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Mexico is the 8th largest producer of tomatoes. Meloidogyne enterolobii is reported in Sinaloa, affecting tomato cultivars with genetic resistance to Meloidogyne spp. We aimed to evaluate field applications of fluopyram, fluensulfone, and fluazaindolizine treatments for managing M. enterolobii on tomatoes. Experiments were set on raised beds in a shade house. Nematicides were applied via drip irrigation. Under fluopyram treatment, M. enterolobii did not reduce the number of extra-large-size fruits. The number of large-size fruits with fluopyram and fluazaindolizine plus fluopyram treatments was also unaffected by M. enterolobii. Yield from the treatments fluopyram, fluazaindolizine plus fluopyram, and fluensulfone plus fluopyram was similar to the control treatment without M. enterolobii. Finally, fluazaindolizine plus fluopyram, fluopyram, and fluensulfone plus fluopyram treatments showed the highest reduction of root galling. We conclude that the fluopyram was more effective as an individual treatment. Pre-plant applications of fluensulfone and fluazaindolizine reduced the damage to the plant and the loss of yield; however, the complementary application of fluorinated nematicides improved the management of M. enterolobii in the tomato crop.

A survey conducted from May 1995 through August 1998 revealed diverse nematode communities in Louisiana sugarcane fields. High populations of Mesocriconema, Paratrichodorus, Pratylenchus, and Tylenchorhynchus were widespread in nine sugarcane production parishes. Comparisons of plant cane and ratoon sugarcane crops indicated that nematode community levels increase significantly in successive ratoon crops. Nematicide trials evaluated the efficacy of aldicarb, ethoprop, and phorate against indigenous nematode populations. Aldicarb consistently increased the number of millable stalks, cane tonnage, and yield of sucrose in soils with a high sand content. Yield increases were concomitant with reductions in the density of the nematode community shortly after planting and at harvest. In soils with a higher clay content, the chemicals were less effective in controlling nematode populations and, as a result, yield increases were minimal.

Field experiments were conducted to determine peanut growth and yield responses to selected fumigant and nonfumigant nemaficide treatments in 1988 and 1989. All treatments with the fumigant 1, 3-D significantly suppressed nematode reproduction (Meloidogyne arenaria, M. hapla, and Mesocriconema ornatum) and enhanced peanut yields over the other treatments in four tests in 1988. Yield increases with the fumigant ranged from about 20% to 100% over the untreated control. Test sites in 1989 had lower nematode levels than those for 1988, and fewer positive plant and nematode responses were detected. Treatments with 1,3-D improved peanut quality but not yield in one experiment with low levels of M. hapla and M. ornatum in 1988. The 1,3-D + chloropicrin treatments at another site gave higher peanut yields than 1,3-D alone.

During the 1991 and 1992 soybean growing seasons, field plots were established in South Carolina to study the effect of planting date on at-planting nematode densities and subsequent yield losses caused by Hoplolaimus columbus. The susceptible and intolerant soybean cv. Braxton was planted on five dates from to May to 28 June in 1991 and from 12 May to 28 June in 1992. Nematodes were recovered from soil samples collected before nematicide treatment with 1,3-D (Pi), at 6 weeks after planting (Pm), and at harvest (Pf). Initial nematode population densities did not differ among the five dates of planting in either year. The increase in numbers of nematodes from planting to 6 weeks after planting (Pm/Pi) and from planting to harvest (Pf/Pi) were not different among the five planting dates in either year. Root samples also were collected at 6 weeks after planting and at harvest, but planting date did not affect the number of nematodes extracted from roots on any sample date in either year. Altering planting dates between early May and late June was not effective in preventing yield suppression due to H. columbus.

Avermectin B, isazofos, and fenamiphos were evaluated in greenhouse experiments for efficacy against two common turfgrass parasites, Hoplolaimus galeatus and Tylenchorhynchus dubius. Treatments in all experiments were arranged in a completely randomized design and replicated four times. In the first experiment, avermectin B at rates of 0.2 and 0.4 kg a.i./ha and isazofos at rates of 2.3 and 23 kg a.i./ha significantly reduced populations of both species of parasitic nematodes compared to controls at 14 and 28 days after treatment (P

Granular (Rugby 10G) and liquid (Rugby 100 ME) formulations of cadusafos were evaluated for the control of Tylenchulus semipenetrans on mature lemon trees in a commercial citrus orchard at Yuma, Arizona. Three applications of cadusafos, with 2 months between applications, at the rate of 2 g a.i./m(2) reduced nematode populations to undetectable levels and increased the yield and rate of fruit maturity of 'Rosenberger' lemons. Yields were increased 12,587 kg/ha with Rugby 100ME and 8,392 kg/ha with Rugby 10G. Nematode populations were suppressed for at least 12 months after the last application.

Ethoprop and disodium tetrathiocarbonate (TTC) were evaluated as replacements of fenamiphos and 1,3-dichloropropene (1,3-D) for control of Rotylenchulus reniformis on pineapple in Hawaii. Treatments were established in a field on the Del Monte Fresh Fruit (Hawaii) plantation in spring 1991. Preplant soil treatments consisted of fumigation with 1,3-D at 226 kg a.i./ha and TTC at 135 kg or 270 kg a.i./ha. Postplant nematicides for the 1,3-D treated plots were fenamiphos (3.4 kg a.i./ha trimonthly) and ethoprop (3.4 or 6.7 kg a.i./ha monthly). Tetrathiocarbonate was applied postplant to the TTC-treated plots every 2 months at 67 kg a.i./ha. Nematode population densities were monitored in all plots at 3-month intervals. Tetrathiocarbonate was not effective in reducing the preplant soil population densities of R. reniformis or limiting subsequent nematode damage to the plants. Ethoprop and fenamiphos reduced nematode damage, resulting in greater yield in the first and second crop harvests (P < 0.05). Ethoprop was an effective alternative to fenamiphos for control of R. reniformis in pineapple.

Pearl millet is used mainly as a temporary forage crop in the southern United States. A new pearl millet hybrid has potential as a major grain crop in the United States. The effects of nematodes, irrigation, a nematicide, and nitrogen rates on a new pearl millet grain hybrid, HGM-100, and nematode population changes were determined in a 2-year study. Root-knot nematodes (Meloidogyne incognita race 1) entered the roots of pearl millet and caused minimal galling, but produced large numbers of eggs that hatched into second-stage juveniles. Root-gall indices ranged from 1.00 to 1.07 on a 1-5 scale and were not affected by irrigation or rates of nitrogen. Yield of pearl millet was up to 31% higher under no supplemental irrigation than under irrigation, 16% higher in fenamiphos-treated plots than untreated plots, and 56% higher in plots treated with 38 kg nitrogen/ha than plots treated with 85 kg nitrogen/ha. In southern Georgia, pearl millet appears to be resistant to ring nematode (Criconemella ornata) but favors development and reproduction of M. incognita.

The effects of irrigation on the efficacy of nematicides on Meloidogyne incognita race 1 population densities, yield of sweet corn, and the carry-over of nematicidal effect in the squash crop were determined in a sweet corn-squash-vetch cropping system for 3 years. Fenamiphos 15G and aldicarb 15G were applied at 6.7 kg a.i./ha and incorporated 15 cm deep with a tractor-mounted rototiller. Ethylene dibromide (EDB) was injected at 18 kg a.i./ha on each side of the sweet corn rows (total 36 kg a.i./ha) at planting for nematode control. Supplemental sprinkler irrigation (1.52-4.45 cm), applied in addition to natural rainfall (4.60-10.80 cm) within l0 days after application of nematicides, did not affect nematicide efficacy against M. incognita or yield of sweet corn. Soil treatment with fenamiphos, EDB, and aldicarb increased the number and total weight of sweet corn ears and the weight per ear each year over untreated controls (P

Aldicarb, ethoprop, and fenamiphos were evaluated for their efficacy in controlling various species of root-knot nematodes on flue-cured tobacco and for their residual activity, as determined through periodic sampling and bioassays of soil taken from field plots. Field experiments were conducted at five locations over 2 years with flue-cured tobacco. Soil in plots treated with nematicides were formed into high, wide beds before transplanting with 'Coker 371-Gold' or 'K 326' tobacco. Residual control of Meloidogyne spp. was greatest (P

Over the past 30 years, methyl bromide (MBr), a broad spectrum fumigant, has been used extensively for soilborne disease and pest control in the production of many fruit, vegetable, turf, and nursery crops. Recently, agricultural emissions of MBr were implicated as a potentially significant contributor to stratospheric ozone depletion. As a precautionary measure for global ozone protection, the U.S. Environmental Protection Agency has enforced federal legislation which mandates a complete phase-out of MBr use within the United States by 1 January 2001. Thus, new cost effective, environmentally compatible strategies for control of nematodes and other soilborne pests and pathogens must be developed and tested in a relatively short time to avoid significant losses in crop productivity. The extent to which certain agricultural industries that are now heavily reliant on MBr are affected will depend on the development of sustainable, integrated tactics to pest control, such as combinations of cultural, chemical, and biological tactics. New muhidisciplinary research and extension programs must be developed to address and overcome major constraints and incompatibilities that have prevented such tactics from being widely adopted.

Pratylenchus penetrans is a pest for producers of oriental lilies in northern California. Concern over groundwater contamination from 1,2-dichloropropane following shank injections of 1,3-dichloropropene-l,2-dichloropropane mixture and granular applications of aldicarb prompted testing for alternative methods of controlling P. penetrans. In field trials, nematicides applied by drip irrigation (ethoprop, fenamiphos, oxamyl, sodium tetrathiocarbonate, water extracts of marigold and vetch, and 1,3-D plus emulsifier) were tested with and without foliar applications of oxamyl. Nematode populations were reduced (P = 0.05) relative to controls in soil or roots on one or more sampling dates by all drip-applied nematicides except the plant extracts. On some sampling dates, additional reductions (P = 0.05) occurred as a result of three foliar applications of oxamyl. Foliar-applied oxamyl alone also reduced (P = 0.05) nematodes in soil or roots. Lily bulb weight was not affected (P = 0.05) by chemical treatments.

Field trials were conducted with a chitin-urea soil amendment and several other nematicides on four crop-nematode combinations: tomato-Meloidogyne incognita; potato-Meloidogyne chitwoodi; walnut-Pratylenchus vulnus; and brussels sprouts-Heterodera schachtii. Significant (P

Soybean cultivars in maturity groups III, IV, and V that were resistant or susceptible to Heterodera glycines were evaluated for their response to in-furrow applications (5.43 kg a.i./ha) of aldicarb. Tests were conducted over three years (1988-1990) in various H. glycines-infested locations in Missouri for a total of 16 environments. In 7 environments, overall yields were higher (P

The value of cotton (Gossypium hirsutum cv. Deltapine 90) in rotation with peanut (Arachis hypogaea cv. Florunner) for the management of root-knot nematode (Meloidogyne arenaria) and southern blight (Sclerotium rolfsii) was studied for 6 years in a field at the Wiregrass Substation in southeast Alabama. Peanut yields following either 1 or 2 years of cotton (C-P and C-C-P, respectively) were higher than those of peanut monoculture without nematicide [P(-)]. At-plant application of aldicarb to continuous peanut [P(+)] averaged 22.1% higher yields than those for P(-) over the 6 years of the study. The use of aldicarb in cotton and peanut in the C-C-P rotations increased yields of both crops over the same rotations without the nematicide. When the nematicide was applied to both crops in the C-P rotation, peanut yields were increased in only two of the possible three years when peanut was planted. Application of aldicarb to cotton only in the C-P rotation did not improve peanut yields over those obtained with the rotation without nematicide. Juvenile populations of M. arenaria determined at peanut-harvest time were lowest in plots with cotton. Plots with C-P or C-C-P had lower populations of the nematode than those with either P(-) or P(+). The incidence of southern blight (Sclerotium rolfsii) in peanut was lower in plots with the rotations than in those with peanut monoculture. Aldicarb application had no effect on the occurrence of southern blight.

The efficacy of controlling Meloidogyne hapla on potato with water incorporation of ethoprop was compared to physical incorporation before planting. The standard practice of aldicarb application for insect control was also evaluated for M. hapla suppression with and without ethoprop. Physical incorporation before planting by rototilling or discing reduced (P

Ditylenchus dipsaci (Kühn) Filipjev is a serious pest of commercial daffodil (Narcissus sp.) in northern California. The control measures practiced by growers in recent years are postharvest treatment of planting bulbs for 3 hours in a 1% solution of formalin at 44 C combined with preplant soil fumigation with 1,3-dicbloropropene and (or) at-planting applications of phorate. In field trials, several combinations of rates (1.12, 2.24, or 4.48 kg a.i./ha in 189 liters of water/ha) and timings (one, two, or three applications at weekly intervals) of foliar applications with oxamyl on three daffodil varieties (Fortune, Ice Folley, and King Alfred) were evaluated as alternatives. Several treatments reduced nematode levels in leaves and bulbs. Phytotoxicity was not observed at any rate or combination of treatments.

Preplant soil applications of oxamyl to shade grown tobacco in Globodera tabacum-infested field soil increased green leaf yields over untreated plots by 10.7 and 21.0% for 2.2 and 6.7 kg a.i. oxamyl/ha, respectively. Green leaf yield was negatively correlated (r = -0.60, P = 0.04) with initial G. tabacum density, which ranged from 33 to 154 second-stage juveniles (J2)/cm(3) soil. Numbers of G. tabacum J2 and developing juveniles and adults (J3-adults) per gram root were fewer in plants from oxamyl-treated plots than in plants from untreated plots. Numbers of J2 in roots 4, 6, and 8 weeks after transplanting were reduced by 80, 89, and 4%, respectively, and numbers of J3-adults were reduced by 96, 89, and 21%, respectively, in high-rate oxamyl plots, compared with untreated plots. Globodera tabacum reproduction, as measured by the ratio of final to initial soil densities, was less in oxamyl-treated plots than in untreated plots.

Tests were conducted in 1987-88 to compare the efficacy of spring or fall fumigant nematicide applications for control ofMeloidogyne arenaria and M. incognita on tobacco. Chloropicrin, 1,3-D, methyl isothiocyanate, and a methyl isothiocyanate-l,3-D mixture were applied as row treatments. Fenamiphos, fenamiphos + fensulfothion, or ethoprop were applied in the spring as nonfumigant nematicide standards. Fumigant nematicides increased yields and reduced galling (P = 0.01) in all four tests. Spring or fall applications of fumigant nematicides were effective in controlling M. arenaria and M. incognita and were superior to the nonfumigant nematicides tested.

Preplant soil applications of oxamyl to shade grown tobacco in Globodera tabacum-infested field soil increased green leaf yields over untreated plots by 10.7 and 21.0% for 2.2 and 6.7 kg a.i. oxamyl/ha, respectively. Green leaf yield was negatively correlated (r = -0.60, P = 0.04) with initial G. tabacum density, which ranged from 33 to 154 second-stage juveniles (J2)/cm(3) soil. Numbers of G. tabacum J2 and developing juveniles and adults (J3-adults) per gram root were fewer in plants from oxamyl-treated plots than in plants from untreated plots. Numbers of J2 in roots 4, 6, and 8 weeks after transplanting were reduced by 80, 89, and 4%, respectively, and numbers of J3-adults were reduced by 96, 89, and 21%, respectively, in high-rate oxamyl plots, compared with untreated plots. Globodera tabacum reproduction, as measured by the ratio of final to initial soil densities, was less in oxamyl-treated plots than in untreated plots.

A 3-year study was conducted to evaluate fenamiphos at 20.2 kg a.i./ha applied in both fall and spring or in spring only for the control of Pratylenchus penetrans on apple, Malus domestica cv. Granny Smith on M7a rootstock. The initial population densities of P. penetrans within the plot area were 89/250 cm(3) soil and 268/g root dry weight. Fenamiphos increased (P < 0.05) trunk diameter in years 2 and 3 and shoot length in years 1 and 2. Yield data obtained in year 3 showed that the spring only and the fall plus spring fenamiphos treatments increased (P < 0.05) yields by 36 and 80% with a net gain of $2,352 and $5,456/ha, respectively. Results suggest that P. penetrans may be of economic importance in Washington state.

Field experiments were conducted to evaluate the efficacy of five nematicides for the management of Rotylenchulus reniformis and for their effects on growth, development, and yield of cotton. Treatments included 1,3-dichloropropene (1,3-D), fenamiphos, phorate, terbufos, aldicarb, and 1,3-D + aldicarb. Average R. reniformis population densities across all treatments increased from 5,284 at 10 days after planting to a final density at harvest of 15,622 nematodes/500 cm(3) soil. The 1,3-D + aldicarb combination was the only treatment with an average R. reniformis population density significantly (P

The efficacy of ABG-6162A (1.5 L formulation of thuringiensin) for control of Heterodera glycines on soybean (Glycine max cv. Williams 82) was evaluated in the greenhouse at rates of 0, 10, 100, 500, and 1,000 ppm a.i. and in a field experiment at rates of 0, 3.4, 10.2, and 20.3 g a.i./100 m of row applied in an 18-cm-wide band. In the greenhouse, the 100-ppm rate was as effective as an equivalent rate of aldicarb and caused no phytotoxicity, but the higher rates of thuringiensin were highly phytotoxic. In the field experiment, numbers of females recovered from plots treated with thuringiensin at the 3.4-g and 10.2-g rates were greater (P

Seven experiments, three on soybean and four on cotton, were conducted in Hoplolaimus columbus-infested soil in southern North Carolina to determine the benefits of chemical soil treatment. Locations were selected to give a range of initial population (Pi) densities. Soil fumigation with 1,3-D and soil treatment with a combination of aldicarb plus fenamiphos (1.1 kg a.i./ha) each provided good control of this nematode. Yield responses considered to be significant were achieved only on the high Pi site.

The principal soil fumigants and their order of discovery are carbon disulfide, chloropicrin, methyl bromide, 1,3-dichloropropene, ethylene dibromide, 1,2-dibromo-3-chloropropane, and methyl isothiocyanate. Biological activity of soil fumigants ranges from limited to broad spectrum. Fumigants diffuse through the continuous soil air space as gases. Physical and chemical characteristics determine diffusion rates, distribution between the soil air and moisture, and sorption onto and into the soil particles. The principal soil factors affecting the efficacy of each treatment are the size and continuity of air space, moisture, temperature, organic matter, and depth of placement. Application can be made overall with tractor injection or plow-sole, or as a row or bed treatment. Treatment for trees is best made in conjunction with tree site backhoeing.

In laboratory testing, egg hatch of Tylenchulus semipenetrans was stimulated at concentrations of 1 and 10 microg/ml aldicarb solution and inhibited at 50 and 100 microg/ml. Aldicarb was more inhibitory to egg hatch than the aldicarb sulfoxide and the aldicarb sulfone. Inhibition of hatch at the high concentration was associated with delays in the molting processes, lack of larval movement within the egg, and delays in embryonic development. Nematode motility was reduced at 10, 50, and 100 microg/ml of aldicarb and aldicarb sulfoxide solution, and at 50 and 100 microg/ml aldicarb sulfone. Male development was retarded at 10 microg/nrl and almost completely inhibited at 50 and 100 microg/ml of the three chemicals. In greenhouse tests, female development antl reproduction on roots of citrus seedlings were suppressed by aldicarb at rates of 2.6 microg/ml and completely inhibited at 10.6 microg/ml of soil solution during a 50-day experimental period. Under field conditions, there was little systemic movement of aldicarb into roots located outside treated areas. Aldicarb reduced the nematode larvae and the female adult population in the second year after the second treatment. There were no differences in egg hatch and sex ratio of citrus nematodes between treated and nontreated roots.

A field study was conducted to evaluate soybean cultivar sensitivity to Pratylenchus brachyurus and selected nonfumigant nematicides for control of this nematode. 'Essex', a tolerant cultivar, yielded more than 'Forrest' , a sensitive cultivar, in an infested field. Plots treated with aldicarb, carbofuran, and fenamiphos had fewer nematodes 40 days after planting than nontreated plots. Plots planted with Forrest and treated with carbofuran had a greater yield than the untreated controls.

Nematodes are considered major pests on most economic crops in the Philippines, particularly on banana, pineapple, citrus, tomato, ramie, and sugarcane. Radopholus similis is the most destructive nematode on banana, while Meloidogyne spp. are more serious on various vegetable crops such as tomato, okra, and celery and on fiber crops such as ramie. Tylenchulus semipenetrans is a problem on citrus and Rotylenchulus reniformis on pineapple and some legume crops. Hirschmanniella oryzae and Aphelenchoides besseyi are becoming serious on rice, and Pratylenchus zeae is affecting corn in some areas. Lately, Globodera rostochiensis has been causing serious damage on potato in the highlands. Control measures such as crop rotation, planting resistant varieties, chemical nematicide application, and biological control have been recommended to control these nematodes.

Metalaxyl significantly reduced population of Pratylenchus coffeae, Radopholus similis, and Tylenchulus semipenetrans in roots of Citrus limon (rough lemon) under greenhouse conditions. Postinoculation treatment of rough lemon seedlings was not as effective i n reducing nematode populations as was treatment before inoculation. Fewer nematodes infected metalaxyl-treated roots than nontreated roots. However, incubation of nematodes in metalaxyl did not inhibit nematode motility or their ability to locate and infect roots. Cellular responses to nematode injection differed between treated and nontreated tissues. Metalaxyl appeared to confer nematode contraol by modifying citrus roots such that a normally susceptible rootstock became tolerant.

Soaking potato tuber pieces for 15 min in 8,000 mug/ml of oxamyl just before planting reduced the number of Globodera rostochiensis cysts that developed on potato roots, but this treatment was phytotoxic. Five foliar applications of 1.12 kg a.i./ha of oxamyl or carbofuran at 10-day intervals beginning when 90% of the plants had emerged suppressed increase in G. rostochiensis densities. Similar foliar applications of phenamiphos were ineffective in controlling G. rostochiensis. Soil applications (in the row at planting) of aldicarb, carbofuran, phenamiphos, ethoprop, and oxamyl at 5.6 kg a.i./ha reduced the numbers of white females that developed on potato roots, but only those treatments involving aldicarb and oxamyl suppressed G. rostochiensis population increase. Combined soil and foliar treatments did not provide any advantage over soil treatment alone, as soil applications of 5.6 kg a.i./ha alone were equal to, or better than, combined soil (3.4 kg a.i./ha) and foliar (2.2 kg a.i./ha) applications in controlling G. rostochiensis.

Experiments were conducted for 3 years at four locations and 1 year with six soil types at a common location in North Carolina to determine damage and control-cost functions for Heterodera glycines races 1 and 2 on soybean. In the experiments on native loamy sand and sandy soils, tolerance limits for initial population densities were 0 or very low, whereas in a muck, the tolerance limit was 315 eggs/500 cm(3) soil. The aggressive race 2 was more damaging than race 1 in Lakeland sand and Norfolk loamy sand. The crop response was not different between races in the Appling sandy clay loam and Belhaven muck. Soybean yield responses to H. glycines were linear in six soil types in microplots at a common site. The amount of damage varied among these soil types, with lowest yields in the muck because of severe drought stress in this soil. An exponential function adequately described soybean yield response relative to nematode control with increasing rates of aldicarb in Norfolk loamy sand. Treatment with aldicarb in the Lakeland sand decreased the effective egg population of H. glycines but had only a minor effect in the muck.

Greenhouse and field tests established that fenamiphos at 6.7 and 13.4 kg ai/ha applied in a 30-cm band directly on iris bulbs at planting effectively controlled Ditylenchus destructor. Aldicarb at rates of 5.6 to 11.2 kg ai/ha was less effective. Carbofuran, fensulfothion, and oxamyl at 6.7 to 13.4 kg ai/ha were ineffective. When applied on the bulbs, fenamiphos (granular or liquid) reduced nematode infection from 31 to 0.6% as determined by visual inspection of bulbs at harvest. Populations of D. destructor were reduced from 5.7 nematodes/g of fresh weight of bulb tissue to 0.04, 0.05, and 0.14 with applications of 13.4, 6.7, and 3.3 kg ai/ha fenamiphos, respectively. The most effective treatment was fenamiphos (granular or liquid) applied in a 30-cm band directly on the bulbs at time of planting.

Phenamiphos, ethoprop, and carbofuran each at 6.7 kg a.i./ha were applied to squash, southern pea, and corn via injection into a sprinkler irrigation system. This method was then compared with a conventional application of phenamiphos and ethoprop granules spread on the soil surface and incorporated into the top 15 cm for control of Macroposthonia ornata and Meloidogyne incognita. Nematode populations in the soil and root-gall indices were lower, and yields greater, in treated than in untreated plots, but there were no significant differences between the methods of application in most comparisons.

Oxamyl was applied to both uncut and cut potato tubers in aqueous solutions of 1,000 to 32,000 mug/ml. Emergence in greenhouse pots was delayed for a day or more after soaking cut tuber pieces in 32,000 mug/ml. After 10 weeks plant growth was greater, relative to the control, when Pratylenchus penetrans-infested soil was planted with cut tubers soaked for 20 minutes in 32,000 mug/ml. Soaking for 40 minutes did not increase nematode control nor affect plant growth. Oxamyl applied to tubers at 1,000 mug/ml reduced the numbers of P. penetrans in the soil by 20% and in the roots by 35%; at 32,000 mug/ml, the numbers of P. penetrans in the soil were reduced by 73-86% and in the roots by 86-97%. The numbers of P. penetrans did not increase in the roots of plants developed from cut tubers soaked in 32,000 mug/ml over a period of 10 weeks, but numbers of lesion nematodes had begun to increase in the soil.

Foliar applications of oxamyl prevented nematodes from invading roots of diploid bananas. One spray with 1,250 microg/ml was more effective than 1, 2, or 3 sprays with 625 microg/ml applied at 5-day intervals. After 3 sprays with 1,250 microg/ml, invasion may be prevented for up to 4 weeks and possibly longer. Washing roots after oxamyl treatments prevented nematicidal control. When applied to nematode-infected plants, three sprays of oxamyl decreased nematode populations in the roots.

Root-knot nematodes suppress yields of flue-cured tobacco an estimated 0.1 to 4.8% annually in the southeastern United States, even though nematode management practices have been widely adopted. Although Meloidogyne incognita races 1 and 3 have predominated, M. arenaria, M. javanica, and M. incognita races 2 and 4 are increasingly important. Seventy-five percent of the flue-cured tobacco hectarage in North Carolina and Virginia is rotated on 2-year or 3-year intervals. Over half of the hectarage in the southeastern United States was planted with tobacco cultivars resistant to M. incognita races 1 and 3 in 1986. Resistance to other species or races of root-knot nematodes is not available in commercially available flue-cured tobacco cultivars. Most producers plow and (or) disc-out flue-cured tobacco roots and stalks after harvest. Nematicide use ranges from virtually 100% in Florida and Georgia to 60% in Virginia. Continued research is needed to develop management strategies for mixed populations of root-knot nematodes and to incorporate resistance to more root-knot nematode species and races into tobacco cultivars. Nematode advisory programs that allow producers to optimize nematicide use from an economical and ecological point of view are also needed.

Three tests were conducted to evaluate the efficacy of fumigant and nonfumigant nematicides for control of Meloidogyne arenaria race 1 on peanut. Methyl bromide, 1,3-D, methyl isothiocyanate, and methyl isothiocyanate mixtures were applied 7 or 8 days preplant either broadcast or in-the-row. Aldicarb, ethoprop, fenamiphos, and F5145 were applied at different rates and by different methods at-plant or at early flowering. Of the 32 treatments evaluated, only seven resulted in yield increases (P = 0.05), although early season vigor was high in all treated plots. During the latter one-third of the growing season, however, nematode control was not adequate in most treatments resulting in heavy peg, pod, and root infection by M. arenaria.

The fumigant 1,3-dichloropropene (1,3-D) effectively controlled Meloidogyne chitwoodi on Russet Burbank potato, Solanum tuberosum. There was a maximum of 4% infected and galled tubers from the 1,3-D treatment after 2,028 degree-days with a base temperature of 5 C (DD5). This compared to 66% infected and galled tubers in aldicarb at-plant treated plots. Soil temperature, as determined by DD5, and timing of chemical applications affected the nematicidal activity on M. chitwoodi (P < 0.05). Aldicarb was most effective when applied postplant (PP) during the nematode reproductive cycle. After 1,684 DD5 of growth, there were 59, 26, 22, and 6% infected and galled tubers from untreated control plots and aldicarb treatments of 2.1 g/m row at 600 DD5, 2.1 g/m row at 1,228 DD5, and 1.3 g/m row at 600 DD5 plus 2.1 g/m row at 1,228 DD5, respectively. No aldicarb treatments were effective over a growing period of 2,028 DD5; 34% of the tubers were infected and galled following the most effective aldicarb treatment (1.3 g/m row at 504 DD5 plus 2.1 g/m row at 996 DD5).

Four nonfumigant nematicides applied three times during the wet season were used to study dosage sequence and nematicide effectiveness. Control of Helicotylenchus multicinctus (Cobb) Thorne and Meloidogyne javanica (Treub) Chitwood increased plantain (Musa AAB) yields. The nematicide (aldicarb, carbofuran, oxamyl, and miral) performance and yield response varied with dosage sequences. Applications of 2, 3, and 2 g ai/tree in March, July, and October (sequence I), respectively, gave greater control of M. javanica than did applications of 3, 2, and 2 g ai/tree in March, June, and September (sequence II), respectively. However, the high initial dose sequence was effective against H. multicinctus. Persistence of the different nematicides differed over the 14-month experimental period. Miral, aldicarb, and carbofuran were the most effective treatments against either species by the end of the wet and dry seasons. Dry season residual nematode populations were significantly lower in nematicide treated than in control plots. Yield increases over controls were 96.9, 90.1, 78.4, and 70.1% for carbofuran applied by sequence II, aldicarb by II and I, and oxantyl by II, respectively. Nematode populations directly fluctuated with rainfall and dropped to low (H. multicinctus) or to undetectable (M. javanica juveniles) levels during the dry season. Of the two nematodes studied, the more serious pest to plantain was H. multicinctus; it was tolerant to drought and survived the dry season in untreated soils.

Ethoprop, oxamyl, PP 156, fenamiphos, carbofuran , AC 64,475, Bunema M, CG 12223, aldicarb, aldicarbsulfoxide, and aldicarbsulfone were tested for their effects on hatching and emergence of larvae from cysts of Heterodera schachtii. The oxime carbamates and carbofuran inhibited hatching , but this response was reversed by removing the chemical treatment . Inhibition of hatching by Bunema M and all organophosphates tested was irreversible .

Three nematicides were evaluated for control of Belonolaimus longicaudatus, Hoplolaimus galeatus, Criconemella spp., and Meloidogyne spp. in 'Tifgreen II' bermudagrass mowed at golf course fairway height (1.3 cm) in Fort Lauderdale, Florida. Bermudagrass plots were treated with fenamiphos (13.5 kg a.i./ha), oxamyl (13.5 kg a.i./ha), or 30% formaldehyde (6.4 liter a.i./ha). The plots treated with fenamiphos or formaldehyde were split 14 days later and one-half of each plot received two biweekly applications of formaldehyde. Forty-two days after the treatments were applied, the turfgrass vigor ratings and dry root weights in plots treated with fenamiphos were higher (P < 0.05) than the control, oxamyl, or formaldehyde treatments. The population levels of B. longicaudatus were suppressed (P < 0.05) in the fenamiphos, fenamiphos plus formaldehyde, and oxamyl treatments.

Nematode population densities and yield of sweet potato and onion as affected by nematicides and time of application were determined in a 3-year test. Population densities of Meloidogyne incognita race 1 in untreated plots of sweet potato increased each year, but Helicotylenchus dihystera and Criconemella ornata did not. Ethoprop (6.8 kg a.i./ha) incorporated broadcast in the top 15-cm soil layer each spring before planting sweet potato reduced population densities of nematodes in the soil and increased marketable yield in 1982, but not in 1983 and 1984. When DD, fenamiphos, and aldicarb were applied just before planting either sweet potato or onion, nematode population densities at harvest were lower in treated than in untreated plots. No additional benefits resulted when the nematicides were applied immediately before planting both sweet potato and onion. Correlation coefficients (P

The population dynamics of Heterodera glycines as influenced by alachlor, fenamiphos, and ethoprop alone and in herbicide-nematicide combinations were studied in the field. Numbers of H. glycines juveniles and eggs were higher at midseason and harvest where nematicides were applied. Fenamiphos alone or in combination with alachlor provided better control of H. glycines and greater seed yields than treatments with ethoprop. Numbers of H. glycines eggs at harvest in 1980 were positively correlated with numbers of juveniles at planting in 1981 and negatively related to seed yield in 1981.

The population density of Meloidogyne incognita was significantly reduced in land that was fallowed or cropped to crotalaria, marigold, bermudagrass, or bahiagrass. The rate of population decline caused by different cropping systems was influenced by initial population densities. Crotalaria, marigold, and bare fallow were about equally effective in reducing the density of M. incognita below dctectable lcvels, usually requiring 1-3 yr. Bahiagrass and bcrmudagrass required 4-5 yr or longer to reduce M. incognita below a detectable level. A high population density of Trichodorus christiei developed in land cropped 5 yr to bermudagrass, bahiagrass, okra, and marigold. Population densities of Pratylenchus brachyurus and Xiphinema americanum increased in land cropped to crotalaria or bermudagrass. Belonolabnus Iongicaudatus was detected only in land cropped to bermudagrass, The effectiveness of nematicides in reducing M. incognita infection was rclatcd to nematode population density resulting from 5 yr of different cropping systems. Treatment with aldicarb reduced M. incognita below detectable levels following all cropping systems; treatment with ethoprop following all cropping systems except okra, treatment wflh ethylene dibromide following bahiagrass or fallow; and treatment with DBCP only after 5 yr of fallow. Tomato transplant growth was affected .by both cropping systems and nematicide treatment. Transplants grown after crotalaria and bahiagrass were significantly larger than those grown after other crops. Also, treatment with aldicarb and ethoprop significantly increased transplant size.

Greenhouse tests were conducted to determine the effects of two kinds of Meloidogyne hapla inoculum on the growth and quality of carrot roots, and the protection afforded in each case by nonfumigant nematicides in organic soils. For all treatments the percentage of carrots damaged was greater with larvae alone as inoculum than with larvae and eggs, indicating that most of the damage occurs early during formation of the taproot. Fosthietan, aldicarb, and oxamyl at 4 and 6 kg ai/ha protected the roots during formation and gave a lasting control of root-knot nematode. There was some nematode damage to the roots with phenamiphos and carbofuran at 4 and 6 kg ai/ha. Isazophos, diflubenzuron, and fenvalerate gave little protection to carrot roots and did not control root-knot nematode effectively.

A 2-year field study evaluated the influence of subsoiling and nematicide application, alone and in combination, on the growth and yield of field corn in a sandy soil in north-central Florida. The field had a 25-30-cm-deep tillage pan (plowpan) and was infested with Belonolaimus longicaudatus, Hoplolaimus galeatus, Trichodorus christei, and Pratylenchus spp. Subsoiling increased corn yield both years, and the residual effect of subsoiling in the first year increased yields in the second year. Preplant application of DD injected in-row increased yields and reduced nematode populations. At-planting applications of DD injected in-row and carbofuran in-furrow or in a band were less effective than subsoiling in increasing yields and reducing nematode numbers. Interactions between subsoiling and nematicide treatments occurred in the second year.

The duration of effectiveness of a foliar spray of oxamyl against Heterodera schachtii and the location of the protective effect were determined by applying a foliar spray at 0.04 kg (a.i.)/100 liters of water to cabbage seedlings. Oxamyl, or a metabolite of oxamyl, apparently is translocated to anti becomes prolective in the root within 7 days. Between 7 and 14 days, the location of the protection shifts from within the root In the root surface or rhizosphere. The chemical remains active for at least 21 days unless it is removed from the root or rhizosphere by washing with water.

Replicated trials were conducted near Alliston, Ontario, in 1983 and 1984 to evaluate the efficacy of five chemical treatments in controlling the root-lesion nematode Pratylenchus penetrans on potato, Solanum tuberosum cv. Russet Burbank. The fumigants Vorlex, at 55 liters product/ha, and Telone II B, at 75 liters product/ha, were more effective in suppressing high initial population densities of 18,320 and 50,880 P. penetrans/kg soil in 1983 and 1984, respectively, than single applications of the systemic pesticides Temik 10 G at 22 kg product/ha, Vydate L at 18 and 9 liters product/ha, and Furadan 10 G at 33 kg product/ha. The combination of Vorlex + Temik resulted in greatest nematode suppression and lowest populations at harvest. In 1983, marketable tuber yield (> 7 cm) in the Vorlex + Temik plots was 20.7 t/ha, compared to 4.7 t for the untreated check. Vorlex alone and Telone II B plots yielded 17.3 and 15.9 t/ha, respectively; Temik with 7.5 t also yielded better than the check. Vydate and Furadan did not influence yields significantly. Total yields differed from the check in all treatments except with Furadan. In 1984, marketable yields ranged from 15.5 t/ha for the Vorlex + Temik treatment to 11.2 for the untreated check, but the differences were not statistically significant. Total yields, however, were significantly increased by the fumigants. The difference in response to chemical treatment in the 2 years was attributed to greater heat stress and lack of supplementary irrigation in 1983.