Pepper wilt disease intensity was assessed on-farm in Bako Tibbe and Nonno districts of West Shewa Zone, Ethiopia during the main cropping season of October 2012. The wilt causing pathogens were identified from 50 diseased samples collected from the two districts. Of the 120 hot pepper fields surveyed, 116 fields were found to be infected with wilt disease. The overall percent prevalence and incidence of wilt disease was 96.7 and 86.4%, respectively. Identification and pathogenicity tests revealed that Ralstonia solanacearum and four fungal wilt pathogens (Rhizoctonia solani, Fusarium spp., Phytophthora spp. and Verticillium spp.) were detected in the surveyed fields. The percentage of occurrence of Rhizoctonia solani, Fusarium spp., Phytophthora spp. and Verticillium spp. were 45.0, 17.48, 12.59 and 11.89%, respectively; whereas, the frequency of R. solanacearum was 100%. Wilt disease in pepper in these two districts was caused by more than one wilt causing pathogen, thus management strategies should focus on these complex pathogens.

Root-knot nematode disease caused by Meloidogyne incognita (Kofoid and White) Chit wood) is one of the major constraints for successful cultivation of tomato (Lycopersicon esculentum Mill.) in Ethiopia. Hence, the present study was conducted to evaluate the effect of leaf and seed extracts of four botanicals viz., Rape seed (Brassica napus L.), Lantana (Lantana camara L.), African marigold (Tagetes erecta L.) and Neem (Azadirachta indica L.) at 5% and 10% concentrations and T. harzianum at 5% plus control were tested on root-knot nematode under in vitro and also to evaluate their against root-knot nematode development and their role on plant growth parameters of tomato under in vivo condition. Plant extracts were more effective and significantly inhibited egg hatching and immobilizing the J 2 larval mortality of M. incognita than T. harzianum. Aqueous extract of all the tested plants inhibited egg hatching of nematode and resulted 84.67-100% mortality of the J 2 juveniles of M. incognita in vitro at the 10% concentration after 72 h of exposure time. There were no significant differences among the treatments of rape seed leaf (84.7%) at 10% concentration and Lantana camara (87%), African marigold (86.3%) and Neem leaf (85%) at 5% concentration after 72 h. Aqueous seed extracts of A. indica more significantly inhibited egg hatching and larva mortality of the J 2 of M. incognita in vitro at the 10% concentration and immobilized by 89, 93 and 100% after 24, 48 and 72 h of exposures, respectively, while at similar concentration of T. erecta, B. napus and L. camara leaf extracts exhibited 92, 89 and 93.2% inhibition of egg hatching and 75, 62.1 and 73% larval mortality, respectively. The effect of different botanicals and T. harzianum singly and in combination were studied for the management of tomato root-knot nematode under greenhouse condition. There was a significant difference in the reduction of root-knot nematode incidence, root-knot nematode population, nematode reproduction rate (NRR), number of galls and egg masses per plant were recorded. In pot culture condition, the application of leaf extract of individual plant in the presence of the nematode significantly enhanced the growth of tomato seedlings in comparison to the control. A significant increase in plant height, shoot weight and root weight of the seedlings were observed at the 10% concentration of leaf extracts in comparison to control. There was a significant difference in the reduction of root-knot nematode population, nematode reduction rate, number of galls and egg masses per plant of L. camara combined with T. harzianum. The mean fruit weight and total yield were observed highest in the combination treatment of L. camara combined with T. harzianum. This study results revealed that the test plants are readily available to farmers at no cost and able to reduce nematode population below economic threshold.

Root-knot nematode, Meloidogyne incognita (Kofoid and White) Chit wood) is one of the major constraints for the successful cultivation of tomato (Lycopersicon esculentum Mill.) in Ethiopia. Among different management strategies, biological control is important in the light of increased awareness of environmental and human health hazards. Therefore, the present study was conducted to evaluate the effect of different locally available botanicals and an antagonistic fungus, Trichoderma harzianum to control root-knot nematode attacking tomato under in vitro condition. Leaf and seed extracts of four botanicals viz., Rape seed (Brassica napus L.), Lantana (Lantana camara L.), African marigold (Tagetes erecta L.) and Neem (Azadirachta indica L.) at two different concentrations (5 ml and 10 ml) and Trichoderma harzianum (5 ml) were tested. Plant extracts were more effective and significantly inhibited egg hatching and immobilizing the J 2 larval mortality of M. incognita than T. harzianum. Aqueous extracts of all the botanicals inhibited egg hatching of nematode and resulted in 84.67 -100 % mortality of the second juveniles of M. incognita at the 10% concentration after 72 h of exposure time. Leaf extracts of T. erecta and A. indica exhibited 100% inhibition of egg hatch and larva mortality, while at similar concentration of B. napus and L. camara leaf extracts exhibited 92 and 93.2% inhibition of egg hatch and 62.1 and 73% larval mortality, respectively. Egg inhibition and larval mortality decreased with increase in the dilution (10 ml) of extracts. Juvenile mortality increased corresponding to an increased time of exposure. Aqueous seed extracts of A. indica more significantly inhibited egg hatching and larva mortality of the J 2 of M. incognita at 10% concentration and immobilized by 89, 93 and 100% after 24, 48 and 72 h of exposures, respectively, This study revealed that the test plants are readily available to farmers at no cost and able to reduce nematode population below economic threshold. There is a need for further studies in identifying new classes of bio-pesticides from natural plants to replace the synthetic chemicals used at present.

A number of studies have reported the presence of wheat septoria leaf blotch (Septoria tritici; SLB) disease in Ethiopia. However, the environmental factors associated with SLB disease, and areas under risk of SLB disease, have not been studied. Here, we tested the hypothesis that environmental variables can adequately explain observed SLB disease severity levels in West Shewa, central Ethiopia. Specifically, we identified 50 environmental variables and assessed their relationships with SLB disease severity. Geographically referenced disease severity data were obtained from the field, and linear regression and Boosted Regression Trees (BRT) modeling approaches were used for developing spatial models. Moderate-resolution imaging spectroradiometer (MODIS) derived vegetation indices and land surface temperature (LST) variables highly influenced SLB model predictions. Soil and topographic variables did not sufficiently explain observed SLB disease severity variation in this study. Our results show that wheat growing areas in central Ethiopia, including highly productive districts, are at risk of SLB disease. The study demonstrates the integration of field data with modeling approaches such as BRT for predicting the spatial patterns of severity of a pathogenic wheat disease in central Ethiopia. Our results can aid Ethiopia's wheat disease monitoring efforts, while our methods can be replicated for testing related hypotheses elsewhere.