Journal of Research in Weed Science
Volume:2 Issue: 3, Sep 2019

A field study was carried out in Uyo, Southeastern Nigeria in 2011 and 2012 to compare the potential of using pumpkin intercrop as a means of cost effective weed management in water yam (Dioscorea alata) farm. The experiment was laid out in a randomized complete block design. The treatments were included no weeding, weeded (3x), chemical weeding (Raft 500) + supplemented hoe weeding at 12 weeks after planting (WAP), Dynamic population densities of 10,000, 20,000, 30,000 and 40,000 supplemented with one hoe weeding at 4 WAP. The result of the study showed that weeded 3x treatment performed better in all the growth and yield parameters assessed but not significantly (P<0.05) above the growth and yield values obtained from 30,000 population density of pumpkin. The weeded (3x) resulted to tuber yield of 22.81 and 20.75 t.ha-1 in 2011 and 2012 respectively, while, the 30,000 pumpkin population density had tuber yield of 19.81 and 19.35 t.ha-1 in 2011 and 2012 respectively. The least tuber yields 3.22 and 2.18 t.ha-1 was obtained from no weeding treatment. The weeded (3x) treatment had 9-86 and 8-90 percentage tuber yield above other treatments but 13 and 8% over 30,000 pumpkin population density alone. The study suggests that pumpkin intercrop at 30,000 stands per hectare could effectively reduce weed interference in water yam farm.

The soluble carbohydrates play a major role in germination, growth, reproduction, defense and survival of perennial plant species reproducing with rhizomes under normal and adverse environmental conditions. The information regarding the amount of carbohydrates present in the rhizomes of such species could provide valuable insights for making decisions regarding the best time to control these species. Therefore, seasonal changes in the concentrations of soluble carbohydrates (fructose, glucose, sucrose) and their sum termed as total amount of soluble carbohydrates (TSCs) in the rhizomes of Russian knapweed were investigated during 2013-2014. The TSCs were low at sprouting and then slightly increased until mid-June (beginning of flowering). Thereafter, TSCs were slightly decreased from mid-June to minimal values in August (flowering period) (6.2 mg/g), and then gradually increased until the highest values in January (170.6 mg/g). Fructose (131.5 mg/g) was detected as the main soluble carbohydrate, followed by sucrose (98.8 mg/g) and glucose (73.1 mg/g). Keeping in view the results of current study, the best time to control Russian knapweed is flowering, where the amount of TSCs in the rhizomes is minimal. It is therefore recommended that the species should be controlled either at flowering stage or during the production of first rhizomes for its sustainable management in the country.

Parthenium hysterophorus weeds are one of the major problems in almost all types of agricultural lands, forest lands, pastures, farmlands and disturbed land including roadsides. It is also responsible for health problems in human and animals besides loss to agriculture and ecosystems. It causes allergic respiratory problems, contact dermatitis and mutagenicity. The main strategy of Parthenium control is the use of chemical herbicides. The increasing side effects of chemical herbicide and growing resistance against them in weeds have attracted the attention of researchers to search for some novel herbicidal compounds from natural sources. A significant barrier in the mycoherbicide metabolites production is the development of an economically viable fermentation process. The production of these compounds is largely affected by certain parameters like pH, temperature, incubation days and media constituents etc. Adjustment of these parameters up to optimum level leads to maximum production of mycoherbicidal compounds. Therefore, the purpose of this study was to standardize physiochemical conditions (Nutrient media, pH, Temperature, and Incubation periods) for maximum production of mycoherbicidal metabolites from phytopathogenic fungi Fusarium sp. FGCCW#16 isolated from Parthenium hysterophorus weed. Fusarium sp FGCCW#16 grew well and produced optimum mycoherbicidal metabolites in Richard’s broth medium at 25 to 28°C on the 21 studay of the incubation. The optimal growth, however, was obtained at pH 6. The results of this investigation indicated that cultural conditions like culture media as well as physical factors such as temperature, pH and incubation period greatly affected the growth and production of mycoherbicidal metabolites by Fusarium sp FGCCW#16.

The study of citrus weeds in the Skikda region during the 2017/2018 crop year included 40 phytoecological surveys of different crops. They were distributed throughout the study area in order to take into account the variability of ecological and Agronomic factors. The results obtained by the Correspondence Factor Analysis (CFA) highlight two groups of surveys including two groups of species. These results explain the distribution of citrus weeds in the Skikda region according to climate and edaphic conditions. The appearance of weed species was selective, for example, Oxalis Latifolia. Kunt. is a very common and abundant species in the more or less humid northern zone, whereas it is almost absent in the southern zone of the study area. On the other hand, Papaver rhoeas. was frequent and abundant in the southern zone, which is a somewhat dry zone, was almost absent in the northern zone.

The experiment was conducted in farmer field with farmer managed in Randomized Complete Block Design (RCBD) with three treatments and seven replications. The treatments were weed management practices including (i) Farmer’s Practice (FP) (ii) Two manual weeding (iii) First manual weeding and 2nd weeding by post emergence herbicides (Temboterine and Atrazine) application in Inner-terai, Dang, Nepal. Results showed that first manual weeding and 2nd weeding by herbicides significantly reduced weed infestation and gave higher maize grain yield. The yield attributes were cob length, total number of grain, number of grain per row, cob weight with husk and cob weight without husk. Thus, herbicides used after 1st manual weeding is successful for high maize yield.

Over centuries, agricultural practices have undergone the transition from extensive and traditional to intensive and specialized. Thus, the weeds colonizing cultivated fields are subjected to major shifts due to increased use of herbicides, fertilizers and tillage. There are a total of 176 weed species in Agro-ecosystems of Himachal Pradesh and not less than 46 in maize. Weeds, in maize, are hardier in nature and compete with the crop significantly reducing its yield. Also, slow initial growth and wider spacing favour the growth of weeds even before crop emergence. Commelina benghalensis, Ageratum conyzoides, Echinochloa colona, Panicum dichotomiflorum, Cyperus iria, Digitaria sanguinalis, Polygonum alatum and Aeschynomene indica were dominant weeds observed under Kangra district conditions of Himachal Pradesh. The phytosociological study showed that the species which invaded the non-cropped lands are increasingly infesting the cultivated fields. In 2008, most abundant weed was Fimbristylis miliacea followed by Cyperus difformis, Eragostis tennela, Ageratum conyzoides, Ammannia baciferra, Bidens pilosa and Hackelia uncinata. In 2018, Ageratum conyzoides was the most abundant followed by Phyllanthus niruri, Panicum dichotomiflorum, and Commelina benghalensis. Ageratum conyzoides was the most important weed in 2008 followed by Echinochloa colona, Fimbristylis miliacea, and Digitaria sanguinalis, in that order. The Important Value Index (IVI) for individual weed species in the maize field crop in 2018 indicated that Ageratum conyzoides was again the most important weed species followed by Phyllanthus niruri, Echinochloa colona, Alternanthera philoxeroides, Aeschynomene indica, Commelina benghalensis and Digitaria sanguinalis. The weed species viz. Ammannia baccifera, Bidens pilosa, Brachiaria ramose, B. reptans, Dactyloctenium aegyptium, Fimbristylis miliaceaum, Galinsoga parviflora, Hackelia uncinata, Ipomoea pestgridis, and Physalis minima those recorded in 2008 were not found in the survey of 2018. Aeschynomene indica, Alternanthera philoxeroides, Amaranthus viridis, Echinochloa crusgalli and Oxalis sp. recorded during 2018 were not found in the survey of 2008.

Weeds are among the most harmful factors limiting crop production in savannah zone of Africa. However, they are crucial for biodiversity and ecosystems sustainable management. A field experiment was conducted in savannah zone of Senegal to determine the effect of organic and mineral fertilization on weed flora in peanut crop. The experiment was laid out in randomize complete block design with four replicates and four treatments (Control, Cattle manure, Compost, and Mineral fertilizer). Our findings show that weed density was not significantly affected by the type of fertilization. However, dry matter of grasses and broadleaf weeds was significantly affected by the treatment respectively in forty and sixty days after treatment. The highest dry weight of grasses was observed in forty days after sowing in cattle manure treatment followed by inorganic fertilizer with respectively 23.7 and 15.2 g/m2. In sixty days after sowing, the highest dry matter of broadleaf weeds was recorded in cattle manure treatment with 4.5 g/m2. It was noticed that Digitaria horizontalis and Mesosphaerum suaveonlens were the dominant species in all treatment. The biodiversity indices were not significantly influenced by the type of fertilization but the highest values of Shannon-Webber and Simpson indices was recorded in cattle manure treatment. Moreover, the linear correlation between grain yield and diversity indices revealed that Shannon index is highly correlated with the peanut yield.

Parthenium hysterophorus (Asteraceae) is known as one of the most troublesome weeds, causing severe environmental, economic, human and animal health problems in India and around the world. During a series of surveys for natural enemies of P. hysterophorus, a leaf blight pathogen was isolated from the affected parts of the Parthenium following the standard isolation techniques using potato dextrose agar (PDA) media. Koch’s postulates were performed and found satisfactory for the isolate and proved to be pathogenic to this weed. On the basis of cultural, morphological and molecular characteristics, the pathogen was identified as Alternaria macrospora MKP1. The pathogen was studied for various histopathological parameters and the results showed that this pathogen has a good potential to control Parthenium weed.