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Mhlanga B.,University of Zimbabwe | Cheesman S.,CIMMYT Zimbabwe | Maasdorp B.,University of Zimbabwe | Muoni T.,University of Zimbabwe | And 3 more authors.
Crop Protection | Year: 2015

Weed management is a challenge to resource constrained smallholder agricultural production in sub Saharan Africa due to insufficient and inadequate management strategies. When weeds are controlled with herbicides or through rotations under conservation agriculture, shifts in weed spectra are expected, increasing the need to adapt to this new situation. Experiments were conducted at four experimental sites namely the University of Zimbabwe farm (UZ) (clay soil), Domboshava Training Centre (DTC) (sand soil) and two contrasting soil types at Henderson Research Station (HRS sand (s), HRS clay (c)) to investigate the responses of weed communities to crop rotations. The trial was carried out from the 2008-09 to the 2013-14 cropping season. Rotations consisted of maize (Zea mays L.) rotating with a range of green manures, and the control treatment was maize monocropping. Herbicides were only applied in the maize phase at seeding, supplemented by hand weeding whenever weeds were 10cm tall or 10cm in diameter for weeds with a stoloniferous growth habit. Weed count data was collected between 2011 and 2014. Weed density, the Shannon-Weiner index and its components were used to explain weed community responses to rotations. There was a decrease in weed densities over time at all sites with a percentage decrease as high as 92% (i.e. from 357 to 30 weedsm-2) observed in maize-velvet bean (Mucuna pruriens (L.) DC) rotation. At all sites, some maize-green manure rotations were associated with high weed densities and these included maize-black sunnhemp (Crotalaria juncea L.) and maize-cowpea (Vigna unguiculata Walp) rotations. The two weeds Galinsoga parviflora Cav. and Ricardia scabra L. remained abundant throughout the study at all sites with densities reaching above 1000plantsm-2 per season in some plots. Shannon's E' index was highest at HRSs and HRSc sites in the maize-velvet bean rotation and maize-common rattle pod (Crotalaria grahamiana Wight & Arn.) rotations respectively suggesting that in these treatments dominant weeds were reduced in numbers. This suggests that rotations with cover crops such as velvet bean may reduce weed numbers and dominance of problematic weeds over time. This can potentially lead to a less intense weeding schedule, which is more cost effective and affordable for smallholder farmers. © 2014 Elsevier Ltd.

Muoni T.,University of Zimbabwe | Rusinamhodzi L.,CIMMYT | Rugare J.T.,University of Zimbabwe | Mabasa S.,University of Zimbabwe | And 3 more authors.
Crop Protection | Year: 2014

Increased challenges of weed control in the smallholder farming sector of southern Africa have often resulted in small yields. The objective of this study was to evaluate the effects of different weed control strategies on weed flora and composition under conservation agriculture (CA) systems in Zimbabwe. This study was conducted at three on-station trial sites namely Domboshawa Training Centre (DTC), University of Zimbabwe farm (UZ farm) and Henderson Research Station (HRS) in a maize-soybean rotation for four seasons from 2009-2010 to 2012-2013 seasons. Hand weeding was done whenever weeds were 10 cm tall or 10 cm in circumference for weeds with a stoloniferous growth habit. Weed identification was done up to the weed species level, and the Shannon-Weiner diversity and evenness index was used to determine the response of weed flora to herbicides. Results showed that there were more weeds in the early years which decreased gradually until the final season. Weed species diversity was not affected by herbicide application and the results indicated that weed species diversity was small in CA systems. Annual weed species constituted a greater proportion of species, and species richness decreased with the duration of the study. Richardia scabra L. and Galinsoga parviflora Cav. were the most common dominant weed species at all sites and in all seasons. Moreover, herbicide application had no effect on the evenness of weeds in the plots but site characteristics had a significant effect on the distribution of weed species (weed species evenness). The results presented in this study suggest that herbicide application facilitates a depletion of weed seed bank/number of weeds over time. Thus, herbicide application in CA has potential to reduce weed density, species richness and species diversity in the long term which may lead to more labour savings and larger yields. © 2014 Elsevier Ltd.

Madzimure J.,Henderson Research Institute | Madzimure J.,University Of Fort Hare | Saina H.,Henderson Research Institute | Ngorora G.P.K.,University Of Fort Hare
Tropical Animal Health and Production | Year: 2011

The survey evaluated the market potential for guinea fowl (GF; Numidia meleagris) products in the city of Harare, Zimbabwe. Questionnaires were administered to traders/producers (n = 17), retailers (n = 12), cafeteria industry (n = 33) and consumers (n = 1,680) to establish their perceptions on guinea fowl products. The average household size was 6 ± 2. Each trader sold 10 ± 6.30 keets (mean ± standard error), 33 ± 15.05 growers, 20 ± 12.69 breeders and 20 ± 10.1 crates of 30 eggs per month. Each household consumed 2.5 ± 1.39 kg of GF meat and 3 ± 0.65 dozens of GF eggs per month. Retailers purchased 52 ± 44.42 crates of GF eggs and 41 ± 30.50/kg of GF meat whilst cafeteria purchased 33.6 ± 14 crates of GF eggs and 65.5 ± 33.52 kg of GF meat per month. Growers for breeding were the major product for sale by traders (94.1%) at a price of US$7.50 ± 1.74/bird. Different industries were offering different prices for guinea fowl products because of their scarcity on the market. The mean purchase price per crate of 30 guinea fowl eggs sold to the retail and cafeteria were US$3.00 ± 0.58 and US$4.50 ± 0.50, respectively. The mean purchase prices for GF meat was lower (P < 0.05) for retailers (US$2.5 ± 0.81/kg) than cafeteria (US$3.67 ± 0.83/kg). The challenges faced by producers in the marketing of guinea fowl products included poor supply due to the absence of good road networks to connect source areas and the market, perishability of dressed chickens due to power cuts and poor publicity. Overall, the study showed that there is greater market potential for guinea fowl products and farmers can channel their products through traders, cafeteria and retail industries. © 2011 Springer Science+Business Media B.V.

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