persistence of flurochloridone and terbutryn in...
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TECHNICAL BULLETIN 173 ISSN 0070-2315
PERSISTENCE OF FLUROCHLORIDONE
AND TERBUTRYN IN SOIL
N.A. Vouzounis and P.G. Americanos
:====....===
- 9MAY 1996 .•UCULTURAL R, .,Lt\RCH
INS1ITUTE
AGRICULTURAL RESEARCH INSTITUTE MINISTRY OF AGRICULTURE, NATURAL RESOURCES AND
THE ENVIRONMENT
NICOSIA CYPRUS
OCTOBER 1995
PERSISTENCE OF FLUROCHLORIDONE AND TERBUTRYN IN SOIL
N.A. Vouzounis and P. G. Americanos
SUMMARY
The residual activity of flurochloridone and terbutryn on many vegetable crops sown in spring, autumn and winter was evaluated in two soil types by means of bioassays. Persistence, measured as biological activity, was shorter for terbutryn than for flurochloridone. Degradation was most rapid in spring and slowest following autumn or winter application. Soil type affected the longevity of phytotoxicity in the case of spring application of flurochloridone only. Flurochloridone phytotoxicity persisted for more than 32 weeks on the most sensitive crops while terbutryn persisted for shorter periods (14-20 weeks). Carrot, celery, chickpea, coriander, okra, parsley and peanut were tolerant to the residues of both herbicides.
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I
INTRODUCTION with flurochloridone observed bleaching effects for more than one year. Cesari et al.
Weeds in irrigated crops, and especially (1975) found terbutryn residues to be toxic in vegetables, have become a very serious to spinach and beetroot 82-144 days after the problem in Cyprus because of the favourable last application. In the present work, bioasclimate and the intensification of agriculture. says were used to study the persistence of The scarcity and high cost of labour make flurochloridone and terbutryn under different the use of soil-acting herbicides imperative. conditions. The objective was to determine A range of herbicides are used at appropriate the safe-sowing intervals for a range of crops rates for each soil type. Two residual herbi following application of flurochloridone and cides with long persistence namely fluroch terbutryn on two soil types in three different loridone and terbutryn, can have disastrous seasons. effects on succeeding sensitive crops. Although flurochloridone has not yet been reg MATERIALS AND METHODS istered in Cyprus it was found that it can be
Flurochloridone and terbutryn were apused effectively in potatoes to control spepliedcies of the resistant weed Gaiium (Ameri on two soil types, a clay-loam (35% clay, 1.25% organic matter (O.M.), 21%canos et ai. 1994), and as a pre-emergence CaC03, pH 8,0), and a clay (50% clay, herbicide in okra (Americanos and Vouzou
nis 1991). 1.25% O.M., no CaC03, pH 7.4). For flulunila et al. (1994) using lettuce bioas rochloridone rates of application were 0.5 kg
says with soils cropped with potatoes treated on the clay-loam and 0.75 kg/ha on the clay
3
and for terbutryn 1.5 kg and 2.0 kg/ha on the c.lay-loam and c.lay, respectively. ApplicatIons were made In autumn (October), winter (January), and spring (March), so that the rate of dissipation of the herbicides under different weather conditions could be studied. They were repeated in two years, i.e. 1991-92 and 1992-93. The herbicides were applied with a knapsack sprayer fitted with a flat fan nozzle delivering 500 l/ha on plots 3 x 1 m arranged in a randomized complete block and replicated four times. All plots w~re .sprinkler-i~ig~ted the day prior to applIcatIOn and agaIn Immediately after.
Beginning two weeks after application and at three-or-four-week intervals thereafter, 15 seeds of each test crop were sown in all treated as well as in untreated control pl?ts to dept~s appropriate for each species. Pnor to SOWIng the top soil (10-15 cm) was worked to a tilth with a spade in a way that mixed the soil thoroughly.
The plots were irrigated after sowing and subsequently as required for the duration of the trials. When germination was complete emerged seedlings were thinned to 10 in each plot.
Fast-growing crops were allowed to grow for three weeks and slow growing ones for four weeks before the activity of the herbicides was visually assessed. Visual assessment was preferred to fresh weight reduction determination since according to Krauskopf and Wetcholowsky (1990) this method seems to be a less time consuming and a more efficient tool for monitoring degradation processes with bioassays. When reduction in growth, as visually assessed, fell to 10% or less it was considered that the crop concerned could be safely sown in treated soil. The scientific names of test crops appear in Appendix G while Fig. 1 shows the monthly mean temperatures during the period of the trials.
RESULTS AND DISCUSSION
The se!1sitive periods for all crops after flurochlondone and terbutryn application are shown in Table 1. Appendices A to F show the progress in time of the reduction in growth of the crops. In both the table and the appendices absence of data indicates that it was either too cold or too hot to sow the crop concerned or that sowings were discontinued
4
because of germination problems. Thus, for example February is too cold to sow cucumber while June is too hot for onions.
Flurochloridone Following spring application of fluroch
loridone, cabbage, cauliflower, chard, pepper, cucumber, eggplant, lettuce, marrow, melon, onion, radish and watermelon were sensitive to residues for 14 to over 23 weeks while carrot, celery, chickpea, okra, parsley and peanut were tolerant. Cowpea, French bean, purslane and tomato were found to be intermediate, with sensitivity ranging from 8-11 weeks (Table 1). Flurochloridone at 0.5 kg/ha was shown to be suitable as a preemergence treatment in okra (Americanos and Vouzounis 1991). Similar results were obt.aine? for the above crops following applicatIon In autumn and winter but herbicide persistence was prolonged, ranging from 20 to over 41 weeks for the most susceptible crops (Table 1).
Broadbean, cowpea and French bean, all me~~ers of the Leguminoseae family, were senSItIve to flurochloridone residues for 8-17 weeks, while spinach and the graminaceous crops barley, oat, ryegrass and wheat were sen.sitive fo: m?re than 20 weeks. Following sprIng applIcatIOn of flurochloridone sensitivity. of most c~ops was shorter in the heavy' than In the medIUm soil. This is attributed to greater adsorption of the herbicide on the clay colloids of the heavy soil. Walker et al. (1985), a~d. Harper (1988), working with ?ther herbICIdes found that their adsorption Increased as the clay content of the soil increased. After autumn application sensitivity to flurochlori~one residues lasted, for many crops, longer In the heavy than in the medium soil. This is attributed to the high amount of rainfall which followed the application in that period and leached the herbicide faster in the medium than in the heavy soil. Ando et al. (1987) investigating the movement of other herbicides found that they moved more easily in soils of low clay content and that the degree of movement increased with increasing value of precipitation.
Terbutryn Terbutryn was less persistent than flu
rochloridone, with phytotoxicity lasting for 11 wee~s following spring application, 17 weeks In autumn and 20 weeks in winter
Table 1. Safe sowing interval for various crops following application of flurochloridone and terbutryn* in spring, autumn and winter on a clay loam soil (M) and a clay soil (H)
Safe sowing interval (weeks after application)
Crop Soil Flurochloridone Terbutryn type
Spring Autumn Winter Spring Autumn Winter
Barley M >20 8 H >20 11
Beetroot M 20 14 >11 14 H 20 11 >11 14
Broadbean M 8 2 H 17 2
Cabbage M >23 >41 <20 11 H <20 >41 <20 11
Carrot M 2 2 2 2 2 2 H 2 2 2 2 2 2
Cauliflower M >23 >41 <20 5 H <20 >41 <20 8
Celery M 2 <23 <11 2 <23 <11 H 2 <23 <11 2 <23 <11
Chard M 14 17 17 11 14 17 H 14 20 17 11 14 20
Chickpea M 2 2 2 2 2 2 H 2 2 2 2 2 2
Coriander M 2 2 2 2 H 2 2 2 2
Cowpea M 11 <23 11 5 <23 2 H 8 <23 11 5 <23 2
Cucumber M 20 32 20 8 <23 11 H 14 32 20 11 <23 14
Eggplant M 20 32 23 2 <23 <8 H 14 35 20 2 <23 <8
French bean M 8 <23 8 5 <23 2 H 8 <23 8 8 <23 2
Lettuce M >23 38 20 2 <20 <8 H 17 >38 20 2 <20 <8
Marrow M 23 32 17 5 <23 11 H 14 35 20 8 <23 14
Melon M 20 32 23 8 <23 11 H 14 32 20 8 <23 11
Oat M >20 8 H >20 11
Okra M 2 <23 <8 2 <23 <8 H 2 <23 <8 2 <23 <8
Onion M 17 32 23 11 11 14 H 14 32 23 11 11 14
Parsley M 2 2 2 2 2 2 H 2 2 2 2 2 2
Pea M 5 2 2 2 H 5 2 2 2
Peanut M 2 <26 <11 2 <26 <11 H 2 <26 <11 2 <26 <11
Pepper M 14 35 20 5 <23 <8 H 14 35 20 5 <23 <8
Ito be continued
5
Table 1 continued
Purslane M 11 29 17 8 <26 <11 H 11 29 20 8 <26 <11
Radish M >23 41 32 5 8 5 H 17 41 26 5 11 5
Ryegrass M >20 11 H >20 11
Spinach M >20 >11 14 11 H >20 >11 17 11
Tomato M 8 <23 8 2 <23 <8 H 8 <23 11 2 <23 <8
Vetch M 2 2 H 2 2
Watermelon M 17 32 23 5 <23 <8 H 14 32 17 5 <23 11
Wheat M >20 11 H >20 11
* Rates of application, kglha in a medium and heavy soil respectively:flurochloridone 0.5, 0.75, terbutryn 1.5,2.0
30
/ / .-- --- --
/•/
"""""-.25 1--- 1991-92 --- 1992-93 1 '/
/
/
/•/
>- I \ /\ /
\ /\ / \ I
~
I I
I I
I I
I /
/ •10 ..........- //
/
~~.
5 o N o J F M A M J J A s month
Figure 1. Average manthly mean temperature (0C) during the experimental period. Athalassa meteorological Station.
6
(Table 1). Thus, damage was observed in chard, cowpea, cucumber, French bean, marrow, melon, onion, pepper, purslane, radish and watennelon for 5-11 weeks after spring application, whereas following autumn or winter treatments, symptoms were evident for 11-14 weeks in most of those crops. The most sensitive crops were spinach after autumn and chard after winter treatment, with phytotoxic symptoms appearing for upto 17 and 20 weeks respectively.
The cereals barley, oat, ryegrass and wheat were affected for a period of 11 weeks. Many crops exhibited good tolerance of terbutryn and were safely sown in treated soil two weeks after application (Table 1). They included broadbean, carrot, celery, chickpea, coriander, eggplant, lettuce, okra, parsley, pea, peanut, tomato, and vetch. Terbutryn is recommended in Cyprus for pre-emergence application to peas, broadbeans and okra (Americanos 1984; 1986; Americanos and Vouzounis 1991). The longevity of the phytotoxicity of terbutryn in the two soils was in most cases similar because higher rates were applied to the heavy soil to compensate for the increased adsorption on the clay. Barriuso and Calvet (1992) in their investigations with different residual herbicides, including terbutryn, found a clear relationship between soil types and herbicide adsorption but the latter was also highly dependent on the electrical state of the herbicides (i.e. whether cationic, anionic or neutral).
Season and, therefore by implication temperature, was the major factor influencing activity of biological residues. Thus, the two herbicides dissipated faster after spring applicaf'Jn when ambient temperatures were higher (Table 1, Fig. 1). Similar results have been reported for several other herbicides (Walker and Allen 1984; Vouzounis and Americanos 1992, 1995; Americanos and Vouzounis 1995).
In conclusion, the use of bioassays to determine safe-sowing intervals provides useful infonnation for Cypriot farmers enabling them to select crop rotations within multiple cropping sequences least likely to suffer damage from herbicide residues. However, the data in Table 1 must be viewed as an indication only, since the safe-sowing intervals reported here will be influenced by environmental factors (temperature, rainfall and irrigation), soil type and crop cultivar sown.
One way to reduce the risk of toxicity from herbicide residues is to plough deeply in preparation for follow-up planting (Gottesbueren et al. 1992).
ACKNOWLEDGEMENTS
We express our thanks to Dr. G. Orphanides and Dr A. Papasolomontos for the critical reading and helpful criticism of the manuscript. The technical assistance of Mr G. Economides in the field is acknowledged with thanks.
REFERENCES
Americanos, P.G. 1984. Herbicides for peas. Technical Bulletin 62, Agricultural Research Institute, Nicosia. 7p.
Americanos, P.G. 1986. Herbicides for broadbeans. Technical Bulletin 76, Agricultural Research Institute, Nicosia. 4p.
Americanos, P.G. and N. A. Vouzounis. 1991. Herbicides for okra. Technical Bulletin 127, Agricultural Research Institute, Nicosia.6p.
Americanos, P.G., N.A. Vouzounis and S. Christofi. 1994. Chemical control of Galium in potatoes. Technical Bulletin 164, Agricultural Research Institute, Nicosia. 7p.
Americanos, P.G. and N.A. Vouzounis. 1995. Residual activity of chlorthal-dimethyl, metribuzin and prometryn determined by bioassays in field trials. Technical Bulletin 167, Agricultural Research Institute, Nicosia.8p.
Baniuso, E. and R. Calvet. 1992. Soil type and herbicide adsorption. International Journal of Environmental Analytical Chemistry 46: 117-128.
Cesari, A., P. Flori and G. Malucelli. 1975. Effetti fitotossici determinati da residui di diserbanti su colture in rotaziene. Notiziario sulle Malattie delle Piante. No 92/93: 191-208. Bologna, Italy.
Gottesbueren, B., W. Pestemer and D. Bunte. 1992. Application of a simulation model (VARLEACH) for calculation of herbicide distribution in the soil under field conditions. Part. 2. Implementation into the expert system HERBASYS. Zeitschrift-fuer-Pflanzenkrankeheiten-undPflanzenschutz 13:327-336.
7
Harper, S.S. 1988. Sorption of metribuzin in surface and subsurface soils of the Mississippi Delta region. Weed Science 36:84-89.
Junnila, S., H. Heinonen-Tanski, L.R. Ervio, P. Laitinen and R. Mutanen. 1994. Phytotoxic persistence and microbiological effects of flurochloridone in Finnish soils. Weed Research 34:79-88
Krauskopf, B. and I. Wetcholowsky. 1990. Collaborative study comparing different bioassay methods to monitor the behaviour of herbicides in the soil. Preliminary report, European Weed Research Society, Leverkusen. 3p.
Vouzounis, N.A. and P.G. Americanos. 1992. Effect of temperature and soil moisture on degradation of alachlor, pendimethalin and prometryn. Technical Bulletin 147, Agricultural Research Institute, Nicosia. 5p.
Walker, A. and R. Allen. 1984. Influence of soil and environmental factors on pesticide persistence. Monograph, British Crop Protection Council 27:89-100.
Walker, A., P.A. Brown and P.R. Mathews. 1985. Persistence and phytototoxicity of napropamide residues in soil. Annals Applied Biology 106:323-333.
8
I
Appendix A. Growth reduction (%) In seasonal crops following field application of flurochloridone and terbutryn* on a clay-loam soil in spnng 1992 and 1993
Sowing time (weeks after application)
Crop Flurochloridone Terbutryn
2 5 8 11 14 17 20 23 2 5 8 11 14 17 20
Cabbage 25 20 0 Carrot 0 0 0 0 Cauliflower 25 20 0 Celery 0 0 0 0 Chard 70 55 40 20 5 0 85 70 30 0 0 Chickpea 0 0 0 0 Cowpea 30 20 15 5 0 15 0 0 Cucumber 100 90 50 20 20 15 0 20 15 0 0 Eggplant 75 60 45 25 20 15 5 0 0 0 French bean 40 20 0 0 20 0 0 Lettuce 100 100 100 75 45 20 15 10 0 0 Marrow 95 85 50 35 25 20 15 0 20 8 0 0 Melon 95 80 45 25 20 15 8 0 30 15 0 0 Okra 0 0 0 0 Onion 100 90 70 25 20 0 0 50 30 20 0 Parsley 0 0 0 0 Peanut 0 0 0 0 Pepper 100 70 30 15 0 0 15 0 0 Purslane 100 90 70 0 0 80 75 0 0 Radish 100 90 70 50 20 25 20 15 15 0 0 Tomato 35 20 0 0 8 0 0 Watermelon 90 80 40 25 15 5 0 20 5 0
* Rates of application : flurochloridone 0.5 kg, terbutryn 1.5 kg/ha - : crop not sown
Appendix B. Growth reduction (%) in seasonal crops following field application of flurochloridone and terbutryn on a clay soil in spring 1992 and 1993
Sowing time (weeks after application)
Crop Flurochloridone Terbutryn
2 5 8 11 14 17 20 23 2 5 8 11 14 17 20
Cabbage 0 a a Carrot a a a a Cauliflower 8 a a Celery a a a a Chard 70 65 40 20 a a 80 70 40 a a Chickpea a a a a Cowpea 30 20 8 a a 15 8 a Cucumber 100 90 40 20 a a a a 40 20 15 a a Eggplant 70 60 40 20 a a a a French bean 40 20 a a 15 15 a Lettuce 100 100 100 60 25 8 a a 8 a Marrow 95 80 50 20 a a a a 30 15 8 a Melon 95 90 40 20 a a a 0 40 15 a a Okra a a a a Onion 100 90 60 20 a a a 50 30 20 a Parsley a 0 0 a Peanut a 0 0 a Pepper 100 70 40 20 a a 30 8 a Purslane 100 100 100 a 90 80 a a Radish 100 100 100 40 20 8 a a 15 a a Tomato 20 15 5 a a a a Watermelon 90 80 40 20 a a a 15 8 a
* Rates of application : flurochloridone 0.75 kg, terbutryn 2.0 kg/ha -: crop not sown
Appendix C. Growth reduction (%) in seasonal crops following field application of flurochloridone and terbutryn* on a clay-loam soil in autumn 1991 and 1992
Sowing time (weeks after application)
Crop Flurochloridone Terbutryn
2 5 8 11 14 17 20 23 26 29 32 35 38 41 2 5 8 11 14 17 20 23 26
Barley Beetroot Broadbean Cabbage Carrot Cauliflower Celery Chard Chickpea Coriander Cowpea Cucumber Eggplant French bean Lettuce Marrow Melon Oat Okra Onion Parsley Pea Peanut Pepper Purslane Radish Ryegrass Spinach Tomato Vetch Watermelon Wheat
100 95 90 90 100 70 60 30 20 15 0 0
100100 80 80 0 0
100100 100 70
90 60 30 30 0 0 0 0
100100 90 90
100100 100 75 0 0
12 0
100100 100 100 100 60 50 25 100100 100 90
0 0
100100 100 90
80 20
80
70
15
70
75
90 20 80
60
70 10
80
60
0
50
70
80 15 70
50
60 0
60
50
0
-
100 -
-
30
50
-
75 15 40
-
20
30
40 0
0 40 50
0 80 60 60
0 25
40 -
80
0
30
30
35
30 20
60 30 30
15
0 15 70 60
15
25
35
15 15
30 20 15
15
15 0
30
12
20
30
0 0
30 0 0
0
15
30
0
20
25
15 0 0
0
0
15
15
15
8
12
-
-
15
15
-
-
-
5 -
-
-
70 100
0 80
0 30
100 0 0
75
100 0 0
30 50 90
0
50
15 60
0 40
0 8
40 0 0
15
90 0 0
20 20 60
0
20
0 50
15
0
40
0
45
5 10 40
12
0 40
0
30
0
0
0 0
25
0
0
0
0
0
0
0
0 0 0 0
0 0
0
0
0
0
0
0
• Rates of application : flurochloridone 05 kg, terbutryn 1 5 kg/ha - : crop not sown
Appendix D. Growth reduction (%) in seasonal crops following field application of flurochloridone and terbutryn* on a clay soil in autumn 1991 and 1992
Sowing time (weeks after application)
Crop
2 5 8 11 14
Flurochloridone
17 20 23 26 29 32 35 38 41 2 5
Terbutryn
8 11 14 17 20 23 26
Barley Beetroot Broadbean Cabbage Carrot Cauliflower Celery Chard Chickpea Coriander Cowpea Cucumber Eggplant French bean Lettuce Marrow Melon Oat Okra Onion Parsley Pea Peanut Pepper Purslane Radish Ryegrass Spinach Tomato Vetch Watermelon Wheat
100100 100 100100 70 40 30 20
100 100 100 0 0
100100 100
100100 90 0 0 0 0
100100 100
100100 100 0 0
12 0
100100 100 100 90 85 100100 100
0 0
100100 100
90 40 15
100
100
90
100
100
100 60
100
90
90 70 25 15 12 0
100 100
100 100
45 20
-
90 70
100 80
100 100 100 60 100 80
80 70
60 0 0
90 60
100 90 0
0
0 - 50 - 60
0 100 100
- 70 70
40 0
75 60
- 70 -
100 95 50 50
0
- 40 70
60
80
35 30
70 40 35
40
0 40 90 60
20
40
60
20 15
40 35 20
20
20 0
40
12
30
40
0 15
40 15 0
8
15
40
0
25
30
0
20 0 0
0
0
25
20
25
20
15
-
-
15
20
-
-
-
8 --
-
90 100
0 60
0 45
100 0 0
90
100 0 0
60 60 95
0
100
50 90
0 30
0 25
90 0 0
50
80 0 0
30 20 90
0
60
15 80
15
8
90
20
40
20 15 45
30
0 80
0
0
85
0
0
0 0
30
8
0
15
0
0
-
0
0
0 0 0 0
0 0
0
0
0
0
0
0
* Rates of application : flurochloridone 0.75 kg, terbutryn 2.0 kg/ha -: crop not sown
Appendix E. Growth reduction (%) in seasonal crops following field application of flurochloridone and terbutryn' on a
Crop
clay-loam soil in winter 1991-92 and 1992-93
---' - --- ~~_._-
Sowing time (weeks after application)
--------
Flurochloridone
2 5 8 11 14 17 20 23 26 29 32 2 5
Terbutryn
8 11 14 17 20
Beetroot 50 40 Carrot 0 0 Celery Chard 40 30 Chickpea 0 0 Coriander 0 0 Cowpea 30 20 Cucumber Eggplant -
French bean 30 20 Lettuce -
Marrow Melon Okra Onion 100 100 Parsley 0 0 Pea 0 0 Peanut Pepper Purslane Radish 100 100 Spinach 100 70 Tomato Watermelon
30
35
20 30
100 5
100 30 40
0 100
90
70 80
0 20
20
0 15
5 30 50 0
90 20 30
80
0 50 70 70 70
0 30
0
15
0 20 30
80 15 30
60
25 50 60 40
25
8
15 15
40 5
15
30
15 0
30 20
15
0
0 10
0 0
15
10
0 0
25 0
10
0
0
0
20
0
15 10 5
60 0
60 0 0 0
0
65 0 0
30 50
45 0
60 0 0 0
0
50 0 0
0 45
40
60
10 0
0 10 10 0
40
8
0 25
0 0
25
0 35
8
5 0
30
0 0 0
0
0
15
0
0
0
8 0
* Rates of application : flurochloridone 0.5 kg, terbutryn 1.5 kg/ha -' crop not sown
Appendix F. Growth reduction (%) in seasonal crops following field application of flurochloridone and terbutryn* on a clay soil in winter 1991-92 and 1992-93.
Sowing time (weeks after application)
Crop
2 5 8
Flurochloridone
11 14 17 20 23 26 29 32 2 5
Terbutryn
8 11 14 17 20
Beetroot 30 30 Carrot a a Celery Chard 30 25 Chickpea a a Coriander a a Cowpea 30 20 Cucumber Eggplant -
French bean 30 20 Lettuce -
Marrow Melon Okra Onion 100 100 Parsley a a Pea a a Peanut Pepper -
Purslane Radish 100 100 Spinach 100 60 Tomato Watermelon
15
20
15 70
100 a
100 70 60 a
90
100
80 60 20 50
0
a 20
a 50 70
90 60 30
80
a 80 90 80 70
0 40
15
40 40
80 50 45
65
50 70 60 40
30
5
15 15
50 25 20
35
25 20 30 15
a
a
a a
a a a
15
a a
20 a
a
12 5 a
90 a
90 a a a
a
70 0 a
25 70
80 a
90 a a a
a
60 a a
a 60
60
85
20 a
a 15 20 a
60
a
40 a
15
35
a 60
10
10 a
35
a
a
a
a
a
25
a
a
a
15 a
* Rates of application : flurochloridone 0.75 kg, terbutryn 2.0 kg/ha - . crop not sown
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