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1.
Kenaf (Hibiscus cannabinus L.) and sunn hemp (Crotalaria juncea L.) are industrial fiber crops that are being grown increasingly in areas where cotton (Gossypium hirsutum L.) is the major crop. The nematodes causing most cotton yield losses in the USA are the southern root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood, and the reniform nematode, Rotylenchulus reniformis Linford and Oliveira. For nematode management, knowledge about the comparative effects of kenaf, sunn hemp, and cotton on nematode population densities in the soil is important. The objective of this study was to clarify the host status of kenaf and sunn hemp to M. incognita and R. reniformis by directly comparing reproduction of each nematode on each crop with the same nematode's reproduction on nematode-resistant and nematode-susceptible cotton. Comparisons were made in six experiments under growth chamber, microplot, and field conditions. The results showed that sunn hemp is resistant, but not equally resistant to M. incognita and R. reniformis. Reproduction of R. reniformis on sunn hemp was nearly undetectable, whereas reproduction of M. incognita was greater than on resistant cotton (Auburn 623, Auburn 634) and up to 20% of that on susceptible cotton (Deltapine 16, Deltapine 50, or Deltapine 5409). Kenaf was confirmed to elevate populations of M. incognita to levels that devestate cotton, but found to support substantially less reproduction by R. reniformis than cotton does. Two populations of R. reniformis differed substantially in reproduction on kenaf even though the same populations reproduced similarly on cotton. In conclusion, distinguishing M. incognita from R. reniformis is essential to the management of nematodes in rotations involving kenaf, sunn hemp and cotton.  相似文献   

2.
Zucchini, Cucurbita pepo L., is often colonized by economically important insect pests such as the striped (Acalymma vittatum Fab.) and spotted (Diabrotica undecimpunctata howardi Barber) cucumber beetles. To evaluate the impact of an interplanted cover crop on arthropods associated with zucchini, field experiments were conducted in which sunn hemp (Crotalaria juncea L.) was interplanted with zucchini as a living mulch and compared with zucchini monoculture (bare-ground) during 2009, 2010 and 2011 growing seasons. The experiment consisted also of two types of fertilizer usage including the application of synthetic or organic fertilizer in the form of chicken manure. Foliar counts of arthropods conducted on zucchini plants showed significantly lower numbers of the striped cucumber beetle in sunn hemp interplanted plots compared to bare-ground treatment plots. Also, fewer spotted cucumber beetles were found on zucchini plants in sunn hemp plots. Aphid abundances were variable during the study and significantly lower in sunn hemp treatment plots at one study site in 2009. Among predators, spiders were significantly more abundant in sunn hemp treatment plots during 2009. Fertilizer type did not have a significant effect on arthropod numbers on zucchini plants. Potential causes of arthropod population differences among the two treatments are discussed.  相似文献   

3.
Crude extracts of wild cucumber (Cucumis myriocarpus) fruit, without information on their effects on nodulation, had been touted as having potential as a nematicide and a fertiliser in low-input cowpea (Vigna unguiculata) production systems. Interactive effects of the southern root-knot nematode (Meloidogyne incognita), Bradyrhizobium japonicum and crude extracts of wild cucumber (C. myriocarpus) fruit on each other and growth of cowpea variety Eureka were investigated in a 23 factorial experiment. At harvest, 70 days after initiating the treatments, significant (P ≤ 0.05) first order interactions between any two of the three main factors on variables measured were observed, with interactive effects being either stimulatory or inhibitory. Crude extracts of C. myriocarpus fruit were basically suppressive on nematode numbers but stimulated nodulation and growth of cowpea. Consequently, the material is suitable for use in managing population densities of M. incognita on cowpea production in low-input cowpea production systems.  相似文献   

4.
Sunn hemp is a tropical, herbaceous annual legume that has potential as a cover crop during the summer in temperate climates. Due to the recent increased interest in sunn hemp breeding and seed production for temperate climates, there is a need for weed control in sunn hemp production. No herbicide product currently on the market specifically identifies sunn hemp as a tolerant crop. The aims of this research were 1) to evaluate herbicides with the intent of identifying a herbicide program that can assure near weed free sunn hemp intended for seed harvest and 2) to demonstrate and quantify sunn hemp-weed suppression. Pre-emergence applied treatments consisted of pendimethalin alone, imazethapyr alone, and pendimethalin plus imazethapyr. Pendimethalin alone provided consistent effective weed control and maximum sunn hemp biomass, but when yellow nutsedge was present, imazethapyr was required for effective control and greater sunn hemp biomass. The combination of pendimethalin and imazethapyr was detrimental to sunn hemp biomass yield. Results also established that sunn hemp is tolerant of 2,4-DB applied post-emergence, but was not necessary for weed control in these studies because of the lack of broadleaf weed pressure. In a separate study with variable sunn hemp densities, weed biomass reductions of ≥50% were obtained with sunn hemp densities of only 20 to 50 plants m−2. This degree of weed suppression obtained from relatively modest sunn hemp densities is likely indicative of the ability of sunn hemp to grow faster and taller than other plants.  相似文献   

5.
Sunn pests (Eurygaster spp.) are among the most important insect pests of wheat (Triticum sativum L.) and barley (Hordeum vulgare L.). Cultural practices can prevent or minimize common sunn pest (Eurygaster integriceps Puton) population densities and crop damage. A three-year field experiment (Jun 05 to Aug 07) was conducted in Diyarbakır in the southeast Antolia region of Turkey, to evaluate the effects of planting method (no-till ridge planting and conventional planting) and earliness of durum wheat (Triticum durum L.) varieties (early, mid-season and late varieties) on E. integriceps density, grain damage and overall grain yield. The effect of the planting method on the sunn pest density and percent of grains damaged by sunn pest was not significant; however, there was a significant difference among the different varieties used in this study. While Çeşit-1252 (late wheat variety) had the highest nymph density (11.2 nymphs m−2) and percent of sunn pest damaged grains (2.8%), Sarıçanak-98 (early wheat variety) had the lowest nymph density (4.3 nymphs m−2) and percent of sunn pest damaged grains (0.8%). Grain yield was the highest (5.99 t ha−1) for Sarıçanak-98 while there was no significant difference between Aydın-93 (5.06 t ha−1) and Çeşit-1252 (4.99 t ha−1). In conclusion, this study suggests that planting methods may not have a significant effect on sunn pest density, percent of sunn pest damaged grains or grain yield; however, the use of early durum wheat varieties, such asSarıçanak-98, may reduce sunn pest population densities, percent of damaged grains, allowing increases in grain yield in southeast Anatolia region, Turkey.  相似文献   

6.
Studies to estimate root-knot nematode infestations on cucumber were conducted during mid- to late-season at 378 randomly selected sites in 126 villages of the four districts across the Pothowar zone of the country. The overall mean infestation of root-knot nematodes in the region was found to be 15.66%. The studies revealed variations in the incidence and severity of root-knot nematodes in the four districts. The incidence of root-knot nematodes was the highest in Rawalpindi district (21.86%), followed by 13.89% in Attock. Of the four districts, the minimum incidence of 10.97% was recorded in Jhelum district. The maximum mean severity (3.79), measured in terms of the galling index, was found in Rawalpindi district, while the minimum (1.86) was observed in Jhelum district. The mean severities of root-knot nematodes in the districts of Attock and Chakwal were 2.66 and 2.19 respectively. Variations in incidence and severity were also observed among subdivisions of the districts. Of all the associated species of root-knot nematodes, Meloidogyne incognita constituted 78.53%, Meloidogyne javanica 19.03%, Meloidogyne arenaria 1.82% and Meloidogyne hapla 0.62%. M. incognita and M. javanica were recorded in all of the districts, with M. incognita predominating. M. incognita as a pure population was recorded in 29.63% of the villages, while the other three species were found as mixtures. The most common mixed population was M. incognita and M. javanica, observed in 70.37% of villages in the region. M. arenaria and M. hapla were not found together in any of the population mixtures. The results indicate that cucumber is severely attacked by root-knot nematodes, warranting adoption of strict control measures for its management.  相似文献   

7.
Replicated field trials were conducted to determine the effect of 1,3-dichloropropene (1,3-D) as a potential alternative for methyl bromide (MeBr) in tomato–cucumber rotations in two successive cropping seasons in China. Fumigation with MeBr (400 kg ha−1), three 1,3-D doses (180, 120 and 90 l ha−1), an avermectin dose (187.5 g ha−1) and an untreated control were compared. Tomato data revealed that MeBr was generally superior to the treatments involving 1,3-D and avermectin, which in turn were superior to the control, for improving tomato crop yield and inhibiting Meloidogyne incognita, weeds and mortality caused by plant disease. In a successive cucumber crop, all fumigants tested except avermectin, showed significant continual influence in the same plots. In most cases, the highest 1,3-D dose was comparable to MeBr. Overall, in both growth seasons, 1,3-D at the dose of 180 l ha−1 was as effective as MeBr in increasing plant height, yield and in reducing the incidence of soil borne disease, especially in maintaining excellent M. incognita control, but it provided only moderate control of weeds. On the basis of these results, combining 1,3-D with other alternatives to MeBr, is recommended for satisfactory control of soil pests in tomato–cucumber rotations in China.  相似文献   

8.
Nitrogen fertilization is a common practice for sustaining forage production in forage systems in southeastern United States. Warm-season annual legumes may be an alternative forage to warm-season perennial grasses that do not require N fertilization. Sunn hemp (Crotalaria juncea L.) is a fast-growing, warm-season annual legume native to India and Pakistan. The objective of this 2-year study was to assess the herbage accumulation (HA), atmospheric N2 fixation (ANF) and nutritive value of sunn hemp. Treatments were the factorial arrangement of two sunn hemp cultivars (“Crescent Sun” and “Blue Leaf”), three seeding rates (17, 28 and 39 kg seed/ha) and seed inoculation (inoculated or non-inoculated seeds), distributed in a randomized complete block design with four replicates. Crescent sun had greater HA (3,218 vs. 1764 kg DM/ha) and ANF (41 vs. 25 kg N/ha). Blue leaf had greater crude protein (CP) (188 vs. 176 g/kg) and in vitro digestible organic matter (IVDOM) concentrations (564 vs. 531 g/kg) than crescent sun. Non-inoculated seed had greater CP than inoculated seed, 188 and 177 g/kg, respectively, and inoculation did not affect HA. Intermediate seeding rate (28 kg/ha) decreased HA (2002 kg DM/ha), while HA from high and low seeding rates (17 and 39 kg/ha, respectively) did not differ (2,863 and 2,615 kg DM/ha respectively). Planting non-inoculated crescent sun at 17 kg/ha seeding rate is a feasible management practice to produce sunn hemp in subtropical regions; however, inoculation should always be recommended for proper establishment.  相似文献   

9.
The root-knot nematode, Meloidogyne incognita, is one of the major limiting factors affecting plant growth and yield causing an estimated $100 billion loss per year worldwide. Synthetic pesticides, though instantaneously effective, are usually prohibitively expensive, not readily available, may cause hazards to both man and livestock, and inflict injury to the environment. Notable among the alternatives to nematicides is the use of resistant cultivars which are inexpensive and eco-friendly. In the present studies, twelve okra (Abelmoschus esculentus L) cultivars were evaluated for their resistance against M. incognita under field conditions. Ten-day old okra plants of test cultivars were inoculated with 3000 freshly hatched second stage juveniles of M. incognita. The nematode caused reductions in various growth parameters of all the cultivars to varying levels over their respective controls. None of the cultivars was found completely resistant. The cultivar ‘Sharmeeli’ was highly susceptible as >100 galls were recorded on the roots. Sharmeeli also showed maximum reductions in growth among the cultivars evaluated. The cultivars Anmol and Sindha were susceptible with 71–100 galls. The cultivars Sabz Pari, Super Star, PMS-55 and PMS Beauty were moderately susceptible with 31–70 galls and comparatively less reductions in growth. Cultivars Sanam, Dikshah, Arka Anamika, Ikra-1 and Ikra-2 with 11–30 galls were rated as moderately resistant and showed less damage by the nematode as compared to susceptible cultivars and their planting could provide a useful tool to control root-knot nematodes.  相似文献   

10.
Field trials were conducted to determine the potential use of thiacloprid for integrated Meloidogyne incognita and Bemisia tabaci B biotype control in cucumber (Cucumis sativus Linn.) in China. The following five treatments were evaluated: three thiacloprid doses (7.5, 15, and 30 kg ha−1), an avermectin treatment (7.5 L ha−1) and an untreated control. All thiacloprid application rates were effective for reducing the M. incognita and B. tabaci B biotype populations. M. incognita was reduced by 51.0%∼86.7% on 60th day and B. tabaci B biotype was reduced by about 37.2%∼95.3% within 21 days, respectively. In addition, greater thiacloprid doses resulted in fewer nematodes and whiteflies. Over two successive years, the cucumber plants that were treated with thiacloprid at a dose of 15 kg ha−1 had the greatest plant height, plant vigor and marketable yield, which were 134.1 cm, 91, 1514.3 g plant−1, respectively in 2010–2011 and 151.9 cm, 93, 1651.4 g plant−1, respectively in 2011–2012. In addition, thiacloprid was superior to avermectin. The results of this study demonstrated that thiacloprid could be used in cucumber production for the integrated control of M. incognita and B. tabaci B biotype. Furthermore, a dose of 15 kg ha−1 of thiacloprid was recommended for controlling nematode and whitefly populations according to the control effect and marketable cucumber yield.  相似文献   

11.
Loop-mediated isothermal amplification (LAMP), a novel DNA amplification technique, has been used to detect a variety of pathogens including viruses, fungi, bacteria and parasites. However, diagnosis of sedentary plant-parasitic nematode (PPN) species has not yet been attempted. In this study, we developed a universal LAMP set (RKN-LAMP) for the diagnosis of four common Meloidogyne species (Meloidogyne incognita, M. arenaria, M. javanica and M. hapla), and M. incognita-specific LAMP set (Mi-LAMP). In both assays, a typical ladder-like pattern on gel electrophoresis was observed in all positive samples but not in the negative controls. Amplification products were further confirmed using restriction analysis of the Hpa II enzyme, detection by visual inspection using SYBR Green I and the lateral flow dipstick (LFD) assay. The two LAMP sets were specifically able to detect four common Meloidogyne species and M. incognita populations having several different geographical origins and pathotypes. No cross reaction with DNA of other PPNs was observed. Sensitivity of the RKN- and Mi-LAMP was 10 and 100 fg of pure genome DNA respectively. Both LAMP sets could also amplified crude DNA isolated from the galled root tissue and from soil containing juveniles of M. incognita. The RKN- and Mi-LAMP sets offer the advantages of simplicity, rapidity and cost effectiveness. Both LAMP sets will be instrumental for the diagnosis of Meloidogyne spp. by local extension and regulatory personnel.  相似文献   

12.
Root-knot nematodes (Meloidogyne spp.) are one of the most destructive pathogens of vegetables. The cultivars resistant to root-knot nematodes have comparatively better crop yield than susceptible varieties and can be employed as a component of integrated nematode management. In the present study, 15 cultivars of cucumber (Cucumis sativus) were tested for their response to Meloidogyne incognita by inoculating with 3000 2nd stage juveniles of the nematode. All cultivars varied significantly in causing reductions in growth parameters over their controls. Likewise, all cultivars behaved differently regarding formation of galls and egg masses and reproductive factor. It was found that none of the tested cultivars was found immune or highly resistant. Long Green was the only cultivar which was found resistant against M. incognita as it showed minimum galls (8.2) and reductions in growth parameters. On the other hand, cultivars Mehran, Mirage, Thamin-II, and Royal Sluis were highly susceptible as evident by maximum galls (>100) on their roots and reductions in growth parameters. Similarly, the cultivars Green Wonder, Cucumber Citriolo and Poinsett were moderately susceptible (31–70 galls) while Babylon, Cobra and Falcon-560 (71–100 galls) were susceptible and reductions in growth parameters of these cultivars were less than those in highly susceptible cultivars. Four cultivars, Marketmore, Dynasty, Pioneer-II, and Summer Green, were rated as moderately resistant (11–30 galls) as these cultivars showed less damage by the nematode than moderately susceptible, susceptible and highly susceptible cultivars.  相似文献   

13.
Herbicides applied to combat weeds and increase crop yields may also have undesired effects on beneficial soil microorganisms. Field studies were conducted in 2005 and 2006 in Zaria, Nigeria, to evaluate the response of weeds and soil microorganisms to imazaquin applied at 0.05, 0.10, 0.20 and 0.40 kg a.i./ha and pendimethalin applied at 1.0, 2.0, 4.0, and 8.0 kg a.i./ha in cowpea and soybean. Hoe-weeded and unweeded (no herbicide) plots were controls. Both herbicides significantly reduced weed biomass in both crops, when compared to the unweeded control, which had the highest weed biomass at all sampling dates. Treatments with 0.40 kg a.i./ha of imazaquin, 2.0 and 4.0 kg a.i./ha of pendimethalin, and the hoe-weeded control, had the highest cowpea grain yield. The unweeded control had the lowest grain yield which was comparable to that in all other herbicide treatments. All treatments except 4.0 and 8.0 kg a.i./ha of pendimethalin had higher soybean grain yield than the unweeded control. Soybean yield was lowest in the unweeded control, and treatments that received 4.0 and 8.0 kg a.i./ha of pendimethalin. All rates of imazaquin gave similar soybean grain yields that were 29–41% higher than that from pendimethalin. The hoe-weeded control had the highest yield, which was 79% more than that in the unweeded control. Higher rates of imazaquin and pendimethalin reduced nodulation, nitrogen fixation, and vesicular arbuscular mycorrhizal (VAM) fungi colonisation in both crops. VAM fungi species diversity and species richness in cowpea rhizosphere soil and species diversity in soybean rhizosphere soil were reduced relative to the controls due to application of both herbicides with the rates of 0.10, 0.20, and 0.40 kg a.i./ha of imazaquin and 8.0 kg a.i./ha of pendimethalin being significantly effective.  相似文献   

14.
《Crop Protection》1988,7(3):186-189
The effect of mixed cropping of cowpeas with maize on light intensity in the cowpea canopy and on population density of Megalurothrips sjostedti (Trybom) was investigated in the field and in cages. Significantly less (P< 0 · 05) light was intercepted by the cowpea canopy in the cowpea/maize mixed crop than in the cowpea crop alone. The population density and activity of M. sjostedti were significantly less in the mixed crop than in the single crop. There were significant correlations between light interception and differences in the population density of nymphs (r=0 · 79), adults (r=0 · 84) and the overall activity (r=0 · 93) of M. sjostedti. In a screenhouse choice test, M. sjostedti preferred unshaded cowpea plants to shaded ones. The results suggested that reduced light intensity in the cowpea/maize mixture contributes to the relative scarcity of M. sjostedti in the mixture.  相似文献   

15.
Root-knot nematodes (Meloidogyne spp.) are non-quarantine pests that are subject to regulations in Brazil because they are limiting to coffee production and easily spread by planting infected seedlings. Containing their dissemination requires knowledge of their distribution in coffee-producing areas in order to establish phyto-sanitary measures. The object of this work is to evaluate the distribution of Meloidogyne spp. in Coffea spp. in Espírito Santo state, where coffee growing is expanding. Soil and root samples were collected in Coffea arabica and Coffea canephora Conilon. Identification of Meloidogyne spp. was carried out by esterase isoenzyme phenotype and by the host range. In Espírito Santo, Meloidogyneincognita, Meloidogyne exigua, and Meloidogyne paranaensis were identified. Phenotypes I1 and I2 of M. incognita were present in 21% of all the sampled properties. This species was found mainly in the Serrana region and north of the state, and principally in plantations of C. canephora. Only phenotype E1 of M. exigua was detected, distributed in 23.8% of the properties and only in plantations of C. arabica. M. exigua was found in all the municipalities sampled in the southern region of the state and in 66.6% of the municipalities of the Serrana region. M. paranaensis, phenotype P1, was detected only in the northern region, and in 100% of the properties sampled in Baixo Guandu municipality. The study was complemented by sampling in the Zona da Mata region of Minas Gerais state, where only M. exigua, phenotype E1, was found in C. arabica plantations. M. exigua was detected in all the sampled municipalities except Paula Cândido. The populations were subjected to differential host plant tests to determine the physiological races. Races 1 and 2 of M. incognita and M. exigua were found in Espírito Santo state, and race 2 of M. exigua in Zona da Mata in Minas Gerais state. The presence of the three most important root-knot nematodes in coffee plants in Espírito Santo state indicates the need to establish measures that will contain their dissemination.  相似文献   

16.
The susceptibility of three sweet potato cultivars (Ipomoea batatas L.) C4, TIS 3290 and TIS 9162 was evaluated against 156 isolates of Meloidogyne spp. with the aim to include resistant/tolerant sweet potato cultivars in a crop rotation scheme for the management of root-knot nematodes. The nematode isolates corresponded to races 1, 2 and 3 of Meloidogyne arenaria (n = 7), races 1, 2, 3 and 4 of M. incognita (n = 131) and Meloidogyne javanica (n = 18). Also, the isolates of M. incognita were differentiated in virulence groups: Pepper (n = 35), Pepper-Mi (n = 25), Tomato (n = 41) and Tomato-Mi (n = 30), depending on their ability to parasitize resistant pepper and tomato cultivars. The tested isolates of M. javanica parasitized C4 and TIS 3290, but not TIS 9162, whereas M. arenaria parasitized C4 and TIS 9162, but not TIS 3290, and M. incognita was able to parasitize the three sweet potato cultivars tested. C4 was the most susceptible cultivar to all nematode species tested, especially M. incognita, TIS 3290 was the most resistant and TIS 9162 was in between (7.2, 62.9 and 26.9% of resistant plants, respectively). Susceptibility of the sweet potato cultivars showed slight variations depending on the race or virulence group of M. incognita. The results suggest that sweet potato cultivars TIS 3290 and TIS 9162 may be used as rotation crops in fields where root-knot nematodes are present, their selection depending on the Meloidogyne isolates present. The use of resistant sweet potato cultivars would be preferably combined with other management practices to avoid virulence selection in nematode isolates.  相似文献   

17.
The effects of tillage on Heterodera glycines, the most important yield-reducing pathogen of soybean in the U.S., were examined in a long-term tillage and crop sequence study initiated in 1975 on a mollisol at Purdue University. Population densities of H. glycines were monitored under corn–soybean rotation and soybean monoculture in 2003 and 2004. Tillage treatments included: (A) fall moldboard plow + spring secondary tillage; (B) fall chisel plow + spring secondary tillage; (C) ridge tillage; and (D) no-tillage. In both years in the rotational plots, final population densities of H. glycines were proportional to tillage intensity. Under both soybean and corn rotation crops, highest population densities were observed with plowing + secondary tillage and lowest population densities were detected under no-tillage. In 2004, population densities in monoculture soybean soil declined with depth intervals in layers of 0–10, 10–20, and 20–30-cm depth under no-till, but not in plowed plots. Multiple regression analysis determined that the stratification of nematode population densities was strongly correlated to penetrometer resistance and potassium concentration of the soil. Tillage seemed to affect population densities of H. glycines by modification of the soil physical parameters in corn–soybean rotation plots. Reducing tillage intensity was beneficial in reducing population densities of H. glycines in rotational soils. Thus, the choice of tillage system can reduce the risk for damage by this widely distributed pathogen.  相似文献   

18.
The effect of intercropping cover crops was with yam was assessed for nematode management both in pot and field conditions in Nigeria. The cover crops were sown with yams in pots containing sterile soil and inoculated with 5000 eggs of Meloidogyne incognita. In the field, each cover crop was separately intercropped with yams inoculated with 10,000 nematodes. From both pot and field experiments, no nematode damage was observed on yam tubers that were intercropped with Aeschynomene histrix, Crotolaria juncea, and Tagetes erecta. Damage in intercropped tubers was reduced by 72.7% with Mucuna pruriens, Centrosema pubescens, and Pueraria phaseoloides and by 58.3% with Stylosanthes guianensis compared to yams planted without cover crops; they also had lower (p ≤ 0.05) nematode populations. Cajanus cajan, Lablab purpureus and Vigna unguiculata however, supported high nematode populations and led to nematode damage in intercropped yams. Tubers from M. incognita-inoculated plants were more damaged and lost 42% more weight (p ≤ 0.05) following three months of storage than tubers from uninoculated plants. Intercropping yams with selected cover crops can be useful in managing M. incognita without reducing yam yields.  相似文献   

19.
We assessed soil suppressiveness against root-knot caused by Meloidogyne javanica, following the incorporation of crop residues (organic amendments [OA]) and soil solarization, under agricultural conditions. Two field experiments were established in tomato greenhouses and a third in a nethouse for growing Antirrhinums, all infested with M. javanica. Dried residues of wild rocket (WR) were incorporated into the soil and then it was solarized to moderate temperatures to partially effect the pathogen population. Root galling on the roots of the successive tomato crop was significantly reduced to different levels by WR, solarization or their combination, in two experiments. Solarization, alone or combined with WR amendment, significantly reduced root knot incidence in the roots of snapdragon, but suppression of root galling in the roots of snapdragon in the following crop was not evident. We further assessed the potential of various herb residues, incorporated in small plots, and solarization to induce soil suppressiveness against root-knot caused by M. javanica. Amending soil with residues of WR, tarragon, peppermint or sage induced soil suppressiveness to root knot even when M. javanica was introduced into the soil after the termination of the treatment, and reduced the galling index in subsequently grown tomato plants, compared with non-amended soil. Our findings further validate the potential role of OA and solarization in inducing soil suppressiveness, which contributes to sustainable management of soilborne pathogens.  相似文献   

20.
The cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a widespread pest of many cultivated and wild plants in Europe, Africa, Asia, and Australia. In 2013, this species was reported in Brazil, attacking various host crops in the midwestern and northeastern regions of the country and is now found countrywide. Aiming to understand the effects of different host plants on the life cycle of H. armigera, we selected seven species of host plants that mature in different seasons and are commonly grown in these regions: cotton (Gossypium hirsutum, “FM993”), corn (Zea mays, “2B587”), soybean (Glycine max, “99R01”), rattlepods (Crotalaria spectabilis), millet (Pennisetum glaucum, “ADR300”), sorghum (Sorghum bicolor, “AGROMEN70G35”), and cowpea (Vigna unguiculata, “SEMPRE VERDE”). The development time of immatures, body weight, survivorship, and fecundity of H. armigera were evaluated on each host plant under laboratory conditions. The bollworms did not survive on corn, millet, or sorghum and showed very low survival rates on rattlepods. Survival rates were highest on soybean, followed by cotton and cowpea. The values for relative fitness found on soybean, cotton, cowpea, and rattlepods were 1, 0.5, 0.43, and 0.03, respectively. Survivorship, faster development time, and fecundity on soybean, cotton, and cowpea were positively correlated. Larger pupae and greater fecundity were found on soybean and cotton. The results indicated that soybean, cotton, and cowpea are the most suitable plants to support the reproduction of H. armigera in the field.  相似文献   

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