Screening for resistance to big-vein disease of lettuce (Lactuca sativa)

A methods was developed for screening of breeding populations and evaluation of genotypes of lettuce for resistance to big vein. First and rapid screening of plant populations or large numbers of genotypes was in greenhouse trials by inoculation of the substrate in which the seedlings to be tested were grown with viruliferous zoospores of Olpidium brassicae. Further testing with limited numbers of genotypes was in container tests, using dry soil with viruliferous resting spores as inoculum. No single criterion or simple and early parameter was found to represent fully the final effect of the disease on yield and quality at the time of harvest. Effect on head weight was not correlated with disease incidence or sympton severity. The final effect on promising lines and cultivars could only be studied in field experiments after zoospore inoculation of seedlings in the greenhouse or on naturally infested soil. All 55 lettuce genotypes tested, including American ‘resistant’ crisphead cultivars and breeding lines, developed symptoms of big vein in either test, but there were considerable differences in length of incubation time, sensitivity, and capacity to recover from disease. Loss of head weight was considerable in all nine genotypes tested for yield reduction after early inoculation, and for the crisphead cultivars also after late inoculation. Cos lettuce ‘Lobjoit's Green’ and ‘grasse’ lettuce ‘Little Gem’ are promising parental genotypes for breeding for resistance, as are two entries of Lactuca virosa.     

Influence of treatment of soil with carbofuran on the subsequent performance of insecticides against cabbage root fly (Delia radicum) and carrot fly (Psila rosae)

A sandy loam soil was treated with 2·5 kg carbofuran/ha on each of five occasions between May and October 1984. In 1985, the field performance of benfuracarb, carbofuran, carbosulfan, chlorfenvinphos and furathiocarb against cabbage root fly (Delia radicum) and carrot fly (Psila rosae) was studied in this soil and in identical but previously untreated soil by applying exponentially increasing doses of granular formulations to radish and carrots at drilling. Chlorfenvinphos reduced numbers of larvae of both pests by >90% in both soils but the performance of all the carbamates was significantly worse in the previously treated soil than in the previously untreated soil. Dazomet, a partial soil sterilant, was applied to part of the experimental area in October 1985 and the performance of aldicarb, carbofuran, carbosulfan, chlorfenvinphos and thiofanox against cabbage root fly was assessed in 1986. The efficiency of aldicarb and chlorfenvinphos was not affected by any of the pre-treatments but that of carbofuran and carbosulfan was reduced in all the pre-treated soils, including the soil treated with dazomet. Carbofuran residues in radish were detectable only in plants grown in previously untreated soil. In laboratory incubations, a dustless base formulation of carbofuran was degraded more quickly in pre-treated than in untreated soils but a granular formulation was degraded more slowly and at a similar rate in both soils.     

The joint action of nitrogen and nematicides onPratylenchus penetrans and potato yield

The joint action of nitrogen fertilizer and nematicides onPratylenchus penetrons and yield was investigated using three potato varieties (Superior, Onaway and Russet Burbank), three rates of nitrogen (84, 168 and 336 kg/ha), five edaphic pesticides (disulfoton, aldicarb, 1,3-D + MIC, carbofuran and thiofanox), and an insecticide spray to minimize the role of foliar feeding insects In 1977, disulfoton, aldicarb, and disulfoton plus 1,3-D + MIC significantly increased the yield of Superior at all nitrogen rates. The yield increases ranged from 37–56% for Superior, 15–35% for Onaway and 13–27% for Russet Burbank. Nitrogen had no detectable influence on yield. Population densities ofP. penetrans were significantly reduced by disulfoton plus 1,3-D + MIC and by aldicarb. Superior was most susceptible toP. penetrans, Onaway intermediate, and Russet Burbank moderately tolerant. Neither the potato variety or nitrogen significantly influenced the population densities ofP. penetrans In 1978 aldicarb, 1,3-D + MIC and thiofanox significantly increased yields of Superior at all nitrogen rates. Nitrogen also significantly increased yields, but only where aldicarb and 1,3-D + MIC were applied. Total yield was increased 12–14% and 17–23% by 1,3-D + MIC and aldicarb at 168 and 336 kg N/ha, respectively. Aldicarb, 1,3-D + MIC, and thiofanox appeared to increase tuber set, while nitrogen increased tuber size. Although all of the nematicides provided some control ofP. penetrans, aldicarb had the highest degree of efficacy and gave excellent season-long control     

Effects of insecticides applied to control cucumber beetles (Coleoptera: Chrysomelidae) on watermelon yields

Foliar insecticides applied to control the striped and spotted cucumber beetles, Acalymma vittatum (Fab.) and Diabrotica undecimpunctata howardi Barber, on watermelon, Citrullus lanatus, were of little or no value in three studies conducted in two locations over 2 years. However, an at-planting application of the systemic, soil insecticide carbofuran resulted in higher early yields, although the differences were not statistically significant in small plots. In 1991, large plots comparing carbofuran-treated watermelons with untreated watermelons in two commercial fields showed large and statistically significant increases in melon yield when carbofuran was applied, especially in early yield. Studies in 1992 and 1993 showed that the application of carbofuran at planting stimulated root and shoot growth after transplating and increased yields when compared with untreated plots, plots treated with methyl bromide, or another soil insecticide, terbufos. These studies suggest that carbofuran may be acting as a growth stimulant, as well as an insecticide.     

Effects of nematicides on the chemical composition of the fruits of egg-plant (Solanum melongena L.)

Five nematicides — aldicarb, carbofuran, phorate, fensulfothion and DBCP — were studied in a field experiment to investigate their effect on the chemical composition of the fruits of egg-plant. There were no significant differences in the dry matter content of fruits from different treatments. A significant decrease in the crude protein content was observed with nematicide treatments. Phenolic compounds increased on application of phorate while all other treatments, except carbofuran, decreased these compounds. A significant increase over control in solasodine content of fruits was observed with all treatments.     

机械插秧与条播对盐粳15号生育性状与品质的影响

对水稻新品种盐粳15号2018、2019年连续2年在江苏盐城地区机插和机条播2种栽培方式的种植表现进行考察,主要测试该品种的生育期安全性、叶龄、分蘖动态、产量和品质性状。结果表明,该品种在盐城地区具有安全稳定的生育期,2年机插条件下全生育期分别为158、155 d,机条播条件下全生育期分别为138、134 d。该品种分蘖能力强,机插条件下2年成穗数分别为25.8万、26.1万个/667 m^2,机条播条件下2年成穗数分别为28.8万、27.9万个/667 m^2。该品种产量潜力高,2年机插和机条播产量均在700 kg/667 m^2以上。该品种机插条件下直链淀粉含量2年分别为15.3%、15.6%,蛋白质含量分别为9.8%、9.7%;机条播条件下直链淀粉含量2年分别为16.2%、16.7%,蛋白质含量分别为9.1%、9.0%。     

The control of weed,pest and disease complexes in cowpea (Vigna unguiculata (L.) Walp.) by the application of pesticides singly and in combination

Several pesticides were evaluated singly and in combination or mixtures for their effectiveness against insects, nematodes, diseases and weeds in cowpea at Ibadan and Amakama in Nigeria. Of the granular insecticides/nematicides, carbofuran at 3·0 kg a.i./ha applied at planting reduced the population of thrips (Megalurothrips sjostedti) below control level up to 42 days after planting, but did not appear to translocate to the pods. Ethoprofos, isazophos and phorate were ineffective against thrips. Carbofuran also showed excellent control of the root-knot nematode, Meloidogyne incognita. The herbicides metolachlor and fluorodifen generally kept the plots weed-free up to 35 days after planting but had no effect on the nematodes. The fungicide benomyl applied as a seed treatment was not effective against web blight (Corticium solani) and brown blotch (Colletotrichum truncatum) but, when applied as a wettable powder in combination with monocrotophos as a foliar spray, offered effective control of the diseases and the combination gave the best grain yield across locations. The possible use of carbofuran with a cowpea variety that is resistant to larvae of the pod-boring moth (Maruca testulalis) is discussed.     

Use of pesticides to determine relative importance of pest and disease factors limiting establishment of sod-seeded lucerne

The most likely reasons for seeding failures of sod-seeded lucerne ( Medicago sativa L.) were determined from eight field experiments, where the effects of a range of pesticides on the establishment of and damage to lucerne were compared. The experiments were conducted during 1979–80 at four sites near Ithaca, N.Y., USA. Pesticides evaluated were: methyl bromide (MeBr), carbofuran, acylalanine (1979, 1980); fonofos, diazinon, methiocarb, metaldehyde and combinations of carbofuran with methiocarb or metaldehyde (1980). Seeded areas were pretreated with glyphosate for vegetation control.
In 1979 seedling losses were decreased by carbofuran and methyl bromide whereas in 1980 seedling losses were decreased by methyl bromide at two sites and by methiocarb at all sites. Methiocarb was the only pesticide to reduce defoliation damage. The effect of combining methiocarb and metaldehyde each with carbofuran tended to be additive in terms of reducing seedling numbers and damage, and increasing yield. Treatment effects on lucerne yield were still apparent up to 12 months after seeding. Based on the consistent results of methiocarb, it was concluded that molluscs were probably the main factor limiting the establishment of sod-seeded lucerne but an arthropod component also appeared to be involved.     

An assessment of insidious pest damage to 26 varieties of seven species of herbage legumes

During 1977–79 the dry-matter yield of 26 herbage legume varieties receiving frequent applications of the organophosphorous pesticide phorate was compared with that of untreated plots. The total annual DM yield of sainfoin and lucerne was not affected by pesticide treatment. White clover yield was affected: pesticide application increased the DM production of the nine varieties studied by, on average, 9% in 1978 and 13% in 1979. The proportion of white clover present in white clover/ryegrass plots was enhanced by pesticide treatment. No attempt was made to establish the identity of the pest group(s) that may have been responsible for these effects. In a second experiment there was no significant effect on seedling establishment from phorate treatment applied to six legume varieties at the time of sowing.     

Effect of pythium root rot on yield of white bean, Phaseolus vulgaris L.

The effects of Pythium paroecandrum and P. ‘spherical’ on seed yield of white bean (Phaseolus vulgaris L.) were determined under field conditions. Fenaminosulf (Lesan) applied as a soil drench selectively suppressed Pythium populations in soil and increased seed yields by 47% in 1976 and by 33% in 1977. Fumigation of soil with DD-MIT (Vorlex), a commercial mixture of methyl isothiocyanate, dichloropropenes and dichloropropanes, reduced populations of Pythium and Fusarium in soil and increased seed yields by 79% in 1976 and by 29% in 1977. The combination of fenaminosulf and DD-MIT produced the greatest reductions in soil populations of Pythium and Fusarium and increased seed yields by 65%. Pythium paroecandrum and P. ‘spherical’ were associated with feeder-root necrosis and were the only bean-root pathogens detected at the experimental site. In this study, losses in seed yield of white bean due to Pythium root rot were estimated to be 44% in 1976 and 39% in 1977.     

Long-term dry preservation of viable mycelia of two mycoherbicidal organisms

The production of large amounts of fungal spores for preservation and formulation are considered constraints to effective use of fungal biocontrol agents. Few successful attempts have been made to store fungal mycelia alone. Late log-phase liquid fermenter cultured isolated mycelia of two Fusarium spp. specific to the parasitic broomrapes (Orobanche spp.) from fermenters were formulated in alginate beads or in ‘Stabileze’ (starch, sucrose, corn oil, and silica) and air-dried. ‘Stabileze’ formulations exhibited <30% loss of mycelial viability for >9 months and retained pathogenicity to the weed for over a year, while mycelia harvested earlier, and conidia from liquid culture exhibited >40% loss of viability. Mycelia from liquid culture yielded >20 times more colony forming units (cfu) of F. arthrosporioides and >2 times more cfu of F. oxysporum than spores at late log phase. Efficient formulation of mycelia should significantly change the economics of biocontrol.     

Possible alternative utilization of Cynara spp.: I. Biomass, grain yield and chemical composition of grain

Globe artichoke (Cynara scolymus L.) and cultivated cardoon (C. cardunculus L. var. altilis DC.) are horticulturally important crop plants. These species have potential as biomass and oilseed crops. We field tested, for 3 years, two artichoke and two cardoon cultivars and one wild cardoon (C. cardunculus L. var. sylvestris Lam.) population on the Sicilian plain of Catania (37°27′ N, 15°04′ E, 10 m a.s.l.). On a 3-year average, the dry aboveground biomass resulted about 31 t ha⁻¹ in both cultivated cardoons, 18.8 t ha⁻¹ in wild cardoon, 13.7 t ha⁻¹ in globe artichoke ‘3/10 V.S.’ and 9.9 t ha⁻¹ in globe artichoke ‘374’ F₁. The caloric values of aboveground biomass (except for seeds), which was not significantly different among genotypes, ranged between 16 005 and 17 028 KJ kg⁻¹ of dry matter. The cultivated cardoon ‘Gigante di Lucca’ had the greatest grain yield (on 3-year average, 2.6 t ha⁻¹), whereas the two globe artichokes had the lowest yield (on 3-year average, 0.5 t ha⁻¹). Regardless of genotypes and years, the grains contain 20.1% crude protein, 24.4% oil, 18.5% crude fiber and 4.1% ash (dry weight basis). The grains of globe artichokes showed the highest crude protein content (21.6%), whereas those of cardoons the highest oil content (25.2%).     

Response of Potatoes to Soil-Applied Insecticides, Fungicides, and Herbicides

Non-target impacts of pesticides are well documented in crops such as soybeans and corn. However, little effort has been made to evaluate these impacts in potatoes. Field trials were conducted at the Parma and Aberdeen Research and Extension Centers during 2005 and 2006 to evaluate the potential for systemic insecticides, fungicides, and herbicides to affect disease development, crop injury, and tuber yield. The first set of trials evaluated six insecticide treatments (aldicarb, oxamyl, phorate, imidacloprid, thiamethoxam, and non-treated) in a factorial combination with in-furrow application of the fungicide azoxystrobin. Azoxystrobin significantly decreased Rhizoctonia stem canker, while aldicarb and phorate tended to increase it compared to the non-treated control. There was a significant insecticide by fungicide interaction due to a bigger reduction in disease index by the fungicide when certain insecticides were used. Despite the association of these insecticides with increased disease incidence, there was no significant impact on yield. In the second set of trials, sulfentrazone herbicide was applied just prior to plant emergence to potatoes treated with the same six insecticides to evaluate the potential for the in-furrow treatments to increase plant injury. Sulfentrazone caused stunting and visible plant injury, but the level of plant injury was influenced by insecticide treatment in only one out of four trials.     

Controlled-release insecticide granules, compared with other soil insecticides, for use against the termite, Macrotermes natalensis Haviland, in the establishment of Eucalyptus plantations

Following the banning of DDT and dieldrin, and pending the withdrawal of other organochlorine insecticides in many countries, there is a need to find alternative treatments against termites for the establishment of Eucalyptus forestry plantations. Controlled-release granules (CRG) of carbosulfan, carbofuran and phorate were nearly as effective as chlordane emulsifiable concentrate (0·6 g a.i./tree) in reducing attack on Eucalyptus grandis W. Hill ex Maiden by Macrotermes natalensis Haviland. The optimum application rate of CRG formulations was 1·0 g a.i./tree mixed with the surrounding soil at planting out. Changes in granule size and release rate had no discernable effect on the efficacy of the granules, nor was there any advantage in incorporating part of the dose in the seedling planting medium. Chlorpyrifos CRG was significantly less effective in protecting the trees. There was evidence that under dry soil conditions phorate CRG was ineffective. Of 11 other non-controlled-release insecticides tested, alphamethrin suspension concentrate at 0·1 g a.i./tree was the only non-organochlorine material as effective as the CRG formulations.     

Accelerated degradation of aldicarb and its oxidation products in previously treated soils

The persistence of aldicarb, aldicarb sulphoxide and aldicarb sulphone was studied in soils used for crops grown commercially and in experimental soils with different histories of treatment with a granular formulation of aldicarb. Total aldicarb residues declined more rapidly in incubations in all the previously treated soils (initial 50% loss in 5–17 days at 15°C) than in the corresponding untreated soils (initial 50% loss in 25–50 days). This was largely because of more rapid breakdown of aldicarb sulphoxide and, to a lesser extent, of aldicarb sulphone. Accelerated degradation was induced more readily by pretreatment with carbofuran than with aldicarb or thiofanox and seemed to be influenced at least as much by dose level as by frequency of pretreatment. It is concluded that rotation of chemical usage should suppress development of the phenomenon with commercially recommended doses of aldicarb but that the potential for cross-enhancement is still little understood.     

Effects of row application of insecticides at sowing on leaf miner (Pegomya betae) injury to sugar beet

Injury to the leaves of sugar-beet seedlings caused by the mining of Pegomya betae larvae was greatly decreased by applying insecticide granules in the furrow with the seed: carbofuran, carbosulfan, terbufos and aldicarb were very effective but bendiocarb was only partially effective. Carbosulfan applied as a band spray along the row was less effective than the better granule treatments, while band sprays of gamma-HCH, quinalphos and oxamyl were ineffective or even increased the incidence of damage.     

Effects of new field resistant cultivars and in-furrow applications of phorate insecticide on tomato spotted wilt of peanut

Field experiments were conducted at Tifton, Georgia from 2008 to 2014 to determine the effects of new peanut (Arachis hypogaea) cultivars and in-furrow applications of phorate insecticide on severity of tomato spotted wilt (TSW) caused by Tomato spotted wilt virus. Several cultivars, including Florida-07, Georgia-06G, Georgia-07W, Georgia Greener, and Tifguard, had final incidence of TSW that were less than that of Georgia Green. In-furrow applications of phorate insecticide reduced incidence of TSW in Georgia Green in three experiments in which that cultivar was included. In-furrow application of phorate insecticide reduced incidence of TSW in most cases where incidence in nontreated plots was 10% or higher. Cultivars Georganic, and Georgia-10T, had final incidence of TSW that was lower than that of Georgia-06G, or Florida-07 within nontreated plots across 2011–2012. Georgia-10T and Georgia-12Y had final incidence that was lower than that of Georgia-06G, Georgia-07W, Georgia-09B and Georgia Greener across insecticide treatments in 2013. In-furrow application of phorate increased yields across cultivars in 2008–2009, and increased yield of Georgia-09B in 2010. In most other cases, phorate had no significant effect on yield. With higher levels of field resistance in most of these cultivars, especially those such as Georgia-12Y, benefits from use of phorate insecticide for TSW suppression were small, and typically did not result in yield increase. Based on these results, several of these cultivars should allow greater flexibility for insecticide choice for thrips management without increasing the risk of losses to TSW.     

Control of barley brown rust, Puccinia hordei Otth., by benodanil and oxycarboxin in the field and the effects on yield

Infection of barley by Puccinia hordei Otth. was more severe in the field under a high-nitrogen than under a low-nitrogen regime. Benodanil and oxycarboxin controlled rust and gave significant yield increases. Spray programmes were compared: a single spray applied after a ‘risk period’ of favourable weather gave control equivalent to a single mid-season spray. Yield was affected through a reduction in fertile tillers, number of grains per ear and grain weight. There were significant negative correlations between disease level and yield and grain weight. Based on regression analysis, yield losses of 0·6% were estimated for each 1% increment of disease assessed at GS75 (Zadoks) under the high-nitrogen regime, and losses of 1·5% under the lower-nitrogen condition.     

Break crop benefits in temperate wheat production

Changes in the sequence of crops grown on agricultural land are well known to enhance the yield of grain crops such as wheat. A survey of the literature gathered from around the world show mean yield benefits of up to 20% or more. Much is known about the principal mechanisms responsible for these benefits, including effects on disease control, improved nitrogen nutrition and water supply, although researchers continue to be challenged by inexplicable “rotation effects” that have yet to be documented or fully understood. This review summarizes our current understanding of the ‘better-known’ mechanisms of crop rotation, and discusses other mechanisms (e.g. changes in rhizosphere biology, allelopathy or soil structure) that may help to account fully for the rotation benefits that have been observed by agricultural producers for more than 2000 years. Where possible we emphasise new techniques employed to investigate these less well-understood aspects of the “rotation effect”. At the farm level, the inability to capitalize on the benefits of break crops may owe more to economics, the availability of suitable break crops and the complexity of the crop response. Computer-based decision support tools have been developed to assist growers to apply the information gathered from scientific studies, although efforts to integrate this information at whole-farm scales are embryonic.     

Management of the root-knot nematode Meloidogyne graminicola infesting rice in the nursery and crop field by integrating seed priming and soil application treatments of pesticides

The study evaluates the effects of seed priming (5 g or ml kg⁻¹ seed) and soil application (2 kg or l ha⁻¹) of eight organophosphate pesticides on rice root-knot disease caused by Meloidogyne graminicola. Seed priming (SP) or soil application (SA) of phorate, carbofuran and chlorpyriphos (1000 J₂ of M. graminicola kg⁻¹ soil) suppressed galling in the rice nursery by 92 and 99%, 80 and 88% and 76 and 80%, respectively, over control. Relatively similar decreases in the galling were recorded when this nursery was grown for four months in the sterilized soils in earthen pots. Rice cv. PS-5 grown in naturally infested soil in earthen pots (1000 J₂ kg⁻¹ soil) became stunted, showing chlorotic foliage, and terminal galls developed on the roots. The treatment of SP + SA 15 + 30 days after planting (DAP) with phorate, carbosulfan, and chlorpyriphos significantly suppressed the root-knot development and improved the plant growth of rice over the controls (P ≤ 0.05). The overall effect of the SP + SA 15 DAP treatments was marginally weaker than the SP + SA 15 + 30 DAP treatments but statistically on par. Under field conditions, the greatest decrease in the galling occurred due to SP + SA 15 + 30 DAP of phorate (69−71%) and SP + SA 15 DAP (65−67%) followed by carbosulfan and chlorpyriphos. The yield of rice plants was also highest with phorate (32−36% and 29−34%) over the control during the two years of the study. The soil population of M. graminicola decreased by 58–84% over four months due to the phorate treatments. The study demonstrates that seed priming with phorate effectively controls nematode infections in the nursery and that soil application at 15 DAP (2 kg ai ha⁻¹) prevents root-knot development in an infested field under irrigated conditions. Use of SP + SA 15 DAP may enable to avoid one soil application of phorate in the field.