Browsing by Author "Hakiza, J.J."

Now showing 1 - 4 of 4
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    Efficacy of different fungicide spray schedules for control of potato late blight in Southwestern Uganda
    (Crop protection, 2003) Kankwatsa, P.; Hakiza, J.J.; Olanya, M.; Kidenamariam, H.M.; Adipala, E.
    Potato cultivars grown in Uganda have low levels of general resistance to late blight. As such, most commercial potato farmers rely on fungicide applications for control of Phytophthora infestans, the causal agent of late blight. This study investigated the comparative advantages of using different frequencies of application of Ridomil (MZ 58), Ridomil once and Dithane M-45 (Mancozeb, 80% WP) subsequently, and Dithane M-45 for management of potato late blight. The highest marginal benefit was achieved by applying Ridomil once and Dithane M-45 subsequently at intervals of 14 and 21 days. The lowest marginal benefit was with sole Ridomil application at 21 day spray interval. With weekly sprays it was more economical to apply Dithane M-45 than Ridomil first followed by Dithane M-45 subsequently.
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    Fungicide application and host-resistance for potato late blight management: benefits assessment from on-farm studies in S.W. Uganda
    (Crop Protection, 2004) Namanda, S.; Olanya, O.M.; Adipala, E.; Hakiza, J.J.; El-Bedewy, R.; Baghsarif, A.S.; Ewell, P.
    Late blight caused by Phytophthora infestans, is one of the most significant constraints to potato production in Uganda and other regions of the world. Fungicides and host plant resistance are among the most efficient control options available to growers. Field trials were conducted in 1999 and 2000 in South-western Uganda to evaluate the cost effectiveness of fungicide application regimes on six potato varieties. A factorial experiment with five fungicide application intervals (weekly, fortnightly, IPM, no spray and farmers’ practice) and six potato varieties was established. Late blight infection was prevalent in both years, and a significant amount of disease was detected (P<0.05). Application of fungicide treatments considerably reduced late blight progress, with a corresponding increase in tuber yield. Based on monitoring of late blight disease occurrence and weather variables, two applications of the contact fungicide mancozeb on a moderately resistant variety was the most economical. Marginal rates of return and net benefits were significantly affected by fungicide applications. In the IPM treatment, late blight disease monitoring or scouting prior to first fungicide applications resulted in significant economic gains compared to scheduled applications of weekly and biweekly or no application (control) treatments.
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    Metalaxyl resistance, mating type and pathogenicity of Phytophthora infestans in Uganda
    (Crop Protection, 2001) Mukalazi, J.; Adipala, E.; Sengooba, T.; Hakiza, J.J.; Olanya, M.; Kidanemariam, H.M.
    A total of 81 isolates of Phytophthora infestans (Mont.) de Bary were recovered from late blight infected samples collected from different areas of Uganda in 1998/1999. They were analyzed for their resistance to metalaxyl fungicide, mating types, and cross infection between potato and tomato hosts. Sensitivity to metalaxyl was determined by growing isolates on 10% V8 medium amended with 0, 5 and 100μg/ml metalaxyl. Overall 44.4% of the isolates tested were resistant to metalaxyl, 23.5% were intermediate and 31.2% were sensitive. Mating type was determined on 80 isolates using an A1 (1724) isolate and by growing the same isolates in pure culture (selfing). Fifty percent of the isolates produced oospores by matings and selfings, 22.5% by mating only and 10% by selfing only; 18% did not produce oospores in the two tests. Twenty seven of the P. infestans isolates from potato-infected tomato. The majority of these isolates were highly resistant to metalaxyl and produced oospores by either mating or selfing or both.
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    Potato Production in the Tropical Highlands: Constraints, Fungicide Use and The Impact of IPM Strategies
    (Outlooks on Pest Management, 2004) Olanya, O.M.; Hakiza, J.J.; Crissman, C.C.
    Potato (Solanum tuberosum) is an important cash and food crop in various tropical highlands of Africa, Asia and Latin America. Potato production in the tropical regions of the world is quite diverse involving ecological, cultural and economic considerations. The total production in the tropics is estimated at about 100 million metric tons and per capita consumption is about 20 kg/per person per year. In the tropical highland regions, ambient temperature conditions during the cropping season range from 14 to 25 C. The rainfall received during the cropping seasons is often adequate (> 1,200 mm/annum). Potato production (total acreage & yield) and consumption is increasing in the tropical highlands. The majority of potato production in the tropical regions of the world is however, found in the IndoGangetic plains and southern China where growing conditions, IPM techniques and other practices are very different from the tropical highlands of Africa and Latin America.