The effects on soil fauna of insecticides tested against wireworms (Agriotes spp.) in wheat

The organophosphorus insecticides Bayer 38156 (O-ethyl S-p-tolyl ethyl phosphonodithioate), trichloronate, Stauffer N 2790 (O-ethyl S-phenyl ethyl phosphonodithioate), thionazin and fenitrothion were compared with aldrin, dieldrin and γ-BHC for their effects on soil fauna, particularly wire-worms, and on crop yields in 1964 and 1965. At 1·5 lb active ingredient/acre, none of the organophosphates had as great an effect on wireworms as an aldrin spray at 2·25 lb a.i./acre or a dieldrin seed dressing at 2·25 lb a.i./acre. Some treatments significantly increased and some significantly decreased numbers of mites and Collembola. Except for Allolobophora chlorotica in plots treated with Bayer 38156, earthworm numbers were greater in plots sprayed with Bayer 38156 or aldrin, or sown with dieldrin-dressed seeds, than in untreated plots. In May 1964, one month after sowing, untreated plots had significantly fewer plants than plots sprayed with aldrin, trichloronate or Bayer 38156, or sown with γ-BHC or dieldrin-dressed seeds, but yields from untreated plots at harvest were high for such a large wireworm population and did not differ significantly from yields of treated plots in either year. The persistence of thionazin and Bayer 38156 in treated plots was measured by a bioassay using Collembola. Bayer 38156 was detected in plots 1 month after spraying but not after 6 months. Thionazin left detectable residues 1 month after spraying in the two acid plots but not in the two alkaline plots. More frequent samples taken from thionazin-treated plots in 1965 showed a similar pattern of persistence, and laboratory tests, using soil mixed with various amounts of powdered calcium carbonate, confirmed that thionazin persisted longer in more acid soils.     

Desulfuration of Dialkyl Thiophosphoric Acids by a Pseudomonad

A strain of Pseudomonas acidovorans used the organophosphorus pesticide breakdown products, ionic O,O-diethyl phosphorothioate and ionic O,O-diethyl phosphorodithioate, as sulfur sources. The growth yields from the thiophosphates and sulfate were 3.6 to 4.1 kg of protein per mol of sulfur. Elemental sulfur and sulfide also served as sulfur sources but gave lower growth yields.     

The effects of insecticides on the biting behaviour of wireworms (Agriotes spp.)

Filter-paper discs soaked in nutrient were used to study how insecticides affect the biting behaviour of wireworms. When wireworms were buried in soils treated with 3.7 ppm aldrin, Bayer (38156¹), N 2790 or thionazin they stopped biting several days or weeks before they died. Three out of ten wireworms slowly recovered their biting ability after being buried for 4 days in soil containing 3.7 ppm -BHC. Biting behaviour was little affected when wireworms were confined to soils containing insecticides known to be not very toxic to wireworms.Nutrient discs treated with thionazin or -BHC were bitten less often than discs containing nutrient alone. Those treated with nutrient and aldrin were bitten almost as often as nutrient discs but the wireworms later stopped biting and died.

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Die wirkungen von insektiziden auf das fressverhalten von drahtwürmern (Agriotes spp.)

Zusammenfassung Um den Einfluß von Insektiziden auf das Freßverhalten von Drahtwürmern zu prüfen, wurden auf zweierlei Weise Filtrierpapierscheiben benutzt, die mit dem Nährstoff vollgesogen waren: a) durch Zumischen der Insektizide in den Boden, so daß die Drahtwürmer ihrer Kontaktwirkung nicht entgehen konnten (Bodenbehandlung), b) durch Aufbringen der Insektizide auf die Nährscheiben selbst (Scheibenbehandlung).Drahtwürmer hörten einige Tage oder Wochen vor ihrem Tode auf zu fressen, wenn sie in Böden vergraben waren, die mit 3,7 ppm Aldrin, Bayer 38156 (O-ethyl-S-p-totyl-ethyl phosphonodithioate), N 2790 (O-ethyl-S-phenyl-ethyl-phosphonodithioate) oder Thionazin behandel waren. 3 von 10 Drahtwürmern gewannen ihre Freßfähigkeit langsam wieder, nachdem sie für 4 Tage in Boden vergraben gewesen waren, der mit 3,7 ppm -BHC behandelt war. Die Freßfähigkeit wurde wenig beeinflußt, wenn die Drahtwürmer in Boden eingeschlossen wurden, der Bromophos, Dichlofenthion, Ethion oder RD 14838 (3-isopropylphenyl N-acetyl N-methylcarbamate) enthielt, von denen keines sehr giftig für Drahtwürmer ist.Wenn die Insektizide den Nahrungsscheiben zugefügt wurden, wurden die mit Thionazin oder -BHC behandelten Scheiben weniger oft befressen als diejenigen, die nur die Nahrung enthielten. Mit Nahrungsstoffen und Aldrin behandelte Scheiben wurden bereitwillig befressen, aber die Drahtwürmer hörten später zu fressen auf und starben.

     

Control of potato cyst-nematodes, Heterodera rostochiensis and H. pallida, in sandy, peaty and silt loam soils by oximecarbamate and organophosphate nematicides

Small amounts (5.6 or n-2 kg a.i./ha) of aldicarb or oxamyl, incorporated in the soil before potatoes were planted in spring, controlled potato cyst-nematodes (Heterodera rostochiensis and H. pallida) on susceptible cultivars equally well in sandy, peaty and silt loam soils. In soils treated with either nematicide, nematode numbers increased little or decreased; in untreated soils nematode numbers increased greatly. In contrast organophosphate nematicides, similarly applied, fenamiphos (proposed BSI common name for O-ethyl-O-(3-methyl-4-methylthiophenyI)-isopropylamido-phosphate), ethoprophos (proposed BSI common name for (O-ethyl S, 5-dipropyl phos-phorodithioate), CGA 12223 (O, O-diethyl O-[i-isopropyl-5-chloro-i,2,4-triazoIyl-(3)] phosphorothioate) and Dowco 275 (O, O-diethyl O-(6-fluoro-2 pyridyl) phosphorothioate), were ineffective at one or more of the experimental sites. Potato yields were greatly increased by oximecarbamate or organophosphate nematicides only in soils heavily infested with the nematodes.     

THE PHYTOTOXIC EFFECTS OF D.D.T., B.H.C., PARATHION AND TOXAPHENE ON TOBACCO

No phytotoxic effect was seen following a pre-sowing spray of tobacco seed-beds with 27 lb./acre technical D.D.T. or after an application of the same material at 75.6 lb./acre to 3-week-old tobacco seedlings.
A pre-sowing application of parathion (diethyl para nitrophenyl thiophosphate) (2 % dust) at 1–8 lb. parathion per acre had no harmful effect. Used on 3-week-old tobacco seedlings at the excessive rate of 22.7 lb./acre it caused serious stunting and many deaths.
Toxaphene (chlorinated camphene: empirical formula C₁₀H₁₀Cl₈), applied as a 25 % wettable powder in a pre-sowing spray at 6-4 lb. toxaphene per acre, did not injure tobacco seedlings.
No residual phytotoxic effects appeared in beds re-sown 4 months after being treated with parathion or toxaphene at the pre-sowing doses given above.
Benzene hexachloride, applied before sowing at doses above 1.6 lb. technical B.H.C. per acre, suppressed root development in newly germinated tobacco seedlings. B.H.C. dusts used on n-day-old seedlings at 2–25 lb. technical B.H.C. per acre caused temporary distortion and stunting. Up to 11 lb./acre these symptoms were transitory: at 37.5 lb./acre many plants were killed and the remainder severely stunted. Resistance to these phytotoxic effects increased with age of plant, but 3-week-old tobacco seedlings showed considerable mortality after the application of 75.6 lb./acre of technical B.H.C.
Beds re-sown 4 months after the application of 6-4 and 12.8 lb. respectively of technical B.H.C. per acre showed no phytotoxic effect, but, as tobacco seed is sown on the soil surface, the effect of the B.H.C. may have been merely masked, and it is not safe to assume that there was no residual effect. The actual persistence of B.H.C. in the soil was not determined.
The possible mechanism of action of the B.H.C. effect is discussed.     

The action of some systemic aphicides on the eggs of Anthocoris nemorum (L.) and A. confusus Reut

Comparisons were made of the systemic action of phorate, menazon and dimethoate on Aphis fabae Scop, and on the eggs of the aphidophagous Anthocoridae Anthocoris nemorum (L.) and A. confusus Reut., which are laid within plant tissue. Against 4th-instar apterous A. fabae the order of toxicity of the insecticides taken up by roots of the field bean Vicia faba L. was: menazon > dimethoate > phorate. Phorate concentrations needed to kill all A. fabae (10–15 ppm of wet weight of plant) killed most A. nemorum eggs but did not harm A. confusus eggs. Few A. nemorum eggs were killed by 15 ppm of menazon or 5 ppm of dimethoate. In the field a commercial in-row treatment of 1·5 lb/acre of phorate applied as granules in the seed drill of field beans sown in late April killed 86 % of eggs laid in June by overwintered A. nemorum and 30% of those laid in late July by second-generation females. Plants initially treated with 6 lb of in-row phorate per acre killed 74% of A. nemorum eggs in late July but did not harm A. confusus eggs. A. nemorum eggs laid in early June were unharmed by 1·5 lb/acre of in-row menazon. Of the A. nemorum eggs, 92–96% were inserted into the stipules and leaf margins of young bean plants, i.e. in the region (peripheral and distal part of the leaf) where most ³²P from labelled phorate accumulates after root uptake. The egg-laying sites of A. nemorum in potatoes and brussels sprouts (edges of the leaves) and in oats (the leaf tips) are also where most of the ³²P accumulates. In contrast, 98% of A. confusus eggs were laid in the stems, petioles and leaf midribs of field beans, where there was generally much less ³²P from labelled phorate.     

Control of potato cyst-nematode, Globodera rostochiensis, and root-knot nematode, Meloidogyne incognita, by organosphosphorus, carbamate, benzimidazole and other compounds

Control of potato cyst-nematode, Globodera rostochiensis, was examined on potato or tomato in pots and on potato in field plots by various chemicals incorporated into the soil at planting. The most effective nematicides were organophosphorus compounds, generally of the type O,O-diethyl O-phosphoro-thioates or O,O-diethyl phosphorodithioates, carbamates and benzimidazoles. In organic soils, the more lipophilic compounds were less effective, presumably because of sorption onto soil organic matter. Foliar sprays of chemicals, including oxamyl which is known to be translocated to roots, gave poor control of G. rostochiensis. The root-knot nematode, Meloidogyne incognita, on tomato, widely used in screening for nematicidal activity, was controlled by aldicarb or phoxim incorporated into the soil at planting, but not by benomyl or thiabendazole, in contrast to the moderate effectiveness of these latter two chemicals against G. rostochiensis.     

Influence of Organic Pesticides on Nematode Populations and Seed Production of Centipede Grass

Applications of ethyl 4-(methylthio)-m-tolyl isopropylphosphoramidate, O,O-diethyl O-((p-(methylsulfinyl)phenyl) phosphorothioate, and O,O-diethyl S-[2-(ethylthio)ethyll phosphorotbioate effectively controlled Trichodorus christiei on centipede grass. Populations of Pratylenchus spp. and Xiphinema americanum were significantly reduced with a mixture of methanesulfonic acid, 2,4-dichlorophenyl ester and 1,2-dibromo-3-chloropropane. Ethyl 4-(methylthio)-m-tolyl isopropylphosphoramidate and O,O-diethyl O-((p-(methylsulfinyl)phenyl phosphorothioate significantly suppressed populations of Pratylenchus spp., and the latter reduced populations of X. arnericanum. Ethyl 4-(methylthio)-m-tolyl isopropylphosphoramidate and O,O-diethyl O-((p-methylsulfinyl) phenyl) phosphorothioate significantly reduced populations of Criconemoides ornatus. Increased seed production was correlated with nematode control.     

Improved Deproteciton Procedure for DPSE Protected Phosphorothioates

Abstract

Deprotection of 2-(diphenylmethylsilyl)ethyl (DPSE) protected (O,O,O)-and (O,O,S)-trialkyl phosphorothioates with tetrabutylammonium fluoride affords the corresponding phosphorothioate. Formation of phosphodiester linkages is not observed.     

Wireworms and the sugar-beet crop; field trials and observations

Observations on wireworms in the sugar-beet crop during 1937–40 indicated the importance of alternative food, such as buried turf, weeds, excess seedlings and interdrilled wheat in determining the degree of injury to the crop.
In 1938, out of thirty-six recorded fields growing sugar beet after ploughed-up grass only one suffered severe wireworm damage. Six of these fields were selected for resowing with sugar beet in 1939, and all suffered moderate or severe attacks. Several other fields in their first year from grass showed only slight damage. These observations were supported by an analysis of the Norfolk War Agricultural Committee crop records for 1940.
Seven trials were carried out in 1939 to determine the effect of increasing the seed rate from normal (about 14–16 lb./acre) to 17–25 lb., and of interdrilling with wheat. In three trials, increasing the seed rate gave significantly higher plant populations before singling. It gave significant increases after singling in one out of two trials. However, in the one trial harvested the increase in 'washed beet' was only 7.6% and 'total sugar' 15%. Interdrilling with wheat at 40–70 lb./acre gave significant increases in the plant population before singling in three out of five trials, and after singling in three out of four trials. Increased plant populations both before and after singling were obtained in two other trials with alternating treatments. Increased seed rate and interdrilled wheat together gave greatly improved plant populations before singling in each of two trials and after singling in the one trial where such an observation was possible.     

Control of pea cyst-nematode, Heterodera goettingiana, by small amounts of aldicarb, Du Pont 1410, Ciba-Geigy 10576 or Dowco 275 applied to the soil at planting time

Aldicarb, or Du Pont 1410 (S-methyl-I-(dimethylcarbamoyl)-N-[(methyl-carbamoyl)oxy]thioformimidate), at 2.8–22.4 kg a.i./ha incorporated in the seed-bed before sowing greatly increased the yield of peas in a clay loam and two sandy clay soils infested with pea cyst-nematode, Heterodera goettingiana, and lessened or prevented increase in the number of nematodes. CibaGeigy 10576 (an organophosphorus compound) at 5.6–22.4 kg a.i./ha was similarly effective in a sandy clay soil. Dowco 275 (O, O-diethylO-(6-fluoro-2 pyridyl) phosphorothioate) at 5.6 or 11.2 kg a.i./ha also controlled the nematode well in the clay loam and in a sandy clay soil but although it greatly increased the yield of peas in the clay loam, it did not increase yield in the sandy clay.     

The Systematic Separation and Identification of Pesticides in the First Division

The systematic identification and determination of many kinds of pesticides were tried by a combination of column, thin-layer and gas chromatography. Pesticides in the first division,¹⁾ e.g., aldrin, DMC ethylene, CPAS, DDDS, o,p′-DDT, p,p′-DDT, heptachlor, quintozene, Telodrin and tetrasul, were separated from pesticides in the second division,¹⁾ e.g., α-BHC, β-BHC, γ-BHC, trifluralin, CPA, CNP, nitrofen, endrin, dieldrin, dicofol, etc. by column chromatography. Further, pesticides in the first division were separated from each other and determined approximately by thin-layer and gas chromatography.

The recoveries of these pesticides, except for aldrin and CPAS, were about 100%. The recoveries of aldrin and CPAS were about 70 %, due to decomposition during the procedures, or to adsorption on the adsorbent during the column chromatography. It was presumed from GC-MS data that CPAS was decomposed to DDDS, tetrasul and other compounds during the procedures.     

Absorption,Translocation and Metabolism of O,O-Diisopropyl S-Benzyl Phosphorothiolate (Kitazin P®) in Rice Plant

Behavior and metabolism of O,O-diisopropyl S-benzyl phosphorothiolate (Kitazin P©) in rice plant were examined using ³²P, ³⁵S-double labeled compound. Uptake of Kitazin P by the plant was different with the growth stages of the plant, and the rate of uptake was rapid in early growth stage. Kitazin P penetrated into plant tissues was gradually hydrolyzed to produce O,O-diisopropyl hydrogen phosphorothioate which was converted to diisopropyl hydrogen phosphate, isopropyl dihydrogen phosphate and phosphoric acid. As toluene soluble metabolites, eight spots were detected by thin-layer chromatography, but their percentages in toluene soluble fraction were extremely low as compared with that of Kitazin P. Only two metabolites, dibenzyl disulfide and O,O-diisopropyl O-benzyl phosphorothionate were identified by a gas-liquid chromatography with a flame thermionic detector or a flame photometric detector. Diisopropyl hydrogen phosphorothioate was detected as a persistent metabolite even in rice grains.     

Effects of skin spot (Oospora pustulans) on potatoes

King Edward and Majestic seed potatoes selected as ‘clean’ (macroscopically symptomless), moderate and severe according to the extent of skin spot were planted in field experiments at Rothamsted between 1964 and 1968. Usually crops from ‘clean’ and moderately infected seed did not differ detectably in growth or yield. Plants from severely infected seed tubers emerged more slowly, had fewer stems and yielded less (King Edward 20 %, Majestic 13 %). Seed infection also affected tuber size distribution; severely infected seed of King Edward yielded almost 4 tons/acre less of 1 1/4-2 1/4 in tubers and Majestic, 1 ton/acre less of these and 2 tons/acre less 2 1/4-3 1/4 in tubers. However, the total yield from diseased seed stocks was only slightly less (King Edward, o-6 ton/acre and Majestic o-8 ton/acre) than the yields from the ‘clean’ tubers selected from them. Seed severely infected by Oospora pustulans often increased infection of the progeny tubers, and usually decreased their infection by Rhizoctonia solani and sometimes by Helmintho-sporium solani. Another series of experiments compared King Edward seed tubers classified according to the number of live eyes showing in March. Seed with one, two, three and more live eyes yielded equally. About half the tubers without live eyes in March eventually produced plants, but late, with few stems and giving only half the yield of seed with three or more live eyes. Surprisingly, the progeny tubers from seed without live eyes were least infected by O. pustulans, R. solani and H. solani. Progenies of King Edward and Majestic seed from a common source grown on seven widely separated farms were infected more in 1963 than in 1964, but in each year infection differed widely between farms. Often where O. pustulans was common, R. solani was scarce and vice versa. By contrast, when King Edward stocks very differently infected by O. pustulans were grown at Rothamsted their progenies were almost uniformly infected by O. pustulans and R. solani.     

Isolation of the Bromo Analogues of Pyrrolnitrin from Pseudomonas pyrrolnitrica

The metabolism of an organophosphorous fungicide, Kitazin P® (S-benzyl O, O-diisopropyl phosphorothioate) by mycelia of Pyricularia oryzae, the rice blast fungus, was studied by using ³²P- and ³⁵S-doubled-labeled, ³⁵S-labeled and non-labeled compounds.

The mycelia incorporated the fungicide from the medium, metabolized most of it to water-soluble metabolites and released them into the medium. The main metabolite from Kitazin P was identefied as O, O-diisopropyl hydrogen phosphorothioate by ion-exchange chromatographic separation of double-labeled metabolites. S-Benzyl O-isopropyl hydrogen phosphorothioate, diisopropyl hydrogen phosphate and/or isopropyl dihydrogen phosphate were suspected to be minor metabolites. From the toluene-soluble fraction several metabolites were separated by thin-layer chromatography. The most eminent metabolite among them was found to be the m-hydroxy derivative of Kitazin P by thin-layer chromatographic identification of the labeled metabolite and gas-liquid chromatographic identification of the metabolite and its methylated and acetylated products with respective authentic samples. The o- and p-hydroxy derivatives were not found in the metabolites.

No significant difference in the rate and extent of metabolism was found between susceptible and resistant clones against the fungicide, when its concentration was below the growth-inhibitory concentration to the both clones.     

The effect of small doses of nematicides on migratory root-parasitic nematodes and on the growth of sugar beet and barley in sandy soils

Smaller amounts of D–D (6–12 gal/acre) (68–135 1/ha) or ethylene dibromide (9 gal/acre) (100 1/ha) than are customarily used to disinfest field soils killed many root-parasitic nematodes (Trichodorus, Pratylenchus, Tylenchorhynchus and Longidorus attenuatus) when injected 6–8 in (15–20 cm) deep during early autumn in rows 10 in (25 cm) apart in well-drained sandy soils. They also increased the yield of sugar beet grown in fields infested with Trichodorus or Longidorus attenuatus, without affecting sugar percentage or juice purity of the roots, and in some places increased the yield of barley grown after the beet. D–D was much less effective when injected 8–12 in deep during late autumn or winter. Increasing nitrogen dressings to the seedbed from 1·5 to 3 cwt/acre (188 to 376 kg/ha) increased sugar beet yield in one field, decreased it in another and decreased juice purity in both. In two other experiments extra nitrogen did not affect sugar beet yield. Even smaller amounts of the nematicides ‘placed’ in the rows, before or after sowing sugar beet in them, killed many of the nematodes and also increased sugar yield. Phytotoxic nematicides can be placed in the rows during autumn, winter or spring but placement is simpler during spring, when the treated rows are indicated by the position of the marks of the tractor wheels left when the nematicide was applied. When applied during autumn or winter, the rows need to be indicated by drilling wheat or grass.     

Metabolic Fate of O-Ethyl S,S-Diphenyl Phosphorodithiolate (Hinosan®) in Rice Plant

Metabolism and residual fate of O-ethyl S,S-diphenyl phosphorodithiolate (Hinosan®) applied on rice plant was examined by using ³⁵S-labeled or ³²P-labeled compound. Ion exchange chromatography, thin-layer chromatography and gas-liquid chromatography with flame thermionic detector or flame photometric detector were applied for identification of water soluble and toluene soluble metabolites of Hinosan. Degradation of Hinosan at the initial stage of metabolism was mainly the cleavage of P-S linkage, and a large portion of phenyl dihydrogen phosphorothiolate and a minor portion of O-ethyl S-phenyl hydrogen phosphorothiolate were found as water soluble metabolites. Phenylthio radical released on the production of the above mentioned metabolites was recovered as diphenyl disulfide, which was finally converted to sulfuric acid through benzenesulfonic acid. Triphenyl phosphorotrithiolate and O,O-diethyl S-phenyl phosphorothiolate were produced by transesterification between molecules of Hinosan at the initial stage of metabolism. Examination of metabolites in rice grains showed that sulfur and phosphorus atoms in Hinosan were incorporated into neutral or cationic substances probably after several steps of chemical transformation.     

Experiments on integration of chemical and biological control of aphids on brussels sprouts

Two field experiments were made to test whether natural enemies would take over control of brussels sprouts aphids at the time when protection from a selectively acting, soil-applied systemic insecticide, menazon, began to fail. The natural enemies, notably Syrphidae, proved ineffective against Brevicoryne brassicae L. despite advantages given by the insecticide and by close planting, which greatly increased the ratio of numbers of syrphid eggs and larvae to aphids. Thus, development of the aphid population was little altered when infested plants were kept free of most natural enemies by hand removal. I lb/acre (1–12 kg/ha) of menazon applied as spot treatments to the soil at planting-out time decreased the number of overwintering parasite mummies by 70 % but such ‘mortality’ was compensated for by decreased mortality from hyperparasites and other causes, so the numbers of adults of the primary parasite Diaretiella rapae (McIntosh) which emerged in the spring were similar to those from untreated plots. Soil cultivation in winter drastically decreased the numbers of emerging adult primary parasites, hyperparasites and syrphids. The menazon treatment designed for integrated control (1 lb/acre) seemed too unpredictable in action, e.g. less effective in dry than in damp conditions, to provide the hoped-for chemical control needed until natural enemies became abundant. Menazon at 4 lb/acre (4·48 kg/ha) protected the crop throughout the growing season and bioassays showed that menazon or its toxic derivatives continued to occur in leaves during cool periods in winter and also in the following April-May nearly 1 year after application. The same amount of menazon per unit area of crop was less effective on 1 ft 6 in (45·6 cm) spaced than on 3 ft (91·2 cm) spaced brussels sprouts plants.     

Effect of different soil types,pH and phosphorus levels on the wheat seedling and the incidence ofPythium graminicolum

Summary In the present study, the effect of different types of soil, pH and phosphorus levels on root, shoot development and browning extent on shoot of wheat seedlings growth in soil inoculated withPythium graminicolum; was studied. Out of the four soil types the development of root and shoot was better in Domatta soil where as the disease development was more in black clay soil. The pH values below 5.5 and above 8.0 are favourable for the root and shoot development whereas these values are unfavourable for the development of the Pythium and consequently for infection by it. The percentage of browning of the collar region was more in soils near neutral (pH 6.5–7.1) and it was less in acidic (pH 5.0) or alkaline (pH 8.6) soils. The development of wheat roots and shoot in soil with 30 lb/acre phosphorus was good as compared to that in soil with P₀, P_15,45 and P₆₀ lb/acre in inoculated soil. The percentage of extent of browning on collar region was less at 15 lb and 30 lb/acre P, due to less development of the disease.     

Metabolism of O,O-Dipropyl S-[2-(2′-Methyl-1′-piperidinyl)-2-oxo-ethyl] Phosphorodithioate (C 19 490) in Paddy Rice

The fate of O,O-dipropyl S-[2-(2′-methyl-1′-piperidinyl)-2-oxo-ethyl] phosphorodithioate (C 19 490, piperophos) was followed in greenhouse-grown rice after application of 1.6 kg/ha ¹⁴C-labeled C 19 490 into the paddy water. At maturity the shoots contained 2.5 ppm and the hulled grains 0.16 ppm ¹⁴C-C 19 490 equivalents. Small amounts of unchanged C 19 490 were found in the shoots but none in the grains.

The main metabolites found were:- 2-(2′-methyl-1′-piperidiny])-2-oxo-ethane sulfonic acid, 2-(2?-methyl-1?-piperidinyl)-2-oxo-ethanoic acid and a fraction of polar unknown substances. O,O-Dipropyl S-[2-(2?-methyl-1′ -piperidinyl)-2-oxo-ethyl] phosphorothioate, 2-(2?-methyl-1?-piperidinyl)- 1-methyl-sulfinyl-2-oxo-ethane, 2-(2?-methyl-1?-piperidinyl)-1-methyl-sulfonyl-2-oxo- ethane, 2-methyl-piperidine and CO₂ were found in smaller amounts.