Impact of crop rotation and fertlilizers (chemical, organic and bio) on diseases and yield of maize (Zea mays) in Far North Cameroon

Many fertilizers are used in the Far North of Cameroon for maize production. The aim of this work was to reveal diseases and yield performance of maize in response to different fertilizers during two years (2018 and 2019). CMS 9015 maize variety was used. Three sites were selected. In the site of Kongola (crop rotation), the experimental design was in completely randomized blocks consisting of four treatments: Control (To); Bio fertilizer (Myc); mineral fertilizer (EM); organic fertilizer (EO) with three replications.Two other sites were used and where fertilizers have been used for more than 5 years. At the Meskine site, the fertilizer used was mineral (Urea 46% and NPK 23-10-5) and in Pitoaré, organic manure (cow dung, chicken dropping) was used as fertilizer. Mycorrhizae used were Glomus sp and Gigaspora sp. Several diseases were identified. Fungal diseases such as the leaf gray spot (Cercospora zeae), corn leaf blight (Helmintosporum turcicum) and physoderma brown sport (Physoderma maydis) were observed during the two years in the organic manure plots in Pitoare site. One viral disease, maize streak, was observed in all plots with higher incidence and severity during the two years (100 and 50 respectively).The gray spot was not influenced the yield, whereas maize streak caused adecrease of yield when the infection attack was early.Corn leaf blight and physoderma brown spot were fungal diseases with highest incidence (more than 70%) during the two seasons. The highest yield was obtained in EO treatment (9.3 t/ha) at Pitoare in 2019 growing season and the lowest was obtained in the mycorhizal plot (1.05 tonnes/ha) in 2018. Fetilizers reduce development of maize diseases when there are used in rotational cropping system than in a continuous system than in continuous system. Keywords: Zea mays, fertilizers, diseases, rotation, incidence, severity, yield.