Control of potato cyst-nematode, Globodera pallida, on tomatoes grown under glass, by applying steam or chemical nematicides to the soil

In a sandy loam under glass, potato cyst-nematode, Globodera pallida, was controlled in soil to 20 cm deep, and tomato yields were greatly increased by sheet steaming for 4 h, by 977 kg methyl bromide ha^-1 or by 448 kg Telone (1,3-dichloropropene mixture or Di-Trapex CP (20% methyl isothiocyanate: 15% chloropicrin:65% dichloropropene-dichloropropane mixture) ha^-1 followed by 441 kg dazomet or 11.2 kg oxamyl ha^-1. Sheet steaming, unlike the other treatments, had relatively little effect on the nematode in soil 20 to 40 cm deep. Until the apices of the plants were cut off production of fruit was curvilinear against time in all treated soil but linear against time in untreated soil.     

Incorporating granular nematicides in soil to control potato cyst-nematode, Heterodera rostochiensis

Incorporating either Du Pont 1410 or Nemacur P at 11-2 kg a.i./ha in peaty loam topsoil in Spring, controlled potato cyst-nematodes (Heterodera rostochiensis) to 20 cm deep as well as did 5.6 kg incorporated in Winter before ploughing followed by another dose of 5.6 kg incorporated in the seedbed in Spring. In pots Du Pont 1410 remained effective after several months incubation in soil at 5 or 10 ^oC. Dazomet at 440 kg/ha incorporated in the topsoil in Winter (220 kg before ploughing and 220 kg after ploughing) did not control the nematodes as consistently as 5.6 or 11.2 kg a.i./ha of Du Pont 141 o or Nemacur P, even when the dazomet-treated plots were covered with Polythene sheeting to prolong fumigation. In large containers, aldicarb at 45 mg a.i./13 l soil increased the yield of Arran Banner potatoes as much when incorporated to 13 cm deep in moderately infested peaty loam as when incorporated to 25 or 38 cm deep, but not as much as when all the soil (to 51 cm deep) was treated. Treating the soil to 13 cm deep did not control the nematodes 13–25 cm deep even though some of the nematicide was probably leached into this layer. In field plots, the nematodes were better controlled when Du Pont 1410 or Dowco 275 was rotavated into the top 10 cm than into the top 20 cm of a peaty loam soil. Rotavating soil twice instead of once after applying aldicarb, Du Pont 1410 or Dowco 275 to the soil surface did not increase nematode control. Although small amounts of aldicarb incorporated into the topsoil in Spring controlled the nematodes, the same amounts concentrated in the seed furrows, just before susceptible potatoes were planted in them, did not.     

Effects of D-D, Telone or dazomet applied to potato ridges in spring on potato cyst-nematode, Heterodera rostochiensis, in sandy loam and silt loam soils

Large amounts of dazomet (329, 439 kg/ha) applied to potato ridge soil in spring, before potatoes were planted, controlled potato cyst-nematode (Heterodera rostochiensis) in sandy loam and silt loam more effectively than large amounts of D-D (359, 448 kg/ha). In heavily infested sandy loam, 329 kg dazomet/ha or 857 kg methyl bromide/ha applied in spring 1969 or 439 kg dazomet/ha applied in autumn 1968, greatly decreased the number of larvae able to invade potato roots, so Majestic potatoes grew and yielded well without increasing the number of nematodes left in the soil after harvest. Large amounts of D-D or Telone applied to the topsoil in autumn or to the ridges in spring were less effective in controlling potato cyst-nematode or increasing potato yields. Applied in spring 1969 to silt loam ridges, 439 kg dazomet/ha had more effect than 448 kg D-D/ha on potato cyst-nematode and on the increase in yield of Majestic potato. The yield of Maris Piper potatoes (resistant to H. rostochiensis pathotype A) in infested silt loam was increased greatly by D-D, as much by 112 as by 224 or 448 kg/ha.     

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.     

Treating potato ridges in spring with aldicarb, D-D or dazomet to control potato cyst-nematode, Heterodera rostochiensis, in sandy clay and peat loam soils

Applied to potato ridge soil in spring, before potatoes were planted, small amounts of aldicarb (10-3 kg/ha or less) controlled potato cyst-nematodes (Heterodera rostochiensis Woll.) better than large amounts of dazomet (110–466 kg/ha) or D-D (102–439 kg/ha). Applied in spring 1968 and 1969 to heavily infested sandy clay soil 466 kg dazomet/ha allowed Majestic potatoes to grow and yield well in both years without increasing the number of nematodes in the soil after harvest, but in peaty loam dazomet was toxic to potato plants and, when applied in autumn, killed fewer nematodes. D-D in potato ridges in spring controlled nematodes less well than dazomet or aldicarb, but 896 kg D-D/ha injected in sandy clay soil in autumn increased potato yield the following year without increasing the number of nematodes after harvest.     

Control of potato cyst-nematode, Heterodera rostochiensis, in sandy loam, by Du Pont 1410 (S-methyl l-(dimethylcarbamoyl)-N-[(methylcarbamoyl) oxy] thioformimidate) applied to the soil at planting time

When applied to heavily infested sandy loam soil at planting time, as little as 5 ppm Du Pont 1410 (5-methyl I-(dimethylcarbamoyl)-N-[(methylcar-bamoyl) oxy] thioformimidate) in pots, or 2–5 ppm in field plots, effectively controlled potato cyst-nematode, Heterodera rostochiensis Woll., and greatly increased the growth and yield of susceptible potatoes. Dipping the shoots of potted King Edward potatoes once in aqeuous solution containing 2000 ppm did not control potato cyst-nematode. Nematode control was not increased when 2 or 4 kg a.i./ha was sprayed on the foliage of young Pentland Crown potatoes growing in soil already treated with the nematicide.     

Control of potato cyst-nematode, Heterodera rostochiensis, in three soils by small amounts of aldicarb, Du Pont 1410 or Nemacur applied to the soil at planting time

Aldicarb or Du Pont 1410 (S-methyl 1-(dimethylcarbamoyl)-N-[(methylcarbamoyl) oxy] thioformimidate) at 2.6–11.2 kg a.i./ha applied to the soil at planting time controlled potato cyst-nematode, Heterodera rostochiensis, in sandy loam, peaty loam and silt loam and greatly increased tuber yields of susceptible potatoes. Nemacur (O-ethyl-O-(3-methyl-4-methylthiophenyl) isopropylamido-phosphate) controlled potato cyst-nematode in sandy loam at 2.9–10.3 kg a.i./ha and in silt loam at 11.2 kg a.i./ha but did not control the nematode well in peaty loam even at 22.4 kg a.i./ha. In peaty loam aldicarb and Nemacur were more effectively incorporated by rotavation than by a modified power harrow.     

Control of potato cyst-nematode, Heterodera rostochiensis, in sandy, peaty and silt loam soils by dazomet and Telone applied in different ways

Dazomet applied in the ridges in autumn or in spring, before potatoes were planted in them, controlled potato cyst-nematode (Heterodera rostochiensis), British pathotype A, better in sandy loam and peaty loam than Telone (1,3-dichloropropene mixture). In sandy loam dazomet controlled potato cyst-nematode as well when applied in spring as when applied in autumn and as well when the soil was ridged after treatment as when it was not. Telone was as effective when applied to ridges in autumn as when applied to ridges in spring. In peaty loam potato cyst-nematodes were least abundant after a crop of Maris Piper potatoes. The yields of King Edward potatoes were greatly increased and nematode multiplication was greatly reduced by dazomet incorporated in the ridges in autumn. Two equal doses of dazomet, one incorporated in the topsoil before, the other after ploughing, controlled potato cyst-nematode as well and increased the yield of King Edward potatoes more than an equivalent amount of dazomet applied after ploughing. Dazomet applied to silt loam soil in two dressings, one before, the other after, ploughing, controlled potato cyst-nematode better than an equal amount applied as a single dressing after ploughing. The nematode was controlled best by two large dressings of dazomet or by a combined treatment of dazomet and Telone.     

Control of potato cyst-nematode, Heterodera rostochiensis, in silt and peat loams by ten pesticides applied to the soil at planting time

Incorporated in silt or peat loam top-soil in spring before susceptible potatoes were planted, three carbamoyl oximes, aldicarb, Tirpate (2,4-dimethyl-2-formyl 1-1,3-dithiolane oxime iV-methylcarbamate) and Du Pont 1410 (S-methyl i-(dimethylcarbamoyl)-N-((methylcarbamoyl) oxy) thioformimidate) and one organophosphate, Nemacur (O-ethyl-O-(3-methyl-4-methylthiophenyl)-isopropylamidophosphate) all at n-2 kg a.i./ha greatly increased the yield of tubers and effectively controlled potato cyst-nematode (Heterodera rostochiensis Woll.). At the same dosage thionazin was as effective in the peat loam but was ineffective in the silt loam; phorate and Mocap (O-ethyl S,S-dipropyl phosphorodithioate) were less effective and chlorfenvinphos, diazinon and a coarse granule formulation of fensulphothion were ineffective in controlling potato cyst-nematode.     

The effect of nematicides, applied to the seed rows in spring, on growth and yield of sugar beet in Docking-disorder-affected fields

Both Trichodorus spp. and Longidorus spp. damage roots of sugar-beet seedlings in sandy soil, causing Docking disorder. Trials in infested fields between 1969 and 1972 tested the effects of fumigation along the rows with different amounts of D-D or Telone applied either two weeks before sowing or immediately before sowing, application of the systemic nematicide aldicarb (Temik) in the furrow with the seed during sowing, and top-dressing with nitrogen. Seedling establishment was often decreased by fumigation immediately before sowing, especially when followed by excessive rainfall, but only rarely by earlier fumigation or by aldicarb; differences in numbers of roots harvested were smaller because hand-singling removed excess seedlings. There was usually little difference between the yield increases given by the most effective treatments, which were aldicarb at 1·12 kg active ingredient/ha and 2·2–6·6 ml D-D or Telone/m of row at either time of application. Nitrogen top-dressing never affected sugar yield significantly. Longidorus spp. and Trichodorus spp. were both controlled well in the fumigated row but much less well at 13 cm, and not at all at 25 cm from the row (i.e. mid-way between two treated rows).     

Control of potato cyst-nematodes, Globodera rostochiensis and G. pallida, in different soils by small amounts of oxamyl or aldicarb

In eleven field trials on peaty, sandy or silt loam soils, aldicarb or oxamyl, incorporated in the soil to 15 cm deep before susceptible potatoes were planted, controlled potato cyst-nematodes (Globodera rostochiensis (Woll.) Mulvey & Stone, 1976 and G. pallida (Stone) Mulvey & Stone, 1976) better at 5–6 kg than at 3–4 or 2-2 kg a.i./ha. Incorporated in the soil to 7-5 cm deep 5–6 kg/ha of aldicarb or oxamyl controlled the nematodes less effectively at some sites. At 3–4 kg a.i./ha there was no difference in nematode control between the two incorporation depths.     

Effects of soil fumigation on soil nitrogen and on disease incidence in winter wheat

Winter wheat was grown in soil fumigated with D-D, 85% dazomet dust or formalin, and top-dressed with o or 125 kg nitrogen/ha. Six weeks after fumigation, there was much more ammonium nitrogen in fumigated than in unfumigated soil. Nitrate was also more after fumigation with dazomet, but less after D-D and formalin. After 5 months, only D-D plots had less nitrate and more total mineral nitrogen than unfumigated plots. Take-all (Ophiobolus graminis) was less prevalent in the first crop after dazomet or formalin, but was more prevalent in the second crop than after other treatments. Eyespot (Cercosporella herpotrichoides) was decreased only by formalin and only in the first crop after applying it. Fumigation had little effect on the incidence of other diseases recorded or on grain yield, except that yields were light on D-D plots in the first crop after fumigation, when ears were severely deformed.     

The effects of soil fumigation and nitrogen fertilizers on nematodes and sugar beet in sandy soils

In fifteen experiments on light land infested with plant-parasitic nematodes, fumigating the soil during the previous winter with D-D increased the average yield of sugar-beet roots from 25 to 36 t/ha; this was more than that obtained with various forms of nitrogenous fertilizers used in amounts up to 250 kg N/ha. Application of 85 kg N/ha increased yields on fumigated plots by 7 t/ha, and there was little benefit from giving more. Fumigation killed 65 % of the Pratylenchus spp., 80% of the Trichodorus spp. and 90% of the Tylenchorhynchus spp. in the top 5 cm of the soil and, at 15–20 cm deep, 90, 93 and 95% of these three genera. The increased yield from fumigant at different sites was not correlated with the initial populations of nematodes. The average increase in yield from fumigation was only poorly correlated with rainfall during May. The increases in nematode populations between April and August depended on rainfall, and were 0positively correlated both with the accumulated rainfall for the 10 weeks before sampling the soil in August and with the rainfall during the week previous to sampling. Fumigation not only improved the health of roots, and so enabled them to use nitrogen more efficiently, but also increased the amount of available nitrogen in the soil and decreased the amount lost by leaching. Injected anhydrous ammonia did not affect the populations of nematodes.     

Effects of Fumigants and Systemic Pesticides on Pratylenchus penetrans and Potato Yield

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.     

Differential Vertical Movement of Nonvolatile Nematicides in Soil

When incorporated in the top 5-cm of Tifton sandy loam at 11.2 kg/ha in the field, B-68138 [ethyl 4-(methylthio)-m-tolyl isopropyl phosphoramidate] prevented galling of tomato roots by Meloidogyne sp. down to 20 cm. A similar application of 16.8 kg/ha of V-C 9-104 [0-ethyl S,S-dipropyl phosphorodithioate] was 99% effective down to 20 cm. Aldicarb [2-methyl-2-(methylthio) propionaldehyde 0-(methylcarbamoyl) oxime], B-25141 [0,0-diethyl 0-{p-(methylsulfinyl) phenyl}phosphorothioate], and carbofuran [2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] prevented galling only in the zone of incorporation (top 5-cm of soil). When aldicarb (11.2 kg/ha) was applied to the surface of Ontario fine sandy loam contained in clay pots in the greenhouse, it prevented galling of tomato roots down to 20 cm deep. V-C 9-104 and B-68138, applied similarly, were 100% effective to a depth of 5 cm. B-25141 was 100% effective in the zone of incorporation only. D-1410 [S-methyl-l-(dimethylcarbamoyl)-N-l(methylcarbamoyl)oxy] thioformimidatel did not control 100% of the root-knot nematodes at any depth.     

Dispersion,Dissipation, and Efficacy of Methyl Bromide-Chloropicrin Gas vs. Gel Formulations on Nematodes and Weeds in Tifton Sandy Loam

Dispersion, dissipation, and efficacy of gas and gel formulations of methyl bromidechloropicrin (202, 269, 336, and 403 kg/ha) on nematodes and weeds on tomato were studied in field plots. Concentrations of methyl bromide and chloropicrin 4 hr after soil treatment were greater at a depth of 15 cm than at 30, 45, or 60 cm. The concentrations of both chemicals decreased with lower doses, greater depths, and longer times after application. The gel formulation was more persistent than the gas formulation at both 336 and 403 kg/ha at depths of 30 and 45 cm, especially 24 and 36 hr after chemical application. Plant growth and yield were improved when nematodes and weeds were controlled.     

Control of potato cyst-nematode, Globodera rostochiensis Rol, by picrolonic acid and potato trap crops

Small, sprouted tubers of potatoes (cv. Pentland Crown) grown for 6 wk and then pulled out of soil infested with potato cyst-nematode, Globodera rostochiensis Roi, increased the hatch of larvae, so that 100 days after planting the top 20 cm of the soil contained only one third of the original number of eggs. The artificial hatching agent picrolonic acid alone at 8-6, 17*2 or 34-4 kg/ha rotavated into the soil did not increase hatch but 17*2 kg, incorporated in the soil after potatoes grown for 4 wk, did.     

Effects of Cover Cropping, Solarization, and Soil Fumigation on Nematode Communities

Impacts of sustainable soil-borne pest management strategies on the soil ecosystem were compared to that of methyl bromide fumigation using nematode community analysis. A field experiment was conducted in 2003 and repeated in 2004. Soil treatments carried out in summer months included methyl bromide (MB) fumigation, solarization (S) for 6 weeks, cowpea (Vigna unguiculata) cover cropping for 3 months (CP), combination of solarization and cowpea cover cropping (S + CP), and a weedy fallow throughout the summer used as a control (C). All treated plots were planted to pepper (Capsicum annuum) after the application of the treatments at the end of the summer. In general, responses of nematode communities to soil treatments were more obvious at pepper planting than at 4 months after planting. In 2003, initial population densities of bacterivores and fungivores at pepper planting followed a hypothesized pattern of MB > S > S + CP > CP > C. However, this perturbation did not persist after a cycle of vigorous growth of a pepper crop. Omnivorous nematodes were the most sensitive nematode trophic group, with impact from soil treatment lasting until the end of the pepper crop. Nematode community indices such as ratio of fungivores to fungivores plus bacterivores, richness, and structure index were especially useful in detecting impacts by the various soil treatments. While disturbance from MB on the nematode communities lasted at least until the end of the pepper crop, that from the solarization often reduced or disappeared at the end of the experiment. The CP treatment enhanced many of the beneficial nematodes but failed to suppress the final population densities of herbivorous nematodes at pepper harvest (Pf). However, CP + S consistently reduced the Pf of herbivores to levels equivalent to MB in both years, whereas, this level of suppression could not be achieved by either CP or solarization alone.     

Control of potato cyst nematode (Globodera rostochiensis) by nematicides and a resistant potato cultivar at four sites in Scotland

The control of potato cyst nematode (Globodera rostochiensis) by the oxime-carbamates aldicarb and oxamyl was tested in four fields in Scotland. Dazomet was tested in three of these fields and carbofuran in one. In untreated plots in the three most heavily infested fields Maris Piper (resistant) yielded better than Pentland Crown (non-resistant). All nematicides increased the yields of both potato cultivars but had a greater effect on the yield of Pentland Crown. Dazomet increased yields of tubers most. Heavy nematode infestation reduced yield of tubers more in a sandy soil than in two sandy loams. In a field with few potato cyst nematodes nematicides did not significantly affect tuber yields. Although the nematicides greatly increased yields, they were not completely effective in controlling potato cyst nematodes. In treated plots in the lightly infested field, there were more nematode eggs following a crop of Pentland Crown than before. In contrast, Maris Piper markedly decreased post-cropping populations and except at one site, where dazomet further decreased nematode numbers, combining nematicides with the resistant cultivar failed to decrease nematode numbers further. Nematicides decreased the numbers of larvae invading potato roots by up to 95%, oxamyl at 5–6 kg/ha being consistently the best treatment.     

Preplant Fumigation for Citrus Nematode Control in Florida

Preplant soil fumigation experiments were conducted to control the citrus nematode, Tylenchulus semipenetrans. Generally, D-D (1,3-dichloropropene, 1,2-dichloroptopane and related chlorinated C₃-hydrocarbons), Telone (1,3-dichloropropene and related chlorinated C₃-hydrocarbons), Telone PBC (80% 1,3-dichloropropene, 15% chloropicrin, 5% propargyl bromide), and EDB (ethylene dibromide) controlled T. semipenetrans effectively for 4 years. The trials involved four scion varieties, two rootstock varieties and three soil types. Tree growth and yield were increased with application of D-D at 374 or 561 liters/ha (40 or 60 gal/acre) or Telone at 299 or 449 liters/ha (32 or 48 gal/acre) in broadcast and strip treatments.