Diurnal Abundance and Spatial Distribution of Armyworm, (Lepidoptera: Noctuidae) in No-till Corn

Armyworm, Pseudaletia unipuncta (Haworth), spatial and diurnal abundance in no-till corn was sampled at six-h intervals (at 0200,0800, 1400, and 2000) during three 24 h periods. During the early growth stages of corn, armyworm density on corn plants was higher during nighttime, and differed significantly between 0200 and 1400 hours. The number of armyworm feeding on leaf edges of the early growth stages of corn was significantly higher at 0200 than during any other time, and the proportion of total larvae on corn plants that were on leaf edges was significantly higher at 0200 than during the daytime. Daytime foliage sampling will underestimate the true populations of armyworm feeding on foliage by 1.8 to 31 fold, depending on the time and thoroughness of the sampling program.

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Coastal Mangrove Response to Marine Erosion: Evaluating the Impacts of Spatial Distribution and Vegetation Growth in Bangkok Bay from 1987 to 2017

Remote Sensing ◽

10.3390/rs12020220 ◽

2020 ◽

Vol 12 (2) ◽

pp. 220 ◽

Cited By ~ 2

Author(s):

Han Xiao ◽

Fenzhen Su ◽

Dongjie Fu ◽

Qi Wang ◽

Chong Huang

Keyword(s):

Spatial Distribution ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Mangrove Ecosystem ◽

Early Growth ◽

Growth Stages ◽

Human Disturbances ◽

Vegetation Growth ◽

Two Parameters ◽

The Impact

Long time-series monitoring of mangroves to marine erosion in the Bay of Bangkok, using Landsat data from 1987 to 2017, shows responses including landward retreat and seaward extension. Quantitative assessment of these responses with respect to spatial distribution and vegetation growth shows differing relationships depending on mangrove growth stage. Using transects perpendicular to the shoreline, we calculated the cross-shore mangrove extent (width) to represent spatial distribution, and the normalized difference vegetation index (NDVI) was used to represent vegetation growth. Correlations were then compared between mangrove seaside changes and the two parameters—mangrove width and NDVI—at yearly and 10-year scales. Both spatial distribution and vegetation growth display positive impacts on mangrove ecosystem stability: At early growth stages, mangrove stability is positively related to spatial distribution, whereas at mature growth the impact of vegetation growth is greater. Thus, we conclude that at early growth stages, planting width and area are more critical for stability, whereas for mature mangroves, management activities should focus on sustaining vegetation health and density. This study provides new rapid insights into monitoring and managing mangroves, based on analyses of parameters from historical satellite-derived information, which succinctly capture the net effect of complex environmental and human disturbances.

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Response of Asiatic Dayflower (Commelina communis) to Glyphosate and Alternatives in Soybean

Weed Science ◽

10.1614/ws-08-087.1 ◽

2009 ◽

Vol 57 (1) ◽

pp. 74-80 ◽

Cited By ~ 10

Author(s):

Santiago M. Ulloa ◽

Micheal D. K. Owen

Keyword(s):

Growth Stage ◽

Field Research ◽

Early Growth ◽

Growth Stages ◽

Anecdotal Evidence ◽

Single Application ◽

Emergence Period ◽

Early Growth Stage ◽

Greenhouse Experiments ◽

Corn Plants

Asiatic dayflower has recently become a troublesome weed in eastern Iowa. This weed demonstrates an extended emergence period and there is anecdotal evidence of glyphosate tolerance. Thus, Asiatic dayflower is difficult to manage in glyphosate-resistant (GR) corn and soybean. Greenhouse experiments were conducted to evaluate the response of Asiatic dayflower to glyphosate applied at different rates and growth stages. Field research was conducted in 2005 and 2006 to evaluate different herbicides for Asiatic dayflower control in soybean. PRE herbicides were applied at planting and POST herbicides were applied 21 and 42 d after planting (DAP). In addition, shikimate accumulation in response to glyphosate was compared among Asiatic dayflower and GR and non-GR corn and soybean. Under greenhouse conditions, a single application of glyphosate (0.84 kg ae ha−1) did not control Asiatic dayflower. Only the highest rate evaluated, 13.44 kg ae ha−1 (16X), was lethal to Asiatic dayflower. Even when applied at an early growth stage (two leaves) and using high rates (3.36 kg ae ha−1), glyphosate controlled Asiatic dayflower just 28%. In the field, metribuzin and KIH-485 controlled Asiatic dayflower 80 and 73%, respectively. Early POST applications (21 DAP) of cloransulam or lactofen controlled Asiatic dayflower 80 and 67%, respectively. A single glyphosate application of 0.86 kg ae ha−1 controlled Asiatic dayflower approximately 50%. Glyphosate-treated Asiatic dayflower and non-GR corn and soybeans accumulated shikimate after application. GR corn and soybeans did not accumulate shikimate in response to glyphosate. Twenty-one days after treatment, all the non-GR soybean and corn plants died; however, Asiatic dayflower plants survived.

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

Agronomy ◽

10.3390/agronomy11061074 ◽

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.

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Osmotic Stress or Ionic Composition: Which Affects the Early Growth of Crop Species More?

Agronomy ◽

10.3390/agronomy11030435 ◽

2021 ◽

Vol 11 (3) ◽

pp. 435

Author(s):

Agnieszka Ludwiczak ◽

Monika Osiak ◽

Stefany Cárdenas-Pérez ◽

Sandra Lubińska-Mielińska ◽

Agnieszka Piernik

Keyword(s):

Osmotic Stress ◽

Stress Responses ◽

Ionic Composition ◽

Degradation Process ◽

Early Growth ◽

Cultivated Plants ◽

C3 Plants ◽

Growth Stages ◽

Crop Species ◽

Ionic Salt

Salinization is a key soil degradation process. An estimated 20% of total cultivated lands and 33% of irrigated agricultural lands worldwide are affected by high salinity. Much research has investigated the influence of salt (mainly NaCl) on plants, but very little is known about how this is related to natural salinity and osmotic stress. Therefore, our study was conducted to determine the osmotic and ionic salt stress responses of selected C3 and C4 cultivated plants. We focused on the early growth stages as those critical for plant development. We applied natural brine to simulate natural salinity and to compare its effect to NaCl solution. We assessed traits related to germination ability, seedlings and plantlet morphology, growth indexes, and biomass and water accumulation. Our results demonstrate that the effects of salinity on growth are strongest among plantlets. Salinity most affected water absorption in C3 plants (28% of total traits variation), but plant length in C4 plants (17–27%). Compensatory effect of ions from brine were suggested by the higher model plants’ growth success of ca 5–7% under brine compared to the NaCl condition. However, trait differences indicated that osmotic stress was the main stress factor affecting the studied plants.

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