Effect of herbicides and herbicide mixtures on weeds in wheat

Transcription

1 Indian J. Agric. Res., 50 (2) 206 : 07-2 Print ISSN: / Online ISSN: X AGRICULTURAL RESEARCH COMMUNICATION CENTRE Effect of herbicides and herbicide mixtures on weeds in wheat Dhirender Choudhary, P.K. Singh, N.K. Chopra and S.C. Rana* Indian Agricultural Research Institute Regional Station, Karnal-32 00, India. Received: Accepted: DOI: /ijare.v50i ABSTRACT A field investigation was carried out to evaluate the effect of herbicides and their mixtures on weeds in wheat (Triticum aestivum L.) cv. PBW-343. Minimum weed density per m 2 and weed dry weight (5.3 and 7.3g) was recorded with sulfosulfuron at 25g ha - followed by clodinofop at 60g + metsulfuron methyl at 4g ha - (5.9 and 8.45g), metribuzin at 200g ha - (5.85 and 25.98g), pendimethalin at 000g fb 2,4-D at 400g ha - (6.49 and 3.73g) and hand weeding twice (7.0 and 35g), respectively. Also, maximum weed control efficiency was recorded under sulfosulfuron at 25g ha - (83.85%) followed by clodinofop at 60g + metsulfuron methyl at 4g ha - (83.7%) and metribuzin at 200g ha - (75.85%), respectively. All the weed control treatments recorded significantly higher harvest index than the weedy check (40.24). Among various herbicidal treatments, application of clodinofop at 60g + metsulfuron methyl at 4g ha - recorded highest harvest index (4.9) followed by sulfosulfuron at 25 g ha - (4.83) and pendimethalin at 000g fb 2,4-D at 400g ha - (4.25) respectively. The harvest index recorded under clodinofop at 60g + metsulfuron methyl at 4g ha - and sulfosulfuron at 25 g ha - was significantly at par with weed free (42.06). Key words: Harvest index, Herbicides, Weeds, Wheat. INTRODUCTION Wheat is the most important winter cereal of north India. Wheat fields are generally infested with both grassy as well as broad leaf weeds and cause yield loss of 7 to 50 per cent depending upon the type of weed flora and their intensity (Singh et al., 2004). Herbicides represent a cheap, reliable and effective method of weed control, which provides consistently higher net return to the farmers. Among the herbicides, isoproturon and pendimethalin are being used for the last two decades for weed control in wheat (Chopra et al., 200; Walia et al., 998). Regular use of the same herbicide year after year has led to problem of herbicide resistance. In the recent past, sulfosulfuron, clodinafop, fenoxaprop and metsulfuron methyl have shown high efficacy against grasses and broad leaf weeds and produced significantly higher grain yield of wheat compared to isoproturon and 2,4-D. Herbicide combination or mixtures are used for effective and economical weed control. The resistant biotypes of Phalaris minor which were not controlled by isoproturon and the broad leaf weeds showing resistance to 2, 4-D were controlled by the mixture of two herbicides for increasing the wheat yields (Balyan et al., 999; Singh and Singh, 2005). Herbicide combination offers certain advantage like broad spectrum of herbicidal action, enhance herbicide efficiency through synergistic or additive effect, needed in a fewer quantity, reduce cost of weed management, arrest weed shifts, prevent herbicide resistance in weeds and facilitate improvement in overall weed management (Bharat and Kachroo, 200). Hence, an experiment was conducted to evaluate the effect of herbicides and their mixtures on weeds in wheat under western Uttar Pradesh conditions of northern India. MATERIALS AND METHODS A field investigation was carried out during winter season of and at Agricultural Farm of R.K. (P.G.) College, Shamli (Parbudhnagar, U.P.) to evaluate the effect of herbicides and their mixtures on weeds in wheat (Triticum aestivum L.) cv. PBW-343. The sandy loam soil of the experimental plot having a ph of 7.4 was low in nitrogen (0.42% organic carbon.), moderate in phosphorous (9.8 kg ha - ), high in potash (232 kg ha - ) and.44 mmhos cm - electrical conductivity. The fourteen treatments viz. sulfosulfuron at 25g ha -, metribuzin at 200g ha -, pendimethalin at 000g ha -, isoproturon at 000g + 2, 4-D at 400g ha -, clodinafop at 60g + 2,4-D at 400g ha -, fenoxaprop at 00g + 2,4-D at 400g ha -, metribuzin at 200g + 2,4-D at 400g ha -, pendimethalin at 000g followed by (fb) 2,4-D at 400g ha -, isoproturon at 000g + metsulfuron methyl at 4g ha -, clodinofop at 60g + metsulfuron methyl at 4g ha -, fenoxaprop at 00g + metsulfuron methyl at 4g ha -, hand hoeing twice ( 30 and 45 DAS), weed free and weedy check were tested in randomized block design with three replications. Application of herbicides as per treatment was made with knap sack sprayer having flat fan nozzle using 600L water per hectare. Pendimethalin was applied as pre emergence spray one day after sowing, while all other *Corresponding author s sureshiariknl@gmail.com. Dept. of Agronomy, R.K. College, Shamli (U.P.)

2 08 INDIAN JOURNAL OF AGRICULTURAL RESEARCH herbicides were applied (post emergence application) 30 days after sowing. Wheat cv. PBW- 343 was sown on 2 November, 2007 and 5 November, 2008 in lines 20 cm apart at a depth of 5 cm using 00 kg seed ha -. The crop was harvested during third week of April in both seasons when the color of the ear was totally changed and moisture of seed was below 0 percent. N 40 kg, P 2 O 5 60 kg and K 2 O 40 kg per ha was applied as basal dose through urea, single super phosphate and murate of potash, respectively. Additional nitrogen was applied in two splits of 30 kg N each after first and second irrigation. Repeated hand weeding was done in weed free plot to keep the plots weed free for whole season. Other recommended cultural practices were followed as per requirement of the treatment and crop. Weed count was made at 90 days after sowing. Observations related to weed density, weed dry weight, weed control efficiency, weed index and harvest index were recorded by adopting the standard procedure and the results (average of two years) were statistically analyzed. Weed control efficiency (WCE) was calculated as per formula given below: WCE (%) = Weed dry weight in weedy plots-weed dry weight in treated plots X 00 weed dry weight in weedy plots Weed index (WI) was calculated with the following formula (Gill and Kumar, 969): WI (%) = seed yield of weed free plot seed yield of treated plot x 00 seed yield of weed free plot Harvest index (%) was calculated by using the following formula: Harvest index (H.I.) = grain yield x 00 biological yield RESULTS AND DISCUSSION Major weed flora observed in the experimental plots during the two seasons comprised of Phalaris minor, Cornopus dydimus, Melilotus indica, Chenopodium album, Anagalis arvensis and Rumex maritimus. Various herbicidal treatments exerted significant effect on weed density, weed dry matter, weed control efficiency, weed index and harvest index in wheat cv. PBW-343. Effect on individual weeds: The perusal of data in Table indicated dominance of Phalaris minor among the six major weed species observed during the two seasons of experimentation. Weed density (m 2 ) of individual weeds recorded under weedy check at 90 DAS was Phalaris minor (83.3), Cornopus dydimus (25), Melilotus indica (22.99), Chenopodium album (26.33), Anagalis arvensis (7.66) and Rumex maritimus (23.5), respectively. Among different herbicides, application of clodinofop at 60g + metsulfuron methyl at 4g ha - resulted in maximum control of individual weeds followed by sulfosulfuron at 25g ha - and metribuzin at 200g ha -, respectively (Table-2). Application of clodinofop at 60g + metsulfuron methyl at 4g ha - and sulfosulfuron at 25g ha - reduced the weed density of individual weeds viz. Phalaris minor, Cornopus dydimus, Melilotus indica, Chenopodium album, Anagalis arvensis and Rumex maritimus by 85.50, 88.25, 89.85, 88.52, 90.07, 9.75 and 87.67, 90.47, 87.57, 88.67, 87.22, percent, respectively. Hand hoeing twice recorded 73.2, 78.70, 80.80, 78.65, and % control of Phalaris minor, Cornopus dydimus, Melilotus indica, Chenopodium album, Anagalis arvensis and Rumex maritimus, respectively. Application of clodinafop at 60g + 2, 4-D at 400g ha - and fenoxaprop at 00g + 2, 4-D at 400g ha - reduced the weed density of individual weeds viz. Phalaris minor, Cornopus dydimus, Melilotus indica, Chenopodium album, Anagalis arvensis and Rumex maritimus by 60.2, 85.85, 83.87, 84.32, 82.45, and 64.08, 84.57, 79.75, 86.55, 79.00, % respectively. However combination of clodinafop and fenoxaprop with 2, 4-D resulted in less control of Phalaris minor because clodinafop and fenoxaprop showed antagonism with 2,4-D as tank mixture. The results are in line with those reported by Singh and Singh (2005) and Punia et al. (2006). Efficacy of grass weed control was reduced when fenoxaprop, clodinafop and metribuzin herbicide were tank mixed with 2, 4-D and fenoxaprop was mixed with metsulfuron methyl compared to clodinafop + metsulfuron methyl treatment. Weed density at 90 DAS: Total weed density decreased significantly due to different weed control treatments compared to weedy check at 90 DAS (Table 3). Weedy check treatment recorded maximum weed density per m 2 (4.3). Among different herbicidal treatments, minimum weed density per m 2 (5.3) was recorded under sulfosulfuron at 25g ha - followed by clodinofop at 60g + metsulfuron methyl at 4g ha - (5.9), metribuzin at 200g ha - (5.85) and pendimethalin at 000g fb 2,4-D at 400g ha - (6.49), respectively. Isoproturon at 000g + 2, 4-D at 400g ha - recorded highest weed density per m 2 (7.70) followed by metribuzin at 200g + 2, 4-D at 400g ha - (7.63), clodinafop at 60g + 2,4-D at 400g ha - (7.58), isoproturon at 000g + metsulfuron methyl at 4g ha - (7.57), pendimethalin at 000g ha - (7.56) and fenoxaprop at 00g + 2,4-D at 400g ha - (7.48), respectively. However, these treatments recorded significantly more weeds per m 2 than hand weeding twice (7.0). Post emergence application of sulfosulfuron was observed to be effective against grassy as well as broad leaf weed (Bisen et al., 2006; Jat et al., 2007; Pandey and Kumar, 2007). Singh and Singh (2005) with isoproturon + metsulfuron methyl and isoproturon + 2,4-D; Singh and Singh (2002) with isoproturon + metsulfuron methyl and

3 Volume 50 Issue 2 (206) 09 Table : Effect of weed control treatments on weed density (m 2 ) of different weeds in wheat at 90 DAS Treatment Dose (a.i. g ha - ) Phalaris minor Coronopus dydimus Melilotus Indica Chenopodium album Anagalis Arvensis Rumex Maritimus Weedy check - 9. (83.3) * Weed free - Hand Hoeing at 30 & 45 DAS (20.66) Sulfosulfuron (.6) Metribuzin (7.99) Pendimethalin (22.83) Isoproturon + 2,4-D (40.33) Clodinofop + 2,4-D (36.83) Fenoxaprop + 2,4-D (33) Metribuzin + 2,4-D (37) Pendimethalin fb 2,4-D 000 fb (33.99) Isoproturon + Metsulfuron methyl (38.83) Clodinofop+ Metsulfuron methyl Fenoxaprop + Metsulfuron methyl (30) CD at 5% -.56 (5.32) 5.08 (25) 2.6 (5.99).86 (2.5) (7) (3.6) (3.99) (3.6) (3) (.80) 4.89 (22.99) 2.37 (94.66) (3.6) (7.6) (4.83) (2.33) (.44) 5.7 (26.33) (0.5) 2.55 (5.66) 2.08 (3.6) 2.75 (6.66) (5.5) (3.6) (.72) 4.23 (7.66) 2.56 (5.83).9 (2.83).63 (.66) 2.65 (6.6) (3.6) 2.2 (4.6) (3.6) (2.6) (.05) 4.85 (23.5) 2.48 (5.33).8 (2.33) 2.05 (3.49) 2.66 (6.33) (4.5) (3.6) (2) (.72) *(Data subjected to square root x+ transformation and figures in parenthesis are original value) Table 2: Effect of weed control treatments on weeds (%) in wheat crop at 90 DAS Treatment Dose (a.i. g/ha) Phalaris minor Coronopus dydimus Melilotus Indica Chenopodium album Anagalis Arvensis Rumex Maritimus Weedy check Weed free Hand Hoeing at 30 & 45 DAS Sulfosulfuron Metribuzin Pendimethalin Isoproturon + 2,4-D Clodinofop + 2,4-D Fenoxaprop + 2,4-D Metribuzin + 2,4-D Pendimethalin fb 2,4-D 000 fb Isoproturon + Metsulfuron methyl Clodinofop+ Metsulfuron methyl Fenoxaprop + Metsulfuron methyl Jat et al. (2007) and Chopra and Chopra (200) with fenoxaprop + metsulfuron methyl recorded similar results in wheat. Effect on weed dry weight: Different weed control treatments exerted significant influence on weed dry weight in comparison to weedy check (.72g). Among various weed control treatments, minimum weed dry weight (7.3g) was recorded with sulfosulfuron at 25g ha - followed by clodinofop at 60g + metsulfuron methyl at 4g ha - (8.45g), metribuzin at 200g ha - (25.98g) and pendimethalin at 000g fb 2,4-D at 400g ha - (3.73g), respectively (Table-3). However, the treatments comprising isoproturon at 000g +

4 0 INDIAN JOURNAL OF AGRICULTURAL RESEARCH Table 3: Effect of weed control treatments on weed parameters and harvest index in wheat cv. PBW-343 Treatment Dose No. of weeds Weed dry Weed control Weed Harvest (a.i. g ha - ) (m 2 ) at 90 DAS wt. (g) efficiency Index Index Weedy check (98.66)* Weed free -.0 (0.0) Hand Hoeing at 30 & 45 DAS (48.6) Sulfosulfuron (25.33) Metribuzin (33.33) Pendimethalin (56.6) Isoproturon + 2,4-D (58.33) Clodinofop + 2,4-D (56.49) Fenoxaprop + 2,4-D (55.00) Metribuzin + 2,4-D (57.33) Pendimethalin fb 2,4-D 000 fb (4.6) Isoproturon + Metsulfuron methyl (56.33) Clodinofop+ Metsulfuron methyl (25.99) Fenoxaprop + Metsulfuron methyl (49.66) CD at 5% (6.06) *Data subjected to square root x+ transformation and figures in parenthesis are original value 2, 4-D at 400g ha - (60.5g), isoproturon at 000g + metsulfuron methyl at 4g ha - (49.67g), clodinafop at 60g + 2,4-D at 400g ha - (44.82g) and metribuzin at 200g + 2, 4- D at 400g ha - (42.80g) recorded significantly more weed dry weight than hand weeding twice (35g) and weedy check (.72g), respectively. Singh and Singh (2002) with isoproturon + metsulfuron methyl, Yadav et al., (200) and Chopra et al., (200) with pendimethalin and Saha et al., (2006) with hand hoeing twice reported significant reduction in weed dry weight in wheat. Effect on weed control efficiency: The perusal of data in table-3 revealed that isoproturon at 000g + 2, 4-D at 400g ha - resulted in minimum weed control efficiency (46.22%) followed by isoproturon at 000g + metsulfuron methyl at 4g ha - (54.72%) and clodinafop at 60g + 2,4-D at 400g ha - (59.97%), respectively. Lesser weed control efficiency with isoproturon application may be attributed to resistant biotypes of Phalaris minor (Malik and Singh, 993; Walia et al., 997). However, Prasad et al. (2005) and Balyan (200) reported good control of narrow and broad leaf weeds in wheat with isoproturon + 2,4-D and isoproturon + metsulfuron methyl, respectively. Among herbicidal treatments, maximum weed control efficiency was recorded under sulfosulfuron at 25g ha - (83.85%) followed by clodinofop at 60g + metsulfuron methyl at 4g ha - (83.7%), metribuzin at 200g ha - (75.85%) and pendimethalin at 000g fb 2,4-D at 400g ha - (70.90%),respectively. Weed index: The perusal of data in table-3 indicated significant differences among various weed control treatments w.r.t. weed index. Highest weed index was recorded under weedy check (36.35). Among herbicidal treatments, metribuzin at 200g ha - recorded maximum weed index (22.90) followed by metribuzin at 200g + 2, 4-D at 400g ha - (22.8) and clodinafop at 60g + 2,4-D at 400g ha - (20.86), respectively. Also, treatments comprising metribuzin at 200g ha -, metribuzin at 200g + 2, 4-D at 400g ha -, clodinafop at 60g + 2,4-D at 400g ha -, isoproturon at 000g + 2, 4-D at 400g ha -, pendimethalin at 000 gm ha -, isoproturon at 000g + metsulfuron methyl at 4g ha - and fenoxaprop at 00 g + 2,4-D at 400g ha - recorded higher weed index than hand hoeing twice (5.60). Application of clodinofop at 60g + metsulfuron methyl at 4g ha - recorded lowest weed index (4.43) followed by sulfosulfuron at 25g ha - (4.74), pendimethalin at 000g fb 2,4-D at 400g ha - (.50) and fenoxaprop at 00g + metsulfuron methyl at 4g ha - (2.63), respectively. These treatments also resulted in lower weed index than that recorded under hand weeding twice. Harvest Index: All the weed control treatments recorded significantly higher harvest index than the weedy check (40.24). Among various herbicidal treatments, application of clodinofop at 60g + metsulfuron methyl at 4g ha - recorded highest harvest index (4.9) followed by sulfosulfuron at 25 g ha - (4.83) and pendimethalin at 000g fb 2,4-D at 400g ha - (4.25) respectively. The harvest index recorded under clodinofop at 60g + metsulfuron methyl at 4g ha - and sulfosulfuron at 25 g ha - was significantly at par with weed free (42.06) treatment. However, among various herbicidal treatments, application of metribuzin at 200g ha - recorded lowest harvest index (40.59). Hand hoeing twice recorded a harvest index of The treatments comprising clodinofop at 60g + metsulfuron methyl at 4g ha - and sulfosulfuron at 25 g ha - indicated their superiority in controlling weeds in comparison to other herbicidal weed control treatments. Use of herbicides reduced weed competition resulting in availability of more moisture, plant nutrients and space to the crop. It is apparent that weeds significantly affected the yield attributing characters which cumulatively resulted in lower biological and grain yield. (Jat et al., 2003; Jain et al., 2006; Walia and Brar, 2006). Singh and Singh (2005) reported better control of Phalaris minor and Chenopodium album in wheat with clodinafop +

5 metsulfuron methyl as tank mixture. Other workers viz. Chhokar et al. (200), Banga and Yadav (2004) and Kaur et al. (2007) have also reported effectiveness of sulfosulfuron in controlling weeds in wheat, respectively. Lower values of harvest index with metribuzin, metribuzin + 2, 4-D and clodinafop + 2,4-D than other herbicides may be attributed to phytotoxicity to crop, presence of resistant weed biotypes and incompatibility of herbicide mixtures. Though metribuzin indicated higher weed control efficiency than other herbicides (excepting sulfosulfuron and clodinofop + metsulfuron methyl), however, its application resulted in lower harvest index than all the other herbicides, which was attributed to phytotoxic effect of metribuzin on wheat (Sharma et al., Volume 50 Issue 2 (206) 2004; Singh et al., 2002). Similarly, lower yields with metribuzin + 2,4-D and clodinafop + 2,4-D in comparison to other herbicides could also be attributed to their reduced efficacy in controlling weeds owing to presence of resistant weed biotypes (Balyan et al., 999) or incompatibility of herbicide mixtures (Singh and Singh, 2005), respectively. CONCLUSION On the basis of the results obtained in this study, it is concluded that post emergence application (30 days after sowing) of clodinofop at 60g + metsulfuron methyl at 4g ha - or sulfosulfuron at 25 g ha - may be adopted for efficient weed management in wheat cv. PB under western Uttar Pradesh conditions of northern India. REFERENCES Balyan, R.S. (200). Evaluation of new herbicides against mixed weed flora in wheat. Indian Journal of Weed Science, 33: Balyan, R.S.; Yadav, A.; Pahwa, S.K. and Malik, R.K. (999). Response of fenoxaprop and other herbicides on Isoproturon resistant and susceptible biotypes of little canary grass and other weed in wheat. Indian Journal of Weed Science, 3: Banga, R.S. and Yadav, A. (2004). Effect of fenoxaprop and sulfosulfuron alone and as tank mixture against complex flora of weeds in wheat. Indian Journal of Weed Science, 36: Bharat, R. and Kachroo, D. (200). Bio efficacy of herbicides on weeds in wheat (Triticum aestivum) and its residual effect on succeeding cucumber (Cucumis sativus). Indian Journal of Agronomy, 55: Bisen, P.K.; Singh, R.K. and Singh, R.P. (2006). Relative composition of weed and wheat yield as influenced by different weed control and tillage practices. Indian Journal of Weed sciences, 38:9-. Chhokar, R.S.; Chauhan, D.S. and Sharma, R.K. (200). Time of sulfosulfuron application in wheat for Phalaris minor control. Indian Journal of Weed Science, 33: Chopra, N.K.; Chopra, N. (200).Evaluation of tillage system and herbicide on wheat performance under rice wheat cropping system. Indian Journal of Agronomy, 55: Chopra, Nisha; Singh, H.; Tripathi, H.P. and Chopra, N.K. (200). Performance of metasulfuron methyl and pendimethalin alone and their mixtures with isoproturon on weed control in wheat (Triticum aestivum) seed crop. Indian Journal of Agronoy, 46: Gill, G.S. and Kumar, V. (969). Weed Index - A new method for reporting weed control traits. Indian Journal of Agronomy, 6: Jain, N.; Kewat, M.L.; Mishra, J.S. and Jain, V. (2006). Effect of tillage and herbicides on weed and wheat in transplanted rice-wheat system. Indian Journal of Weed Science, 38:6-9. Jat, R.K.; Punia, S.S. and Malik, R.K. (2007). Efficacy of herbicide mixtures and sequential applications against different weeds in wheat (Triticum aestivum L.). Indian Journal of Weed Science, 39: Jat, R.S.; Nepalia, V. and Chaudhary, P.D. (2003). Influence of herbicides and methods of sowing on weed dynamics in wheat (Triticum aestivum). Indian Journal of Weed Science, 35:8-20. Kaur, T.; Brar, L.S. and Walia, U.S. (2007). Effect of sulfosulfuron and mesosulfuron + Iodosulfuron on weeds and wheat yield. Indian Journal of Weed Science, 39:48-5. Malik, R.K. and Singh, S. (993). Evolving strategies for herbicide use in wheat resistance and integrated weed management. Proceedings of International Symposium on Weed Management and Sustainable Agriculture. pp Hissar Pandey, I.B. and Kumar, K. (2007). Manipulation of sowing techniques and weed Science, 39: Prasad, S.; Singh, Y.; Singh, R.P. and Singh, G. (2005). Effect of crop establishment, weed control method and time of nitrogen application on late sown wheat. Indian Journal of Weed Science, 37: Punia, S.S.; Singh, S.; Malik, R.K. and Yadav, D. (2006). Studies on herbicide mixture in wheat. Indian Journal of Weed Science, 38:-4. Saha, M.; Banerjee, H. and Pal, S. (2006). Relative efficacy of herbicides in wheat. Indian Journal of Weed Science, 38:27-28.

6 2 INDIAN JOURNAL OF AGRICULTURAL RESEARCH Sharma, S.D.; Singh, S.; Punia, S.S. and Narwal, S. (2004). Effect of doses and stages of application of Isopropagyl on Phalaris minor in wheat. Indian Journal of Weed Science, 36:7-74. Singh, G. and Singh, M. (2002). Effect of doses and stages of application of fenoxaprop-p-ethyl on weed control and grain yield of wheat. Indian Journal of Weed Science, 34:2-3. Singh, G.; Singh, M. and Singh, V.P. (2002). Effect of doses and stages of application of sulfosulfuron on weed and wheat yield. Indian Journal of Weed Science, 34: Singh, G.; Singh, V.P. and Singh, M. (2004). Bio-efficacy of metribuzin and prometryn in wheat. Indian Journal of Weed Science, 36: Singh, G. and Singh, V.P. (2005). Compatibility of clodinafop propargyl and fenoxaprop-p-ethyl with carfentrazone-ethyl, metsulfuron-methyl and 2,4-D. Indian Journal of Weed Science, 37:-5. Walia, U.S. and Brar, L.S. and Dhaliwal, B.K. (998). Performance of clodinafop and fenoxaprop-p ethyl for the control of Phalaris minor in wheat. Indian Journal of Weed Science, 30: Walia, U.S. and Brar, L.C. (2006). Current status of Phalaris minor resistance against isoproturon and alternate herbicides in the rice-wheat cropping systems in Punjab. Indian Journal of Weed Science, 38: Walia, U.S., Dhaliwal, B.K. and Brar, L.S. (997). Resistance to isoproturon in Phalaris minor in Punjab. Plant Protection Quarterly, 2: Yadav, R.P.; Shrivastava, U.K. and Dwivedi, S.C. (200). Response of wheat (Triticum aestivum) and associated weeds to irrigation schedule and pendimethalin. Indian Journal of Agronomy, 46:22-25.