scholarly journals Maize Yield Response to Chemical Control of Spodoptera frugiperda at Different Plant Growth Stages in South Africa

Agriculture ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 826
Author(s):  
Johnnie van den Berg ◽  
Carmen Britz ◽  
Hannalene du Plessis
Keyword(s):  
Plant Growth ◽  
Spodoptera Frugiperda ◽  
Yield Loss ◽  
Fall Armyworm ◽  
Maize Yield ◽  
Field Trials ◽  
Yield Response ◽  
Growth Stages ◽  
Yield Losses ◽  
Plant Growth Stages

Fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), is a major pest of maize. Yield losses between 30 and 70% in the Americas and between 11 and 100% in Africa have been reported. Little information exists on the effect of pest damage during different plant growth stages on yield loss. Previous studies showed that insecticide applications at weekly intervals did not always provide a yield gain comparable to only a single or two well-timed applications. In this study, we completed four field trials under high natural pest pressure. Treatments consisted of different regimes of insecticide applications that provided protection against damage during different growth stages. In one trial, the mean incidence of infested plants was 65%, and the yield benefit gained from four insecticide applications was 32.6%. The other three trials had 16 treatments which were divided into two spray sequences to protect plants against FAW damage for different lengths of time, between early vegetative stages and tasseling. Yield losses were 41.9, 26.5 and 56.8% for the three respective trials if no insecticides were applied. Yield loss of plants protected during earlier growth stages was significantly lower than that of the treatments which provided protection during later growth stages. More than three spray applications generally completed did not provide further yield gains. Plants that were protected more during early growth stages yield higher than plants protected during later growths stages.

scholarly journals Exploring entomopathogenic fungi from South Sumatra (Indonesia) soil and their pathogenicity against a new invasive maize pest, Spodoptera frugiperda

2020 ◽  
Vol 21 (7) ◽  
Author(s):  
Siti Herlinda ◽  
OCTARIATI Noni ◽  
Suwandi Suwandi ◽  
Hasbi Hasbi
Keyword(s):  
Entomopathogenic Fungi ◽  
Spodoptera Frugiperda ◽  
Fall Armyworm ◽  
Maize Yield ◽  
Yield Losses ◽  
The Third ◽  
Pest Insects ◽  
Dark Green ◽  
Yellowish White ◽  
Third Instar Larvae

Abstract. Herlinda S, Octariati N, Suwandi S, Hasbi. 2020. Exploring entomopathogenic fungi from South Sumatra (Indonesia) soil and their pathogenicity against a new invasive maize pest, Spodoptera frugiperda. Biodiversitas 21: 2955-2965. Fall armyworm (Spodoptera frugiperda) is a new invasive maize pest in Indonesia that can cause maize yield losses of 18 million tons/year. To overcome the pest, local-specific entomopathogenic fungi are needed. This study aimed to explore entomopathogenic fungi from soil in South Sumatra and to determine their pathogenicity against S. frugiperda larvae. The fungi exploration was carried out in the lowlands and highlands of South Sumatra and the pathogenicity of obtained isolates were tested against the third instar larvae. The entomopathogenic fungi found were Metarhizium spp. and were successfully isolated as many as 14 isolates. All of the isolates were pathogenic to S. frugiperda larvae (70.67−78.67% mortality), the most pathogenic caused 78.67% mortality and significantly suppressed the emergence of adults up to 81.2%. Unhealthy larvae had a dry, shrunken, shrinking, odorless body, and its integument was covered in mycelia and conidia like yellowish-white powdery mixed with dark green. The unhealthy pupae and adults were in the abnormal and malformation shape. The abnormal pupae were shorter in size, bent, the to-be wings got wrinkled, and darker color, while the unhealthy adults had folded wings and were unable to fly. The two most pathogenic isolates were found from the lowland (PirOI) and highland (CasPsPGA) soil of South Sumatra. In conclusion, both of these isolates had the potential to be developed into local-specific mycoinsecticides to control pest insects in the highlands and/or lowlands in Indonesia.

scholarly journals The impact of maize stand density on herbicide efficiency

2011 ◽  
Vol 49 (No. 1) ◽  
pp. 29-35 ◽  
Author(s):  
M. Lešnik
Keyword(s):  
Yield Loss ◽  
Stand Density ◽  
Maize Yield ◽  
Field Trials ◽  
Yield Losses ◽  
Weed Population ◽  
Perennial Weeds ◽  
Maize Cob ◽  
The Impact

The impact of maize stand density (4, 8 and 12 plants per m<sup>2</sup>) on herbicide efficiency (in %) and cob yield loss (in %) was studied in four field trials. The mixture of soil-applied herbicides (HS) isoxaflutole and S-metolachlor and the mixture of foliar-applied herbicides (HF) dicamba and rimsulfuron was applied in two dosages (100 and 75% of dose recommended by manufacturers). The 100% dose of HS was (75 g isoxaflutole + 960 ml S-metolachlor) per ha and 100% dose of HF was (12.5 g rimsulfuron + 240 ml dicamba) per ha. In all four trials, the studied factors (stand density, herbicide type and dose) had significant impact on herbicide efficiency and on maize cob yield loss. The herbicide efficiency decreased significantly, when herbicides were applied to maize of lower stand density and the maize yield losses increased. When weed population was composed predominantly of annual seed weeds higher efficiency was obtained by HS herbicides, conversely, when the weed population was composed predominantly of perennial weeds the HF herbicides provided better control. The reduction of herbicide dose always caused the significant reduction in herbicide efficiency and increase in maize yield loss.

scholarly journals Stand Reduction and Foliage Damage Reduce Yield of Dehydrating Onion

HortScience ◽  
2004 ◽  
Vol 39 (5) ◽  
pp. 1005-1007 ◽  
Author(s):  
George H. Clough
Keyword(s):  
Plant Growth ◽  
Growth Stage ◽  
Leaf Growth ◽  
Field Trials ◽  
Growth Stages ◽  
Leaf Stage ◽  
Plant Growth Stages ◽  
The Impact ◽  
Stage Yield ◽  
Different Growth Stages

Field trials were conducted at Hermiston, Ore., from 1995 through 1998, to determine impact of stand loss and plant damage at different growth stages on yield of onions (Allium cepa) grown for dehydration. Stand reduction (0%, 20%, 40%, 60%, 80%) and foliage damage (0%, 25%, 50%, 75%, 100%) treatments were applied at three-, six-, nine-, and twelve-leaf onion growth stages. Although average bulb weight increased as stand was reduced, marketable, cull, and total yields decreased as stand reduction increased (plant population decreased) at all plant growth stages. Bulb weight was not changed by up to 100% foliage removal at the three-leaf stage. At the six- and twelve-leaf stages, weight was reduced when ≥50% of the foliage was removed. The most severe response occurred at the nine-leaf stage. At the three-leaf stage, yield was not affected by foliage damage. At the six-leaf growth stage, yield was reduced by 75% or more foliage loss, but at the nine- and twelve-leaf stages, ≥50% foliage removal reduced expected yields. As with bulb weight, the impact of foliage removal on yield was most severe at the nine-leaf growth stage.

scholarly journals Effectiveness of Push–Pull Systems to Fall Armyworm (Spodoptera frugiperda) Management in Maize Crops in Morelos, Mexico

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 298
Author(s):  
Ouorou Ganni Mariel Guera ◽  
Federico Castrejón-Ayala ◽  
Norma Robledo ◽  
Alfredo Jiménez-Pérez ◽  
Georgina Sánchez-Rivera ◽  
...  
Keyword(s):  
Spodoptera Frugiperda ◽  
Insect Pest ◽  
Fall Armyworm ◽  
Maize Yield ◽  
Morphological Development ◽  
Main Method ◽  
Development Of Resistance ◽  
Pull Systems ◽  
Complex Scenario ◽  
Block Experiment

Chemical control is the main method used to combat fall armyworm in maize crops. However, its indiscriminate use usually leads to a more complex scenario characterized by loss of its effectiveness due to the development of resistance of the insect pest, emergence of secondary pests, and reduction of the populations of natural enemies. For this reason, efforts to develop strategies for agroecological pest management such as Push–Pull are increasingly growing. In this context, the present study was carried out to evaluate field effectiveness of Push–Pull systems for S. frugiperda management in maize crops in Morelos, Mexico. In a randomized block experiment, the incidence and severity of S. frugiperda, the development and yield of maize were evaluated in nine Push–Pull systems and a maize monoculture. The Push–Pull systems presented incidence/severity values lower than those of the monoculture. Morphological development and maize yield in the latter were lower than those of most Push–Pull systems. Mombasa—D. ambrosioides, Mulato II—T. erecta, Mulato II—C. juncea, Tanzania—T. erecta and Tanzania—D. ambrosioides systems presented higher yields than those of monocultures.

scholarly journals Impact of an Exotic Invasive Pest, Spodoptera frugiperda (Lepidoptera: Noctuidae), on Resident Communities of Pest and Natural Enemies in Maize Fields in Kenya

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1074
Author(s):  
Bonoukpoè Mawuko Sokame ◽  
Boaz Musyoka ◽  
Julius Obonyo ◽  
François Rebaudo ◽  
Elfatih M. Abdel-Rahman ◽  
...  
Keyword(s):  
Natural Enemies ◽  
Spodoptera Frugiperda ◽  
Fall Armyworm ◽  
Invasive Pest ◽  
Growth Stages ◽  
Insect Communities ◽  
Exotic Invasive Species ◽  
Before And After ◽  
Exotic Invasive ◽  
Lepidoptera Noctuidae

The interactions among insect communities influence the composition of pest complexes that attack crops and, in parallel, their natural enemies, which regulate their abundance. The lepidopteran stemborers have been the major maize pests in Kenya. Their population has been regulated by natural enemies, mostly parasitoids, some of which have been used for biological control. It is not known how a new exotic invasive species, such as the fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera, Noctuidae), may affect the abundance and parasitism of the resident stemborers. For this reason, pest and parasitism surveys have been conducted, before and after the FAW invaded Kenya, in maize fields in 40 localities across 6 agroecological zones (AEZs) during the maize-growing season, as well as at 3 different plant growth stages (pre-tasseling, reproductive, and senescence stages) in 2 elevations at mid-altitude, where all maize stemborer species used to occur together. Results indicated that the introduction of the FAW significantly correlated with the reduction of the abundance of the resident communities of maize stemborers and parasitoids in maize fields; moreover, the decrease of stemborer density after the arrival of FAW occurred mostly at both reproductive and senescent maize stages. It also suggests a possible displacement of stemborers by FAW elsewhere; for example, to other cereals. However, since this study was conducted only three years after the introduction of the FAW, further studies will need to be conducted to confirm such displacements.

Evaluation of Harvest-Aid Herbicides as Desiccants in Lentil Production

2016 ◽  
Vol 30 (3) ◽  
pp. 629-638 ◽  
Author(s):  
Ti Zhang ◽  
Eric N. Johnson ◽  
Christian J. Willenborg
Keyword(s):  
Adverse Effects ◽  
Crop Yield ◽  
Seed Yield ◽  
Yield Loss ◽  
Field Trials ◽  
Growth Stages ◽  
Yield And Quality ◽  
Seed Field ◽  
Dry Down ◽  
General Reduction

Desiccants are currently used to improve lentil dry-down prior to harvest. Applying desiccants at growth stages prior to maturity may result in reduced crop yield and quality, and leave unacceptable herbicide residues in seeds. There is little information on whether various herbicides applied alone or as a tank-mix with glyphosate have an effect on glyphosate residues in harvested seed. Field trials were conducted at Saskatoon and Scott, Saskatchewan, Canada, from 2012 to 2014 to determine whether additional desiccants applied alone or tank mixed with glyphosate improve crop desiccation and reduce the potential for unacceptable glyphosate residue in seed. Glufosinate and diquat tank mixed with glyphosate were the most consistent desiccants, providing optimal crop dry-down and a general reduction in glyphosate seed residues without adverse effects on seed yield and weight. Saflufenacil provided good crop desiccation without yield loss, but failed to reduce glyphosate seed residues consistently. Pyraflufen-ethyl and flumioxazin applied alone or tank mixed with glyphosate were found to be inferior options for growers as they exhibited slow and incomplete crop desiccation, and did not decrease glyphosate seed residues. Based on results from this study, growers should apply glufosinate or diquat with preharvest glyphosate to maximize crop and weed desiccation, and minimize glyphosate seed residues.

Developmental stability, canalization and phenotypic plasticity in annual herbaceous species under different biotic and abiotic conditions

2021 ◽  
Author(s):  
Shu Wang ◽  
Dao-Wei Zhou
Keyword(s):  
Phenotypic Plasticity ◽  
Plant Growth ◽  
Mean Value ◽  
Developmental Stability ◽  
Soil Conditions ◽  
Growth Stages ◽  
Herbaceous Species ◽  
Fertile Soil ◽  
Plant Growth Stages ◽  
Positive Correlations

Abstract The relationships among developmental stability, canalization and phenotypic plasticity have not been well understood. Inconsistent conclusions from different studies suggested the complexity of their associations, probably depending on specific traits, environmental contexts and plant growth stages. To address this issue, we conducted three experiments (EXP I ~ III) with several annual herbaceous species, to investigate the relationships among leaf (or cotyledon) developmental stability, canalization and plasticity and their variations with different biotic and abiotic environmental conditions and plant growth stages, with comparisons among different species at their early growth stage. We analyzed variations in mean trait value, lamina fluctuating asymmetry (FA), coefficient of variation (CV) and plasticity (RDPIs) and their correlations for lamina size (LS) of individual plants, for LS, petiole length (PL) and petiole angle (PA) of different plant layers in Abutilon theophrasti at three densities in infertile and fertile (or only fertile) soil conditions at three (or two) stages, and for cotyledon size (CS) of five species in contrasting light conditions and seeding depths. High vs. low density decreased LS (with negative RDPIs), FA indexes and CVs, either for individual plants or different layers, especially in fertile soil. Shading was more likely to increase CS (except for A. therophrasti) and FA and decrease CV; deep seeding increased CS of some species in full light, but decreased CS and FA of other species in shading (except for A. therophrasti). FA indexes more likely had positive correlations with mean value, CV and RDPIs of traits; correlations between CV and RDPIs can be positive, negative or insignificant. Correlations among the three variables were more likely positive or insignificant for traits of LS, CS and PL, but more likely negative or insignificant for PA. High density and infertile soil may favor more positive over negative correlations among variables. Results suggested higher levels of lamina FA more likely indicate higher growth rates of plants or modules. Developmental stability was more likely to have positive correlations with canalization, and negative correlations with plasticity, indicating certain common mechanisms associated with them. Environmental stresses can lead to greater phenotypic variations at different levels, facilitating cooperation between the three processes in dealing with environmental challenges.

Sign in / Sign up

Export Citation Format

Share Document