Sprayed Plots Research Articles

Effects of Preceding Cowpea on the Performance of Maize in Cowpea-Maize Sequential Cropping

Abstract Field experiment was conducted at the Federal University of Agriculture in 2004/2005, 2005/2006 and 2006/2007 cropping seasons to investigate the effects of cowpea varieties on succeeding of maize crop. The experiment was laid out in split-plot design and the treatment replicated three times. The main plot treatment was sprayed and unsprayed cowpea (Vigna unguculata L.) while variety constituted the subplot treatment (IT90K-76, IT90K-277-2, Drum, Olo, Oloyin, Mallam and Sokoto varieties). Maize variety cv TZESR-W was planted as the test crop in the early cropping season of 2005, 2006 and 2007 on each subplot of the preceding cowpea. The biomass of cowpea in the spray plots were higher than those of unsprayed at 8, 10 WAP in 2004. Olo variety had significantly lower biomass compared to others in 2004. The grain yield of cowpea from the sprayed plots was significantly higher than the unsprayed plots in all the years. IT90K-76 variety had the highest grain yield whereas Mallam and Drum had the lowest in all the years. Maize grain yields from the preceding cowpea plots were significantly higher than that of 0 N kg/ha. The fertilizer equivalent of the preceding varieties of cowpea ranges between 24 and 38 N kg/ha. Thus, preceding cowpea enhances the performance of succeeding maize.

Effect of Some Micronutrients on Damage Compensation and Yield Parameters in Okra.

The effect of micronutrients on damage compensation and yield components of okra was investigated, using three foliar sprays (at 15 days interval) of Effective microorganisms (EM-1), Wokozim and Kissan Supreme Tonic (KST). Weekly observations on sucking complex (thrips, jassid, whitefly) and pod borers were carried out. The yield ha-1 of green pods was recorded to ascertain the compensation of the damage done by the insect pests. The damage done by sucking complex and borers was markedly compensated by the micronutrients, and okra pod yield in EM-1, Wokozim and KST sprayed plots were 10911, 9507 and 8948 kg ha-1, respectively as compared to 8034 kg ha-1 in control. The effect of micronutrients on crop growth and subsequently on sucking complex infestation was significant and thrips, jassid, whitefly and borer infestation was relatively lesser in plots sprayed with micronutrient as compared to the control. KST was most effective in damage compensation of sucking complex and borers with highest okra green pod yield (P

Efecto del control de malezas con paraquat y glifosato sobre la erosión y pérdida de nutrimentos del suelo en cafeto.

Effects of weed control with paraquat and glyphosate on erosion and soil nutrient losses in coffee. A trial was conducted during 2002-2003 at Alajuela, Costa Rica to determine weed control, weed dynamics, soil erosion and nutrient losses due to successive applications of paraquat and glyphosate. Two plots of 900 m2 were treated with paraquat and two more plots were treated with glyphosate. During 2003 one plot of each treatment was ammended with calcium carbonate and organic mater (shell of coffee berry). Run-off water and sediments from a 2 x 7 m plot were collected into a 200 l drum. The amount of nutrient lost from each plot was determined. The first year both treatments provided 90-100% of weed control but tolerant weeds were selected. A mechanical control and an increase of the herbicides application rate were necessary to keep these weeds under control. During 2002 soil losses from glyphosate treatments were double (3.956 MT/ha) compared to that occurred from the paraquat treated areas (1.936 MT/ha). During 2003 at the amended plots again areas treated with paraquat had less erosion (0,231 MT/ha) vs 0,329 MT/ha from glyphosate sprayed plots. Soil losses from the amended plots were 0,170 MT/ha and 0,187MT/ha, respectively. Sediment analysis indicates that Ca, Mg & K losses were similar in both treatments. In 2003 the estimated yield was similar in both areas.

English

Insecticide spray offers the most effective control of insect pests where resistant varieties are not available as is the case with the legume pod borer and pod sucking bug complex. Field experiments were conducted in the northern Guinea and Sudan savannas (Samaru and Minjibir, respectively) zones of Nigeria during 2005 to 2007 rainy seasons to evaluate the efficacy of common and new insecticides in the Nigeria markets for field control of insect pests of cowpea. Post spray insect counts showed that the new insecticide combinations gave control of thrips, Megalurothrips sjostedti (Order: Thysanoptera, Family: Thripidae) statistically similar to Monocrophos. Maruca vitrata (Order: Lepidoptera, Family: Crambidae) population densities were significantly reduced by the application of the insecticide regime of Imidacloprid (first spray), Cypermethrin (second and third) which however was not different from Cypermethrin-Dimethoate. The no spray plots gave significantly higher fodder yield in Samaru. The highest mean grain yields at Minjibir were obtained from plots sprayed with Imidacloprid + Cypermethrin + Cypermethrin (1391 kg/ha) while highest mean grain yield (924 kg/ha) in Samaru was from Monocrophos applied three times. Considering safety issues and environmental concerns, Imidacloprid (first spray) and Cypermetrin (second and third sprays) is recommended in a three insecticide spray recommendation for cowpea cultivation, especially in the Sudan Savanna of Nigeria and three sprays of Cypermethrin-Dimethoate in the northern Guinea Savanna. Key words: Cowpea, Megalurothrips sjostedti, Maruca vitrata, tricel, courage, grain yield.

Cover crop and conidia delivery system impacts on soil persistence of Metarhizium anisopliae (Hypocreales: Clavicipitaceae) in sugarbeet

The sugarbeet root maggot, Tetanops myopaeformis (Röder), is a major North American pest of sugarbeet, Beta vulgaris L. Previous research suggests that moderate T. myopaeformis control is possible with the entomopathogen Metarhizium anisopliae (Metch.) Sorok. We conducted a three-year (2002–2004) experiment to assess impacts of oat, Avena sativa L. and rye, Secale cereale L., cover crops on persistence of corn grit-based granular or spray formulations of M. anisopliae isolate ATCC 62176 (i.e. MA 1200) applied at 8×1012 viable conidia/ha in sugarbeet. More colony forming units (CFUs) were detected immediately after application [0 days after treatment (DAT)] in spray plots than granule-treated plots. However, 76–92% declines in CFUs per gram of soil occurred in spray plots within 30 DAT. Substantially (i.e. 83–560%) more rainfall occurred in June 2002 than during June of any other year. Subsequently, 71–670% increases in CFU concentrations occurred by 60 DAT in M. anisopliae granule-treated plots with oat or rye cover crops that year. CFU density increases were higher in cover crops in 2002, but no significant cover crop effects were detected. Conidia persisted for up to 30 DAT in M. anisopliae spray plots and 60 DAT in granule-treated plots in 2002; however, no increases occurred in the years with less June rainfall. Trends suggest that M. anisopliae aqueous sprays result in greater conidia concentrations than granules at sugarbeet plant bases in June during T. myopaeformis oviposition and larval establishment on host plants. Increases are possible when delivering conidia via granules, but high post-application rainfall could be necessary for conidia production.

The Effects of Extracts of Lantana camara (L.) and Azadirachta indica (A. Juss) on the Population Dynamics of Plutella xylostella, Brevicoryne brassicae and Hellula undalis on Cabbage

<p>The effects of ethanolic extract of neem, <em>Azadirachta indica</em> (Meliaceae), seeds and petroleum ether extract of <em>Lantana camara</em> leaves (Verbenaceae) on the populations of three cabbage pests, <em>Plutella xylostella</em>, <em>Brevicoryne brassicae</em> and <em>Hellula undalis</em> were studied. The study was conducted between January and April 2008. Extracts of the two plants were sprayed on cabbage plants to control these pests. A standard synthetic chemical insecticide (Mektin) was used as reference product. The experiment was conducted in a randomized complete block design and each treatment was replicated four times. The effects of plant extracts on the population dynamics of the pests’ species, the level of infestation and yield were assessed. Significantly more of the pests infested the control plants than the treated plants (<em>P</em>< 0.01). The mean weight of cabbage heads on the sprayed plots was significantly heavier than that of the control unsprayed plots. The use of <em>A. indica</em> seeds and <em>L. camara</em> leaf extracts increased yield by 37.05% and 25.80%, respectively. Spraying the cabbage plants with the plant extracts significantly reduced the numbers of pests compared with the control plants. The use of these plant extracts can be incorporated into an overall control programme of these pests.</p>

Investigating the Role of Herbicides in Controlling Invasive Grasses in Prairie Habitats: Effects on Non-target Butterflies

Invasive grasses severely impact prairies in the northwestern United States, leading to the decline of several butterfly species. Controlling these invasive species is a high priority for land managers. The use of herbicides is a promising management technique, yet effects on non-target butterflies are virtually unknown. We conducted a field investigation on the effects of a widely used grass-specific herbicide, sethoxydim, on butterfly habitat and demography using Puget blue (Icaricia (Plebejus) icarioides blackmorei Barnes and McDunnough) butterfly as a model species. Habitat use of adult silvery blue (Glaucopsyche lygdamus Doubleday), ochre ringlet (Coenonympha tullia Müller), and wood nymph (Cercyonis pegala Fabricius) butterflies was also quantified. The results suggest that the herbicide had very little to no impact on larval performance, flower species, or Puget blue oviposition, while adult butterflies spent significantly less time in sprayed plots than in controls. Given the necessity of invasive grass control in natural areas, we recommend several strategies to minimize herbicide effects on butterflies.

Management of white mold in type III common bean with plant spacing and fungicide

White mold is a yield-limiting disease during the fall-winter season in southeastern Brazil when irrigated type III common beans are generally sown 0.5 m apart with 10 to 12 plants per meter. The aim of this study was to evaluate the efficacy of combining increased row width (RW) and reduced planting density (PD), with or without fungicide, for white mold management. Treatments were arranged as a 23 factorial: RW (0.50 or 0.75 m), PD (6 or 12 plants per meter), and fungicide (sprayed or unsprayed). Two trials were conducted in Vicosa, State of Minas Gerais. In 2002, the average incidence of white mold was 43.2%, the severity index, 31.1%, and the yield, 2513 kg ha-1. In 2003, the values of these variables were 48.0%, 22.6%, and 2159 kg ha-1, respectively. Interactions involving both RW and PD were not significant for either disease intensity or yield in the combined analysis across years. Increasing RW led to reduction in white mold intensity in 2002. The lower PD reduced disease incidence in 2002 and did not affect yield in the combined analysis. In fungicide sprayed plots, wide RW decreased yield in 2002, but RW did not affect yield in 2003. In unsprayed plots, RW did not affect yield in both years. We conclude that increasing RW to 0.75 m combined with low PD is a promising strategy for white mold management when fungicide is not applied. When fungicide is applied, the current row width (0.50 m) combined with low PD maximize the yield.

Evaluation of responses of five cowpea (Vigna unguiculata (L.) Walp.) varieties to field infestation by major insect pests of cowpea

The study was conducted to evaluate yield response of five cowpea (Vigna unguiculata (L.) Walp.) varieties to field infestation and damage by major insect pests of cowpea. Three local varieties of cowpea, namely, Sokoto, Oloyin and Drum, and two International Institute of Tropical Agriculture (IITA) varieties, IT 90K-277-2 and IT90K-76, were planted on the Teaching and Research Farm of University of Agriculture, Abeokuta (UNAAB), Ogun State, Nigeria in September, 2006 and repeated in September, 2007. The experiment was laid out in Randomised Complete Block Design in split plots arrangement. Insecticidal spray constitutes the main plot while variety was the sub-plot. The main plot size was 19.4 m × 19 m and each of the sub-plot was 2.4 m × 3 m. The space between sub-plots was 1 m. Data from the sprayed plots were significantly (P < 0.05) higher than the unsprayed ones in the two seasons. Irrespective of season, the unsprayed plot of IT 90K-277-2 has a significantly (P < 0.05) high incidence of Ootheca mutabilis. The local variety, “Drum” has the highest incidence of flower thrip – Megalurothrips sjostedti in the two planting seasons. The highest mean number of peduncles/plant and pods/plant was in “IT 90K-277-2”. In both seasons, “IT90K-76” has a significantly (P < 0.05) lower number of damaged seeds and pods and “Oloyin” a significantly (P < 0.05) higher mean number of total pod sucking bugs. The grain yield was in the order IT90K-76 > Oloyin > IT 90K-277-2 > Sokoto > Drum.

Role of Antagonistic Microbe Pseudomonas fluorescens on Colletotrichum capsici Infecting Curcuma longa

The present study was attempted to find out the efficacy of commercially formulated Pseudomonas fluorescens in the form of foliar spray on Colletotrichum capsici infecting leaf spot disease in turmeric. The rhizomes dipped in biocontrol/chemical fungicide (bavistin) solution for overnight was planted in their respective triplicate plots for field study. 90-days old plants were sprayed with C. capsici spore spray (7-12×104 spores/ml) and subsequently on the next day by Pseudomonas fluorescens/bavistin spray in their respective plots. The second dosage of biocontrol/bavistin spray was given 15 days after the 1st biocontrol/bavistin spray. The leaf samples were collected from healthy; infected; biocontrol and bavistin sprayed plots on the 10th day after I and II spray schedule were subjected to various biochemical analyses. The result revealed that P. fluorescens (2%) in the form of rhizome treatment as well as foliar spray (two times) was found to be best antagonistic microbe in controlling C. capsici infecting Curcuma longa. The superiority of Pseudomonas spray over bavistin was mainly due to rapid cumulative antagonistic and antibiotic action against the pathogen.

Pre-establishment of Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) using Pinus brutia (Ten.) (Pinales: Pinaceae) pollen for thrips (Thysanoptera: Thripidae) control in greenhouse peppers

ABSTRACT The predatory mite Amblyseius swirskii (Athias-Henriot) benefited from the addition of pollen of Pinus brutia (Ten.) to the sweet pepper (Capsicum annum L.) plants on which they occurred. The mite was able to survive, in the absence of prey, on pepper plants sprayed 2 weeks prior to bloom with pollen at 50, 5, and 0.5 kg/ha dosages. In addition, A. swirskii effectively controlled the western flower thrips, Frankliniella occidentalis (Pergande), in the plots sprayed with pollen. Within 5 weeks after the introduction of the mite, the population density of A. swirskii reached up to three predatory mites (nymphs and adults) per leaf and they remained in high numbers on the leaves until the end of the study, even when the prey F. occidentalis was present in low numbers. In flowers, the population density of A. swirskii (3 weeks after its release) was 4.35, 2.29, and 1.25 mites per flower in the 50, 5, and 0.5 kg/ha pollen sprayed plots, respectively. Clear trends existed among the various treatments; more predators and fewer pests were found in the plots where pollen was applied compared with those where pollen was not applied. The pollen of P. brutia provides food for the predator, so that they can be introduced and established prior to the arrival of the thrips. This predator-in-first technique makes biological control of thrips on sweet pepper relatively reliable.

Can Imazapic Increase Native Species Abundance in Cheatgrass (Bromus tectorum) Invaded Native Plant Communities?

Native plant communities invaded by cheatgrass (Bromus tectorum L.) are at risk of unnatural high intensity fires and conversion to cheatgrass monocultures. Management strategies that reduce cheatgrass abundance may potentially allow native species to expand and minimize further cheatgrass invasion. We tested whether the selective herbicide imazapic is effective in reducing cheatgrass and “releasing” native species in a semiarid grassland and shrub steppe in north-central Oregon. The experiment consisted of a completely randomized design with two treatments (sprayed with 70 g ai · ha−1 of imazapic and unsprayed) and three replicates of each treatment applied to either 2.5 or 4 ha plots. We repeated this experiment in three different sites dominated by the following native species: 1) bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Löve ssp. spicata) and needle and thread (Hesperostipa comata [Trin. & Rupr.] Barkworth), 2) needle and thread and Sandberg bluegrass (Poa secunda J. Presl), and 3) big sagebrush (Artemisia tridentata Nutt.). Nested frequency of all plant species in 1-m2 quadrats was collected for 1 yr pretreatment and 4 yr posttreatment. In all three sites, cheatgrass frequencies were significantly lower in sprayed plots than unsprayed plots for 3–4 yr posttreatment (P < 0.1). Other annual plant species were also impacted by imazapic, but the effects were highly variable by species and site. Only two native perennial species, hoary tansyaster (Machaeranthera canescens [Pursh] Gray) and big sagebrush, increased in sprayed plots, and increases occurred only at two sites. These results suggest that a short-term reduction in cheatgrass alone is not an effective strategy for increasing the abundance of most native perennial plant species. Las comunidades de plantas nativas que están invadidas del pasto cheatgrass (Bromus tectorum L.) están en riesgo de fuego intencionales de alta intensidad y convertirse en monocultivos de éste pasto. Estrategias de manejo que reduzcan la abundancia del pasto cheatgrass podrían tener el potencial de permitir que especies nativas se expandan y minimicen la posible invasión por el cheatgrass. Probamos sí el herbicida Imazapicis que es efectivo en reducir el pasto cheatgrass y “liberar” especies nativas en pastizales semiáridos y matorral estepario en la parte centro-norte de Oregon. El experimento consistió en un diseño completamente al azar con dos tratamientos (asperjar con 70 g ia · ha−1 de Imazapic y sin asperjar) y tres repeticiones por cada tratamiento aplicado ya sea a parcelas de 2.5 o 4 ha. Repetimos el experimento en tres diferentes sitios dominados por las siguientes especies nativas: 1) (Pseudoroegneria spicata [Pursh] A. Löve ssp. spicata) y (Hesperostipa comata [Trin. &Rupr.] Barkworth), 2) (Hesperostipa comata [Trin. &Rupr.] Barkworth) y (Poa secunda J. Presl), y 3) Artemisa (Artemisia tridentata Nutt.). Se recolectaron todas las especies en un cuadrante de 1 m2 en frecuencia anidada por un año como pre-tratamiento y cuatro años como post-tratamiento. En todos los sitios las frecuencias de pasto cheatgrass fueron significativamente más bajas en las parcelas asperjadas que en las parcelas de control en tres de cuatro años de post-tratamiento (P < 0.1). Otras especies anuales fueron impactadas por Imazapic pero los efectos fueron muy variables por especie y sitio. Solo dos especies perennes nativas (Machaeranthera canescens[Pursh] Gray) y la Artemisa aumentaron en solo dos de las parcelas asperjadas. Estos resultados sugieren que en el corto plazo la reducción de pasto cheatgrass por sí solo no es una estrategia efectiva para aumentar la abundancia de muchas especies de plantas nativas.

Evaluation of ULV Applications Against Old World Sand Fly (Diptera: Psychodidae) Species in Equatorial Kenya

Reducing populations of phlebotomine sand flies in areas prevalent for human leishmaniases is of ongoing importance to United States military operations and civilian populations in endemic regions. However, not enough is known regarding the efficacy of Department of Defense-approved pesticides and equipment against sand flies; specifically, the potential for ultra-low volume (ULV) pesticide applications to control Old World sand fly vectors. In this study we examine two sprayers, the Terminator ULV and the Grizzly ULV, with UV-labeled Duet and Fyfanon in four combinations against caged Phlebotomus duboscqi (Neveu-Lemaire) and wild sand fly populations in a natural environment in western Kenya. All equipment and Fyfanon have United States military National Stock Numbers and both pesticides are registered with the United States Environmental Protection Agency. Caged sand flies were reared from local P. duboscqi and the area has long been studied because of high incidences of human cutaneous and visceral Leishmania. Patterns of mortality across grids of caged sand flies showed greater efficacy from the Grizzly ULV regardless of chemical. The Terminator ULV performed well with Duet but with a less uniform and overall lower rate of mortality across the spray grid. Sampling of wild populations before and after treatments suggested local population suppression from ULV treatments, as well as a possible repellent effect in nearby untreated areas. Surprisingly, ULV active ingredient deposition inferred from patterns of UV-labeled droplets captured on cotton ribbons adjacent to sand fly cages in spray plots did not match patterns of mortality. We discuss the implications of this study, the first of its kind, for future military preventive medicine activities, including relative performance costs and benefits of larger or smaller sprayers, and the relative stability of ULV-induced mortality patterns in varied or sub-optimal conditions.

Resistance of eight Iranian onion cultivars to onion thrips (Thrips tabaci Lindeman) in the Markazi Province of Iran

Thrips tabaci L. is one of the most important pests of onion in Iran. In this research, eight Iranian onion cultivars (Ghermez-e-Azarshar, Sefid-e-Kashan, Sefid-e-Native Khomein, Sefid-e-Improved Khomein, Sefid-e-Qom, Sefid-e-Kordestan, Sefid and Ghermez-e-Shahroud) were cultivated in a RCB design with four replications in Arak, between 2001 and 2003. The number of thrips on five plants was recorded every two weeks and ten days interval on non-sprayed and sprayed plots, respectively. The symptoms of pest feeding, which includes chlorosis and necrosis were rated based on a scale from 1 to 10 for usual damaging and leaf curling another symptom a 1 to 6 scale. The control field was sprayed with current insecticides every 10 days in order to decrease the thrips population. In this study, the highest number of thrips was observed on Ghermez-e-Azarshahr and Sefid-e-improved Khomein and Sefid-e-Shahroud and the lowest number was recorded on non-sprayed fields and then on Ghermez-e-Shahroud, Sefid-e-Kordestan. The highest amount of damage was observed on Ghermez-e-Azarshahr while, the lowest one for Sefid-e-Kordestan and Qom. In non-sprayed plots, the highest yield was recorded for Sefid-e-Kashan and Qom cultivars and the lowest yield for Sefid-e-Kordestan cultivar. The results of the study over the three years showed Sefid-e-Kashan and Sefid-e-Qom as the genotypes resistant to thrips, Sefid-e-improved onion of Khomein as a tolerant genotype and Ghermez-e- Azarshahr having high level of thrips density (more than 25 thrips in each plant) and high level of damage, and leaf curling is introduced as a genotype sensitive to thrips. Key words: Onion cultivar, Thrips tabaci, resistance.

Assessing the short‐term impact of an insecticide (Deltamethrin) on predator and herbivore abundance in soybean Glycine max using a replicated small‐plot field experiment

Abstract A greater understanding of the relative impact of insecticide use on non‐target species is critical for the incorporation of natural enemies into integrated pest management strategies. Here we use a small‐plot field trial to examine the relative impact of an insecticide on herbivores and predators found in soybean (Glycine max L.), and to highlight the issues associated with calculating impact factors from these studies. The pyrethroid insecticide (Deltamethrin) caused a significant reduction in invertebrate abundance in the treated plots, and populations did not recover to pre‐treatment levels even 20 days after spraying. To assess the relative impact of the spray on arthropods we first examined the mean difference in abundance in each plot before and after spraying. All herbivores decreased in abundance in the sprayed plots but increased in the control plots after spraying. Most predators (excluding hemipterans) showed a decrease in the control plots but a proportionally greater decrease in the sprayed plots. Next we examined the corrected percentage population reduction calculated using Abbott's formula. All predators (including Araneae) experienced a greater reduction (mean 87% ± 3.54 SE) than herbivores (mean 56% ± 4.37 SE) and Araneae alone (mean 71% ± 8.12 SE). The range in values across the plots varied and made categorising overall impact subjective for some taxa. Despite the constraints associated with small‐plot trials, by using a combination of impact factors and examining community‐level response across time, we did get some indication of the likely impact of this insecticide if used in a commercial situation.

The impact of the locust control insecticide fipronil on termites and ants in two contrasting habitats in northern Australia

Termites and ants are key ecosystem engineers and nutrient re-cyclers. Extensive spraying of insecticides presents a hazard to these insects. Using a control-treatment paired design comprising 3 replicate pairs of plots per soil type, we quantified the impact of fipronil on termite consumption of cardboard and wood baits, termite repair of deliberately damaged mounds as well as ant community composition and abundance in two different habitats (black vertisol and red kandosol soil) when applied aerially at a dose rate recommended for locust control in Australia. The study was conducted from 2006 to 2008. The diversity of termites and ants was higher and side-effects were more pronounced on kandosol than on vertisol soil. Overall termite consumption of cardboard baits was significantly greater in unsprayed than in sprayed plots while losses were significantly greater in only one (vertisol) or two (kandosol) sprayed plots, respectively, compared to paired unsprayed plots. In the first year, termite consumption of wood baits was generally significantly greater on unsprayed than on sprayed kandosol while only marginally significant on unsprayed vertisol. Again, losses were significantly greater in one (vertisol) and two (kandosol) sprayed plots, respectively, compared to paired unsprayed plots. Overall termite consumption of wood baits was similar among plots in the second year post-spray although consumption remained significantly depressed in one pair of sprayed plots in each habitat. The capacity of the mound-building termite, Drepanotermes rubriceps (Froggatt) unique to kandosol, to repair damaged mounds was significantly reduced by fipronil. Furthermore, colonies of Iridomyrmex greensladei Shattuck, an ant species associated with mounds of D. rubriceps, were not re-located five months post-spray. Ant communities were also adversely affected. On vertisol, species richness and relative abundance were similar among treatments, but significantly fewer species were caught in one individual sprayed plot. In contrast on kandosol, species richness and relative abundance were significantly reduced by fipronil. A drop in species richness was observed in all and a drop in relative abundance in two sprayed plots. On vertisol, abundances of two species were significantly lower in sprayed than in paired unsprayed plots. Likewise on kandosol, abundances of five species were significantly reduced in sprayed plots, and one species was not caught at all. The weight of evidence of our findings indicate that fipronil, even at a low rate, will have substantial adverse impacts on the diversity and activity of termites and ants, especially if applied within one to two years of earlier applications.

Controle do inóculo inicial para redução dos danos pela podridão: 'olho-de-boi' em macieiras

O objetivo deste trabalho foi avaliar o impacto da redução do inóculo no controle da podridão-'olho-de-boi' (POB) causada por Cryptosporiopsis sp. em maçãs e minimização de perdas. Os experimentos foram realizados em Vacaria-RS, nos ciclos 2006/07 e 2007/08. Na fase de dormência de macieiras Pink Lady®, foram aplicados os seguintes tratamentos erradicantes (dose p.i.): calda sulfocálcica (3,0%); oxicloreto de cobre (0,5%); hidróxido de cobre (0,3%); óxido cuproso (0,3%) e testemunha sem pulverização. A redução do inóculo foi avaliada em solução oriunda da lavagem de ramos, gemas floríferas e frutos, semeados em meio semisseletivo. Na colheita, a incidência da POB foi avaliada em quatro categorias de frutos: caídos sob a área de projeção da copa; nas plantas; infecções latentes, e após três meses de armazenamento em câmara frigorífica. Houve relação linear positiva entre os níveis de inóculo de Cryptosporiopsis sp. em gemas e os danos por POB (R² = 0,948; P = 0,001). O uso da calda sulfocálcica possibilitou a maior redução de inóculo nas gemas, com redução em 50% dos danos totais ocasionados por POB na safra de 2006/07. Nos frutos, o inóculo apresentou um incremento linear ao longo do ciclo, sendo relativamente maior em 2007/08, onde os tratamentos erradicantes possibilitaram controle superior a 40% nos danos com benefício econômico pela redução do inóculo.

Potential of Momordica charantia (L.) Bitter Gourd and Garlic-Pepper Spray Extracts for the Control of Myzus persicae (Sulzer) and Cercospora Leaf Spot on Pepper, Capsicum annuum (L.).

The trials were conducted at the National Horticultural Research Institute, lbadan, during the rainy seasons of 2007 and 2008 to determine the potential of 5 % aqueous extracts of the leaves of Momordica charantia (L.), bulb of garlic, Allium sativum (L.), plus fruit of chilli pepper, Capsicum annum (L.) [15 g : 3 gin 1 L of water l and lambda cyhalothrin (Karate x EC ; 0.5L/ ha) for controlling the green peach aphid [Myzus persicae (Sulzer)] and Cercospora leaf spot on three varieties of pepper: Kano. Katsina, and Gombe local, in a 3 x 4 factorial experiment. In the two years of study. there were insignificant varietal differences in aphid infestation and also insignificant interaction between varieties and spray treatments on aphid infestation and leaf spot severity. M charantia and garlic-pepper sprays were significantly (P=0.05) more effective in reducing the green peach aphids on pepper than lambda cyhalothrin which had mean aphid infestation score of 3.20 in 2007 and 3.13 in 2008. Sprayed plots had significantly less severe disease than the control plots. There were significant (P=0.05) varietal differences in leaf spot severity score with Katsina local variety showing tolerance (severity score of 3.98 in 2007 and 4.05 in 2008); the highest number of fruits/plant (4.97 in 2007 and 4.33 in 2008): and the highest mean weight of fruits/ plant (0.98 kg in 2007 and 0.55 kg in 2008).

Yield loss of faba bean (Vicia faba) due to chocolate spot (Botrytis fabae) in sole and mixed cropping systems in Ethiopia

Two field experiments were conducted during 2004 and 2005 cropping seasons at Adet Agricultural Research Center, Ethiopia to assess yield losses caused by chocolate spot(Botrytis fabae) of faba bean in sole and mixed cropping systems using two cultivars. Cropping systems were sole faba bean (FB), faba bean mixed with field pea (FB: FP), barley (FB: BA) and maize (FB: MA). Mancozeb was sprayed at the rate of 2.5 kg a.i/ha at 7-, 14- and 21-day interval to generate different levels of chocolate spot disease in all the four cropping systems, and unsprayed control was also included. The treatments were arranged in a randomised complete block design (RCBD) with four replications. FB: MA mixed cropping significantly reduced disease severity and the area under disease progress curve (AUDPC) and increased faba bean grain yield. The highest faba bean grain yield among the three mixed croppings under different spray schedules was obtained from FB: MA mixed cropping in both 2004 and 2005 (2.56 and 3.74 t/ha, respectively) cropping seasons. There were highly significant yield differences (P < 0.05) among the spray intervals of mancozeb in both seasons. The highest grain yield (4.9 t/h) was recorded from the 7-day spray interval in 2005. The unsprayed faba bean had a lower grain yield (1.9 t/ha in 2004 and 2.3 t/ha in 2005) compared to the sprayed plots. The highest relative yield loss (67.5%) was calculated in 2005 from FB: FP mixed cropping in unsprayed plots. The relative yield losses in the unsprayed plots were in the range of 35.8–41.5% in 2004 and 52.6–67.5% in the 2005 cropping season. Severity and AUDPC were inversely correlated with faba bean grain yield. Significant differences were recorded in the 100-seed weight and days to maturity (DM). The unsprayed plots had shorter DM ranging from 126 to 128.5 day (except FB: MA mixed cropping) in 2004 and 122–123.9 days in 2005. In the sprayed plots DM was relatively longer than the unsprayed plots. A higher seed weight was recorded in the sole FB (56 g) and FB: MA (55 g) mixed cropping, and the lowest value of 100-seed weight was recorded from FB: FP (53 g) mixed cropping. The productivity of the mixed cropping evaluated by land equivalent ratio (LER) exceeded that of sole cropping. Faba bean grain yield was highly influenced by the severity of chocolate spot. The disease affects the DM, forcing early maturing of the plants.

Evaluation of a Warning System for Controlling Primary Infections of Grapevine Downy Mildew.

A warning system based on (i) a model that simulates the development of all cohorts of Plasmopara viticola oospores, from oospore germination to infection; (ii) short-term weather forecasts; and (iii) a mobile phone short message system was tested in Northern Italy, from 2006 to 2008. An unsprayed control was compared with a "Warning A" treatment (WA, fungicides were applied whenever the warning system predicted an infection period), a "Warning B" treatment (WB, fungicides were applied as in the WA treatment but only when the relative dimension of any oospore cohort predicted by the model exceeded a threshold), and a "grower" treatment (fungicides were applied according to a conventional schedule). Average disease incidence on leaves was reduced by up to 90% in sprayed plots compared with unsprayed plots. On bunches, efficacy was always >90% at fruit set; when most berries were touching, efficacy was higher for the WA (96%) than for grower (89%) and WB (85%) treatments. On average, 6.8 fungicide sprays were applied following the grower's schedule; use of the warning system reduced applications by about one-half (WA treatment) or two-thirds (WB treatment). The grower's schedule had an average cost of 337 €/ha; the average saving with the WA and the WB treatments was 174 and 224 €/ha, respectively.