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8 results on '"Mazarura U"'

3. Screening of Tobacco Genotypes for Tolerance/Resistance to Striga gesnerioides infestation in Zimbabwe

Author

Garwe D, Banwa T, Koga C, Mazarura U, and Mabasa S

Subjects
0106 biological sciences, Resistance (ecology), biology, food and beverages, 04 agricultural and veterinary sciences, biology.organism_classification, medicine.disease_cause, 01 natural sciences, Horticulture, Striga, Germination, Striga gesnerioides, Infestation, Genotype, 040103 agronomy & agriculture, medicine, 0401 agriculture, forestry, and fisheries, Pharmacology (medical), Cultivar, Weed, 010606 plant biology & botany
Abstract

Witch weed (Striga gesnerioides) is a root parasitic weed of tobacco and cowpea in Sub- Saharan Africa. It is very difficult to control and host plant resistance is the most promising effective method affordable to small-scale farmers. This study was done to screen local tobacco genotypes for tolerance and resistance to Striga gesnerioides infection. Laboratory screening experiments were conducted during the 2016/17 season using fifteen local tobacco genotypes. The experiments were done using an Agar gel technique at the University of Zimbabwe, with treatments replicated four times in a Randomised Complete Block Design (RCBD). All tobacco genotypes significantly (p

Published
2018

6. First Reports of Tobacco Witch Weed (Striga gesnerioides) Parasitizing Dalbergia melanoxylon and Richardia scabra in Zimbabwe

Author

Garwe D, Mabasa S, Mazarura U, Rukuni D, and Koga C

Subjects
0106 biological sciences, medicine.disease_cause, 01 natural sciences, Striga, Trap crop, parasitic diseases, Infestation, medicine, Pharmacology (medical), Richardia scabra, biology, business.industry, fungi, food and beverages, 04 agricultural and veterinary sciences, Crop rotation, biology.organism_classification, Biotechnology, Agronomy, Dalbergia melanoxylon, Germination, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, business, Weed, 010606 plant biology & botany
Abstract

Striga infestation presents a major constraint to crop production in agricultural systems. The tobacco witch weed, Strigagesnerioides occurs widely in Africa and other parts of the world where it is known to parasitize mainly cowpea (Vignaunguiculata) and other dicotyledonous plants. In Zimbabwe, the parasitic weed was first confirmed in the Nyikavanhu area of Mvuma in the year 2007 and research was initiated to study this parasitic weed and recommend control strategies. A few more reports have been received of the parasitic weed infesting tobacco in other growing regions. However, despite having been reported widely on cowpea in other countries, S. gesnerioides has not been documented on this and related crops in Zimbabwe. Interestingly, in previous research conducted in Zimbabwe, it was established that cowpea induces suicidal germination of S. gesnerioides seeds but resulting in no further developmental stages such as haustorial attachment. This led to the conclusion that the species strain reported elsewhere on cowpea could be a different biotype from the one currently parasitizing tobacco in Zimbabwe. Thus it was felt that cowpea could then be used in tobacco crop rotations as a trap crop by inducing suicidal germination of parasite’s seed. This current work reports the occurrence of S. gesnerioides on other plants in addition to tobacco.

Published
2017

7. Effects of crude aqueous extracts of indigenous pesticidal plants on the ladybird beetle, <italic>Hippodamia variegata</italic> (Goeze) (Coleoptera: Coccinellidae).

Author

Mazhawidza, E., Mvumi, B. M., and Mazarura, U.

Subjects
PESTICIDAL plants, HIPPODAMIA (Ladybugs), PLANT extracts, PLANT species, DATURA stramonium
Abstract

Effects of pesticidal plant extracts on non-targeted species are rare. Direct topical and residual sprays of crude aqueous extracts of three pesticidal plants: Datura stramonium L. Bobgunnia madagascariensis Kirkbr. & Wiersema and Solanum delagoense L. were assessed in laboratory bioassays and on-station experiments against the ladybird beetle, Hippodamia variegata (Goeze). The plants are routinely used by smallholder vegetable farmers to control aphids, Brevicoryne brassicae L. attacking rape, Brassica napus L. The crude extracts of D. stramonium fresh leaves, S. delagoense fresh fruits and B. madagascariensis dried pods, were applied separately at 5, 10, 15, 20 and 25% w/v under laboratory conditions. Application rates of 20% and 25% w/v of the plant extracts were further evaluated on-station. Negative (tap water) and positive (dimethoate® (36% E.C)) controls were included for comparison. The mortality of H. variegata was recorded 24, 48 and 72 h post-exposure. In on-station experiments, treatments were applied fortnightly and live H. variegata adults were counted at 1, 7 and 14 days post-application. Mortality of H. variegata in laboratory bioassays increased with increase in post-exposure time and B. madagascariensis (25% w/v) caused the highest mortality. Based on LD50 values, B. madagascariensis extracts were most toxic (LD50, 30% w/v) followed by D. stramonium (LD50, 34% w/v) and S. delagoense (LD50, 49% w/v) 24 h post-application. In on-station experiments, the synthetic chemical significantly lowered (P < 0.05) H. variegata numbers compared to the negative control and plant extracts. The results showed that D. stramonium and S. delagoense extracts at the application rates used in the study were relatively safer to H. variegata than B. madagascariensis (25% w/v); hence, the former two plants can be included in integrated pest management programmes. [ABSTRACT FROM AUTHOR]

Published
2018
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