Studies on the effect of mulching and weed management strategies in wheat were initiated at Khumaltar during the winter season of 2000-2002. The treatments were weedy check, handweed alone, post emergence application of sulfosufuron, and NPK application together with or without mulching. Rice straw mulch was applied at the rate of 4 t/ha. Phalaris minor, Alopecuros sp., Chenopodium album, Rumex crispus, Polygonum hydropiper, Stellaria media, Cannabis sativa, and Soliva anthemifolia were the dominant species. Among them, C. album, P. minor and Alopecuros aqualis were the dominant species. The effect of mulching was seen six weeks after wheat planting. The weedy check with mulch suppressed the weeds about fifty percent compared to that of without mulching. Wheat yields together with yield attributing characters were also higher in the treatments with straw mulch.
In 1998, Indian regulatory agencies approved the registration of CGA 184927, MON 37500, and fenoxaprop for postemergence control of isoproturon-resistant littleseed canarygrass. Herbicides used in rice and wheat before 1998 were generally mixed with sand or urea and were applied by hand. Foliar pesticide spray applications consisted primarily of insecticides and fungicides that were applied to high-value crops. These pesticides were often sprayed to runoff with backpack sprayers that were equipped with single hollow-cone or flood nozzles. Applicators walked through the fields, swinging the wands in sweeping motions resulting in uneven pesticide distribution and overapplication. The newly registered postemergence herbicides were applied with the same equipment and in the same fashion. After these applications, control of littleseed canarygrass was strikingly inconsistent, and the growers blamed the lack of control on the manufacturers. It was later clear that basic understanding of the application techniques was lacking. In response to this, an application training workshop was organized and conducted in India and Nepal in 2000. The workshops focused on teaching the participants how to use and fabricate multiple-nozzle booms, the importance of flat-fan nozzles, calibration, drift avoidance, and applicator safety. To date, approximately 3,000 farmers, extension agents, scientists, and industry representatives have attended more than 30 workshops. The participants were unanimously enthusiastic about the value of the workshops. Although simplistic, the adoption of this technology will significantly decrease the amounts of herbicides applied and will increase efficacy and efficiency.
Host-specificity test of Zygogramma bicolorata Pallister (Coleoptra: Chrysomelidae) was conducted in the field and laboratory of National Entomology Research Center, Khumaltar, Lalitpur, Nepal during April to September, 2017. Multiple-choice and no-choice tests were conducted on Agerataum houstoniamum Mill., Bidens pilosa L., Chrysanthemum indicum L., Dahlia pinnata Cav, Guizotia abyssinica L., Helianthus annuus L., Lactuca sativa L., Parthenium hysterophorus L., Perilla frutescence L., Xanthium strumarium L., Zinnia elegans Jacq. and Jasminum officinale L. Among tested plant species, P. hysterophorus was only a preferred host of Z. bicolorata on which both larvae and adults fed. Ovipostion, larval development, pupation and adult emergence of Z. bicolorata occurred successfully on P. hysterophorus completing its life cycle. Larvae consumed H. anuus but could not pupate, and adults fed on it when starved for 5 days in no-choice test. Both adults and larvae of Z. bicolorata consumed X. strumarium and completed larval and pupal developments, but adults did not oviposit. Adult longevity was significantly reduced after feeding on H. annus (19.00 days) and X. strumarium (29.33 days) compared to P. hysterophorus (83.33 days).
Parthenium hysterophorus Linn. is one of the most aggressive, invasive weeds threatening natural and agricultural ecosystems in the world including Nepal. Augmentative release of host-specific, leaf feeding beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) is one of the sustainable management approaches of parthenium weed. Successful mass rearing program requires knowledge on biology of Z. bicolorata for augmentative release. Thus, life cycle and biology of Z. bicolorata were studied in lab at 26±2 °C temperature and 70±10% relative humidity at NARC, Lalitpur, Nepal during March to September, 2016. The average incubation, larval and pupal periods of the insect were 4.33, 12.20, and 11.00 days, respectively. A single female could lay 1,837 eggs in 58.80 days oviposition period with 73.01% egg hatchability. The insect completed its life cycle in 108.40 and 105.50 days with adult longevity of 91.90 and 75.00 days for females and males, respectively. The average length of egg, pupa, adult female and male was 1.19 mm, 5.90 mm, 6.58 mm and 5.32 mm and breadth 0.51 mm, 3.74 mm, 3.94 mm and 3.20 mm, respectively. The average lengths of the first, second, third and fourth instar larvae were found 1.30 mm, 3.02 mm, 4.96 mm and 8.08 mm and breadth of 0.44 mm, 1.13 mm, 2.02 mm and 3.16 mm, respectively. These findings will help in mass multiplication of Z. bicolorata for biological control of parthenium weed.
Soybean (Glycine max L. Merril) is widely grown in the mid hills as intercrop with maize or in paddy bunds, while it is gaining popularity as sole crop in terai and inner terai. Mean temperature at Khumaltar during soybean growing period was mostly fluctuating; but we observed an increasing trend in temperature. Amount of rainfall was not changed dramatically but number of rainy days was decreased during study period. Rainfall during germination time increase soil moisture which also increase germination and found higher early stand. Days from sowing to 50% flowering and 90% maturity were short in the case of higher minimum temperature and low rainfall. Among the genotypes, AGS-377, AGS-378, AGS-379 and Tarkari Bhattmas-1 were more sensitive. However, seed yield decreased in the case of higher temperatures and low rainfall. Cool night temperatures and high moisture increased disease incidence in soybean which, eventually reduced yield. In last three years, plant suffered from moisture stress during early vegetative stage and high moisture during late vegetative stage which reduced seed yield and seed weight. In conclusion, we found that genotypes like AGS- 360, Sathiya and Tarkari Bhatmas-1 are very sensitive to climatic variation.
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