This weed management investigation was carried out at the Zonal Agricultural Research Station (ZARS), Bangalore, during the summers of 2017 and 2018 to standardize agrotechniques for weed management of rice grown under aerobic conditions. The experiment was laid out in a randomized complete block design with eleven treatments replicated thrice. It consisted of two pre-emergence herbicides and one early post-emergence herbicide, the stale seedbed technique, mulching, hand weeding and intercultivation which was compared to the weedy check. The results showed that pyrazosulfuron ethyl 10% wettable powder (WP) at 35 active ingredient (a.i.) g ⋅ ha–1 as PE fb bispyribac sodium 10% SC at 30 ml ⋅ ha–1 a.i. as an early post-emergence herbicide performed better in terms of rice grain and straw yield (5,800 and 9,786 kg ⋅ ha–1, respectively), plant height (58.42 cm), rice total dry matter production (149.84 g ⋅ plant–1), productive tillers ⋅ hill–1 (40.32), panicle length (24.53 cm), 1000 grain weight (25.35 g), net returns (Rs. 62424), higher B : C ratio (2.59) and lower total weed density, weed dry weight at different stages of rice and weed index (3.80%) as well as higher weed control efficiency (90.52%). This practice could be recommended to farmers growing aerobic rice under these climatic conditions.
There are few reports in literature about the selectivity of postemergence application of herbicides for the control of eudicotyledon weeds (broadleaf) in chickpea. For this reason, the aim of this study was to investigate the selectivity of diphenyl-ether herbicides in chickpea influenced by the herbicides and application rates. A field experiment was conducted from February to June 2017 in Urutaí, state of Goiás, Brazil. Cultivar BRS Aleppo was used in the experiment. The experiment was set up in a randomized block design with 2 × 3 + 1 factorial arrangement and three replications. The first factor was herbicides (fomesafen and lactofen) with the second factor being herbicide rate (50, 75, and 100% of referenced rate) plus an untreated check as a comparison. The applied rates of herbicides were 250 and 180 g ⋅ ha–1 of fomesafen and lactofen, respectively. The selectivity of herbicides was evaluated according to agronomic characteristics (plant population, height, dry matter, number of pods per plant and 100-grain weight) and yields. Both herbicides, regardless of dosage, were selective in chickpea cultivation, even exhibiting leaf necrosis symptoms with visible injuries below 20% with no effect on yield.
Field experiments were conducted to evaluate the efficacy of glyphosate (H1) and fluazifop- -P-butyl (H2) herbicides with adjuvants on the common reed without cutting and at two different cutting levels (10 and 30 cm). The adjuvants were urea, nitric acid and sulfonic acid. The relative importance value (RIV), leaf chlorophyll content and plant density were determined to assay the efficacy of herbicides. Glyphosate treatment only (H1a) was more effective than fluazifop-P-butyl (H2a) on reeds without cutting and at the 10 cm cutting level. However, no significant difference was observed between them at the 30 cm cutting level. A positive effect of plant cutting occurred on the efficacy of all herbicides applied alone or in a tank mix with adjuvants. Furthermore, the 10 cm cutting level was more effective in eradication of reeds than the 30 cm cutting level. The adjuvants significantly improved the efficacy of the recommended (Hb) and half recommended (Hc) herbicide rates in comparison to being used alone on uncut reeds. The reduction percentages were 94.5, 86.99, 76.61 and 69.94 for H1b, H1c, H2b and H2c treatments, respectively. However, the adjuvants did not improve the glyphosate effect at different levels of cutting. Conversely the reduction percentage of reeds was improved by the recommended rate of fluazifop-P-butyl with adjuvants (H2b) to 92.77% and 84.62% at 10 and 30 cm cutting levels, respectively.
Two field experiments were established at the Agricultural Experimental Station of the National Research Centre at Nubaria, Beheira Governorate, Egypt to study the herbicidal potential of the leaf extract of Eucalyptus citriodora at 5, 10, 15, 20 and 25% compared to two hand hoeing, unweeded treatments and the chemical herbicides Bentazon + Clethodium, Bentazon + Fluazifop-P-butyl and Butralin on pea plants and associated weeds. The results indicated that two hand hoeing achieved the maximum weed depression as expressed by the dry matter of total weeds. The dry matter of total weeds decreased by 95.08 to 94.77% as compared with unweeded treatment 50 and 70 days after sowing (DAS) followed by Butraline (93.93–94.65%), Bentazon + Clethodium (93.26–94.07%), Bentazon + Fluazifop--P-butyl (91.82–92.77%) and leaf extract of Eucalyptus at 25% (91.61–91.95%). Furthermore, the reduction in weed development was accompanied by enhanced pea growth and yield. The results revealed that two hand hoeing was the best treatment to increase plant height, shoot dry weight and SPAD value at 50 and 70 DAS. Also, two hand hoeing produced the maximum values of pod length and number of seeds/pod. The results also indicated that Bentazon + Clethodium treatment gave observable values [recorded 72.96% in pod yield (ton ⋅ fed.–1) over that of unweeded control] of number of pod/plant, weight of pod/plant, seed yield/fed and protein percentage. Also, the results revealed great increases in the growth of pea as well as yield due to treatment with E. citriodora dry leaf extract at 25%. [recorded 64.8% in in pod yield (ton ⋅ fed.–1) over that of unweeded control]. So, the results indicated using Bentazon + Clethodium as well as E. citriodora dry leaf extract at 25% to control weeds associated with pea plants. The authors suggested application of E. citriodora dry leaf extract at 25% in controlling weeds associated with pea plants as a safe method that avoids environmental contamination.
The “second generation” of glyphosate-tolerant soybean (GT2 soybean) was developed through a different technique of insertion of the glyphosate-insensitive EPSPs gene, in comparison with “first generation” of glyphosate-tolerant soybean. However, there is not enough information available about glyphosate selectivity in GT2 soybean and the effects on the quality of seeds produced. The aim of this study was to evaluate tolerance to glyphosate and seed quality of soybean cultivar NS 6700 IPRO (GT2) with cp4-EPSPs and cry1Ac genes, after application at post-emergence (V4). The experiment was conducted in a randomized block design with four replicates and seven treatments, or rates of glyphosate (0; 720; 1,440; 2,160; 2,880; 3,600; 4,320 g of acid equivalent − a.e. · ha−1). Assessments were performed for crop injury, SPAD index and variables related to agronomic performance and seed quality. A complementary trial with the same cultivar and treatments in a greenhouse was conducted in a completely randomized design with four replications. Data analysis indicated no significant effect of glyphosate on V4 on agronomic performance and physiological quality of seeds, for two growing seasons. The soybean cultivar NS 6700 IPRO (GT2), with cp4-EPSPs and cry1Ac genes, was tolerant to glyphosate up to the maximum rate applied (4,320 g a.e. · ha−1) at post-emergence (V4). The quality of soybean seeds was not affected by glyphosate up to the maximum rate applied (4,320 g a.e. · ha−1) at post-emergence (V4).
Clethodim herbicide (Cle) and three Trichoderma strains (Tri) were applied either alone or in combination (Cle + Tri) for controlling weeds, root knot nematodes (Meloidogyne arenaria) and Rhizoctonia root rot disease (Rhizoctonia solani) as well as for evaluating their effects on total microbial count in the rhizosphere and the number of Rhizobium nodules on roots in two faba bean cultivars cultivated in naturally heavily infested fields. The evaluated characters were very similar for the two tested cultivars (Nubariya 1 and Sakha 3). Treatment with Cle alone highly reduced the fresh and dry matter of tested weeds (Amaranthus viridis, Cynodon dactylon and Cenchrus ciliaris), followed by Cle + Tri and Tri alone. Cle + Tri highly reduced nematode parameters viz. numbers of J2 in soil or roots, females, eggs, galls and egg-masses when compared with each treatment alone. Tri alone caused a great decrease in Rhizoctonia root rot infection, followed by Cle + Tri and Cle alone. Total microbial count and Rhizobium nodules were affected only with Cle treatment. Plant growth parameters (shoot length, shoot fresh and dry weight and numbers of branches and leaves) and yield parameters (fresh pod and dry weight, seed number per pod, seed weight and ash pod weight of plant) were greatly improved for Cle + Tri treatments when compared with either Tri or Cle alone.
The aim of the present work was to evaluate the selectivity of nicosulfuron, alone and in combinations, applied in post-emergence (V4) of glyphosate and sulfonylurea tolerant (RR/STS) soybean. The experiments were conducted in 2015/16 and 2016/17, in Piracicaba – state of São Paulo (SP). In 2016/17, the experiment was also conducted in Palotina – state of Paraná (PR). The experiment was a randomized block design, with four repetitions and 16 treatments, with combinations of nicosulfuron, glyphosate, chlorimuron, sulfometuron and cloransulam, applied alone or in tank mixture. Crop injury and variables related to agronomic performance were evaluated. Data were subjected to analysis of variance and treatment means were compared by the Tukey test. The results obtained are significant in the positioning of herbicides in RR/STS soybean, since in the five experiments, all the treatments were selective, except for glyphosate + sulfometuron which reduced the yield of a cultivar (CD 2630 RR/STS) in the 2015/16 season.
A novel herbicidal controlled release formulation composed of (2,4-dichlorophenoxy) acetic acid (2,4-D) chemically bonded to biodegradable (R,S)-3-hydroxybutyric acid oligomers was investigated. The synthesis of (R,S)-3-hydroxy butyric acid oligomers was carried out via the ring opening polymerization of β-butyrolactone initiated by 2,4-dichlorophenoxy acetic potassium salt in the presence of complexing agents. The formed oligomers were characterized by size exclusion chromatography, proton magnetic resonance and electrospray mass spectrometry in order to fi nd out their molar mass distribution and molecular structures. An assessment of biological effectiveness of the obtained herbicidal formulation was carried out in the greenhouse vs. Sinapis alba var. Nakielska. A promotion of the controlled release formulation with decreased water solubility and with low vapor pressure of the active ingredient, instead of traditional formulations of 2,4-dichlorophenoxy acetic acid may help to ensure a greater safety for workers and reduce the risk of dissemination of the active ingredient in the soil profi le.