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A study was conducted in the East African countries of Kenya, Tanzania and Uganda in the months of July and August 2009 with the objectives of assessing the status of black rot and race structure of Xanthomonas campestris pv . campestris in the three countries. Samples infected with black rot were collected from farmers' fields mainly from Brassica oleracea crops (broccoli, cabbage, cauliflower and kales). A total of 399 farms were surveyed of which 260 were from Kenya, 91 from Tanzania and 48 from Uganda. Following successful isolations, a total of 249 isolates of the causal agent, Xanthomonas campestris pv . campestris were recovered. Pathogenicity of all isolates was confirmed on B. oleracea susceptible cultivars Copenhagen Market F1 and Wirosa F1. Sixty of the 250 isolates were race-typed using a differential set Brassica spp. Only two races, 1 (Kenya and Tanzania) and 4 (Kenya, Tanzania and Uganda) were observed however, another race (5) was observed from one isolate recovered from a B. rapa sample obtained from Tanzania in 2003. Genomic fingerprinting with repetitive-PCR revealed clusters that did not depict significant correlations between isolates and geographical location, isolates and host adaptation or isolates and race. However, it did demonstrate existence of genetic differences within the East African X. campestris pv. campestris population indicating that it is not a similar clonal population of the same genetic background. [ABSTRACT FROM AUTHOR]

Low rainfall has been blamed for the recent crop failure in Kongwa district, within Tanzania’s Central Zone, when 310 out of a total of 331.2 mm of rainfall were concentrated into the first 4 months (November to February) of the 2008-09 cropping season. In May 2009, farmers in this district, expected yields from early maturing (short/intermediate) varieties of sorghum, such as Macia and Pato that were late planted in January and February, to be less than 250 kg/ha. They complained that late delivery of seed of these varieties had led to the poor yields. Records kept by thirty seven subsistence farmers throughout the cropping season indicated that an average of 62 kg of sorghum grain of both early and late maturing varieties was harvested per household by June 2009. This is sufficient for just 14 day’s food supply for an average household comprising three adults, two adolescents (aged 10–18 years) and two children (aged less than 10 years). In addition, each household had accrued financial losses, averaging Tsh64, 527.65 (€33.79) from expenditure on wasted inputs. Furthermore, the high incidence of Covered Kernel Smut in sorghum fields suggested that farmers had been supplied with contaminated seed, while the limited availability of seed of the Striga-resistant sorghum varieties, Hakika and Wahi, had allowed this parasitic weed to flourish in their fields. It was estimated that these two pests could have caused sorghum losses in excess of 50%. Each household that was impoverished by this crop failure will have to raise an average of Tsh436, 070 (€228.36) to cover its grain deficit until June 2010. [ABSTRACT FROM AUTHOR]

White grubs are largely unsolved problems in vegetable and tuber production in East Africa. Novel Rwandan as well as international entomopathogenic nematodes (EPNs) were screened in nine laboratory bioassays and two small-scale field trials in 2014 and 2015. Soil-based laboratory bioassays revealed that all EPNs were able to infect Anomala graueri larvae (Coleoptera: Scarabeidae), although a relatively high number of infective juveniles were needed. Rwandan EPNs were as infectious as their corresponding international strains. At 100 infective juveniles per larva, the Heterorhabditis bacteriophora strains (Rwanda14-N-C4a and international H06) as well as the international Steinernema carpocapsae All caused 18 to 22% grub mortality within 7 days compared to the control. At 1000 infective juveniles, both H. bacteriophora strains as well as the Rwandan S. carpocapsae RW14-G-R3a-2 killed 34 up to 58%. The Rwandan Steinernema RW14-M-C2a-3 least performed in the bioassays (2 to 6%). In two Irish potato fields, the into-soil-applied 1 x 109 infective juvenile Steinernema RW14-M-C2b-1 per hectare reduced 29 ± 33% and 96 ± 3% of grubs within 30 and 60 days, respectively. About 1 up to 2.5 x 109 infective juvenile Steinernema longicaudum X7 per hectare reduced 77 up to 85% of grubs until day 30, respectively, and 82 up to 95% until day 60. Avermectin + Chlorpyrifos tuber coatings reduced 39% of grubs, and Fipronil + Chlorpyrifos reduced 27%, whereas handpicking did not help much. In conclusion, at least Steinernema RW14-M-C2b-1 and S. longicaudum X7 are promising for managing white grubs in tuber production, this is at a rate of at least 1.5 x 109 EPNs per hectare, but H. bacteriophora RW14-N-C4a needs further field research. Findings will support the biocontrol product development in Rwanda, including registration if any would be needed for native macrobial biocontrol agents. [ABSTRACT FROM AUTHOR]