The use ofstrategies such as sequential applications and mixtures may increase the control spectrum and the residual effect ofchemicalcontrolofweedin the cassava crop. Thus, the objective was to evaluate the selectivity and efficacy of sequential applications and tank mixture of herbicides in the controlofweedin the cassava crop cultivar ‘Baianinha’. The experimental design was of randomized blocks, with eleven treatments and four replicates. The treatments consisted in: harrowed control, control without harrow, clomazone, mesotrione, S-metolachlor, clomazone+S-metolachlor, mesotrione+S-metolachlor, clomazone+mesotrione, sulfentrazone/clomazone, clomazone/[mesotrione+S-metolachlor], S-metolachlor/[mesotrione+clomazone]. The doses used for clomazone, mesotrione, sulfentrazone and S-metolachlor in the single applications, in sequence and in tank mixture were of 1.25, 0.24; 0.6 and 1.92 kg ha -1 , respectively. The first
However, the present study, not only evaluated specific authorized fungicides (MRL, 2010; Sagarpa, 2010) for powdery mildew in mango, but also their alternated use and the sprayed order, aiming at the preservation of their effectiveness with a rational phytosanitary approach (Halleen & Holz, 2001). Overall, the best strategy was to initiate chemicalcontrol using a systemic fungicide, followed by a contact one with multisite activity. In addition, the application time should consider the availability of susceptible tissues (full flowering, fruit set of 3–5 mm, and fruit with 8–15 mm diameter), regardless of the number and intensity of the growth flushes (Schoeman et al., 1995; Halleen & Holz, 2001). This strategy should be combined with cultural practices to reduce environmental humidity in the orchard, such as ventilation pruning, elimination of inoculum sources, avoiding excessive irrigation, and improving drainage and the timely controlof weeds (Saifullah et al., 2007).
Therefore, the use of herbicides in mixture with glyphosate becomes an important technique in the managementofweed species with resistance or tolerance to this product. In Brazil, there are nine cases of plants resistant to glyphosate (HEAP, 2019) and around ten tolerant species (CONCENÇO et al., 2014). There are 40 active ingredients registered for the controlof weeds of the maize crop in Brazil (MAPA, 2019). Among these herbicides, there are photosynthesis inhibitors in pho- tosystem II, cell division, pigment inhibitors and inhibitors of acetolactate synthase (ALS), which stand out as important alternatives to assist in the managementof resistant biotypes and glyphosate-tolerant species in maize crop. Studies evaluating the efficacy of the herbicide mixture on the weed community and the selectivity of the crop are extremely important for the elaboration of more effective controlstrategies.
Tillage and weedcontrol are critical components of cropping systems that need to be combined such that crops benefit from reduced competition. However, weeds may also contribute to the biological diversity within the agro-environment. This greenhouse study investigated whether common weeds of arable cropping systems were suitable host plants for arbuscular mycorrhizal fungi (AMF), allowing the development of extraradical mycelium (ERM) that can contribute to the early colonization of a following wheat crop, especially in the absence of soil disturbance. Weeds were allowed to grow for up to 2 months before being controlled by soil disturbance or herbicide application (glyphosate or paraquat). Pregerminated wheat seeds were then planted. Chemicalcontrolof the weeds prior to sowing enhanced the early arbuscular mycorrhiza (AM) colonization rate of wheat roots, whereas mechanical disturbance was less acceptable as a method ofweedcontrol for rapid AM colonization. The type of herbicide (contact or systemic) had no impact on colonization of the wheat crop. Enhanced AM colonization promoted early P acquisition and growth of the crop. Appropriate managementof weeds emerging between two consecutive cropping seasons coupled with no-till soil management could ensure a quick and efficient AM colonization of the following wheat plants.
treatments were applied for chemicalcontrolof anthracnose based on the rotation of active ingredients from different chemical groups and modes of action (Table 1). Fungicide managementstrategies was based on the floral phenology model proposed by Guillen (2000), who considered from swollen buds until fruit with a diameter of 8 mm. However, in this study the record was extended to fruits diameter of ≈15 mm. The systemic ingredients were applied every 15 days, and the contact ingredients were applied every eight days. Sprayings were made with a Swissmex® agricultural handbarrow with a capacity of 500 L and flow of 34.2 L/min at 20 bar, motor 5.5 HP (4.1 kw) at 3,600 rpm, two 50 m hoses with aspersion handles. The fungicides were applied in commercial doses: azoxystrobin 0.25 g/L, myclobutanil 0.08 g/L, cyprodynil+fludioxonil 0.075 g/L, quinoxyfen 0.05 mL/L, copper oxychloride 2.5 g/L, mancozeb 0.8 g/L, captan 1.25 g/L, chlorotalonil 2.88 g/L and elemental sulfur 1.35 mL/L.
With regard to the high efﬁcient treatments (i.e. hand hoeing twice and the combination of butralin+prometryn) in controlling weeds, conventional hand hoeing twice can be expressed as the potent effective treatment with respect to weed elimination in sunﬂower-soybean situations and also as a safety clean non-chemicalweedcontrol method with point of view of environmental conservation. Many investigators have been conﬁrmed that hoeing twice is the most effective weedcontrol practice for diminishing the weed dry matter accumulation in sunﬂower and soybean ﬁelds [7, 12, 15, 26, 17]. Furthermore, butralin herbicide effectively controls grasses and some broad-leaf weeds , while prometryn controls annual broad-leaved and some grasses . The major effect of dinitroanilines (e.g. butralin) is on the growth of roots, the shoots that emerge often appear quite normal, but soon die because of failure of secondary root development. Prometryn is absorbed through roots from soil application and translocated to shoots, and inhibits photosynthesis resulting in blocking electron transport leading to stopping CO 2 ﬁxation and
herbicide options. Furthermore, even with the use of registered herbicides, the outcome is not always as expected, especially for grass weeds (Archangelo et al., 2002; Dan et al., 2010). Prospection of new herbicide alternatives is necessary to overcome this problem, either with products already available in the market or those under development. The present work contributes with alternatives for use in pre-emergence (Tables 1 and 2) and post-emergence (Tables 3 and 4) crops, both with good results inweedcontrol and crop selectivity. In addition, the study shows that the pre-mix atrazine + s-metolachlor has a high level of selectivity to the most hybrid varieties of sorghum (Table 5, Figure 2).
ABSTRACT: In coffee culture, the inadequate controlof invasive plants can degrade the soil used then managements practices to contribute to the improvement of quality physical, chemical and biological of the soil. Should be used the aim of this work were evaluated the influence of various weedcontrol methods on some chemical properties of a Red-Yellow Latosol (RYL) cultivated with coffee. The experimental design was randomized block with strip plots, making a 9x2 factorial, nine control methods and two layers (0-15 and 15-30 cm) and three replications. The control methods evaluated were: maintenance of soil cover with forrage peanut (Arachis pintoi L.) and Signal grass (Brachiaria decumbens), use of disk harrow, mower, agricultural brush, manual hoe, post-emergency herbicide, pre-emergence herbicide and no weeding treatment. The following chemical analyzes were performed: pH, exchangeable cations of sorption complex, sum of bases, base saturation, aluminum saturation, effective cation exchange capacity, potential cation exchange capacity, soil organic matter, total phosphorus and remanescent phosphorus. Among the weedcontrol methods studied, the use of mower provided the best soil chemical characteristics at the two layers evaluated. The pre-emergence herbicide remained the surface of the soil devoid cover, wich negatively influenced the soil chemical attributes, by increasing the acidity and reduced cations of the sorption complex. The Signal grass showed higher efficiency than the forrage peanut in the managementof alkaline front, although the latter was more efficient in phosphorus cycling.
achieved through different strategies, given that the population of these plants changes according to the system used. This study aimed at assessing solarization methods associated with different mulches for weedcontrolin the cowpea crop. The methods used were soil solarization, with plastic sheeting and with solar collector, associated with the following mulches: castor bean, rattlepod and spontaneous vegetation. Weed phytosociology was calculated by frequency, density and abundance. The most infesting families were Asteraceae, Poaceae and Amaranthaceae. The species with the highest frequency, density and abundance in the treatments without mulching was Cyperus rotundus, while Bidens spp. occurred only in non-solarized soil and without mulching. The largest number of weeds was found in the treatments without mulching in non-solarized soil or soil solarized with plastic sheeting, the latter being less efficient than the solar collector. Mulching inhibits the weed infestation in cowpea crops, irrespective of soil solarization. However, rattlepod as mulch is more efficient in the solarization with plastic sheeting than with a solar collector.
The active ingredient atrazine is one of the few herbicides registered for use in sorghum (Rodrigues & Almeida 2011). This product is characterized as an inhibitor of photosystem II, registered for use in pre- and/or early post-emergence, being effective in dicotyledonous and some grasses (Rodrigues & Almeida 2011). Thus, the search for other molecules that can be used for the weedchemicalmanagementin sorghum has great importance for the consolidation and expansion of this crop in Brazil.
For the experiment whose plants of D. insularis were mowed before the first application of the herbicides, without a sequential application, the treatments with glyphosate plus quizalofop (in both doses), at 31 DAFA, and glyphosate plus quizalofop (in the higher dose), at 55 DAFA, have resulted in a higher percentage ofcontrol. On the other hand, with the sequential application, there was not significant difference among the associations of glyphosate with quizalofop or clethodim, at 31 and 55 DAFA, or nicosulfuron (in the lower dose of glyphosate), at 31 DAFA. However, just glyphosate plus quizalofop (int he higher dose of glyphosate) has promoted a control above 90% at 55 DAFA. In both assessment periods, when comparing with and without sequential application, it was found that, for all herbicide treatments, the second application contributed to a better weedcontrol, with significant differences in the control grades of up to 86% at 55 DAFA.
Although indaziflam has a record for initial post-emergence in other countries, as in the United States (Shaner, 2014), in Brazil there is no record and /or recommendation ofcontrolin the initial weed post-emergence condition (Rodrigues & Almeida, 2018). In this experiment it was possible to observe that in the sequential application of indaziflam in sites with plants, that is, where the controlin the post-emergence application was not effective, it resulted in leaves with purplishness, reduced plant size and some cases necrotic spots in the foliar surface, however, throughout the evaluation periods the plants gradually recovered the symptoms, probably by the metabolization of the herbicide by C. benghalensis.
Although subgroup comparisons were made within some of the studies reviewed, these are not reported as they were so few and diverse that between study comparisons was not feasible. However, some studies indicate that major subgroup differences may exist. For example, knowledge of tobacco-related harm is reportedly lower in tobacco-using, compared with non- using, children . State, urban/rural status, sex and education have been described as predic- tors of tobacco-related knowledge , and variation in tobacco-related teaching by school type and location has been observed [33,34]. Data also suggest that tobacco marketing is effec- tively targeted towards younger people, and hint that anti-tobacco messages are not under- stood by all sub-populations . Subgroup differences will not be applicable to all types of intervention, but will be useful to consider in application of interventions, to avoid discrimina- tion, and because those that impact on different groups are likely to produce synergistic effect. Further investigation of such putative associations will therefore be of interest, once sufficient comparable data exist.
this serious drawback by allowing the subsystems to overlap; that is, the requirement of strict disjoint de- composition is relaxed to permit a restricted sharing of states, inputs, and outputs among the subsystems. For systems admitting an overlapping decomposition, the Inclusion Principle allows to design semi-decentralized controllers which are in accordance with the system structure, and which partially maintain the positive features of decentralized controllers. This approach has proven to be useful in a variety of complex control problems appearing in different fields, such as macro- economic modeling, electric power generation, auto- mated highway traffic management, civil structural en- gineering, aerospace structural engineering, and multi- agent robotics (Aybar et al., 1994; Ataslar and ˙Iftar, 1999; Bakule and Rodellar, 1995; Bakule et al., 2005; Chen and Stankovi´c, 2005b; Li et al., 1999; Siljak et al., 1999; Stankovi´c et al., 2000; Stipanovi´c et al., 2004).
In South Africa, eucalyptus crown growth of 10 cm can be attained in 41 days with 20% weeding or in 66 days with 0% weeding (SCHUMANN et al., 1994). Little et al. (1994) used the tree crown diameter as an indication of tree performance. They observed a distinct exponential increase in median crown diameter with weed-free strip width and concluded that a 2-m strip width with no weeding at all in the 1 m between rows proved to be the best management strategy. Light competition can increase plant height at the expense of stem diameter, making eucalyptus more susceptible to tumble (NAVAS, 1991). Eucalyptus trees are extremely susceptible to interspecific competition from establishment until canopy closure, after which the light-limiting effect of canopy closure excludes the development of a competitive weed load.
To inhibit an ongoing flow of thoughts or actions has been largely considered to be a crucial executive function, and the stop-signal paradigm makes inhibitory control measurable. Stop-signal tasks usually combine two concurrent tasks, i.e., manual responses to a primary task (go-task) are occasionally countermanded by a stimulus which signals participants to inhibit their response in that trial (stop- task). Participants are always instructed not to wait for the stop-signal, since waiting strategies cause the response times to be unstable, invalidating the data. The aim of the present study was to experimen- tally control the strategiesof waiting deliberately for the stop-signal in a stop-task by means of an algorithm that measured the variation in the reaction times to go-stimuli on-line, and displayed a warning legend urging participants to be faster when their reaction times were more than two standard deviations of the mean. Thirty-four university students performed a stop-task with go- and stop-stimuli, both of which were delivered in the visual modality and were lateralized within the visual field. The participants were divided into two groups (group A, without the algorithm, vs group B, with the algorithm). Group B exhibited lower variability of reaction times to go-stimuli, whereas no significant between-group differences were found in any of the measures of inhibitory control, showing that the algorithm succeeded in controlling the deliberate waiting strategies. Differences between deliberate and unintentional waiting strategies, and anxiety as a probable factor responsible for individual differences in deliber- ate waiting behavior, are discussed.
The experiment was carried out from October 2012 to February 2013 at the Rafael Fernandes Experimental Farm, which is part of the Federal Rural University of the Semi-Arid (UFERSA), located in the district of Alagoinha (latitude 5°03’49” S, longitude 37º23’49” W, at an altitude of 80 m), 20 km from the town of Mossoró, in the state of Rio Grande do Norte, Brazil. According to the Köppen classification, the climate in the region is the BSwh’ type, i.e., dry and very hot, with a rainy season from summer to autumn, an average annual temperature of 27.4 ºC, very irregular annual rainfall with an average of 673.9 mm, and a relative humidity of 68.9%. Sunlight increases from March to October, with an average of 241.7 h. The maximum relative humidity reaches 78% in April with a minimum of 60% in September (CARMO FILHO; OLIVEIRA, 1989).
In this paper, results for water use were derived with and without stock e¤ects on cost, and presented for varying levels of model uncer- tainty, as expressed by levels of the penalty parameter θ, to explore and illustrate the implications of this particular type of methodology. However, in general θ can be chosen according to di¤erent criteria. For instance, a level of acceptable detection error probability for distin- guishing between the approximating model and the worst case model can be selected. More speci…cally, for each θ the associated detection error probability can be calculated for a given sample using the like- lihood ratios when the approximating model generates the data and when the worst case model is true (see Hansen and Sargent (2003, chp. 13)). Nonetheless, the purpose of this paper was to identify the possibilities of the robust control methodology and its links to un- certainty aversion and the precautionary principle. Further research should be dedicated to analyzing detection error probabilities using real data samples and considering alternative criteria for choosing θ, such as system stability.
With the single purpose and intent of simplifying research Willey  suggests that two fundamental criteria be taken into consideration in the evaluation process of productive advantages: the first criterion is of “biological” nature and is intended for the presence of biological efficient scale and the stability in the crop association system when compared with the monoculture system; the second criterion which is well designed and which is labeled as practical, is designed to determine the concrete advantages of a farmer, who in the running of the enterprise could profit more from a co-association system than from a monoculture system for the same area of land. Below we will deal with the cases of crop association through two cultures, which are the most common ones.