Striga seed avoidance by deep planting and no-tillage in sorghum and maize

The possibility of reducing Striga hermonthica (Del.) Benth. parasitism in severely infested fields, by means of deep planting - thereby reducing the root length in the upper layers of the soil where Striga seeds are predominantly found - was tested in field trials with maize and sorghum in western Kenya. Sorghum seeds were planted in Striga-infested fields approximately 2.5 cm deep in the soil or at the bottom of conically-shaped plant holes (15-20 cm deep). Depth of plant holes for maize varied from 0 to 30 cm, in un-tilled soil. Deep planting in un-tilled soil gave higher (up to double) grain yields, compared with standard planting in tilled soil. Parasite emergence was related negatively to planting depth of maize (p< 0.05). Deep planting in tilled soil gave 74% more sorghumgrain yield relative to standard planting. In this treatment Striga seed production was not reduced but in un-tilled fields with deeply planted sorghum Striga seed production was completely suppressed. Therefore, a combination of zero-tillage and deep planting seems to be the most effective treatment. The probable mechanism causing these results is avoidance of Striga seed by the host root system, resulting in a delay in the onset of Striga attachment and the formation of smaller numbers of attachments.     

A bio-economic model of long-run Striga control with an application to subsistence farming in Mali

A bio-economic model of Striga control is developed and applied to Mali's Mourdiah Zone. Various constraints are added, and optimal production practices identified based on Striga infestation levels, rainfall levels, and economic parameters. Model optimization suggests efforts to suppress Striga with nitrogen applications are both expensive and risky. The efficacy of hand-pulling Striga in reducing the Striga seedbank depends on Striga infestation levels and climatic conditions, as does the profitability of hiring labour to expand cultivated acreage. Under all climatic conditions and infestation levels considered, millet in a pure stand generated greater expected net returns than a millet - groundnut or millet - cowpea association. Under conditions of low rainfall, the model suggests planting millet at a density of 0.5 hills m^?2. With average or higher rainfall, the model suggests planting millet at a density of 3.5 hills m^?2. Estimates of Striga-induced net revenue losses also vary with climatic conditions, ranging from 6% to 85%. Model results are encouraged to be used as a guide in the design and evaluation of research and extension programmes aimed at identifying long-run Striga control strategies and promoting their adoption.     

Some effects of single and split applications of carbofuran on the incidence of and damage by Locris Maculata,Busseola Fusca and Sesamia Calamistis on maize

Abstract

Studies have been carried out on the efficacy of carbofuran (Furadan 5G) in reducing the incidence of the major insect pests of maize in Nigeria. A single dose of 1.5 kg a.i./ha applied in the planting hole was found to reduce the incidence of spittle bug (Locris Maculata F.) and stem borers (Busseola fusca (Fuller) and Sesamia calamistis (Hmps.)) when compared with split applications of the same dose applied at planting and 40 days after planting. The number of damaged plants was reduced from 40% in the control to 11.7% in the treated plots. Yields of fresh maize cobs were also increased significantly in treated plots. A significant positive correlation was established between the mean number of stem borer larvae and mean percentage damage, and significant negative correlations between the mean yield and mean percentage damage and between the mean yield and mean number of stem borer larvae.     

A simple tentative model of the losses caused by the Senegalese grasshopper,Oedaleus senegalensis (Krauss 1877) to millet in the Sahel

Oedaleus senegalensis is a serious pest of millet in the Sahel, but the correlation to crop loss remains largely unknown. Therefore, the correlation between densities of O. senegalensis, defoliation level and millet yields was investigated in Niger in 2008, and a simple model to foresee the yield based on these parameters was developed. The yield was significantly correlated to both the density of O. senegalensis and the defoliation level on 17 September. The best model to foresee millet yield involved grasshopper density and cumulated rainfall and may be regarded a tentative method in O. senegalensis control.     

Corn as trap crop to control Helicoverpa zea in tomato fields: importance of phenological synchronization and choice of cultivar

Trap cropping is an environmentally friendly “alternative” pest management strategy. To maximize the efficiency of corn, Zea mays L. (Poaceae), as a trap crop for Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), we (i) tested the trap crop potential of corn varieties that are not a source of infestation, and (ii) determined the best corn planting time so as to concentrate H. zea in this trap crop and divert the pest from tomato, Solanum lycopersicum L. (Solanaceae). When corn silk emergence was synchronized with tomato flowering and fresh corn silk was present during the tomato flowering stage, H. zea infestation was lower in the tomato field with a corn border than in those without a corn border. Sugar Jean and Java corn varieties were good trap crops because few larvae persisted on the silks and their growth was low. These two varieties could reduce the risk of H. zea development and dispersion from corn borders.     

水分胁迫下不同耐旱性糜子叶片保护酶活性及膜脂过氧化特性

选取耐旱品种陇糜4号和旱敏感品种晋黍7号,利用防雨旱棚与人工控水相结合的方法,研究了水分胁迫对糜子产量、叶片保护酶活性及膜脂过氧化作用的影响。结果表明,与CK处理相比,水分胁迫降低了糜子的穗数、穗粒数和千粒重,重度水分胁迫下差异达显著（P<0.05）水平,且旱敏感品种晋黍7号的降低幅度大于耐旱品种陇糜4号。整个生育时期,糜子叶片的SOD、POD和CAT活性表现为先升高后降低的趋势,在抽穗期达到最大值; 水分胁迫降低了糜子叶片的SOD、POD和CAT活性,与对照相比,重度水分胁迫下达到显著性差异（P＜0.05）,重度水分胁迫下,耐旱品种陇糜4号SOD活性2年内平均降低22.58%,而旱敏感品种晋黍7号2年内平均降低44.94%。水分胁迫处理增加了糜子叶片的膜脂过氧化产物MDA含量和可溶性糖的含量,随着生育期的推进,糜子叶片可溶性糖含量表现为先升后降的趋势,在灌浆期表现为最大值。相关性分析结果表明,糜子产量与叶绿素含量、SOD活性、POD活性和CAT活性呈正相关关系。     

Assessment of loss in yield due to sorghum downy mildew (Peronosclerospora sorghi) of maize in Nigerian guinea savanna

Abstract

The losses in yield due to sorghum downy mildew of maize induced by Peronoscleospora sorghi were assessed from 1982 to 1984 in the epidemic‐prone area of Nigeria. Plots of maize with different downy mildew incidences were obtained by planting seedlots containing different percentages of metalaxyl‐treated seeds. The losses in yield were directly proportional to the incidence of the disease. There was highly significant negative correlation between the incidence of downy mildew and grain yield.     

First record of the tomato leafminer,Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in Sudan

An outbreak of larvae and adults of a devastating moth was noted to be causing severe damage in tomato grown in greenhouses at Khartoum State, Sudan during June 2010. Symptoms included foliage mining and leaves drying. Photographs of symptoms and larvae and adults of the pest (and subsequently specimens) were sent to Russell IPM, UK and the Finnish Museum of Natural History for identification. The pest was identified as Tuta absoluta (Meyrick), (Lepidoptera: Gelechiidae). This is the first official record of T. absoluta in Sudan, based on surveys in tomato production areas in Khartoum, Gezira, Red Sea and North Kordofan States and eggplant and potato in Khartoum State. Severe yield loss due to the serious feeding damage on foliage and fruits infestation was reported on tomato and eggplant fields at Khartoum State.     

Fish-toxicity problems of pesticides in Japan - the present situation and the policies of the Ministry of Agriculture and Forestry

Abstract

A survey of termite damage to groundnuts and an estimation of loss in yield was made between 1977 and 1979 in northern Nigeria. The foliage was attacked by Odontotermes. Damage was restricted to the Sudan savanna and loss in yield was less than 5%. Much more important was the damage caused by Microtermes lepidus Sjöstedt which attacked the pods, the tap root and the haulms. There was a linear relationship between the percentage of stands with the tap root invaded by Microtermes and the loss in yield. Damage varied from year to year, but the higher yield losses (up to 40%) were consistently recorded in the Sudan savanna. There was a significant relationship between the level of Microtermes damage and rainfall, the latter having a marked influence on foraging behaviour and the level of foraging activity. The chemical control of termites is economically viable on mechanised farms in the Sudan savanna, but cannot be justified on peasant farms, where yields are too low.     

Is there need for leaf-galling grape phylloxera control? Presence and distribution of Dactulosphaira vitifoliae in Swiss vineyards

Grape phylloxera (Dactulosphaira vitifoliae, FITCH) was a major pest in Vitis vinifera grape production in the late 19th and early 20th century in Europe. Roots of V. vinifera varieties are susceptible to D. vitifoliae attack whereas the leaves are not affected. The pest has been controlled by using American grapevine varieties as rootstocks. However, in recent years, grape producers have reported higher incidences of leaf galls induced by D. vitifoliae on V. vinifera leaves. Research on the occurrence of D. vitifoliae on grapevine leaves and roots has shown that D. vitifoliae is present in all wine-growing regions of Switzerland. In more than 80% of vineyards claiming to be infested, D. vitifoliae was found on leaves of varieties with interspecific crosses in their parentage. Three locations with leaf-galling individuals on V. vinifera were detected. D. vitifoliae individuals were found emerging from soil potentially associated with the commonly used rootstock varieties, which are assumed to be phylloxera tolerant. As climate change may necessitate the relocation of some viticultural areas to new wine-growing regions, there will be a greater need to control D. vitifoliae on leaves of interspecific crosses and the inspected planting material to limit further spread of the pest.     

Groundnut Rust (Puccinia arachidis) in Brunei

Abstract

A field trial was conducted during the cotton growing seasons of 1978-79 and 1979-80 at Hissar, Haryana (India) to determine the capture threshold of male pink bollworm moths in traps baited with gossyplure for timing the insecticidal application. It was found that application of insecticides when the number of male moths averaged 4 or 8 per trap per night was superior to fixed spray schedule (spraying at an interval of 13-14 days starting from middle of August) in reducing the pink bollworm incidence and obtaining higher yield of seed cotton. For effective and economic control of the pest, insecticides should be applied within 24-48 hours when the number of male moths captured in gossyplure baited traps reaches 8 per trap per night.     

2006-2018年河南省漯河市蛴螬优势种变化及其与秋作物种植面积的关系

为绿色防控蛴螬,于2006—2018年秋作物收获后、小麦播种前,调查河南省漯河市5个区县不同茬口秋作物田内金龟子幼虫种类、虫口密度以及主要秋作物种植面积,同时在漯河市农业科学院试验基地内设置1台黑光灯,监测金龟子成虫的上灯种类和数量。结果表明,2006—2018年,铜绿丽金龟Anomala corpulenta幼虫平均密度由2006年的2.06头/m2下降到2018年的1.01头/m2,所占比例从2006年的94.12%下降到2018年的38.37%;暗黑鳃金龟Holotrichia parallela幼虫平均密度由2006年的0.06头/m2上升到2018年的1.59头/m2,所占比例从2006年的2.61%增加到2018年的60.46%,表明金龟子幼虫优势种由铜绿丽金龟变为暗黑鳃金龟。灯下金龟子成虫种类和数量变化与金龟子幼虫变化趋势相同。暗黑鳃金龟幼虫密度与玉米种植面积、红薯种植面积呈显著负相关,相关系数分别为-0.657和-0.690,暗黑鳃金龟幼虫密度与大豆种植面积、花生种植面积呈显著正相关,相关系数分别为0.753和0.657,表明大豆、花生种植面积增加,玉米、红薯种植面积减...     

Farmers' knowledge of cassava brown streak disease and its management in Malawi

There is little information on farmers’ knowledge about cassava (Manihot esculenta Crantz) brown streak disease (CBSD), despite extensive studies on incidences and severities. The objective of this study was to assess farmers’ knowledge of CBSD diagnosis and management. The study was conducted in three districts of Malawi by administering semi-structured interviews in combination with disease incidence and severity surveys. Farmers’ knowledge of disease diagnosis and management was associated with CBSD incidence and severity. High levels of knowledge about CBSD were observed in areas with high disease incidence. Only 10.1% of the farmers were capable of identifying the foliar symptoms of the disease. On average, 75.0% and 71.7% of the farms had leaf and storage root incidences, respectively. At harvest, 88.3% of the farmers’ fields exhibited storage root necrosis. CBSD leaf and storage root severities differed significantly (P < 0.001) from one district to the other and between varieties. Most farmers were found to lack a source of clean planting material. High needs for extension services on cassava cultivation methods and pest management were identified, but few farmers received such services. The lack of new improved varieties was reported as the most important constraint of cassava production, beyond CBSD. Education of farmers on the efficient management of this viral disease through selection of clean planting material should be provided. Additionally, the development of early root bulking cultivars as a long-term solution in avoiding CBSD impact should be supported.     

Effect of sowing dates and fertilizer on the severity of stem borer (Busseola fusca Fuller,Lepidoptera: Noctuidae) on sorghum in Eritrea

The influence of sowing date and fertilizer application on the incidence anddamage ofthe maize stemborer (Busseolafusca Fuller) in sorghum(Sorghumbicolor L.) was investigated at the Halhale Research Centre in Eritrea during 1997 - 99. The trials were conducted in a splitplot design with sowing date as the main plot and fertilizer as subplots. There were six sowing dates at an interval of 15 days starting fromearly April tomid-June. There were fertilized and unfertilized subplots. Data on larval count, per cent infestation, per cent deadheart, heading and maturity dates, plant height and yield were recorded for each plot. Fertilizer had no effect on the incidence and damage of the stem borer (B. fusca). There was no interaction between fertilizer and sowing dates on the larval population and damage by stem borers. Sowing date had a significant effect on stem borer incidence and damage levels. Early sowing dates (April 1 and 15) had a significantly lower number of larvae, infestation, deadheart and gave higher yields compared with the other sowing dates while late sowing dates (mid-May- mid-June) resulted in significantly higher infestation and damage. The highest infestation and damage were recorded from mid-May sowings. High stem borer infestations in delayed sowing was due to the coincidence of the susceptible stage of the crop (3 - 6 weeks after germination) with high populations ofstemborer larvae fromthe first generationin late June and July. Mid- and late sown crops were also later attacked by the second generation at the grain-filling stage in September- October. These results indicate that early planting (April) is effective in reducing stem borer damage on sorghum in the highlands of Eritrea.     

Eldana saccharina as a Crop Pest in Ghana

Abstract

Eldana saccharina is a serious pest of maize in Ghana on the second rains crop grown in the south of the country. The question is raised whether it is worth growing a second maize crop under present conditions. E. saccharina is also a serious pest of sugarcane, causing severe losses to a valuable cash crop, and more work is needed to find suitable means of control, preferably combining the use of resistant varieties, cultural practices and natural enemies.     

Notices

Abstract

Seed‐bed types, fertilizers, cassava stem portions, planting time and yam cultivars were studied for the incidence of termites in cassava and yam fields. Planting cassava on ridges reduced the incidence of termites and significantly (P<0.05) increased tuber yield. The bottom stem portion of cassava stick was the least attacked by termites. Planting cuttings when rains became steady reduced termite incidence. NPKMg (12:12:17:2) suppressed termites in yam and improved yield significantly. Delay in harvesting yam tubers increased termite infestation. Yield loss was highest for Dioscorea rotundata cv. Nwopoko, with losses of more than 5 metric tonnes/ha when harvest was done after December in termite infested soil. Chinese yam showed the greatest resistance to termites.     

Biological control of the millet head miner Heliocheilus albipunctella in the Sahelian region by augmentative releases of the parasitoid wasp Habrobracon hebetor: effectiveness and farmers’ perceptions

On-farm augmentative releases of the parasitoid Habrobracon hebetor (Say) for controlling the millet head miner (MHM) Heliocheilus albipunctella (de Joannis) were tested in Burkina Faso, Mali and Niger from 2007 to 2009. In addition, a survey of farmers’ perceptions of insect pests, with particular focus on MHM, and the biological control program (BCP) was carried out. There was a significant increase of MHM parasitization rate after the releases, with up to 97% mortality. The survey on farmers’ perceptions revealed a fair knowledge of the MHM and the ability of farmers to describe the pest and the damage it caused. Farmers claimed that the biocontrol agent H. hebetor is effective and perceived a significant gain in grain yield due to this control strategy. Implications of these findings for a large extension of the MHM biocontrol program are discussed.     

超级稻病虫发生特点及其药剂防治技术

超级稻从孕穗末至齐穗期如遇上连续阴雨天,稻曲病大发生,纹枯病发生较普遍;二化螟、稻飞虱发生量大,危害较重。在超级稻大田生长期,抓住施药适期,选用高效、内吸、广谱、环保型农药,进行3～4次防治,可有效防控病虫危害,达到节本增效、减少农药污染的目的。     

Note: Does<Emphasis Type="Italic">Liriomyza cicerina</Emphasis> affect the yield of chickpeas (<Emphasis Type="Italic">Cicer arietinum</Emphasis>)?

Liriomyza cicerina (Rondani, 1875) (Diptera: Agromyzidae) is an important pest on chickpea (Cicer arietinum L.) in some regions of Turkey. The objective of this study was to determine whether the populations ofL. cicerina on different varieties of chickpea plants during the 2004 and 2005 production seasons affected yield in Sanliurfa province. The trials were carried out using eight different varieties of chickpea with three replicates. During each season, larval densities on leaves were assessed weekly. TheL. cicerina larval population was lowest on four varieties for both seasons. There were very minor differences in yield among the eight varieties in the production seasons. There was no correlation found between larval density and yield loss. http://www.phytoparasitica.org posting Jan. 14, 2007.     

Fifth East African Weed Control Conference

Abstract

Curvularia leaf spot of maize is becoming increasingly important in Nigeria. Six fungicides were tested for their effectiveness in inhibiting the growth of Curvularia pallescens Boed. in culture. The fungicides copper oxychloride, copper oxychloride + zineb and benomyl were more effective than mancozeb, zineb or maneb in inhibiting the growth of C. pallescens in culture; however, only copper oxychloride + zineb and copper oxychloride alone effectively controlled Curvularia leaf spot on maize.

Four maize varieties were artificially inoculated in a disease-loss field trial. The yield depressing effect of the disease was found to be significantly dependent on the type of variety infected. Regression coefficients (grain yield versus leaf infection) among the four maize varieties were not statistically homogeneous, percentage grain yield reduction ranged from 3.0 for the variety NCBRbu to 33.3 for the variety Igbira.