicides in soil. H erbicides and the Soil. O xford, B la ck w ell 1960, 8, 63.
[6] N ortran -T e ch n ical Bulletin. Fisons Ltd. 1973.
[7] O s t o j i ć Z., R e i s 1 e r A .: Progress report on greenhouse studies w ith N o r t- ron-I.B .S. W ageningen 1973.
[8] O s t r o w s k i J. : L aboratory studies on soil leaching of some herbicides for sugar beet. Journées Intern. d ’Etudes sur le Desherbage en Cultures de B et teraves, M a rly L e Roi, 1967, 233.
[9] O s t r o w s k i J.: Studies on the adsorption and availability of pyrazon. Rocz. glebozn. 20, 1969, 277.
[10] O s t r o w s k i J.: Bad an ia nad sorpcją m onolinuronu i jego dostępnością dla niektórych roślin. Rocz. glebozn. 23, 1972, 51.
[11] S t i c k l e r R. L., K n a k e E. L., H i n s i e y T. D.: Soil moisture and effect iveness of p re-em ergence herbicides. W e e d Sei. 17, 1969, 257.
[12] Z w e e p W . van der: The reaction of sugar beets and other testplants upon herbicides. V o rtrage anlaszlich der W issenschaftlichen Aussprach e über che mische U n k rau tbek äm p fu n g in Z uck errüben mit Pyram in. B.A.S.F. 8 und 9 Januar 1964. Я. О С Т РО В С К И , A. Р Е Й С Л Е Р О В Л И Я Н И И Р А З М Е Щ Е Н И Я В П О Ч В Е И В Л А Ж Н О С Т И П О Ч В Ы Н А Г Е Р Б И Ц И Д Н О Е Д Е Й С Т В И Е Э Т О Ф У М Е С А Т А Научно исследовательский Институт Органической Промышленности — В арш ава Институт Биологических и Хим ических Исследований К ульт урн ы х Растений — Вагенинген Р е з ю м е Больш ое содержание влаги в поверхностном слое почвы увеличивало ф и - тоцидное воздействие этофумесата (2-этокси-2,3-дигидро-3,3-диметил-5-бензфу- ранилметносульфонат) на сеянцы овса. Область вымывания (перемещения) этофумесата водой возрастала при предшествзчощим применении этого гербицида на песчаную сухую почву, в то время как атразин перемещался одинаково в сухой и влаж ной почве. Этофумесат размещенный в верхнем слое почвы толщиной 1 см, 2,5 см или 5 см проявлял одинаковую эффективность в борбе с E c h in o c h lo a c r u s -g a lli.
J. O S TR O W S K I, A. R E IS LE R *
O W P Ł Y W I E L O K A L I Z A C J I W G L E B IE I W I L G O T N O Ś C I G L E B Y N A D Z I A Ł A N I E H E R B IC Y D O W E E T O F U M E S A T U
Instytut Przem ysłu Organicznego, W a rs z a w a
Instytut Badań Biologicznych i Chemicznych nad Roślinam i U p raw n ym i, W ageningen
S t r e s z c z e n i e
Duża zawartość w ilgoci w pow ierzchow nej w a rstw ie gleby uintensyw niała fito- cydalne oddziaływ anie etofumesatu (m etylosulfolian-2-etoksy-2,3-dw uhydro-3,3-dw u- m etylo-5-benzoruranylu) na siewki owsa. Zakres w y p łu k iw an ia (przemieszczania) w odą etofumesatu w zrastał przy uprzednim zastosowaniu tego herbicydu na suchą glebę piaszczystą, podczas gdy atrazyna by ła przemieszczana podobnie przy glebie suchej i w ilgotnej.
Etofum esat zlokalizowany w wierzchniej w arstw ie gleby grubości 1 cm, 2,5 cm lub 5 cm w yk azał zbliżoną skuteczność w zwalczaniu E c h in o c h lo a c ru s -g a lli.
dor. dr hab. Janusz Ostrow ski In sty tu t Przem yślu O rganicznego Warszawa, ul. A n n o p o l 6 i n g . A n d r e a s R e i s l e r I n s t i t u t v o o r B i o l o g i s c h e n S c h e i k u n d i n g O n d e r z o e k v a n L a n d b o u w g e w a s s e n W a g e n i n g e n , B o r n s e s t e e ç j 65/67
