Pre-emergence Spray Research Articles

Response of sunflower-weed ecosystem to herbicide oxadiagryl and integrated weed management options

Field experiment was conducted during summer, 2021 at Odisha University of Agriculture & Technology, Bhubaneswar to study the response of sunflower as a part of Integrated weed management with suboptimal, optimal and super optimal doses of oxadiargyl as pre-emergence spray with or without quizalofop ethyl 5 EC @ 37.5 g/ha at 15 - 20 DAS in sunflower hybrid "KBSH-44" revealed that weed free control has recorded the highest seed yield (2064 kg/ha), which remained at par with oxadiargyl @ 125 g/ha as pre-emergence spray fb one HW at 30 DAS with a seed yield of 1962 kg/ha with a WCE of 92.6% at harvest.

Integrated Weed Management in Minor Millets: A Review

Presently, agriculture is facing tremendous problem due to climate change and global warming. To ensure food and nutritional security at national level, there is an immediate need to promote the cultivation of millets as millets are considered climate smart and nature friendly crops because of high nutritive value and can withstand under warm and drought conditions with short life, low external inputs requirement, tolerance to water and temperatures stress. Ten millet crops have been declared as ‘Nutri Cereals’ which include three major millets i.e., pearl millet, sorghum and finger millet; five minor millets i.e. foxtail millet, proso millet, kodo millet, barnyard millet, little millet; and two pseudo millets i.e. kuttu (buckwheat) and amaranthus. Due to sluggish growth in initial phases of life, millets proved relatively poor competitors against weeds. Manual weeding is the most commonly adopted for weed control in millets. But the non-availability of labour and ever-increasing labour wages have compelled the farmers to seek alternate method of weed management. Herbicide use is the most viable method of weed control but their continuous and excessive use is not advisable due to its ill effects on environment and development of herbicide resistance in weeds. Very limited options are available in literature for weed control in minor millets. Thus, integrated weed management practices should be followed on site and time specific basis for effective and efficient weed management in minor millets. For integrated weed management in minor millets, 2-3 times inter-cultivation and 1-2 time hand weeding during initial 25 days after sowing in addition to pre-emergence spray with Isoproturon @ 0.5 -1.0 kg a.i./ha and post emergence spray of 2, 4-D sodium salt @ 0.75-1.0 kg a.i./ha at 20-25 days after sowing should be done for effective weed control.

Effect of Different Herbicides in Weed Management in Transplanted Rice

Weed is one of the major yield-limiting factors in rice cultivation. It causes yield losses of around 40-90%, depending on the situation. Manual weeding is the dominant weed management method in rice and limited farmers use herbicides in Nepal. Selecting effective herbicides for different weed species is a crucial task for farmers. So, an experiment with 9 treatments consisting of 5 herbicides was conducted in RCB Design with 3 replications during 2020 and 2021 to find effective herbicides. The recommended agronomic practices were followed. Rice variety Khumal 11 was transplanted in a 4m x 3m plot with a spacing of 20 cm between rows and 15 cm between plants. Pooled data of two years showed the lowest weed density (14.2 m-2) and highest (73.2 m-2) in the treatment pretilachlor @ 0.5 kg ha-1 (pre) as sand mix and in the weedy check. Similarly, the lowest weed dry biomass (7.4 g m-2) and the highest (42.4 g-2) were recorded in the same treatments. The grain yield was the highest (7253 kg ha-1) in pretilachlor applied at 0.5 kg a.i ha-1 as pre-emergence spray and the lowest (4339 kg ha-1) in the control. The treatment pretilachlor @ 0.5 kg a.i ha-1 (pre) applied as spray was superior in managing weed and resulting in the highest grain yield, so it is recommended for mid-hill ecologies under transplanted rice.

Weed control in maize with herbicides and its effect on grain yield

Competition posed by weeds is a major challenge in crop production as weeds cause severe reduction in yield by competing with crop plants for limited resources like light, space applied nutrients and water also. Several researchers and eminent investigators observed that diverse weed flora causes huge losses in maize yield and if the weeds are not managed at right time then it results in huge yield penalty. Among weed management treatments, hand weeding at 15-21 days after sowing and 30-42 days after sowing and integration of pre-emergence application of atrazine 1.5 kg ha-1, pendimethalin at 1.50 kg ha-1, pendimethalin + atrazine both at 0.5 kg ha-1 as pre-emergence spray, atrazine + alachlor at 0.75 + 1.25 kg ha-1, or alachlor at 1.5 kg ha-1fb hand weeding at 30 days after sowing and tembotrione 125 g ha-1+surfactant applied on 20 DAS were proved more effective. In case of sequential treatments, pre-emergence application of atrazine at 1.25 kg ha-1 or pendimethalin at 1.5 kg ha-1 fbparaquat at 0.6 kg ha-1at 3 weeks after sowing or pre-emergence application of atrazine at 1.0 kg ha-1 followed by topramazone at 0.030 kg ha-1 at 30 days after sowing gave higher gross returns, net returns and benefit cost ratio, thus proved more economical.

Weed management practices in Indian mustard (Brassica juncea L.) in lower Gangetic plain Zone

The field experiment was conducted during rabi season in 2017-18 and 2018-19 at the Agronomy Research Farm, A.N.D. University of Agriculture & Technology, Kumarganj, (Ayodhya)to find out the effect of weed management practices on productivity and economics of mustard (Brassica juncea L.). Fifteen treatments were evaluated in randomized block design with three replications. Two hand weedings at 20 and 40 DAS recorded significantly lowest population and dry weight of weeds as compared to rest of the treatments during both the years. Among the herbicides combination, pendimethalin (PE) @ 1000 g ha-1 applied either with hand weeding at 40 DAS or paddy straw mulch @ 10 t ha-1 at 2-3 DAS recorded the lowest weed density and dry weight m-2 followed by metribuzin (PE) @ 175 g ha-1 either with hand weeding at 40 DAS or paddy straw mulch @ 10 t ha-1 at 2-3 DAS. Weedy check till maturity recorded significantly highest density and dry weight of weeds as compared to rest of the treatments during both the years. Pre-emergence spray of pendimethalin (PE) @ 1000 g ha-1 + hand weeding at 40 DAS being at par with two hand weeding at 20 and 40 DAS but recorded highest values of all yield attributes and yields as compared to rest of the treatments. The increase in grain yield due to pendimethalin (PE) @ 1000 g ha-1 + hand weeding at 40 DAS was recorded to the tune of 10.4% over pendimethalin (PE) @ 1000 g ha-1 + paddy straw mulch @ 10 t ha-1 at 2-3 DAS. The yield losses due to weedy check till maturity was recorded to the tune of 58.2%, 53.3% and 43.3% as compared to two hand weeding applied at 20 and 40 DAS, pendimethalin (PE) @ 1000 g ha-1 + hand weeding at 40 DAS, and pendimethalin (PE) @ 1000 g ha-1 + paddy straw mulch @ 10 t ha-1 at 2-3 DAS, respectively. The highest net income (Rs. 57394 ha-1) and B:C ratio (1.5) was recorded with pendimethalin (PE) @ 1000 g ha-1+ hand weeding at 40 DAS which was followed by two hand weeding at 20 and 40 DAS with net income of Rs. 55485 ha-1 and B:C ratio 1.49.

Weed management practices in Indian mustard (Brassica juncea L.) in lower Gangetic plain Zone

The field experiment was conducted during rabi season in 2017-18 and 2018-19 at the Agronomy Research Farm, A.N.D. University of Agriculture & Technology, Kumarganj, (Ayodhya)to find out the effect of weed management practices on productivity and economics of mustard (Brassica juncea L.). Fifteen treatments were evaluated in randomized block design with three replications. Two hand weedings at 20 and 40 DAS recorded significantly lowest population and dry weight of weeds as compared to rest of the treatments during both the years. Among the herbicides combination, pendimethalin (PE) @ 1000 g ha-1 applied either with hand weeding at 40 DAS or paddy straw mulch @ 10 t ha-1 at 2-3 DAS recorded the lowest weed density and dry weight m-2 followed by metribuzin (PE) @ 175 g ha-1 either with hand weeding at 40 DAS or paddy straw mulch @ 10 t ha-1 at 2-3 DAS. Weedy check till maturity recorded significantly highest density and dry weight of weeds as compared to rest of the treatments during both the years. Pre-emergence spray of pendimethalin (PE) @ 1000 g ha-1 + hand weeding at 40 DAS being at par with two hand weeding at 20 and 40 DAS but recorded highest values of all yield attributes and yields as compared to rest of the treatments. The increase in grain yield due to pendimethalin (PE) @ 1000 g ha-1 + hand weeding at 40 DAS was recorded to the tune of 10.4% over pendimethalin (PE) @ 1000 g ha-1 + paddy straw mulch @ 10 t ha-1 at 2-3 DAS. The yield losses due to weedy check till maturity was recorded to the tune of 58.2%, 53.3% and 43.3% as compared to two hand weeding applied at 20 and 40 DAS, pendimethalin (PE) @ 1000 g ha-1 + hand weeding at 40 DAS, and pendimethalin (PE) @ 1000 g ha-1 + paddy straw mulch @ 10 t ha-1 at 2-3 DAS, respectively. The highest net income (Rs. 57394 ha-1 ) and B:C ratio (1.5) was recorded with pendimethalin (PE) @ 1000 g ha-1 + hand weeding at 40 DAS which was followed by two hand weeding at 20 and 40 DAS with net income of Rs. 55485 ha-1 and B:C ratio 1.49.

Productivity and profitability in dry direct sown rice through mechanization

In most of South Asia, common practice of establishing rice cultivation is through puddling followed by manual transplanting. Direct seeding methods have several advantages over transplanting. Firstly, direct seeding saves labour. Farm mechanization is low in the rice crop in India. Complete machinery package is needed to be introduced to enhance the production and also it helps in minimize the input energy and cost involved in rice crop. The development of short duration, early-maturing cultivars and efficient nutrient management techniques along with increased adoption of integrated weed management methods have encouraged many farmers to switch from transplanted to DSR culture. Area under direct sown rice is increasing every year under North coastal Zone as the farmers are switching over from lowland rice cultivation. The causes for such a change over in the method of cultivation is due to the late release of irrigation water in the canals, erratic rainfall pattern and the shortage of labour for transplanting rice. However, the yields of paddy in this situation will be greatly limited by labour costs and lack of proper weed management which needs to be effectively managed for realizing higher productivity. Rice under direct sown conditions has great potential for realization of higher grain yields. However, severe weed infestation has been recognized as one of the major limitations that hamper the enhanced productivity levels in rice grown under this system. Therefore, the present investigation is proposed to study the mechanization in DSR in combination with efficacy of the available pre and post emergence herbicides for efficient and economical weed control. Dry direct seeding (DDS) with total mechanization (Sowing with seed drill, pre-emergence spray of Pretilachlor@500 ml/ac+ post emergence spray of bispyribacsodium@100 ml/ac, power weeding, mechanical harvesting and threshing / Winnowing fan, seed processing) recorded an average grain yield of 6467 kgha-1 with an increase of 28.37% when compared to farmers practice(5269 kgha-1). Similarly the straw yield is also recorded 16.95% high in mechanized practice (6410kgha-1) with that of farmers practice(5690 kgha-1). The total cost of cultivation was reduced to 15.78% in mechanized practice and gross income was increased by 17.12% in comparison with farmers practice. The benefit cost ratio(2.87) is also more in mechanized practice in comparing with farmers practice(2.11).

Soil Persistence of Diuron Applied to Cotton Cultivation in Red and Black Soils

Persistence of diuron applied to cotton as preemergence spray at varied rates of application (0.5, 0.75, 1.0 kg ha-1) was studied in field experiments conducted simultaneously in red and black soils at Professor Jayashankar Telangana State Agricultural University, Rajendranagar during kharif, 2018. In both red and black soils, persistence of diuron was observed beyond 120 days after application and the concentration of diuron in the top soil (0-15 cm) was higher in black soils compared to red soils from 0 Days to 120 Days. Higher dose of diuron showed greater soil persistence in both red and black soil. Diuron dissipation in soil followed first order kinetics in both the soils. Field half life of diuron was higher in black soil was 53.3-77.0 days at different rates of application than in red soil (53.3-69.3 days).

Integrated weed management in preseasonal sugarcane

A field experiment on “Integrated Weed Management for preseasonal sugarcane” was conducted for three consecutive years at Central Sugarcane Research Station, Padegaon, Tal Phaltan District Satara, Maharashtra, India during 2015-16 to 2017-18 to find out tank mix optimum combination dose of post emergence herbicide for effective control in sugarcane. Dominant weeds observed in sugarcane crop were Brachiaria eruciformis, Cyperus rotundous, Alternanthera sessils, Parthenium hysterophorus L., Euphorbia geniculata Linn., Cardiosoermum lalicacabum, Ipomoea hederacea and Hylandis latiprosa. The result showed that mean total weed count and weed dry weight reduced with post emergence application of metribuzin @ 0.50 kg a.i.ha-1 + 2, 4-D @ 1.00 kg a.i. ha-1 at 25 DAP fb hoeing at 60 and 90 DAP and found at par with treatment post emergence application of metribuzin @ 1 kg a.i ha-1 + 2, 4-D @ 1 kg a.i. ha-1 at 25 DAP fb hoeing at 60 and 90 DAP. Among the herbicidal treatments, post emergence application of metribuzin @ 0.50 kg a.i ha-1 + 2, 4-D @ 1 kg a.i. ha-1 at 25 DAP fb hoeing at 60 and 90 DAP recorded significantly the highest germination per cent (66.73 %), number of internodes per cane (22) and average cane weight (1.93 kg) over all herbicidal treatments which was at par with pre emergence spray of metribuzin @1 kg a.i. ha-1 and post emergence spray of 2,4-D @1kg a.i. ha-1 at 60 DAP fb hoeing at 90 DAP for number of internodes per cane (21.90) and average cane weight (1.92 kg). Among the herbicidal treatments, maximum weed control efficiency of 60.59 %, 56.38 % and 75.99 % was found in treatment of post emergence application of metribuzin @ 0.50 kg a.i. ha-1+ 2,4-D @ 1.00 kg a.i. ha-1 at 25 DAP fb hoeing at 60 and 90 DAP to sugarcane crop at 30, 60 and 90 days after application, respectively followed by post emergence application of metribuzin @ 1 kg a.i ha-1 + 2, 4-D @ 1 kg a.i. ha-1 at 25 DAP with hoeing at 60 and 90 DAP. Similarly, the significantly highest cane yield (155.21 t ha-1) and CCS yield (21.38 t ha-1) was recorded by same treatment over all herbicidal treatments which was at par with treatment metribuzin @1 kg a.i. ha-1 as pre emergence, 2,4-D @1 kg a.i. ha-1 as post emergence application at 60 DAP fb hoeing at 90 DAP for CCS yield. The maximum net return (Rs. 278454) and benefit cost ratio (3.13) was also reported by same treatment followed by post emergence application of metribuzin @1.00 kg a.i. ha-1 + 2,4-D @ 0.50 kg a.i. ha-1 at 25 DAP fb hoeing at 60 and 90 DAP. The cane quality like commercial cane sugar %, sucrose %, brix (00) and purity % was not affected by hand weeding, mechanical weed control and application of any herbicide.

Effectiveness of different weed control practices in onion (Allium cepa L.) crop

Onion (Allium cepa L.) is one of the most important vegetables in family Alliaceae, which is cultivated worldwide. In onion, weeds are among one of the major concerns which cause its yield reduction. The present study was designed to assess the effectiveness of different methods for weed control in onion. In this study, five treatments were selected including control, black polythene mulch sheet, white polythene mulch sheet, Dual Gold spray @ 9.0 mL L-1 and Preact spray @ 7.5 mL L-1 to control weeds. The weedicides were applied as pre-emergence sprays before transplanting the seedlings. The experiment was laid out in Randomized Complete Block Design with three replications. From the results, it was concluded that there were significant differences among the studied weed control treatments. Among the five treatments, greater plant height (33.0 cm), number of leaves per plant (8), bulb diameter (4.7 cm) and bulb weight (73 g) were observed in the ridges covered with black mulch sheet. However, the minimum weed biomass (fresh and dry) was recorded in black mulch sheet and Preact pre-emergence weedicide spray (140 and 80 g in both). Thus, black polythene sheet as mulching material was found better option for weed management in onion fields.

Efficacy of pre and post-emergence herbicide on growth, yield and economics of sunflower (Helianthus annuus L.) under modified spacing

Application of pendimethalin @ 1.0 kg a.i./ha as pre-emergence spray along with propaquizafop @ 62 g a.i/haat 15-20 DAS as post emergent spray recorded significantly lower weed dry weight (53.5 g/m2 area), weed index (5.31) and higher weed control efficiency (89.1 %), seed yield (1728 kg/ha), head diameter (16.06 cm), test weight(6.06 g), gross returns (` 65,266), net returns (` 26,248) and B:C ratio (2.48).

Effect of Technological Intervention on Yield of Summer Pearl Millet

Front line demonstrations (FLDs) were conducted by pearl millet Research Station, JAU, Jamnagar on 313 farmers’ field in 125 hectares of different 98 villages of Gujarat state during summer season of 2015 to 2019. Prevailing farm practices were treated as control for comparison with recommended package i.e. improved variety (GHB 558, GHB 538, GHB 732), seed rate 4 kg/ha, timely sowing (15 Feb to 15 March), line sowing with spacing of 60 cm (R-R) and 10-12 cm (P-P), balanced use of fertilizers (NPK @120:60:0 kg/ha, thinning 15 days after sowing, weed management (pre emergence spray of Atrazin @ 0.5 kg/ha and one hand weeding), proper critical stage apply 8-10 irrigation, two foliar spray of profenophos 0.05 % at 20 and 40 days after germination to control shoot fly and stem borer pests infesting pearl millet, timely harvesting and threshing. The cumulative effect of technological intervention over five years, revealed average grain yield 4362 kg/ha and dry fodder yield 7365 kg/ha which is 6.17% and 12.76% higher over the farmers’ practices. The economics and cost benefit ratio of both farmers’ and improved practices was worked out. On an average net profit was obtained 6837 /ha due to adoption of improved package of practices. The average cost benefit ratio was 2.23 under improved demonstration practices, while it was 2.43 under farmers’ practices. By conducting the Front line demonstrations of proven technologies, yield potential and net income from pearl millet cultivation can be enhanced to a great extent with increase in the income level of the farming community.

Occurrence of neonicotinoids in guttation liquid of maize – soil mobility and cross-contamination

ABSTRACTMovement of clothianidin (CLO) and thiamethoxam (TMX) applied as maize seed dressing or pre-emergence spray application was determined in different soil types. Uptake of these neonicotinoids in plants emerging from coated or non-coated seeds was characterised via guttation liquid measurements. Applied in spray at a recommended dosage of 16.5 µmol/L, TMX and CLO occurred in the guttation liquid at peak concentrations of 1.82 and 1.63 mg/L, respectively, in plants in sandy soil and at 20–40% lower levels in plants in clay or loam soils. Peak emergence was substantially higher (above 100 mg/L) in the guttation liquid of plants emerging from neonicotinoid-coated seeds at dosages of 4.87 and 2.07 µmol per seed for CLO and TMX, respectively, strongly influenced by soil type. CLO and TMX levels in plants emerging from non-coated seeds in the proximity of neonicotinoid-coated seeds were demonstrated: cross-contamination may occur by uptake through soil from neighbouring plants. CLO appeared in the guttation liquid of plants emerging from non-coated seeds in proximity to coated ones at a peak concentration (approximately 53 mg/L) in 15 days corresponding to one-fifth of the levels in plants emerging from CLO-coated seeds; CLO concentrations gradually decreased to the same levels (6.6 ± 0.3 mg/L) after 24 days. A similar trend was observed for non-coated seeds near TMX-coated ones, with a gradual increase of TMX in 17–18 days, the levels in the guttation liquid of plants emerged from non-coated seeds (approximately 123 mg/L) corresponding to two-thirds of the levels in plants emerging from TMX-coated seeds. TMX concentrations dropped to the same levels in plants emerging from non-coated and coated seeds by day 20, and CLO occurred as a metabolite. To our knowledge, this is the first scientific record of neonicotinoid levels in guttation liquid of plants emerged from non-coated maize seeds.

Post-emergence herbicides for weed management in groundnut

A field experiment was conducted at Agricultural Research Station, Kawadimatti, Karnataka during Kharif 2012 and 2013 to study the efficacy of post-emergence herbicides for weed management in groundnut. The trial comprised of eight treatments, out of which five treatments were of post-emergence herbicides, viz. quizalofop-ethyl, propaquizafiop, imazethapyr, chlorimuron-ethyl, fenoxaprop-p-ethyl. These were compared with, pre-emergence spray of pendimethalin weed free and weedy treatments. Among the post-emergence herbicides, significantly higher pod yield (2.01 t/ha) was recorded with imazethapyre, which was at par with quizalofop-ethyl (1.91 t/ha) and propaquizafop (1.87 t/ha). Imazethapyre also recorded higher net return (Rs/ha) and B:C ratio. Higher pod yield of these treatments was due to significantly lower total weeds density, weed biomass and higher weed control efficiency.

Effect of crop establishment methods and weed management practices on weeds, growth and yield of direct-seeded rice

Field trials were conducted at Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi during kharif seasons of 2011 and 2012 to study the effect of crop establishment methods and weed management practices on weeds, growth and yield of direct-seeded rice. Results indicated that bed planting of dry-seeded rice suppressed dry matter accumulation of weeds–grasses, sedges and broad leaf weeds most effectively among crop establishment methods, and as a consequence this crop establishment method had markedly higher growth rates, higher growth and yield attributes. Among different weed management practices, integrated weed management practices, namely, pre-emergence spray of pendimethalin 1 kg/ha followed by brown manuring of dhaincha by 2,4-D 0.50 kg/ha at 25 days after sowing (DAS) and combination of pre-emergence spray of pendimethalin 1 kg/ha followed by early post-emergence spray of bispyribac 0.025 kg/ha followed by brown manuring of dhaincha by 2,4-D 0.50 kg/ha at 25 DAS significantly lowered dry matter of all weeds than other weed management practices, thus improved growth and its rate and yield attributes of direct-seeded rice. Though crop establishment methods did not significantly influence grain yield of direct-seeded rice, protein content in grain and its yield were markedly improved by bed and no-till methods than conventional method. Integration of pendithalin application with brown manuring of dhaincha and pendimethalin followed by bispyribac followed by brown manuring of dhaincha registered significantly higher grain yield, protein content in grain and its yield than remaining weed management practices.

Controlling twining weed (Ipomoea sepiaria) in sugarcane

Sugarcane being an important cash crop of India, is cultivated in different Agro-Climatic condition. Weeds are growing along with sugarcane and limits the cane and sugar yield according to the species and intensity. Shift in weed flora was observed due to following the same method of weed management practice for long period. Sedges like Cyperus sp. has been shifted from annuals and broad-leaved weeds by spraying the pre- emergence herbicide viz.,Atrazine. The sedges can also be controlled by spraying of total weed killer (Glyphosate). Further, the nature has encouraged the weeds of twining habit, which are germinated and growing by climbing on the sugarcane stalks after the earthing up operation. These weeds are posing several problems like blocking the sunlight to the cane crop by spreading their branches on the top plane. It also gives trouble to the harvesting labour and increasing the cost of operation. Hence, twining weeds are to be completely controlled by following a suitable measures . With this objective a study was carried out during special season of 2001–02 and 2002–03 at Sugarcane Research Station, Sirugamani, Trichirappalli district where cane is cultivated under flow irrigated condition. Among the different weed management methods, spraying of pre-emergence spray of atrazine @ 1.0 kg/ha followed by post-emergence spray of 2,4-D Na salt @ 1.0 kg/ha on 110 DAP had high weed control efficiency onIpomoea sepiaria and registered the highest cane and sugar yield.

Chemical weed control in rainfed maize (Zea mays)

An experiment was conducted during rainy (kharif) season of 1991 and 1992 on chemical weed control in rainfed maize (Zen my.^ L.). The pooled data on grain yield indicated that metolachlor (I .25 kglha as pre-emergence spray) and atrazine (1.25 kglha as pre-emergence spray) gave the maximum grain yield and were at par with weeded control. Butachlor (1.5 kgiha as pre-emergence spray) was found to be the next alternative to metolachlor and atrazine. Atrazine, metolachlor and alachlor were more than 90% efficient in reducing dry weight of weeds. Both glyphosate and anilophos were observed to be toxic to maize plant.

Evaluation of different pre-and post-emergence herbicides on forage yield, quality and disease reaction of multi-cut forage sorghum (Sorghum bicolor)

A field experiment was carried out during the rainy (kharif) seasons of 2013 and 2014 at Ludhiana, Punjab, to study the efficacy of different weed-management techniques on weed dynamics, fodder yield, quality and disease reaction in multi cut sorghum [Sorghum bicolour (L.) Moench]. The sorghum crop was infested with grassy, broad- leaf weeds and sedges, which reduced 28.1 and 32.7% of green-fodder and dry-fodder yields respectively. Hand- weeding (at 20 and 30 days after sowing) and application of atrazine @ 0.375 kg a.i./ha + pendimethalin @ 0.750 kg a.i./ha as pre-emergence spray significantly reduced total weed population and dry weight of weeds in compari- son to the other weed-control treatments. These treatments showed higher weed-control efficiency (WCE) than that of the other weed-control treatments. Application of propaquizalofop as post-emergence spray was also effec- tive in reducing weed population and dry matter but had phytotoxic effect on the crop and recorded significantly lower fodder yield. Hand-weeding resulted in significantly higher green-and dry-fodder yield of sorghum over all the treatments, but was statistically at par with the application of atrazine @ 0.375 kg a.i./ha + pendimethalin @ 0.750 kg a.i./ha as pre-emergence spray. These 2 treatments enhanced the green-fodder yield by 39.0 and 36.7% and dry-fodder yield by 48.5 and 45.1% respectively, over weedy check. Hand-weeding and application of atra- zine + pendimethalin (0.375 + 0.750 kg a.i./ha) resulted in 58.7 and 53.9% more crude protein yield than weedy check respectively. The maximum net returns ( 37,790/ha and 36,320) and benefit: cost ratio (1.46 and 1.28) were realized with atrazine @ 0.375 kg a.i./ha + pendimethalin @ 0.750 kg a.i./ha (PE) and hand-weeding at 20 and 30 days after sowing respectively. The leaf-spot disease was the minimum (8.54 %) in hand weeded plots and plots sprayed with atrazine @ 0.375 kg a.i./ha + pendimethalin @ 0.750 kg a.i./ha as pre-emergence spray showed moderate leaf spot severity of 15.7% as the weed population was less in these plots.

Response of maize (Zea mays), wheat (Triticum aestivum) and gobhi satson (Brassica napus subsp. oleifera var. annua) to balanced fertilization and azotobacter inoculation in subhumid Punjab

The technology developed for subhumid middle of October at all the locations. Punjab at the research station has no The wheat cv. HD 2329 was sown in significance unless it is accepted by the the fust week of November, using 100 kg farmers. With this objective, a large number seed rateha at 22 em-row spacing. The of on-farm research experiments were wheat seed was treated with aldrin 30 EC 8 4 conducted on the cultivators fields to test m a g seed to control termite attack. their site-specific performance as well aS Fertilizers were applied as per treatments; acceptability with the farmers at large. Three half N and full dose of other fertilizers were \ types of trials were conducted to establish applied at sowing and the remaining N with the fertilizer response (N, P, K and Zn and fust irrigation 28 days after sowing. The azotobactor inoculation) on wheat (Triticum weeds were controlled by spraying aestivum L. emend. Fiori & Paol.), maize isoproturon 75 w p @ 1.25 kgha as post- (Zea mays L.) and gobhi sarson (Brassica emergence spray (30-40 days after sowing). napus L. subsp. oleifera DC. va.. annua L.) The crop was harvested in middle of April at raised under irrigated conditions and all the locations. Likewise, gobhi sarson cv. moisture-constraint situations during GSL 1 was sown in the third week of 1989-90. These trials were conducted at 22 October at all the 22 locations, using 5 kg locations (treated as replications) in seed rateha with 45 cm-row spacing. The .. Hoshiarpur district, representing the whole thinning was done 3 weeks after- sowing to subhumid belt in relation to soil type, maintain plant spacing 10 cm. The fertilizers irrigation facilities and climatic conditions. were applied as per treatments; half N and Maize cv. Navjot was sown in the first full dose of P and K were applied at sowing week of June, using 20 kg seed rateha at 50 and the remaining half N with fust irrigation cm-row and 22 cm-plant spacings. (28 days after sowing). The crop was Fertilizers were applied as per treatments, sprayed with metasystox 25 EC @ 625 mVha one-third N and full dose of P, K, ZnSO, and in 250 litres water to control aphid attack. azotobactor were applied at sowing, the The crop was ready for harvesting in the fust - -. remaining one-thud N at knee-high and one- week of April. thud N. at pre-tasselling stage. The weeds In a study on fertilizer requirement of were controlled by spraying Atrataf 50 w p @ maize under constraint of irrigation, the 20 kgha as pre-emergence spray in 500 maize yield increased with each level of litres water. The crop was harvested in fertilizer. The highest grain yield (26.1 qha)

Weed management in transplanted rice (Oryza sativa) under rainfed, lowland situation

A field experiment was conducted during wet season of 1996 and 1997 to study the effect of various weed-management practices on yield, weed growth, and nitrogen uptake by rice (Oryza sativa L.) and weeds in transplanted situation condition. Keeping the weed-free-up to 60 days after transplanting (DAT) and application of Anilofos 0.4 kg a.i.lha followed by hand-weeding at 40 DAT resulted in at par and significantly higher grain yield and nitrogen uptake over rest of the treatments. Among chemical weed-control methods, minimum weed density and dry weight were recorded with Anilofos 0.4 kg a.i.lha applied as pre-emergence supplemented with 1 hand-weeding at 40 DAT. Weedy check till maturity reduced the grain yield by 49% while minimum reduction was recorded with Anilofos 0.4 kg a.i.lha + 1 handlweeding at 40 DAT (4%) as compared to weed-free up to 60 DAT. Weedy check till maturity removed significantly highest nitrogen through weeds (12.97 kglha). Pre-emergence spray of Anilofos 0.4 kg a.i.lha + 1 hand-weeding at 40 DAT resulted in higher net income and benefit : cost ratio.