MSUIR Collection:

The effect of fever tea tree (lippia javanica) in the control of maize weevil (sitophilus zeamais) in stored maize (zea mays)

Majoro, Mordester — Fri, 01 Jan 2016 00:00:00 GMT

Title: The effect of fever tea tree (lippia javanica) in the control of maize weevil (sitophilus zeamais) in stored maize (zea mays) Authors: Majoro, Mordester Abstract: Sitophilus zeamais Motschulsky is the major insect pest seen damaging stored maize in Zimbabwe. The environmental hazards of synthetic insecticides, the unreliability supply and high costs of these chemicals resulted in the search for cheaper and safer use of the naturally available plant material to control this pest. This study evaluates effective rates for L. javanica leaf powder. Bioactivity of Lippia javanica leaf extracts was evaluated under average room temperature, at three dosage levels (0. 5g, 10g and 15g),negative control of untreated grain were mixed with 1kg of disinfested Pannar 413 maize variety in plastic containers. A positive control of Actellic Gold Dust was also used at label rates and the effect on grain damage, weight loss, insect mortality; progeny production was assessed. The leaf extract showed significant difference between 0.5g and 10g on one hand and 15g and the positive control showed no statistical difference. The 15g that recorded the highest mortality inflicted 85.25%. The maize grain treated with 10g and 15g dosage levels of the leaf extract showed much promise by significantly reducing the number of damaged grains by the maize weevil, reproduction of the maize weevilas well as reducing weight loss in stored maize compared with the negative control. Grain weight loss in leaf powder treated grains was dose dependent ranging from 4% in the highest dose to 44.6% with untreated grain at 59% in untreated maize grain showing significant differences in 21 days

Performance of exotic summer wheat (Triticum aestivum) varieties under wetland conditions

Ivy, Takawira — Fri, 01 Jan 2016 00:00:00 GMT

Title: Performance of exotic summer wheat (Triticum aestivum) varieties under wetland conditions Authors: Ivy, Takawira Abstract: Wheat is the second most important staple food crop in Zimbabwe after maize. However, because of lack of irrigation infrastructure and high cost of production the country is not meeting national demand and is relying on imports thereby losing a lot of foreign currency. Currently winter irrigated wheat production constitutes more than 90% of the local production. The country’s water reserves are also drying up due to low rainfall being received, meaning we cannot increase irrigated area. There is therefore need to explore other ways of increasing wheat production in the country that do not rely on irrigation. Summer wheat had been hindered by lack of suitable varieties with only one commercial variety SC Sahai on the market. With current short rainfall seasons being experienced there is a need to evaluate the performance of the summer wheat varieties under wetlands were they benefit from residual moisture. Agronomic and quality attributes of four summer wheat varieties developed by CIMMYT and are currently cultivated in Ethiopia plus one local check were evaluated under wetlands conditions in Mvuma district of Zimbabwe. The field experiment laid out in a RCBD replicated four times. Wheat varieties were evaluated for yield and its components, growth, quality and disease resistance. Exotic varieties performed significantly better (p < 0.05) than Sahai the local variety. Aguilal gave significantly (p < 0.05) the highest yield and test density and also had a high number of spikelets. The experiment showed that summer wheat can be grown successfully on wetlands giving better yield and quality and can be used to compliment winter wheat stocks.

Evaluating the effects of yeast isolates on the control of sore shin in tobacco (Nicotiana tabacum L.) seedlings

Timbe, Isaac Simbarashe — Mon, 01 Jan 2018 00:00:00 GMT

Title: Evaluating the effects of yeast isolates on the control of sore shin in tobacco (Nicotiana tabacum L.) seedlings Authors: Timbe, Isaac Simbarashe Abstract: Sore shin aused by Rhizoctonia solani is responsible for remarkable economic losses of up to 10% in tobacco (Nicotiana tabacum) seedlings grown in float beds, thereby becoming important production limiting factor of tobacco crop. Sore shin is responsible for wiry stem formation, stem lesions, root rots, root discolouration and damping off of tobacco seedlings. Tobacco production in Zimbabwe contributes about 9% GDP and is form of employment to more than 90 000 people in the country. Currently two fungicides Shavit and Azoxystrobin are being used for controlling sore shin on tobacco but recent trends are showing element of resistance with R. solani therefore becoming a threat. In a bid to circumvent the tobacco losses due to sore shin using eco-friendly methods the researcher hereby sought to evaluate five yeasts isolates for the control of sore shin in greenhouse produced tobacco seedlings. In this study five isolates were used which are TY5, TY3, TY14, TY17 and TY18, the experiment was arranged in a completely randomised design and two controls were included with the untreated as negative control and Azoxystrobin as positive control. R. solani were isolated from the diseased tobacco plants showing sore shin symptoms. The experiment was carried out at Kutsaga Research Station located in Harare Zimbabwe during the September –November 2016 tobacco nursery period. Data was analysed using Genstat 18th edition, on parameters measured the yeast isolates proved to reduce sore shin significantly in comparison with the untreated control but TY18 was similar to the untreated control. The isolates resulted in an increase in shoot fresh weight with the highest recorded on TY3 with an average of 3.76g per seedling, also yeast isolates resulted in an increase root fresh weight, highest weight was recorded on seedlings treated TY5 but TY18 was even less than the untreated control. Significant increase in dry weight was observed on plants treated with yeast isolates seedlings plots treated with TY3 recorded the highest dry weight with an average of 0.39g per seedling. It could be suggested that such yeast isolates might be the promising as alternatives for controlling sore shin on tobacco seedlings and have the ability to be used as bio-fertilisers

Evaluation of super absorbent polymer (hipro-aqua) on the growth, yield and quality of tobacco (Nicotiana tabacum L.) under various irrigation regimes

Chofamba, Anyway — Sun, 01 Jan 2017 00:00:00 GMT

Title: Evaluation of super absorbent polymer (hipro-aqua) on the growth, yield and quality of tobacco (Nicotiana tabacum L.) under various irrigation regimes Authors: Chofamba, Anyway Abstract: Drought is the most important limiting factor in the production of crops in agriculture; it is becoming an increasingly severe problem, sharpening its ends due to dynamic changes in climatic variables. Tobacco is one of the major cash crops that is being grown by many farmers, but its production potential is often constrained by the scarcity of water and poor productivity of sandy soil. In order to counteract the problem of water scarcity, the researcher hereby sought to investigate on the effects of a novel technology towards water conservation and potential production of tobacco in Zimbabwe. The addition of water-saving superabsorbent polymer (SAP) in soil can improve soil physical properties, crop growth and yield and reduce the irrigation requirement of plants. This experiment was conducted on a flue-cured tobacco variety ‘T75’ at Tobacco Research Board, Zimbabwe during the 2015-2016 season. The experimental design was a split-plot with two factors including four irrigation regime (providing 40%, 60%, 80% and 100% from consumptive (ET crop) of tobacco) as main plots and four levels of SAP (0, 75, 150 and 225 kg/ha) as subplots in a randomized complete block design with three replications. Irrigation level and SAP had significant effects on growth parameters of tobacco (leaf length and leaf width) of tobacco leaves, with the highest (77.19cm) leaf length at SAP rate of 150kg/ha under irrigation regime of 80% and the lowest (60.72cm) being at 0kg/ha SAP rate of under 40% irrigation regime. Also there was significant effect of the treatment application of different rates of SAP under different irrigation regimes on yield parameters (fresh and dry cured leaf yield), with the highest (2 017kg/ha) dry cured leaf yield of tobacco at SAP rate of 150kg/ha under 80% irrigation regime and the lowest (653kg/ha) dry cured leaf yield of tobacco at 225kg/ha under 40% irrigation regime. The quality of tobacco (% nicotine, % sugar content and grade index) was also influenced by the treatment applications of SAP rates under different irrigation regimes, with the highest (3.05%) nicotine content attained at an SAP rate of 150kg/ha under irrigation regime of 80%. The results indicate that 150 kg/ha of SAP under 80% irrigation regime produced the desirable outcomes on the growth, yield and quality of tobacco, signifying the importance and role of SAP in moisture retention and its positive contribution towards those parameters.