Smallholders in Southern Africa continue to grapple with low maize productivity despite this being the staple food crop. This study sought to analyze and isolate the relative contribution of agronomic practices to maize yields obtained by smallholders in Malawi and Mozambique using data generated from on-farm trials testing the performance of conservation agriculture cropping systems. The trials were implemented in two communities, namely Kasungu district in Malawi and Sussundenga district in Mozambique, and ran for seven consecutive growing seasons starting in 2010–2011. Maize yield was measured annually in the on-farm trials, which included a ‘control treatment’ representing an improved farm practice, and in neighboring fields managed by the same farmers on their own, hence representing a ‘true farm practice’. Results indicated that maize yield increased linearly with increasing plant population at harvest at both sites. On average, an increase in plant population at harvest by 1000 plants ha–1 resulted in an increase in maize yield of 90 and 63 kg ha–1 at Kasungu and Sussundenga, respectively. The greatest maize yields were obtained when plant population at harvest exceeded 40 000 plants ha–1. Yet, the plant population at harvest was below the generally recommended optimum for most of the cropping systems studied and in most growing seasons. Furthermore, the use of agronomic practices alone without conservation agriculture (i.e., improved varieties, fertilizer management, and timely weed control) resulted in maize yield gains of as much as 54% and 43% relative to the ‘true farm practice’ at Kasungu and Sussundenga, respectively. Overall, the proportion of these yield increases relative to the ‘true farm practice’ accounted for by agronomic practices amounted to 53–70% and 57–85% at Kasungu and Sussundenga for the highest to the lowest-yielding cropping system. Although conservation agriculture significantly improved maize yield at both sites, such increases were smaller in magnitude compared to the yield gains derived from improved agronomic practices. The study suggests that considerable strides toward narrowing maize yield gaps in Southern Africa can be achieved through improvement of current crop management practices, let alone adhering to the conservation agriculture principles of minimum tillage, residue retention, and crop diversification.

Studies of ‘food globalisation’ have traced the dispersal of cereals across prehistoric Eurasia. The degree to which these crops were accompanied by knowledge of soil and water preparation is less well known, however. The authors use stable isotope and archaeobotanical analyses to trace long-term trends in cultivation practices on the Loess Plateau (6000 BC–AD 1900). The results indicate that ancient farmers cultivated grains originating in South-west Asia and used distinct strategies for different species. Barley was integrated into pre-existing practices, while wheat was grown using novel soil and water management strategies. These distinct approaches suggest that the spread of prehistoric crops and knowledge about them varied by local context.

Crop models can be used to explain yield variations associated with management practices, environment and genotype. This study aimed to assess the effect of plant densities using CSM-CROPGRO-Soybean for low latitudes. The crop model was calibrated and evaluated using data from field experiments, including plant densities (10, 20, 30 and 40 plants per m2), maturity groups (MG 7.7 and 8.8) and sowing dates (calibration: 06 Jan., 19 Jan., 16 Feb. 2018; and evaluation: 19 Jan. 2019). The model simulated phenology with a bias lower than 2 days for calibration and 7 days for evaluation. Relative root mean square error for the maximum leaf area index varied from 12.2 to 31.3%; while that for grain yield varied between 3 and 32%. The calibrated model was used to simulate different management scenarios across six sites located in the low latitude, considering 33 growing seasons. Simulations showed a higher yield for 40 pl per m2, as expected, but with greater yield gain increments occurring at low plant density going from 10 to 20 pl per m2. In Santarém, Brazil, MG 8.8 sown on 21 Feb. had a median yield of 2658, 3197, 3442 and 3583 kg/ha, respectively, for 10, 20, 30 and 40 pl per m2, resulting in a relative increase of 20, 8 and 4% for each additional 10 pl per m2. Overall, the crop model had adequate performance, indicating a minimum recommended plant density of 20 pl per m2, while sowing dates and maturity groups showed different yield level and pattern across sites in function of the local climate.

Kernza® intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & Dewey], the first perennial grain crop to come to market in North America, can provide a number of ecosystem services when integrated into cropping systems that are dominated by annual grain crops. However, grain yield from Kernza is lower than comparable annual cereal crops such as wheat and oats. Also, although Kernza is a long-lived perennial that can persist for decades, grain yield tends to decline over time as Kernza stands age leading most farmers to replant or rotate to a different crop after 3–5 yrs. Increased intraspecific competition as stand density increases with age has been reported to cause grain yield declines. We investigated the effect of strip-tillage applied at two different timings, between the third and fourth grain harvests, from a Kernza stand in upstate New York. Strip-tillage applied in late fall as plants were entering dormancy increased grain yield by 61% when compared to the control treatment without strip-tillage. However, total crop biomass was not reduced resulting in a greater harvest index for the fall strip-tillage treatment. Strip-tillage applied before stem elongation the following spring reduced overall tiller density and total crop biomass but did not impact tiller fertility or grain yield compared to the control treatment without strip-tillage. Increased grain yield in the fall strip-tillage treatment was due to an increase in the percentage of tillers that produced mature seedheads. This suggests that grain yield decline over time is at least partially caused by competition between tillers in dense stands. Results support further research and development of strip-tillage and other forms of managed disturbance as tools for maintaining Kernza grain yield over time.

The goal of this research was to determine whether crop management practices could substitute for a herbicide for managing mixed populations of green and yellow foxtail in hard red spring wheat. Crop yield and foxtail growth were measured in two years of field research in North Dakota. Spring wheat yields were as great or greater when early seeding date or 2× seeding rate were substituted for POST diclofop3 at 0.75 kg ai ha−1 for managing foxtail in spring wheat. Yield of spring wheat competing with foxtails was greater for the high seeding rate (2× = 270 kg ha−1) than both the normal (1× = 130 kg ha−1) and low (0.5× = 70 kg ha−1) seeding rates for early or middle seeding dates, but not for the late seeding date. For both early and middle seeding dates, wheat yield at the 2×seeding rate without diclofop was equal to or greater than that of the 1× seeding rate with diclofop. Late-seeded wheat did not yield well in competition with dense foxtail stands for any treatment combination. Early and middle seeding dates favored the relative increase of green foxtail over yellow foxtail in wheat, whereas late seeding favored yellow foxtail over green foxtail. Economic analysis demonstrated that early seeding date was the most critical factor in determining the stochastic dominance of treatments without diclofop over treatments with diclofop. Seeding rate was much less important than seeding date in determining the ranking of treatments in stochastic dominance analysis.

In this paper, novel geospatial services are presented which are able to process on the server-side numerous remote sensing data based on big data frameworks like Hadoop and Rasdaman. The developed system itself features several software modules that orchestrate the different image processing algorithms responsible for the production of consistent value-added maps like canopy greenness and leaf area index. Through distributed multitemporal analysis, the entire crop growth cycle can be continuously monitored through the analysis of time-series observations. These observations cover multiple crop growth cycles, offering invaluable information by linking weather statistical data with the start, the end and the duration of each growth cycle enabling critical decisions by direct comparison with the current crop growth state.

Weeds are an important plant resource for insects, although feeding by insects on weeds can have both positive and negative effects on crop productivity. Weeds also indirectly affect crops via their influence on beneficial insects, and by harboring plant and insect diseases. Weeds may affect the ability of dispersing insects to locate crop plants. The host relationship between insects and plants is highly variable, ranging from very specialized to generalized feeding behaviors. Despite the myriad interactions of weeds and insects, many aspects of the relationship are predictable. Most insects, including crop pests, are specialists, and preadapted to feed only on some plants, often within a single plant family. Even polyphagous insects often have a distinct preference hierarchy, feeding more widely only when preferred hosts are unavailable. Use of plants by insects is a dynamic interaction, with characteristics of the insect (e.g., mandible structure) and the plant (e.g., allelochemicals) affecting feeding behavior. Thus, weeds that are closely related to crops are particularly important in harboring insects that attack those crops. Crop production practices should seek to sever the taxonomic association between the crop and the weeds found within the crop, and nearby, by eliminating weeds related to the crop. This will make it less likely that insects will move easily from weed to crop plants, that damaging population densities of insects will develop in the field, and that insect vectors that harbor plant diseases will be harbored in the field. Particularly important integrated pest management practices include crop rotation, reduced use of chemical herbicides, and management of weeds in noncultivated areas.

Interest in using crop competitiveness as an integrated weed management tool is increasing. Our objective was to describe traits that could be sources of the competitiveness we previously observed in grain sorghum grown in association with shattercane, which is a common annual weed and a close relative of the crop. Such information could aid in developing management practices for cultivated sorghum to improve its competitiveness with weeds. A bioassay was conducted to compare emergence of the crop and the weed in the greenhouse, and vegetative growth was monitored for 31 d in a within-row competition study. Results described a crop that competed well with the weed and other crop plants and agreed with studies showing that relative time of emergence influenced competitiveness. The mechanism by which grain sorghum emerged before the weed was a by-product of domestication that reduced glumes surrounding the wild-type seeds. This could be shown experimentally by hulling shattercane seeds, which then emerged almost as quickly as the grain sorghum. When planted in the grain sorghum row, shattercane plants from hulled seeds decreased the number of leaves and the root mass of the crop. Similarly, the time between emergence of the crop and emergence of shattercane was lessened by planting shattercane seeds early, and this increased the leaf number of the weed and shoot mass of the crop. It might be possible to increase weed suppression in grain sorghum by using management practices, such as more equidistant crop planting patterns that exploit the competitiveness already present, but which is being lost to interactions among crop plants.

The main resistance mechanism of codling moth (Cydia pomonella) in the tree fruit area of Lleida (NE Spain) is multifunction oxidases (MFO). We studied the frequency of MFO-resistant adults captured by different lures, with and without pear ester, and flights in orchards under different crop management systems. The factor year affected codling moth MFO-resistance level, particularly in the untreated orchards, highlighting the great influence of codling moth migration on the spread of resistance in field populations. Chemical treatments and adult flight were also very important but mating disruption technique showed no influence. The second adult flight showed the highest frequency, followed by the first flight and the third flight. In untreated orchards, there were no significant differences in the frequency of MFO-resistant individuals attracted by Combo and BioLure. Red septa lures baited with pear ester (DA) captured sufficient insects only in the first generation of 2010, obtaining a significantly lower proportion of MFO-resistant adults than Combo and BioLure. In the chemically treated orchards, in 2009 BioLure caught a significantly lower proportion of MFO-resistant adults than Combo during the first and third flight, and also than DA during the first flight. No significant differences were found between the lures or flights in 2010. These results cannot support the idea of a higher attractiveness of the pear ester for MFO-resistant adults in the field but do suggest a high influence of the response to the attractant depending on the management of the orchard, particularly with regard to the use of chemical insecticides.

Introduction. Mango-based orchards in Senegal occur in a large diversity of cropping systems, but few typologies of these systems exist and none are associated with their comprehensive and quantitative analysis. In this study we defined and characterized the typology of these systems based on a quantitative assessment of their planting design, management, vegetative state, hedgerow structure and infestation by a major pest of mango, the Bactrocera invadens fly. Materials and methods. Multivariate analysis and clustering methods were applied to data from 64 mango-based orchards and their surrounding hedgerows sampled in the Dakar and Thiès regions, in Senegal. Results and discussion. Four types of cropping systems were identified according to orchard design and management patterns: (1) ‘No-input mango diversified orchards’, (2) ‘Low-input mango orchards’, (3) ‘Medium-input citrus-predominant orchards’ and (4) ‘Medium-input large mango- or citrus-predominant orchards’. Orchard characteristics varied among these patterns. For instance, vegetation was dense and homogeneous in system 1, and the mortality rate of trees was high in system 2 but low in system 3. Orchards of systems 3 and 4 were mostly associated with hedgerows with, respectively, boundary-marking and defensive species. Lastly, the number of B. invadens flies was high in orchards of system 4, whereas it was low in those of system 2. Conclusion. The diversity of mango-based cropping systems in Senegal is now well described and quantified. This characterization is a preliminary step that is essential for further studies aiming to improve these systems.

Pesticide applications have a strong impact on biodiversity in agroecosystems. The present study aimed to assess the impact of pest control strategies on the arthropodofauna of Parus major nests built within nestboxes installed in orchards. Unlike many studied groups, these arthropod communities are not in direct contact with pesticide sprays (on account of their being sheltered by nestboxes) and are also unable to move away from the treated area. In this pilot study, we estimated the prevalence and the taxonomic and ecological diversities of arthropodofauna sampled in the nests and assessed the extent to which the whole and nest-specific arthropodofauna were affected by pest control strategies. Sixteen different insect and arachnid Primary Taxonomic Groups (PTGs, order level or below) were found in nests. The best represented PTGs (⩾10% occurrence in years 2007 and 2008) were Psocoptera (Insecta, detritivorous/saprophagous), detritivorous/saprophagous Astigmata (Acari) and hematophagous Mesostigmata (Acari). Pest control strategies had a large impact on the prevalence of arthropods in nests, with higher proportions of nests hosting arthropods in organic orchards than in conventional orchards and with intermediate proportions in nests in Integrated Pest Management orchards. In contrast, pest control strategies had no significant effect on the composition of the arthropod communities when only nests hosting nidicolous arthropods were considered.

The practice of ecological agriculture involves building the strengths of natural ecosystems into agroecosystems, purposely disturbed to produce food and fiber. The overall strategies include using practices that (a) grow healthy plants with good defense capabilities, (b) stressing pests, and (c) enhancing populations of beneficial organisms. These are accomplished by enhanced habitat management both above ground and in the soil. Many of the practices that contribute to the overall strategies are well known—such as intensive use of cover crops or reduced tillage. Reasons for why they have not been more widely used are discussed. The special challenges facing ecological agriculture in the poor countries of the Third World are also discussed. Re-engaging national governments in the active support of their agriculture and addressing the structural inequalities (including access to land) are essential to overcome the many problems facing farmers in the poor countries.

Introduction. À l’instar d’autres secteurs de produits destinés à l’alimentation humaine, une restructuration profonde de la filière ananas martiniquaise s’accomplit pour répondre à de nouvelles exigences de sécurité alimentaire et de protection de l’environnement : management de la qualité sur l’ensemble de la filière et exploitation de nouvelles variétés d’ananas. À partir de l’analyse des pratiques actuelles, les auteurs ont évalué les besoins de changements, puis proposé quelques outils pour la mise en œuvre d’un système de production. Matériel et méthodes. Des enquêtes ont permis de connaître les pratiques et stratégies actuelles des producteurs d’ananas et d’établir une typologie des exploitations. Un comité de pilotage associant des représentants de l’ensemble de la filière élabore le système de management de la qualité en se basant sur la norme Agriconfiance®. De nouvelles variétés sont en cours d’évaluation pour couvrir au mieux les besoins en ananas de qualité pour la transformation ou pour la vente en frais. Résultats et discussion. Les écarts constatés entre recommandations et pratiques culturales sont apparus très variables mais souvent importants : trop d’intrants en général, soit les pesticides, soit les engrais, soit les deux. Le système de management appliqué repose sur un contrat entre une coopérative et les producteurs. Les règles de qualité sont fixées dans deux cahiers des charges, l’un concernant la qualité de la production au champ, l’autre, la qualité du fruit pour l’usine. Un système de traçabilité à l’échelle de la parcelle a été élaboré. Il permet la prévision et l’enregistrement de toute activité liée à la production, avec la parcelle comme unité de base. Enfin, de nouvelles variétés hybrides sélectionnées par le Cirad ont pu être testées dans le nouveau processus de transformation de la coopérative, donnant de meilleurs résultats que l’ancienne variété Cayenne lisse. Conclusion. La restructuration de la filière ananas en Martinique résulte avant tout de considérations économiques. Cette démarche a conduit au développement d’un programme global d’assurance qualité, avec instauration d’un système de traçabilité parcellaire, destiné à garantir la sécurité alimentaire. Une homogénéisation des pratiques culturales est nécessaire, en se rapprochant des recommandations pour améliorer la qualité. Elles pourraient être rassemblées dans un guide de culture spécifique. L’adoption de nouvelles variétés d’ananas permettant d’obtenir de meilleurs rendements de transformation ainsi qu’une qualité accrue du produit frais ou transformé sera aussi un élément déterminant du succès de la démarche.

Introduction. The chataigne or breadnut, Artocarpus camansi Blanco, has high nutritive value but it is an under-utilised food source. Yield losses due to tree height and limited information on productivity are constraints to commercial production. Our study was undertaken to determine fruit yield and seed yield, the relationship between fruit size and seed yield, and the response of yield to pruning. Materials and methods. Fruit and seed yield data were collected from 1996 to 2002 from three seedling trees established at the University of the West Indies in Trinidad and Tobago in 1993. The trees were pruned in December 1998. Results. The highest fruit mass per tree (139.7 kg), fruit number per tree (126) and seed mass per tree (59 kg) were obtained in 5-year-old trees. Fruit and seed yields were significantly (P < 0.001) lower in the years after pruning. Fruit mass per tree was positively correlated with fruit number (r = 0.99). Seed mass per fruit was positively correlated with seed number per fruit (r = 0.87) and both variables had strong, positive correlations with mean fruit mass (r = 0.83 and r = 0.77, respectively) and fruit volume (r = 0.63 and r = 0.67, respectively). Discussion and conclusions. Chataigne fruit and seed yield potential is greater than originally estimated. Both are strongly related and selection for high seed number per fruit with more effective pollination, disease control and proper tree height management may further increase productivity. In the field, estimated fruit volume is the most practical indicator of seed yield.

Introduction. Le babaco (Carica pentagona Heilb.), plante équatoriale de mon- tagne, est originaire d'Équateur. Ses fruits sont particulièrement appréciés pour leur arôme caractéristique. La plante. Le babaco est un arbuste semi-ligneux de la famille des Caricacées. Cet hybride naturel se cultive en Équateur entre (1500 et 2500) m. Les rendements de production sont compris entre (60 et 80) fruits par plante et par an. Le fruit. Le fruit du babaco est une baie asperme jaune à maturité. Son arôme caractéristique se rapproche à la fois de l'ananas, du citron et de la papaye. Quand le fruit est vert, il exsude un latex qui con- tient une activité protéolytique semblable à celle de la papaye. Transformation. Le fruit est consommé essentiellement à l'état frais. La fabrication de pulpe, conserves et de fruits déshy- dratés est également possible. L'extraction et la purification des enzymes protéolytiques du latex des fruits verts pourrait être une nouvelle voie de valorisation industrielle du babaco. Tendances économiques. Grâce à des rendements de production élevés, ce fruit a éveillé un grand intérêt commercial. L'Équateur et la Nouvelle-Zélande sont les deux seuls pays où le babaco est cultivé à grande échelle. Conclusion. Le babaco présente d'intéressantes perspec- tives économiques, grâce notamment à ses propriétés sensorielles et à ses potentialités comme source d'enzymes protéolytiques.

La plante.Sechium edule Sw. appartient à la famille des cucurbitacées. Originaire du Mexique, cette robuste liane monoïque est aujourd'hui cultivée dans de nombreux autres pays tropicaux. Elle produit des fruits piriformes connus principalement sous les noms de christophine, chayotte ou chouchou. Pauvres en calories et riches en sels minéraux, ces fruits sont intéressants sur le plan diététique. Dans certaines conditions, la plante développe également des tubercules comestibles riches en amidon. Culture. La Christophine est généralement cultivée sous tonnelle, dans des zones humides à températures modérées. Sa culture est peu contraignante et conduit à des rendements de production élevés. Les attaques fongiques et les nématodes peuvent être évités en mettant en œuvre les traitements adéquats. Valorisation. Le principal frein à l'exportation et l'exploitation industrielle de S. edule est sa conservation après récolte. Un emballage sous film plastique associé à des températures voisines de 10 °C permet une conservation pendant 40 à 50 j. Ces résultats sont encore améliorés en utilisant une irradiation λ. Conclusion. De nos jours, les différentes parties de la plante sont utilisées de façon artisanale dans les domaines culinaire et médicinal. La transformation à l'échelle industrielle de la christophine nécessite la recherche de variétés produisant des fruits de qualité homogène, résistant mieux aux maladies et présentant de bons rendements en fruits, jeunes tiges et tubercules.

Among several species of insect pests that attack the millet crop, the earhead caterpillar, Raghuva albipunctella de Joannis and Acigona ignefusalis Hmps., are considered the major pests. The constraints against the successful implementation of an integrated pest management programme of these insects are examined. The relative importance and significance of host plant resistance in such a programme is compared against other modalities.

The use of insecticides is negated by lack of cash value returns, water supply, trained personnel and poor delivery system. Cultural practices, such as the synchronisation of early planting, destruction of harvest residues and end-of-season ploughing, have the potential for reducing carry-over populations. However, the difficulties in their implementation range from farmer education and efficiency to changes in traditional practices and introduction of new labour intensive practices after harvest. While it appears that natural enemies are taking a gradual toll on R. albipunctella, they appear inefficient in controlling A. ignefusalis. A range of plant characters have been identified: tillering in certain varieties as a form of tolerance to borers; maturity cycles that result in escape (pseudo-resistance) from Raghuva infestation, hairiness in relation to preference for oviposition and head compactness in deterring larval penetration into millet heads. Most of these characters are common in landrace types. The real problem appears to be one of incorporating and utilising the identified resistance into germplasm sources which possess other desirable agronomic characters that the farmer requires. This implies multi-disciplinary effort which is the basis for integrated pest management. In most of Africa, and in the Sahel in particular, this basis is remotely present.