Department of Agriculture Production
https://hdl.handle.net/20.500.12504/192
2024-03-29T13:29:24ZDetermination of mealybug population density for transmission of pineapple mealybug wilt disease in Central Uganda
https://hdl.handle.net/20.500.12504/1611
Determination of mealybug population density for transmission of pineapple mealybug wilt disease in Central Uganda
Bosco, Bua; M. E., Mawa; J., Ayiga; A., Ocwa
Pineapple mealybug wilt disease (PMWD) is a complex and most destructive viral disease constraining pineapple production
world over. Pineapple mealybug wilt disease is transmitted by mealybugs (Dysmicoccus species). Currently, in Uganda, the
population of Dysmicoccus brevipes that can transmit PMWD is not known. Yet, closing this knowledge gap would provide a better
understanding of PMWD etiology and development of sound management strategies. Experiment was laid out in a completely
randomized design (CRD) with four replications in the screenhouse at the Faculty of Agriculture, Kyambogo University during
the period 2017 and 2018. Pineapple variety Smooth Cayenne was inoculated with fve levels of viruliferous mealybugs including
one (1), fve (5), ten (10), ffteen (15), and a control (uninoculated). Data collection commenced on symptoms appearance and
continued on a 15-day interval for a period of two months. Data were collected on the incidence and severity of PMWD. All the
data collected were analysed using Genstat computer programme. Results showed that the number of mealybugs signifcantly
(p < 0.05) afected the incidence and severity of PMWD during both trials. Although one viruliferous mealybug was able to
transmit PMWD virus, the efcacy of transmission was recorded with the highest number of mealybugs per plant. It was,
therefore, concluded that the higher the number of viruliferous mealybugs colonising a pineapple plant, the higher the incidence
and severity of PMWD. Te result of this study, therefore, adds to the pool of knowledge on the understanding the population
density of mealybugs transmitting PMWD as well as provide insights to improvement of mealybug vector monitoring as a key
component of integrated PMWD management.
2024-01-01T00:00:00ZGenetic diversity and resistance to cassava brown streak disease in central Uganda
https://hdl.handle.net/20.500.12504/1608
Genetic diversity and resistance to cassava brown streak disease in central Uganda
Sam, Ogwal
Cassava (Manihot esculenta Crantz), a common food security crop in many sub-Saharan African countries is being threatened by cassava brown streak disease (CBSD) which causes up to 100% yield loss in susceptible varieties. Cassava brown streak disease is caused by two distinct Ipomoviruses namely Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV Cassava brown streak disease causes symptoms characterised by chlorotic patches on leaves, dark brown "streaks" on stems, cracked constricted corky, yellow-brown necrotic root tubers of cassava. However, variability of symptoms exists within cassava genotypes and CBSV strains depending on the environmental conditions. Currently in central Uganda, there is limited information on CBSV genetic and symptom diversity, as well as sources of resistance to CBSV. Yet development of CBSD control strategies requires knowledge of CBSV genetic diversity, virus-host interaction and availability of resistant cassava germplasm to CBSD. The objective of this study was therefore to 1) assess genetic diversity and distribution of cassava brown streak disease causal viruses in central Uganda. 21 unravel the symptom diversity of CBSD causal viruses on selected cassava genotypes. 3) identify potential sources of resistance to cassava brown streak disease in central Uganda.
Symptomatic leaf samples collected from the four districts in central Uganda were used for total RNA extraction using CT AB protocol. The purified samples were subjected to PCR amplification of specific DNA sequence by in vitro DNA synthesis done as prescribed by
Mullis and Faloona (1988). PCR products were separated using electrophoresis and the sequencing of PCR products was done in Netherland at Macrogen laboratory and the sequenced products were edited using Edit Seq in DNA Star, aligned using clustal logarithm
MEGA 6 software and coat protein nucleotide sequence data analysed using AMOVA. The results revealed that there was variation in nucleotide sequence and the coat protein among and within CBSV strains with isolates clustering into two groups. Additionally, CBSV was the dominant strain, followed by UCBSV and last mixed infection among 18 out of 20 symptomatic leaves sampled. Symptoms diversity and sources of resistance were identified by inoculating disease free cassava grown in screen house with CBSV strains singly and in combinations using chip bud method of grafting. Symptom diversity was identified based on the dominant symptoms from symptoms appearance at 1 MAI to 3 MAI. For resistance, incidence and severity was assessed. Later severity scores were used to compute area under disease progress curve (AUDPC). Findings showed that there was significant difference (P<0.001) in reaction of cassava genotypes to CBSV viral strains. In addition, significant variety x viral strains interactions (P<0.001) was observed. The highest CBSD incidence and severity was recorded from Kwatampola and the lowest in NASE14. Overall, NASE 14 and NAROCASS were resistant while Aladu, NASE12, Njule, Bam_unanika and Bukalasa were moderately susceptible.
Symptom diversity and severity was scored visually from symptom appearance and continued at monthly intervals for three months using a scale of 1 - 5. Findings showed Variation in symptoms of CBSD existed on leaves and stems of cassava genotypes inoculated with CBSV, UCBSV and CBSV+UCBSV strains. Infact, the symptoms varied from chlorotic spots on leaf tips to mild chlorosis, mottling of secondary to primary veins and mild stem streaks. It was concluded that CBSV and UCBSV were dominant strains of CBSV.
Additionally genotype NASE 14 was most resistant to CBSD. Accordingly CBSD symptoms varied from chlorotic spots to mild stem streaks. This study has an implication on the management of CBSD in Uganda. However another study to assess the relationship of CBSV viral load, CBSD symptom severity and resistance of cassava genotypes needs to be conducted.
xv, 90 p. : ill. (some col.) ;
2019-11-01T00:00:00ZField efficacy and economic viability of entomopathogenic fungal products for managing the tomato leafminer (tuta absoluta) in Uganda
https://hdl.handle.net/20.500.12504/1209
Field efficacy and economic viability of entomopathogenic fungal products for managing the tomato leafminer (tuta absoluta) in Uganda
Kabaale, Fred Peter
Management of the invasive tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has primarily relied on increased application of hazardous synthetic chemical pesticides with limited success. The use of entomopathogens has been advanced among safer and more sustainable management options. The field efficacy of candidate fungal isolates, Metarhizium anisopliae ICIPE 20, M. anisopliae ICIPE 69 (Campaign®) and Dudu Acelamectin (positive check) was evaluated against T. absoluta on tomato through inundative application. Experiments with treatments laid in Randomised Complete Block Design and replicated thrice, were conducted during cropping seasons April – July, 2019 (first season) and December, 2019 – March, 2020 (second season) at Mukono Zonal Agricultural Research & Development Institute, Mukono district in Uganda. Tuta absoluta incidence, injury severity on leaves and fruits, fruit yield loss, and economic viability of test treatments were assessed. Results showed generally reduced injury severity and significantly lower fruit yield loss in treated plots compared to untreated plot in both seasons. Tomato fruit yield was higher in treated plots than the untreated plot. The marketable fruit yield gain for Dudu Acelamectin, M. anisopliae ICIPE 20 and M. anisopliae ICIPE 69 treatments was respectively 130.15, 72.14 and 55.3% during first season, and 41.21, 22.01 and 15.85% during second season. The three respective treatments had Benefit cost ratio (BCR) of 8.92, 4.31 and 3.43 during first season, and 6.30, 2.84 and 2.14 during second season. The treatments showed a degree of effectiveness and economic viability in controlling T. absoluta on tomato in the field. However, the efficacy of M. anisopliae ICIPE 20 and ICIPE 69 should be assessed further at different agro-ecological zones, dosages, formulations, large scale, and their compatibility with the pesticides commonly used in tomato production systems.
xii,92p.:ill (some col)
2022-03-01T00:00:00ZThe potential of ensiled browse/maize forage mixtures of calljandra, gljricidia and leucaena for dairy cattle feeding
https://hdl.handle.net/20.500.12504/1146
The potential of ensiled browse/maize forage mixtures of calljandra, gljricidia and leucaena for dairy cattle feeding
Kato, Habib
The potential of ensiled browse/maize fodder mixtures of Callianc/ra calothyrsus, Gliricidia sepium or Leucaena leucocephala for dairy cattle feeding was assessed in five experiments. Experiment 1 examined the fermentation characteristics, and the effect of fermentation on the chemical composition and rumen degradation of the browses and maize silage. Maize silage fermented best with higher (P $ 0.05) levels of lactic acid (4.98% DM) and lower (P $ 0.05) pH values compared to browse silages. The level of NH3-N (% Total N) was higher (P $ 0.05), in maize silage than in browse silages.
Degradation of dry matter, organic matter and nitrogen was highest with Gliricidia followed by maize, Leucaena and Calliandra was least degraded. Fermentation increased rumen microbial protein synthesis with Gliricidia, Leucaena and maize forage but not with Calliandra.
Experiment 2 assessed the fermentation characteristics, chemical composition and rumen degradation of ensiled browse/maize fodder mixtures in proportions of 0 to 50% browse (DM basis). Butyric acid and lactic acid levels and pH were low at all levels of browse addition. The levels of NH3-N were lower (P $ 0.05) with browse addition levels above 10% indicating less proteolysis with higher levels of browse addition. Maximum degradation of OM, OM and N occurred at 10 - 20% levels of browse addition. Estimated RMP synthesis consistently decreased with higher levels of Calliandra and Leucaena addition to the silage, but increased with higher levels of Gliricidia addition.
2005-03-01T00:00:00Z