Field tests on the efficacy of baits based onBacillus thuringiensis and chemical insecticides against the greasy cutwormAgrotis ypsilon Rdf. in Egypt

Field tests were conducted to determine the effectiveness of wheat-brain baits based onBacillus thuringiensis var.kurstaki HD-1 (dipel 2x) compared to the organophosphorous insecticide Hostathion against the greasy cutwormAgrotis ypsilon infestations on horse bean (Vicia fabae) cultivations. Significant larval reductions were observed in all treated plots after one application with a significant increase in the yield (1.45–1.60 folds) compared to the control plots. The yield was not obviously affected by varying the dose of dipel in the bait between 150–250 g/feddan. The addition of the adjuvant potassium carbonate to the dipel bait caused a significant larval reduction, 10 days after application and showed to be as efficient as baits based on Hostathion.     

The use of Bacillus thuringiensis to control two lepidopterous insect pests (Agrotis ypsilon and Spodoptera littoralis)

An area of 50 feddans cultivated with soybeans was treated withBacillus thuringiensis (B.t.) baits againstAgrotis ypsilon and 60 feddans were sprayed withB.t. spray againstSpodoptera littoralis. WhenB.t. baits were used, the percentage of kill ofA. ypsilon reached 96.1–96.4% compared to 97.4–98% kill on using hostathion baits. WhenB.t. was sprayed againstS. littoralis, a percentage of larval kill 88.3% was obtained. This increased to 97.3% after the second application. On the other hand, the precentage of kill reached 96.8% when lannate was sprayed once. The average yield was 1.54 tons/fed. whenB.t. was sprayed twice againstS. littoralis and 1.42 tons/fed. when sprayed once. Areas, treated with lannate gave 1.44 tons/fed., while in the untreated area the yield was comparatively low being 0.83 tons/fed.Mith 4 tables     

Nutrient contribution and maize performance in alley cropping systems

Dry matter yield and potential contribution of N, P and K of some woody perennials as well as performance of maize were assessed in an alley cropping system at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. Dry matter yield was highest forCassia, followed byGliricidia and theFlemingia. Whereas dry matter yields ofCassia varied significantly at the various pruning times, those ofGliricidia andFlemingia were relatively uniform.Gliricidia contributed the highest amount of N from the cutback (first pruning) and three subsequent prunings. Dry wood yield at cutback was 14.5, 6.8 and 29.7 tonnes/ha forGliricidia, Flemingia andCassia respectively. Coppicing rate was faster inGliricidia thanFlemingia andCassia. Maize height, stover and cob weights were reduced though insignificantly, for the maize rows close to the shrub hedgerows compared to those in the middle of the alleys. For the plots without N application and prunings removed, the maize near the hedgerows showed better performance than those in the middle of the alleys. The results indicate that N supplementation is needed in the alley cropping systems to optimize yield. The amount of N required is higher inFlemingia alleys than forGliricidia andCassia. Root growth of maize was found to be restricted in control plots without hedges; uptake of the major nutrients (N, P and K) was also found to be similarly affected in those plots.     

Effects of alley cropped Calliandra calothyrsus and Cliricidia sipium hedges on weed growth,soil properties,and taro yields in Western Samoa

Field experiments were conducted on a tropical Inceptisol at Apia, Western Samoa to evaluate the effects of alley cropping on soil characteristics, weed populations, and taro yield. Taro yields were compared from Calliandra calothyrsus and Gliricidia sipium alleys, spaced at 4 m, 5 m, and 6 m, and a no tree control. Measurements were made for soil moisture and temperature, weed growth, hedge biomass production, and taro growth and yield. Data was analyzed over 4 consecutive years from 1988 to 1991.Hedge biomass yields ranged from 5.1 to 16.1 t/ha/yr dry weight over the 4 years of the trial, with Calliandra and Gliricidia performing equally well. Biomass yields decreased by about 2 mt/ha with increasing alley width from 4 to 6 m alleys. Weed populations were significantly lower in the 4 m alleys compared to the 5 m, 6 m, and control plots. The 6 m alleys supported the significantly highest weed populations. Soil from alley plots held significantly more water in the 0.3 to 1 bar range than soils from the controls. Four years of mulch application measurably improved soil water holding capacity and bulk density. However, no improvement was seen in nitrogen, phosphorus, potassium, calcium, magnesium and organic carbon content in the alley plots compared to the controls. There was no positive yield effect of alley cropping on taro yield. Yields in the 5 m and 6 m alleys were not significantly different from the control, while the 4 m alleys produce significantly lower yields than the control. Thus, alley cropping did not prove a viable alternative to traditional shifting cultivation after 4 years of continuous cropping, in this trial.     

Wheat cultivation in association with Acacia nilotica (L.) Willd ex. Del. field bund plantation — a case study

The paper presents the results of a case study conducted to find out the influence of single row bund plantation of Acacia nilotica var. juquemontii on the growth and yield of associated wheat crop under irrigated conditions in Haryana, India. The indications are that the tree line does affect all crop parameters like height growth, shoot numbers, ear length, grain number and grain yield in the vicinity of trees upto 4 m distance from the tree line and establishes that as the distance from the tree line increases the growth and yield of wheat crop also improves. The effect on wheat crop was found more pronounced in the plots laid out towards the middle of the tree line as compared to plots towards the outer border.     

Yield, maturation, and forage quality of alfalfa in a black walnut alley-cropping practice

There is interest in producing alfalfa as an alley crop because alfalfa (Medicago sativa L.) is the most profitable hay crop in the USA. Field experiments were conducted near Stockton, MO in 2003 and 2004. Treatments consisted of alfalfa grown in open plots and in plots that were alley cropped between 20-year-old black walnut trees (Juglans nigra L.) planted in rows 24.4- and 12.2-m apart. Alfalfa was sampled for three harvest cycles each year. In the alley-cropping plots, samples were taken beneath the canopy (2.5 m from the tree row) and in the center of the alleys. Data were taken on dry-matter yield, maturity, and forage quality. At all harvest dates over both years, yields from beneath the canopy of both alleys and the narrow alley centers were less than yields from the wide alley centers and open plots. Yield from the wide alley centers was similar to that in open plots in every harvest but the final harvest of 2004. Transects across the plots indicated that yields increased linearly from the tree row to the center of both alleys. Alfalfa tended to mature faster in the open and wide alley centers compared to beneath the canopy of both alleys and the narrow alley centers. Forage quality differences were inconsistent across treatments. Alfalfa yield was significantly reduced and maturity was delayed by the narrow 12.2 m tree spacing, but yield was not reduced in the centers of the wider 24.4 m alleyways.     

Erfahrungen mit verschiedenen Ködermitteln und unterschiedlicher Ausbringungstechnik zur Bekämpfung forstschädlicher Wühlmäuse

On 17 field plots of 0,25 to 1 ha in forest plantations of southern Germany various commercial baits containing zinc phosphide, chlorphacinon and diphenacoum were tested in a pilot study for control of harmful small rodents likeMicrotus agrestis, M. arvalis andClethrionomys glareolus. The baits were dispersed in different concentrations over the ground or alternatively they were put together with a piece of apple in bait stations. The animals in the field plots were trapped by means of live traps, marked and released. The efficacy of the treatments was tested by repeating this procedure in consecutive time intervals and by analysing the fractions of marked and unmarked specimens. In comparision with a disperse distribution of the unprotected baits over the ground surface better results and a more lasting success could be mostly obtained with only 9 earthenware pipes distributed over one hectare and filled with a small amount of baits together with a piece of apple. The advantages and disadvantages of the bait station technique are discussed. It is assumed that the efficiency of the bait station technique can be improved by means of attractants and pheromones.     

Efficacy of aerial application ofBacillus thuringiensis to controlSpodoptera littoralis (Lepidoptera, Noctuidae) infesting soybean cultivations in Egypt

The calculated percentage of droplets deposition ofBacillus thuringiensis var.kurstaki HD-1 Dipel 2X on the foliage of soybean plants in relation to the sensitive “Ciba Geigy” papers showed to be the highest (92.4%) after ground spray application, compared to an average of 67.4, 85.8 and 89.3% following aerial application of the same preparation in spray volumes of 10, 20 and 30 l/F, respectively. Aerial application ofB. t. showed to be more effective during the first 3 days after spraying soybean cultivations and the mortality ofSpodoptera littoralis larvae varied between 36.9–67.2% in correlation to the spray volume. The volume achieving the highest and significant suppression of infestation was 20 l/F. On the other hand, the yield of soybeans obtained from plots receiving a spray volume of 30 l/F was higher compared to plots sprayed with a volume of 20 or 10 l/F, but with no significant difference when compared to those plots receiving ground spray application.     

Seasonal changes of understorey herbage yield in relation to light intensity and soil moisture content in a Pinus pinaster plantation

The relationship of understorey herbage yield with light intensity and soil moisture content was investigated in a 20-year-old Pinus pinaster plantation in Kilkis of Macedonia, northern Greece, in three seasons (fall, winter and spring). The plantation was thinned at three density levels, high, medium and low (2500, 1750 and 1000 trees/ha respectively) and it was seeded with Dactylis glomerata. In addition, two fertilization levels (0 and 110 N+150 P₂O₅ kg/ha) and grazing intensity levels (0 and 0.8 sheep/ha/yr) were applied in a split-split plot experimental design. It was found that herbage yield was highest in the ungrazed and fertilized low tree density stands in all seasons. In the medium tree density stand, although light was lacking, fertilized plots produced higher herbage yield as compared to unfertilized low tree density stands while fertilization is of no use in close stands if herbage production is the goal. Animals seemed to prefer fertilized and medium density stands. Third degree polynomial equations were the best to explain herbage variation through the seasons both in fertilized and unfertilized plots.     

Effect of intercropping maize and closely spacedLeucaena hedgerows on soil conservation and maize yield on a steep slope at Ntcheu,Malawi

A six-year soil conservation trial was conducted on a steep slope, 44%, with a subhumid climate, based on very closely spaced (90 cm) hedgerows, using three intraspecific hybrids ofLeucaena leucocephala. Soil loss averaged 2.0 t/ha per year on theLeucaena plots compared with an initial 80 t/ha per year on the unprotected control plot, falling to 27 t/ha per year after the top soil had been eroded. After 6 years, micro terraces of 35 cm high and 81 cm wide had developed on the intercropped plots, with substantially improved soil properties. Maize yield (unfertilized) were maintained at 1.5–2.0 t/ha on the protected plots, compared with a progressive fall from 0.8 to 0.5 t/ha on the sole maize control.     

Effects of fenamiphos and biocontrol agents on cotton growing in nematode-infested soil

Efficacy of a chemical nematicide, fenamiphos and three microorganisms in controllingRotylenchulus reniformis andTylenchorhynchus latus on cotton planted in field plots was investigated. Monthly records of the nematode population levels showed that fenamiphos had the highest (p0.05) levels of their control which resulted in the top cotton yield. Plots receiving the bacteriumBacillus sp. had various degrees of nematode control though their cotton yield was comparable (P0.05) to the fenamiphos-treated plots. Plots inoculated with a fungusChaetomium spirale recorded the least effect for controlling the two nematode species and their cotton yield was not significantly different from the untreated plots. Plots treated with an actinomycete,Streptomyces sp., had an intermediate effect on both nematode population densities and cotton yield. At harvest,T. latus population densities were equally suppresed (P0.05) in all treatments which should be reflected on the subsequent crop.With 2 tables     

Alley cropping Sesbania sesban (L) Merill with food crops in the highland region of Rwanda

Food production in the densely populated Rwandan highlands is impeded by soil erosion and loss in fertility. Alley cropping leguminous shrubs with food crops on contours is purported to minimize the problem and to provide wood and forage. This study reports the effect of Sesbania prunings plus moderate levels of N and P on bean (Phaseolus sp) and maize (Zea mays) yields in alley cropping. Experimental design was a randomized complete block with split-split plots. Main plots were alley width: 2, 4, 6 and 8 m. Phosphorus (P) at 0, 30 and 60 kg P₂O₅/ha occupied the subplot and nitrogen (N) at 0, 30 and 60 kg/ha were assigned at the sub-sub plot level. No P was applied to maize during the second cropping season. Crop yield in kg/ha included the land space taken by hedgerows. Bean yield in 6 m alleys (1100 kg/ha) was about twice that in 2 m alleys (500 kg/ha). Bean responded to N and P. Optimum alley width and N for bean yield were 6 m and 30 kg/ha, respectively. Cuttings from alley hedgerows provided stakes for climbing beans. Maize responded to N but not to residual P. The highest maize yield came from 8 m alleys with 40 kg/ha, but yields from 8 and 6 m alleys with the same N treatment were not significantly different. Maize plants in middle rows were significantly taller than plants in rows adjacent to hedgerows. Maize rust development showed significant alley width and row position effect. There were significantly fewer uredinia in the Sebania alleys relative to the control plots without shrub hedgerows. Rust development on maize in middle rows was significantly greater than development in border rows.     

Cholecalciferol plus diphacinone baits for vole control: a novel approach to a historic problem

Combination baits containing cholecalciferol plus an anticoagulant are effective against commensal rodents resistant to anticoagulants, and they likely pose less risk than anticoagulant-only rodenticides due to lower concentrations of active ingredients and shorter time to death. However, these combination baits have not been tested for agricultural rodent pests. Therefore, we established a study to test the efficacy of cholecalciferol plus diphacinone artichoke bract and pellet baits to determine their ability to manage California voles Microtus californicus in artichokes, where resistance to anticoagulants is known to occur. Field tests using radiocollared voles indicated that bract baits were highly efficacious (85 %), although pellet baits were less effective (60 %). Low observed efficacy of pellet baits may have resulted from poor weather following application during the second sampling period; further testing may yield more positive results. We observed a bimodal distribution in timing of death, with one group of voles dying between 4.3 and 5.8 days post-consumption; the other group died between 9.0 and 14.5 days post-consumption. Deaths in the first group were attributed to cholecalciferol, while deaths in the second group were likely due to chronic anticoagulant exposure. Almost double the proportion of voles that died from bract consumption did so during the early period when compared to their pellet plot counterparts. This suggests that voles were consuming greater quantities of bract baits over a shorter period of time when compared to the pellet bait. Collectively, these findings indicate that baiting with cholecalciferol plus diphacinone coated bracts is an effective method for controlling vole populations in artichokes.     

Effect of organic fertilizer on the growth and fruit yield of six paprika (<Emphasis Type="Italic">Capsicum annum</Emphasis> L.<Emphasis Type="Italic">)</Emphasis> cultivars in Malawi

The production of paprika (Capsicum annum L.) under small-scale farm conditions in southern Africa is constrained by low soil fertility and lack of appropriate cultivars. The objective of this study was to determine the growth responses and fruit yields of six cultivars of paprika to organic and inorganic nutrient sources. The study was conducted in 2007 and 2008 at Chitedze Agricultural Research Station in Malawi. A combination of six paprika cultivars and four nutrient sources, namely (1) organic input from Gliricidia, (Gliricidia sepium) biomass, (2) inorganic fertilizer, (3) integrated nutrient input (Gliricidia biomass + inorganic fertilizer), and (4) control (no nutrient input) were compared. Each combination was replicated five times. A split-plot design was used where nutrient sources formed the main plot and cultivars the sub-plots. Plant height differed due to nutrient source in 2007 and 2008, while differences due to cultivar were minor. The control plots produced the shortest plants (height < 50 cm), while plots receiving the integrated nutrient input produced the tallest plants (height > 60 cm). Numbers of branches and fruits per plant differed due to nutrient source and cultivar during most of the study period. Plants receiving either organic inputs (Gliricidia biomass) alone or the integrated nutrient input alone had significantly higher stem, leaf and fruit weight compared with the control. Average fruit yield was lower in control plots than in plots receiving the organic input alone or the integrated nutrient input. Among cultivars, Papri-King, Papri-Supreme and Papri-Queen produced higher dry fruit yield. The ASTA and RAL colour rating was within the internationally accepted range for fruit from the treatments.     

Comparing an individual tree growth model for <Emphasis Type="Italic">Pinus halepensis</Emphasis> Mill. in the Spanish region of Murcia with yield tables gained from the same area

To support forest management decisions on converting stands from even-aged to uneven-aged management, tree models are needed that can simulate both options. Therefore, an individual tree model for Pinus halepensis Mill. is compared with the respective yield table. The individual tree model is built from data of two Spanish forest inventories in this province and evaluated with published yield tables, which have been built from permanent observational plots. The individual tree model consists of a basal area increment model and a height increment model, both based on two measurements of about 4,000 trees from single species stands of Aleppo pine. The R2 values of 0.362 and 0.107 for the basal area increment model and the height increment model, respectively, are within the range of other published models of this type. Comparing the model with the yield tables for different site indices, we find that our model matches the yield table well. Only in higher ages where the database for the yield table was poor, our model indicates higher basal area growth rates than the yield table.     

Soil fertility changes and response of maize and beans to green manures of leucaena,sesbania and pigeonpea

Three multipurpose tree species (MPTS)-leucaena (Leucaena leucocephala), sesbania (Sesbania sesban var. nubica) and pigeonpea (Cajanus cajan) were pruned at a height of 60 cm above the ground every two months, and resulting plant biomass was incorporated into the soil as green manure. For comparison, maize (Zea mays) stover was also incorporated into some plots, while some other plots were left fallow. Varying quantities of plant biomass which were incorporated into the soil over a period of 12 months caused large changes in major soil plant nutrients, and it substantially improved soil fertility. To test for improved soil fertility, test crops of maize and beans (Phaseolus vulgaris) were grown on the plots after six biomass incorporations of 4806, 13603, 16659 and 7793 kg. ha^–1yr^–1 for pigeonpea, sesbania leucaena and maize, respectively. Responses of the test crops indicated that sesbania and leucaena green manures improved maize stover, cobs and grain yields; and bean haulms and grain yields by 77.6% when compared to fallow plots. Residual effects of green manures still resulted in significant (P < 0.05) yield differences in the test cropin the third testing season. Economic significance of green manures in increasing food crop yields to small scale farmers is discussed.     

Incidence and Severity of Bean Rust (Uromyces appendiculatus) in Alleys between Leucaena Hedgerows in Kenya

The effects of inter-row spacing of Leucaena leucocephala (Lam.) de Wit in an alley cropping system on the incidence and severity of rust (Uromyces appendiculatus (Pers.) Unger) on intercropped beans (Phaseolus vulgaris L.) and their yield were examined over 2 years (1993 and 1994) at Chepkoilel Campus in Kenya. Each experiment consisted of three randomized blocks with treatments of three alley widths (2 m, 4 m and 8 m) and a treeless control with two intra-row spacings of Leucaena (0.5 m and 1.0 m). Hedgerows were coppiced at 1.0 m height and pruned subsequently at 2–3 months intervals. No fertilizer was applied but Leucaena loppings were incorporated as green leaf manure. Rust on beans was assessed at three growth stages in each season, using the Centro International de Agricultura Tropical (CIAT) scales. Microclimate was monitored in treatments, in 1994. Bean growth and yield were also measured. Rust increased with increasing alley width and was less severe in bean rows adjacent to hedgerows. Bean yield was highest in the treeless control plots and declined with decreasing alley width. Beans in 2 m alleys had significantly lower (p < 0.05) yields than 8 m alleys and treeless control plots. Bean growth was greatly modified in 2 m alleys and close to hedgerows. Light availability and diurnal temperature increased with alley width but relative humidity and leaf wetness duration decreased. Proximity to hedgerows also had marked effect on microclimate. The changes in yield, rust incidence and severity were examined in relation to microclimate, inoculum survival and dispersal.     

Diversity and abundance of carabid beetles in short-rotation plantings of sweetgum, maize and switchgrass in Alabama

This study compares assemblages of carabid beetles, potentially important regulators of herbivorous insect pests, in short-rotation plantings of sweetgum (Liquidambar styraciflua L.) with and without grass cover crops, maize (Zea mays L.) and switchgrass (Panicum virgatum L.). A total of 38 species were trapped during the summers of 1996 and 1997. The dominant carabid encountered was Harpalus pensylvanicus Latreille, a widespread omnivorous species; H. pensylvanicus was particularly prevalent in maize plots. Several other commonly encountered species were primarily associated with one plot type. Overall carabid activity was found to be similar in maize and switchgrass plots and much greater than that in sweetgum plots of both cover types. This may be related to the presence of more consistently available dense ground cover in these plots compared to sweetgum plots, a situation favored by most carabids, although both abundance and diversity were similar in sweetgum plots with and without cover. Diversity, as indicated by species richness and dominance levels, was greater in switchgrass than in maize or sweetgum plots, which were similar. This revised version was published online in June 2006 with corrections to the Cover Date.     

Control ofAgrotis ypsilon (Hufn.) (Lep., Noctuidae) on some vegetable crops in Egypt using the microbial agentBacillus thuringiensis

The effective threshold rate of application of Dipel 2X was 250g/f. Incorporation of some chemical additives such as calcium sulphate (CaSO₄) or calcium oxide (CaO) significantly potentiated the effectiveness of Dipel 2X on larval population. The addition of calcium carbonate (CaCO₃) and zinc sulphate (ZnSO₄) to Dipel 2X greatly reduced the larval population and led to a significant increase in the yield of some vegetable crops. Dipel 2X baits at 250g/f were almost as effective as the chemical insecticide Hostathion when used at 1.5l/f in controllingA. ypsilon larvae attacking vegetable crops. Control of the greasy cutwormAgrotis ypsilon population was better achieved when the biological control agent Dipel 2X was used as baits.     

Evaluation of endophytic bacterial strains as antagonists of take-all in wheat caused by <Emphasis Type="Italic">Gaeumannomyces graminis</Emphasis> var. <Emphasis Type="Italic">tritici</Emphasis> in greenhouse and field

Six endophytic bacterial strains from wheat roots, selected from extensive screening tests, were studied in greenhouse pot experiments against take-all disease of wheat, caused by Gaeumannomyces graminis var. tritici (Ggt). For comparison, the fungicide triadimefon was included. All six bacterial strains and triadimefon significantly reduced take-all in wheat plants between 39.4 and 57.3% compared to the inoculated control. Treatment with the bacterial strains also significantly increased growth parameters of roots (e.g., average length, fresh, and dry weight) in comparison with the inoculated control. One of the endophytic bacterial strains, designated EDR4, which proved to be most consistent in further greenhouse tests, was also examined in field trials against take-all in wheat. In the field experiment 2006/2007, height of wheat plants in Ggt inoculated plots was significantly reduced compared to the non-inoculated treatments. Yield parameters such as kernels per head and thousand kernel weight (TKW) in the inoculated control were lower compared to other treatments. In the inoculated plots, individual treatments with the strain EDR4 increased yield compared to the inoculated control. In the field trial 2007/2008 treatments with strain EDR4 as well as the fungicide triadimefon reduced take-all by 49.6 and 61.9%, respectively, compared to the inoculated control. At harvest, in the inoculated control plant height, seeds per head and TKW were significantly lower compared to the other treatments. Treatments with EDR4 eliminated the detrimental effects of take-all on grain yield to a similar degree as triadimefon application. The strain EDR4 distinctly inhibited growth of Ggt in vitro and was identified as Bacillus subtilis on the basis of its morphology and 16S rRNA sequence analysis as well as physiological and biochemical characteristics. These results indicate that the strain EDR4 has potential in directly controlling take-all disease of wheat.