IL43731A - Nematode control with inorganic azides and a nematicide - Google Patents

Description

4S731/2 NEMATODE CONTROL WITH INORGANIC AZIDBS AND A NEMATOBIDE NEMATODE CONTROL WITH INORGANIC AZIDES AND A NEMATOCIDE Williaa-&,-Wilner— ABSTRACT OF THE DISCLOSURE A material which will enhance the hatching of nematode eggs is applied to soil containing nematode eggs. A nematocide is also applied to the soil in order to control the nematodes hatched from the nematode eggs. The material which will enhance the hatching of nematode eggs is preferably an azide such as sodium azide or potassium azide or mixtures thereof.

DISCLOSURE Nematodes have, in comparatively recent times, become recognized as a principal scourge to effective agriculture in many areas.

These pests are often difficult to control due to both the resistance of nematodes and to the extraordinary hardiness of nematode eggs.

Several nematocides have been developed which serve to control the nematodes but which do not effectively destroy the eggs. When applied at such rates the eggs survive concentrations of nematocide which would kill the emerging nematodes and hatch after the nematocide has dissipated below the effective ne atocidal concentration in the soil. Often amounts of nematocide far in excess of a mere nematocidal amount are applied in an effort to prolong activity. Unfortunately, these large amounts often cause phytotoxicity.

Many azides such as sodium azide or potassium azide are known to possess nematocidal properties when applied at high rates. These applications are often only partially satisfactory because, like other nematocides, they control the nematodes without effectively controlling the eggs.

The present invention takes advantage of the newly-discovered property that relatively low concentrations of azide enhance the hatching of nematode eggs. While not desiring to be bound by any theory, it is believed that azide activity can be summarized as follows: Very low concentrations of azide in the soil provide little or no activity with respect to nematodes. Somewhat higher concentrations enhance the hatching of nematode eggs without significantly controlling the emerging nematodes or older, more mature nematodes. Higher concentrations effectively kill the nematodes and may, in* some instances, also kill a few eggs. The numbers of eggs killed, if any, are inconsequential. At these concentrations, even some delay in the hatching of nematode eggs has been observed. Massive concentrations of azide appear to be ovi-cidal with respect to nematode eggs, but these require rates of application which are not feasible from a practical or commercial point of view. Accordingly, the present invention provides a method for control- inorganic ling nematodes by establishing in soil containing nematode eggs an/azide in an amount effective to enhance the hatching of the nematode eggs and establishing in the same soil a nematocide in an amount sufficient to control nematodes hatched from the nematode eggs. Usually the nematocide is applied in a nematocidal amount.

The nematocide may be applied before, concurrently with, or after application of the azide. If the nematocide is applied before, the time interval until the azide is applied should not be' so great that the A" nematocidal activity of the nematocide has declined to ineffectual levels.

There is much greater latitude in the time interval between applications if the nematocide is applied after the azide because the nematodes resulting from the accelerated hatching prompted by the azide are susceptible to the effects of the nematocide for the remainder of their lifetimes. It is preferred, however, that the nematocide be applied before the hatched nematodes have produced a new colony of eggs. Usually the nematocide is applied within about 30 days after the azide has been applied.

Concurrent application of the azide and the nematocide is the preferred embodiment. This is particularly the case when both azide and nematocide are in the form of granules.

Because azide is itself a 'nematocide at higher rates than those which ordinarily enhance the hatching of nematode eggs, it may be applied for this purpose after a first, lesser application of azide has had an opportunity to enhance the egg hatch. A single application of nemato-cidal amouncs of azide is not effective because nematocidal amounts do not ordinarily serve to enhance the egg hatch and once the concentration has declined to the lower values which do enhance egg hatch, the nematocidal effectiveness has been, lost.

It is permissible for high rates of azide, even nematocidal amounts or greater, to be applied to the soil and, after the concentration has diminished to rates effective to enhance egg hatch, to apply a nematocide, which may or may not be an azide, in order to kill the hatched nematodes.

In a preferred embodiment, nematodes are controlled by applying to soil containing nematode eggs an azide in an amount effective to en-hance the hatching of the nematode eggs and applying to the same soil a nematodde in an amount effective to control nematodes hatched from the nematode eggs.

In practicing both the broad Invention and the narrower preferred embodiments* many different forms of azlde may be used. The azide employed is ordinarily alkali metal azide, alkaline earth metal azlde, ammonium azide, or mixtures thereof.

While lithium azide, sodium azlde, potassium azide, rubidium azide, and cesium azide, or mixtures thereof, may be used in the practice of this invention, sodium azide, potassium azide, and mixtures thereof are preferred. Particularly preferred is potassium azide or sodium azide.

Ammonium azide is advantageously used where the presence of alkali metal ions or alkaline earth metal ions is not desired.

Beryllium azide, magnesium azide, calcium azide, strontium azide and calcium azide. Ammonium azide may also be mixed with any of the alkali metal and/or alkaline earth metal azides.

While it is preferred that the azide be present in the soil in amounts which will enhance the hatching of substantially all of the viable nematode eggs present, significant results can be achieved with those amounts of azide which will enhance the hatch of only a substantial portion of the eggs. The unhatched eggs are often so few 'in numbers that crop damage resulting from their later hatching is small. Amounts of the ' ■ : ■ · . · ■ - ':;· *> azlde or mixtures of azldes established in soil containing nematode eggs,? ace usually ia the range af frem about 0,9 pounds per acre to aba»¾ $(5 pounds per acre. Generally the rates are in the range of from about 1 pound per acre to about 20 pounds per acre. Rates in the range of from about 1 pound per acre to about 10 pounds per acre are often used.

The azlde is often conveniently applied as an aqueous solution.

Sprays, drenches, irrigations, and injections are conveniently used.

These azldes may also be conveniently applied as an ammonia solution. While anhydrous ammonia may be used, the solubility of most of (As used herein anhydrous ammonia refers to liquid ammonia substantially free of water.) the azldes may be increased by the. addition of water.?/Ammonia solutions of azlde may be applied similarly to»aqueous solutions of azide. Sprays, drenches, irrigations, and injections are within contemplation.

Azide may also be applied to the soil in the form of crystals, granules, or finely-comminuted dry dust. When it is desired to apply a dust, the azide may be ground to a very fine powder size, usually minus 100 mesh (U. S. Sieve Series). It is usually desirable to dilute the azide with inert solid diluent such as silica, clay, talc, bentonite, dlatomaceous earth, woodflour, etc. Good distribution of the azide. is usually facilitated by diluting the azide with up to in excess of 99 per cent inert dust. Sometimes formulations containing about 5 to about 75, rarely in excess of 80, per cent of azide are useful.

Another effective method of diluting the azide for solid application is to supply the azide as an absorbed ingredient or coating on inert carrier particles such as attapulgite clay, montmorillonite, corncob, sawdust, bentonite, etc. The azide may also be absorbed or coated on other pesticides, pesticide-containing granules, or fertilizers* Alkali metal azide, alkaline earth metal azide, ammonium azide, or mixtures thereof is usually present In these granular formulations In amounts of less than about 85 per cent by weight basis of the granules* including all absorbed constituents, although greater proportions are possible and within contemplation. The alkali metal azide, alkaline earth metal azide, and/or ammonium azide content of these granular products typically is in the range of from about 1 to about 85 per cent and most often in the range of from about 2 to about 50 per cent.

When the azide is applied to the soil in crystal, granular, or other solid forms, it is sometimes allowed to lie on the soil exposed to normal weather conditions. It is more often watered into the soil. It is frequently harrowed or plowed into the earth. In general, azide may, * because of its very flexible properties, be applied to the soil by any known technique commonly used in the application of presently-available fertilizers and/or pesticides.

The soil is preferably cultivated prior to application of the azide. This loosens the soil and renders it mote receptive to the azide. Following application, the azide is also preferably incorporated into the soil by, for example, harrowing, discing, plowing, rototilling, or hilling. While both cultivation and incorporation are preferably used conjointly, either of these operations may be used alone, or neither may be used at all. The effectiveness of the azide treatment is enhanced by covering the treated soil with sheeting which is substantially vapor impervious, ί usually until the azide has decomposed. Polyethylene sheeting is well suited for this purpose although other materials such as polypropylene, polyvinyl chloride, polyvinylidene chloride, poly(ethylene terephthalate) , and waterproofed paper are suitable. This technique is particularly suitable for seed beds and areas where high value crops are grown. .·'· · ' 'i v ■ ' ■ .

The equipment heretofore used to apply aqueous solutions of ammonia to the soil may be used to apply azide solutions to the soil. Thus, solutions may be applied using a tool bar applicator which draws one or more knives which have at least one injection port through the soil. Another method which may be used to advantage is a plow-down application. Still another method is direct injection into the soil. Spraying is also useful. Where irrigation is used in the preparation or treatment of a field, the azide may be added to the water stream prior to its entering the field. The azide may be dissolved in water to form a solution which is then metered into the stream. Similarly, aqueous solutions or anhydrous ammonia solutions may be injected into the stream. It is not necessary to form a solution "of the azide prior to adding the azide to the stream, but this procedure is preferred since solutions are generally more accurately metered than are solids.

Solid forms of the azide may be applied using broadcasters, spreaders, granule-applying chisels, and similar equipment.

Fields containing nematodes may be treated with azide in various ways. Over-all. treatment may be used wherein azide is applied over the entire field. Row treatment is also suitable and is less expensive than over-all treatment. The azide may be applied in furrows, sometimes combined with fertilizer. When the azide is applied as a chisel or ftir-row treatment at planting, it may advantageously be placed below, to one side of, or both below and to the side of the seed or seedling being planted. Strip treatment may be used where wide-row crops such as orchards, vineyards, groves, and nursery liner plantings are to be planted. The treated strip is usually 6 to 12 feet wide and centered on the future transplanting site. This method is cheaper than over-all treatment due to the savings in azide. However, there is the disadvantage that nematodes and/or nematode eggs are likely to be Introduced to the treated area soon after planting by movement of the soil from the adjacent untreated areas· Spot treatment may be used where nematode infestation or damage is restricted to well-defined spots.

The nematoclde may be any compound or composition which is effective to control nematodes Several such nematocides are available on the open market. While the nematoclde may be an azide, organic nematocides are' preferred. Among the nematocides of relatively large molecular weight that are" satisfactory for the practice of this invention are 2, 3-dihydro'-2,2-dimethyl-7-benzofuranyl-N-methylcarbamate (carbofuran, Furadan); sodium N-methyldithiocarbamate (SMDC, metham, metam, Vapam, S1stan, Trimaton, VPM); 0-ethyl-S,S-dinropylphosphorodithioate (Mocap, Prophos, VC-9-104, ENT-27,318); 0,0-diethyl-0-[p_-(methylsulfinyl)-phenyl]phosphorothioate (fensulfothion, Bay 25141, Dasanit, Terracur P); 0,O-dieth l-0-^,4-dichlorophenyphosphorothioate (dichlorofenthion, Kexa-nema, Tri-VC-13, VC-13); 0,0-diethyl-0-(2-pyrazinyi)phosphorothioate (thionazin, Zinophos, Cynem, Nemaphos); 0,0-diethyl-0-(2-isopropyl-6-methyl-4-pyrimidinyl)phosphorothioate (diazinon, 6-24480, Basudin, Diazajet, Diazide, Diazol, Dazel, Gardentox, Spectracide, Sarolex) ; mixtures of 0, 0-diethyl-0-(2-isopropyl-6-methyl-4-pyrimidinyl)phosphoro-thioate and l,l,l-trichloro-2,2-bis(£-methoxyphenyl)ethane (Alfa-tox); ethyl-4-(methylthio)-m-tolyl isopropylphosphoramidate (Bay 68138, Nema-cur); O-phenyl-Ν,Ν'-dimethylphosphorodiamidate (Dowco 169, Nellite); S-methyl-N-[ (methylcarbamoyl)oxy]thioacetimidate (metho yl, Lannate); l-phenyl-3-(0,0-diethylthionophosphoryl)-l,2,4-triazol«(Hoe 2960, Hosta-thion, Phentriazophos) ; \tetrahydro-3,5-dimethyl-2H-l,3,5-thiadiazine-2-thione (D TT, dazomet, Mylone, Crag Fungicide 974, Crag Nemacide, ico-fu e, Prezervit) and 2-methyl-2-(methylthio)propionaldehyde-0-(methyl- carbamoyl)oxirae (aldlcarb, UC 21149» Tetnik, Ambush). Among the nemato-cldes of relatively low molecular weight (the so-called "contact fumlgants') which may be used in the practice of this invention are tri-chloronitromethane (chloropic^rin, Acqulnite, Chlor-O-Pic, Larvacide, Niklor, Picfume, Tri-Clor) bromomethane (methyl bromide, MeBr, Brom-0-Gas, Meth-O-Gas, Profume); mixtures of bromomethane and trichloronitro-methane (Dowfume MC-2, Dowfume MC-33, Brozone); 1,2-dibromoethane (ethylene dibromide, EDB, Bromofume, Dowfume W-85, Kopfume, Nephis, Pestmaster EDB-85, Soilbrom-85); mixtures of 1,2-dibromoethane and carbon tetrachloride (Dowfume 75, Dowfume C, Dowfume EB-5, Dowfume EB-15 Inhibited, Dowfume 59, Dowfume F, Dowfume V, Dowfume EB-70, Dowfume J, Dowfume C); 1.2-dibromo-3-chloropropane (DBCP, Fumazone, Nemafume, Nemagon); 1,3-dichloropropene (Telone); mixtures of 1, 3-dichloropropene and trichloro-nitromethane (Telone C); mixtures of dlchloropropane and dlchloropropene (Vidden D); mixtures of 1, 3-dichloropropene, dichloropropane-dichloropro-pene and 1,2-dibromoethane (Darlone); mixtures of trichloronitroethylene, dlchloropropene and other chlorinated hydrocarbons (Grandox) ; mixtures of 1.3-dichloropropene, 3, 3-dichloropropene, 1,2-dichloropropane, 2, 3-dichloropropene and related chlorinated hydrocarbons (DD, Nemafene) ; mixtures of trichloronitromethane, 1, 3-dichloropropene, 3 ,3-dichloropro-pene, 1,2-dichloropropane, 2, 3-dichloropropene and related chlorinated hydrocarbons (Nemex); and mixtures of methyl isocyanate and chlorinated hydrocarbons (Vorlex, Di-Trapex) .

The amount of nematocide applied to the soil can vary widely and depends upon such factors as the identity of the nematocide, the identities of the nematodes to be controlled, numbers of nematodes in the soil, soil type, and soil temperature. When a commercial nematocide is used, it may be applied in accordance with the directions and recommenda- datipns on the label. Ordinarily the nematocide applied will be in the range of from about 0.5 to about 1000 pounds per acre. From about 1 to about 800 pounds per acre is more usual. Application in the range of from about 2 to about 200 pounds per acre is preferred. Usually the higher molecular weight organic nematocides are applied in the range of from about 0.5 to about 50 pounds per acre.* From about 1 to about 25 pounds per acre is more often practiced. From about 2 to about 20 pounds per acre is preferred. The fumigant nematocides are usually applied at higher rates than the higher molecular weight organic nematocides. Application in the range of from about 3 to about 1000 pounds per acre is ordinarily the case. A range of from about 5 to about 500 pounds per acre is typical. From about 10 to about 200 pounds per acre is preferred. When azide is applied as the nematocide, it is usually in the range of from about 10 to about 100 pounds per acre. From about 20 to about 50 pounds per acre is preferred. xne commercial nematocides may be applied in the manner recom-mended on their labels. Solid and liquid nematocide formulations may be applied by any of the methods described above for application of the azide. Gaseous nematocides may be injected into the soil or applied under a tarp.

Solid or liquid compositions of nematoc'ides may often be formulated with the azide. The resulting formulation provides a convenient manner of applying both the azide and the nematocide concurrently in one application. Usually the azide and nematocide are present in granules as absorbed ingredients or coatings on inert carrier particles such as atta-pulgite, montmorillonlte, corncob, sawdust, bentonite, etc. The azide A* and the nematocide may often be present on the same inert carrier particle or they may be on separate inert carrier particles. ■ Particularly effective are mixtures of granules containing azide and granules containing the nematoclde. In both the solid and liquid formulations the amounts of azide and nematoclde present are generally such that upon application both the azide and the nematoclde are applied in amounts suf ficient to accomplish their respective purposes.

The following specific embodiments illustrate by way of exampl the basic principles of the present invention.

EXAMPLE I In the spring a field having soil of pH 6.3 and known to be infested with nematodes and pod rot disease is prepared for planting » peanuts. The field is divided into plots 13-1/2 feet wide by 165 feet long.

One plot is treated with 20 pounds of 10% potassium azide granules per acre, 10 pounds of 7.5% 0,0-diethyl-S-[2-(ethylthio)ethyl]-phosphorodithioate formulation (Di-Syston insecticide) per acre and 10 pounds of 7.5% 0,0-diethyl-0-[p_-(methylsulfinyl)phenyl]phosphorothioate formulation (Dasanit nematoclde) . The treatments are then mechanically incorporated into the soil. At the time of planting 8 pounds of 7.5% Di-Syston insecticide per acre are applied in the^ furrow with the seed. Another plot is chosen as the untreated control. Conventional agricultural practices, including the use of herbicide and fertilizer, are used in raising the crop. In the fall, the plots are harvested and soil samples are taken for nematode counts. The results are shown in Tables 1. and 2: Table 1 Nematode Assay Abundance, Number of Nematodes per pint of soil Nematode Untreated Root-Knot (Meloidogyne, sp . ) 25 925 Lesion (Pratylenchus brachyurus) 25 50 Stunt (T lenchorhynchus, spp.) 75 325 Ring (Criconemoides, spp.) 75 300 Table 2 Effect of Treatment on Nematode-Infested Field Plots Yield, Quality, Value, Plot lb/acre $/cwt. $/acre Treated 4200 14.52 609.84 Untreated 3200 14.45 462.40 EXAMPLES II - VI In the spring a field on Farm A known to be infested with nematodes and pod rot disease is prepared for planting, peanuts. ' The different times and methods of chemical application are: Preplant Chemical Application: Test chemicals are applied 14 days prior to planting. Granular formulations of test chemicals are applied on a 12-inch wide band over the row and incorporated 5 inches deep. Rows are spaced 36 inches apart. Liquid formulations of test chemicals are in-jected 8 inches deep in the center of the row and the soil surface is sealed with a press wheel. The soil temperature and moisture are ideal for the application of soil fumigants. Vernolate herbicide (S-propyl-N,N-dipropylthiolcarbamate) is applied 2 days before planting at the rate et 2-1/8 peu.ada aefeive ingredient braadeaet per aere and incorporated with a disc uniformly. " At Planting Chemical Application: Peanuts are planted on the same day that these test chemicals are applied to the plots. Granular formulations and liquid formulations of test chemicals are applied in the same manners as the preplant chemical applications. Soil temperature and moisture are ideal for application of soil fumigants.

Early Pegging Chemical Application; Forty-two days after planting, granular formulations of test chemicals are applied on a 12-inch wide band centered over the row. At this time the first pegs are penetrating the soil. Application is made to dry vines and a heavy piece of burlap is attached behind the granule applicator to shake the vines and allow test chemicals to fall to the soil surface.

Four replications of each treatment are made.

Thirty-seven days after planting the peanut plants are evaluated for plant growth to determine if chemicals are phytotoxlc or beneficial to plant growth. A Plant Growth Index is assigned based upon the following scale: 10 = excellent growth; 15 = gooo" growth; 20 = fair growth; 30 = poor growth; 40 = severely stunted plants.

One hundred eighteen days after planting the per cent of peanut pod rot disease is determined by digging a plant from each of four locations per treated row per replication. Soil in the fruiting area of each plant is searched for healthy and rotted peanut pods which are placed in a paper bag with the plant from that location. Individual plants are washed and all pods are removed by hand. The healthy and diseased pods per plant are separated and counted. The percentage of the removed pods which are diseased is calculated for each plant. The individual percentages £©? eaeh ©£ the sixteen pla ts frea each treatment are then averaged to provide "Average Per Cent Pod Rot Disease."' Nematode populations are ascertained by collecting a composite of ten subsamples of soil to a six-inch depth per replicate 134 days after planting. The flotation-centrifugation method (Osborne, W. W. , Sourcebook of Laboratory Exercises in Plant Pathology, (1967), W. H.

Freeman and Company, San Francisco, pp. 105*106) is employed to extract nematodes from 250 milliliters of soil per replicate. The results from the four replicates of each treatment are averaged.

Peanuts are dug with farmer, equipment 141 days after planting stationary and combined with a stationery-peanut combine 148 days after planting. Immediately after the peanuts are combined, they are dried in the shell to 12% moisture, weighed, and stored in a dry area for two months prior to collecting a sample from each replicate for grading. The yield tor each replicate is calculated. The yields and grades for the four replicates of each treatment are then averaged. The average value per acre for each treatment and the increase or decrease with respect to the untreated plots are calculated.

The results are shown in Table 3 wherein "Rate" refers to the amount of formulation applied to rows per acre of plot (including both treated bands and untreated alleys between the bands) . Abbreviations in this and following tables are: A acre Ring Criconemoides, spp.

AI active ingredient Sting Belonolaimus, spp.

G granules Stunt Tylenchorhynchus, spp.

Root Spiral ' Rotylenchus, spp.

Knot Meloidogyne, spp. Dagger · Xiphinema, spp.

TABU 3 amxDL O tmuTODxs AND tecs BV somrn tarn AND :IKH*TOCIDP ON FAR ITepiant Appl icat ion AC ."l-ir.cJnf Appl ication i fjirlv refi lnc Applicat ion ; Plant far Cone Nematode Genera ixai.ple Chemica and Chenlcol and 7 Chemical and Growth Pod Rot Count it per ISO nl .

Rate Formulation Fornulatlon Rata Formulation Rata Index Disease Rooc Knot Larvae I Rjn 11 NaN_, e: c 66 lb/A Hocep, 10Z C 20 lb/A Nona 20.0 17.0 «3 4 III Η».1}, ex c 66 lb/A Nemagon, 0.7J gal/A Nona 22. S 18.1 10 12.1 lb AI/gal IV NaN.. 81 C (6 lb/A Nena on, 0.7} gal/A Terraclor, 100 lb/A 20.0 16.1 3 12.1 lb AI/gal loz c V ex c 66 lb/A Furadan, 102 C 20 lb/A Nona 10.0 18.1 10 VI 81 C 33 lb/A Ncaagon, 0,75 gal/A None 25.0 28.9 38 4 12.1 lb AI/g«l Vntreacco' — ,. . „ --. 27.J 30.3 8S0 2 EXAMPLES VII - XI The procedure of Examples II - VI le used on Farm S exeepc chat the time sequences are as follows: Event Days After Planting Preplant Chemical Application -19 At Planting Chemical Application 0 Determination of Plant Growth Index 29 Early Pegging Chemical Application 36 Determination of Per Cent Pod Rot Disease 113 Soil Sampling for Nematode Counts 127 Digging 142 Combining 156 The results are shown in Table 4.

TABLE 4 CONTROL ΟΪ NEMATODES AND ECCS BY SODIUH A IDE AND NKHATOCIUE ON 7AK I'ren'iar.f *il ion Λ: Plantllt; .-n l ic-clon Enrlv pcln^ Λrnl lc.-iMon Plant Per Cent Nematode Genera Cno cal an4 1 Ctientcal and Otonical Growth 'cr 250 ml.

Hare Rate Rate Pod Rot Counts 1 formulae lup I rormulae ion Formulation Index Disease Root Knot Lnrvae I st VII NeNj, sx c 6 lb/A Krmaeon, 0.7} gal/A None 23 12.} 2 12.1 lb Al/ttal IX KtXy s: c 6'. lb/A Nemaoon, 0.75 gal/A Terraclor, 100 lb/A 26 26.4 63 12.1 lb Al/gal 10X C X NeKj. ax c &li lb/A Puradan, 10X C 20 lb/A None 10 8.0 30 XI NaX_, ex c 33 lb/A Hcfugon, 0.7} gal/A Nona 25 14.0 6 12.1 lb Al/gal uncreated 30 20.6 423 Plot.

EXAMPLES XII - XVI The procedure of Examples II - VI is used Farm C except that .« the time sequences are as follows: Event Days After Planting Preplant Chemical Application -15 At Planting .Chemical Application 0 Determination of Plant Growth Index 34 Early Pegging Chemical Application 41 Determination of Per Cent Pod Rot Disease 118 Soil Sampling for Nematode Counts 132 Digging 155 Combining 175 The results are shown in Table 5. c J c

Claims (11)

43731/2 i I gASij; g8ft

1. A method for controlling nematodes which comprises adding to soil containing nematode eggs a material effective to enhance the hatching of said nematode eggs, and before, concurrently or subsequently adding to the soil a tmfiana rvjt in an amount effective to kill nematodes hatched from said nematode eggs, said material added to an inorganic the soil to hatch the nematode eggs comprising/azide in a sufficiently low concentration to hatch the nematode eggs but not sufficiently high substantially to kill the nematodes hatched from said eggs.

2. A method according to claim 1, wherein the application of azide for hatching of the eggs is in an amount from 0.5 to 10 pounds per acre of said compound.

3. * A method according to claim 1 or 2, wherein the nematocide is applied within 30 days after the application of the azide as an egg-hatching agent.

4. !{.. A method according to any one of claims 1 to 3, inorganic wherein an/azide is subsequently applied as the nematocide ir. an amount from 10 to 100 pounds per acre0

5. · A method according to any one of claims 1 to 3, wherein the nematocide is selected from the group consisting of 2, 3-dihydro-2,2-diraethyl-7-benzofuranyl-N-methylcarbamate; 0-ethyl-S,S-dipropylphosphorodithioate; 0,0-diethyl-0- p- (methylsulfinyl )phenyl7phosphorothioate; 1, 3-dichloro-propene; mixtures of 1,3-dichloropropene , and trichloronitro-methane; mixtures of 1,3-dichloropropene, 3, 3-dichloropro-pene, 1,2-dichloropropane, 2,3-di.chloropropene, and related chlorinated hydrocarbons; and mixture of methyl isocy- 43731/2 anate and chlorinated hydroca bons*

6. A method according to any one of the preceding claims, wherein the azide comprises an alkaline metal azide, an alkaline earth metal azide, ammonium azide or a mixture thereof.

7. · method according to claim 6, wherein the azide is sodium azide, potassium azide or a mixture thereof*

8. A composition for controlling nematodes which comprises fegf arTIiloPe in an egg-hatching concentration in admixture with anematocide other than an azide, said nematocide being present in a nematocidal concentration.

9. * A composition according to claim 6, wherein the nematocide is selected from the group consisting of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-N- methylcarbamate ; 0-e hyl-S,S-dipropylphosphorodithioate; 0,0 diethyl-0-i£p- (methylsulfinyl )phenyl7phosphorothioate } 1, 3-dichloropropene; mixtures of 1, 3-dichloropropene and trichloronitromethane; mixtures of 1, 3-dichloropropene, 3, 3-dichloropropene, 1,2-dichlorop opane, 2, 3-dichloropropene, and related chlorinated hydrocarbons J and mixtures of methyl isocyanate and chlorinated hydrocarbons.

10. A method for controlling nematodes substantially as herein described with reference to the Examples

11. A composition for controlling nematodes substantially as herein described with refereanncc^e^--fcfcpp tthhee Examples.