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A field survey was conducted for the sampling of Acetyl-CoA carboxylase (ACCase) inhibitor resistance littleseed canarygrass, a major weed of wheat, from Punjab, Pakistan in 2014 for confirmation of resistance. The surveyed regions encompassed four different cropping systems including rice–wheat, maize–wheat, cotton–wheat and mixed cropping. Dose–response assay was conducted for confirmation of resistance. Efficacy of herbicide mixtures including clodinafop–propargyl, metribuzin, pinoxaden and sulfosulfuron at a range of doses was investigated to manage littleseed canarygrass. Results revealed that all populations were resistant to fenoxaprop except PM-BWL-2. The higher level resistance (6.5) was found in populations collected from rice–wheat cropping system. The tested herbicide mixtures at 75% and 100% of the recommended dose of each mixture component provided the effective control of resistant littleseed canarygrass. Mixtures at 50% provided more than 80% control and reduced growth and seed production potential of surviving plants. The confirmation of ACCase inhibitor resistance as the first case of herbicide resistance in Pakistan, leads us to discourage use of ACCase inhibitor herbicides alone. However, herbicide mixtures at 75% and 100% of the recommended dose are suggested to manage this weed for sustainable wheat production in the surveyed cropping systems.

Littleseed canarygrass (Phalaris minor Retz.) is a most dominant weed of wheat (Triticum aestivum L.) in the north-western states of India. Little information is available on germination of littleseed canarygrass and wheat under similar ecological conditions. The present study was conducted under controlled conditions to study germination ecology of littleseed canarygrass population possessing multiple-herbicide resistance, along with wheat. Germination of littleseed canarygrass and wheat was independent of light. Optimum temperature for germination of littleseed canarygrass and wheat was 20°C. Germination of both species was completely inhibited at osmotic potentials lower than −0.4 MPa. Seeds of littleseed canarygrass and wheat were able to germinate even at NaCl concentration of 200 mM, with complete inhibition at 300 mM. Germination of both species was favored in a pH range of 5–8. Moisture, salinity, and pH stresses significantly reduced the speed of germination, with a concomitant increase i...

In this 2-year field study, we investigated the allelopathic effects of three wheat cultivars (Shafaq-06, Faisalabad-08 and Sehar-06) against different density levels (0, 100, 200 and 300 plants m−2) of littleseed canarygrass (Phalaris minor Retz.). Crop was sown on 1 and 3 December during 2010–2011 and 2011–2012 cropping seasons, respectively. The results showed that wheat cultivar Shafaq-06 produced more phenolic compounds at all density levels of littleseed canarygrass during both years, which caused more inhibition of littleseed canarygrass growth. More suppressive advantage of cultivar Shafaq-06 against littleseed canarygrass was responsible for its better morphological and yield related traits, and grain yield than cultivars Faisalabad-08 and Sehar-06. Among the tested cultivars, cultivar Sehar-06 had minimum allelopathic potential in suppressing littleseed canarygrass. In crux, Shafaq-06 possesses allelopathic potential to suppress littleseed canarygrass and may be used for breeding future wheat cu...

A replacement series study was conducted to evaluate the interference interactions between the weeds Phalaris minor or Rumex dentatus and wheat at two nutrient levels to test for changes in the competitive relationships of the weeds with varying nutrient availability. Plants were established in a mixture with proportions of 4:0, 3:1, 2:2, 1:3 and 0:4 (wheat: weed) plants per pot. The weeds exhibited clear differences in growth attributes and competition indices from wheat. Rumex dentatus showed significantly higher values for all growth attributes, relative yield, aggressivity and biomass. Both weeds performed better than wheat at high nutrient levels. Nutrient stress changed the intensity of competition between weeds and wheat, but did not change the weeds’ positions in the hierarchy. Therefore, although the competitiveness of P. minor and R. dentatus appears to be lower under poor nutrient conditions, they outcompete wheat irrespective of nutrient availability. Overall, the findings of the study suggest...

The herbicidal potential of culture filtrates of four Trichoderma spp., namely Trichoderma harzianum Rifai, Trichoderma pseudokoningii Rifai, Trichoderma reesei Simmons and Trichoderma viride Pers., was evaluated against two problematic weeds of wheat, Phalaris minor L. and Rumex dentatus L. In laboratory bioassays, generally, metabolites of all four Trichoderma species significantly reduced various root and shoot growth parameters of the two target weed species. The original concentrations of the culture filtrates of all Trichoderma spp., except T. harzianum, significantly reduced various parameters of root and shoot growth of wheat seedlings. In a foliar spray bioassay, the culture filtrates of all four Trichoderma spp. significantly diminished root and shoot biomass of R. dentatus. The effect of these filtrates on the shoot growth of P. minor and wheat was not significant. Culture filtrates of the four Trichoderma species were successively extracted with butanol, n-hexane, chloroform and ethyl acetate. In detached leaf injection bioassays, n-hexane fractions (3 mg mL(-1)) of T. pseudokoningii, T. reesei and T. viride, and ethyl acetate fractions of T. horzianum and T. pseudokoningii were found to be toxic against R. dentatus. This study concludes that the culture filtrates of Trichoderma species have herbicidal potential in the control of R. dentatus.

Sunflower is a putative source of bioactive allelochemicals, especially phenolics and terpenoids. Because qualitative and quantitative variation is well documented in sunflower types, we screened three commercially grown varieties of sunflower (Hybrid Supper-25, Gulshan-98 and Hybrid Suncross-42) through aqueous extract bioassays against five selected weeds of wheat (i.e., Chenopodium album, Rumex dentatus, Coronopus didymus, Phalaris minor, and Medicago polymorpha). Sunflower proved to be a potential source of allelochemicals as natural herbicides for weed management of selected weeds. The allelopathic effect was found to be dosage dependant, as it gradually increased as the concentration use from 30% to 50%. The lower concentrations of 10% and 20% showed stimulatory effects or insignificant weed reduction. C. album and R. dentatus were found to be the most sensitive to various treatments. The studies were extended to pot trials to determine the ecological significance of the laboratory findings.

Since 1996, several incidents of poor weed control regarding little seeded canary grass (Phalaris minor Retz.) in wheat (Triticum aestivum L.) production have been reported from the Western Cape. Little seeded canary grass showed indications of resistance towards ACC-ase inhibitors. Seed from these suspected resistant biotypes as well as seed from a susceptible biotype were collected from mature surviving plants and transported to the Small Grain Institute, Bethlehem where herbicide resistance studies were done. Herbicides used during the study were diclofop-methyl, clodinafop-propargyl and iodosulfuron. Both diclofop-methyl and clodinafop-propargyl are ACC-ase inhibitors and iodosulfuron is an ALS-inhibitor. Significant differences in the degree of control were found between the susceptible and four resistant biotypes when treated with diclofop-methyl and clodinafop-propargyl. When treated with diclofop-methyl, the LD50 values for the resistant (PMR 1, PMR 2, PMR 3 and PMR 4) biotypes were 594, 700, 225 ...

The wheat crop suffers badly due to heavy weed infestation. Phalaris minor Retz., Chenopodium albam L., Avena fatua L., Melilotus alba Deser., Melilotus indica All., Anagallis arvensis L., Fumaria parviflora Lam. and Convolvulus arvensis L. are common weeds of wheat in the Indian subcontinent. Besides handhoeing and manual weeding, use of herbicides plays a large role in weed management. Minimum tillage has some positive effects on soil. Pre‐emergence application of pendimethalin, terbutryn, methabenzthiazuron, bifenox and oxyfluorfen renders excellent weed control in wheat. Isoproturon, methabenzthiazuron, metoxuron, terbutryn, tralkoxydim and fluroxypyr post‐emergence give effective weed kill. For Avena fatua L. control, triallate, difenzoquat and diclofop‐methyl show promising results. Herbicide mixtures give broad‐spectrum weed control. Integrated weed management performs better. Wheat cultivars Sonilika, WH‐147, WH‐2009 and HD‐2329 are tolerant to isoproturon. Moderately susceptible varietie...

In field experiments carried out at the Punjab Agricultural University, Ludhiana (India) during 1971–72 and 1972–73, methabenzthiazuron (70% a.i. w.p.) and nitrofen (24% wt/vol a.i.) applied pre-emergence gave remarkable control (90%) of Phalaris minor L. (canary grass) in wheat. This work on the successful control of this obnoxious grassy annual weed in wheat is the first of its kind in the country. For these light textured soils (0.21% organic carbon and 75% sand), the effective dose of nitrofen was 1.20 kg a.i./ha and for methabenzthiazuron 0.70–1.05 kg a.i./ha. Nitrofen was specific for Phalaris only, whereas methabenzthiazuron controlled Phalaris, Avena fatua L. and Chenopodium sp. as well. These herbicides exhibited good selectivity to the crop. The maximum gains in grain yield due to herbicidal treatment over the weedy control were 1790 and 2510 kg/ha respectively for nitrofen and methabenzthiazuron.

Results of field experiments, with sodium, amine and ester formulations of 2,4-D, terbutryne, hand weeding and unweeded controls, with and without post sowing planking, showed that terbutryne applied post-emergence almost completely eliminated weed competition from wheat on a clay loam soil notorious for weed growth, and gave a significantly higher grain yield when compared with the standard 2,4-D treatments. As a result of terbutryne applied post-emergence mean increases in grain yield over the unweeded control, 2,4-D sodium, 2,4-D amine, 2,4-D ester and hand weeding were 14.53, 6.94, 9.54, 7.26 and 8.77 quintals (q)/ha; 41.70, 16.30 23.90, 17.20 and 29.06% respectively. Weed dry matter was reduced by 18.57, 6.26, 6.36, 6.31 and 5.87 q/ha respectively. Terbutryne also reduced difficult to control weeds like Phalaris minor and Avena fatua. The use of terbutryne was shown to be economically sound. Post sowing planking seemed to reduce seedling emergence, increase weed dry matter and slightly reduc...

In field experiments conducted at the Punjab Agricultural University, Ludhiana during 1973–74 and 1974–75, pre-emergence application (one day after sowing) of methabenzthiazuron (1.05 kg a.i./ha), metoxuron (1.6 kg a.i./ha) and chlortoluron (0.75 kg a.i./ha) gave effective control of Phalaris minor and Avena ludoviciana in wheat without any phytotoxic effect on the crop. Methabenzthiazuron, metoxuron and chlortoluron gave 1410, 1420 and 1090 kg/ha, respectively, more grain than the unweeded crop and 590, 600 and 270 kg/ha more than the crop hand-weeded twice. Nitrofen (1.25 kg a.i./ha) applied pre-emergence was effective against P. minor only and gave substantial increase in grain yield. Terbutryne, dichlormate and linuron, while effective against P. minor, also had a phytotoxic effect on the crop.

Field investigations were conducted at the Punjab Agricultural University, Ludhiana, India, during 1980–81 and 1981–82 to study the influence of selective broad‐spectrum herbicides (isoproturon, metoxuron and methabenzthiazuron) applied post‐emergence in improving the utilization of applied nitrogen (40, 80, 120 and 160 kg N/ha). Phalaris minor Retz, was the dominant weed in the field. On average (mean of two crops), the herbicide treated crop gave 42.2% higher grain yields than the crop given two hand‐weedings (hoeing). Isoproturon and metoxuron were more effective than methabenzthiazuron. The interaction for nitrogen x weed control treatments was significant for both crop seasons. The isoproturon (0.94 kg/ha) and metoxuron (1.5 kg/ha) treated crop under N80 gave significantly higher grain yield than the hand‐weeded crop given 120 and 160 kg N/ha during both crop seasons. Methabenzthiazuron (1.3 kg/ha) induced a similar response during 1980–81 only.

The selective action of MSMA, benzoylprop-ethyl, nitrofen, dichlormate, terbutryne and methabenzthiazuron and their combinations with 2, 4-D for control of grass weeds in spring wheat (Triticum aestivum L.) was studied in two field experiments at Haryana Agricultural University, Hissar, India, during 1975–76 and 1976–77. The differences in response among wheat, wild canarygrass, wild oats and broadleaved weeds to post-emergence herbicides were very variable. Methabenzthiazuron at 1.75 and 2.0 kg/ha and terbutryne at 0.60 to 0.75 kg/ha sprayed in the wheat crop at maximum tillering stage killed more than 70% of wild canarygrass (Phalaris spp.) and wild oats (Avena spp.) with no injury to the crop plants, resulting in the highest grain yield. The application of 2, 4-D (0.50 kg/ha) controlled only 55% wild canarygrass and 40% wild oats but significantly increased the wheat yields over the unweeded control. The other post-emergence herbicides were not effective in controlling both weeds selectively. ...

Field investigations on a moderately fertile silty clay loam soil in the northwestern Himalayas revealed that the weed flora in wheat crops in this zone comprised mainly of three grassy weeds: Phalaris minor Retz., Avena fatua L. and Lolium temu‐lentum L. Cultural manipulations such as closer spaced rows, i.e. 15 cm spacing between rows, and/or cross row sowing in combination with the application of isoproturon at 0.50 kg a.i./ha applied 2 weeks after sowing significantly reduced the density of Phalaris minor and Avena fatua weeds. The dry weight of these grassy weed species was significantly lowered with the application of isoproturon irrespective of its rate and time of application. Isoproturon application at a rate of 1 kg a.i./ha or 0.50 kg a.i./ha in combination with cross row sowing, normal row spacing of 22.5 cm or closer spaced rows of 15 cm reduced the weed competition and resulted in positive advantages in yield attributes and increased the grain yield of wheat.