Influence of Fertilizer Application, Maize Variety and Tillage System on the Incidence and Severity of Maize Streak Disease and Grain Yield

ABSTRACT Maize streak disease (MSD), one of the most destructive maize diseases causes an estimated yield loss of about 20 % in Ghana. A baseline survey was conducted from July to August, 2015 across three agro-ecological zones within the Volta Region to assess the level of MSD incidence and severity in the zones. In addition, field experiments were conducted at Nkwanta during the cropping seasons of 2015 to assess the effects of tillage practices, maize variety and fertilizer application on the incidence and severity of MSD.The split-split plot design with four replications was used, with tillage as the main plot, maize variety as the sub-plots and fertilizer application as the sub-sub plots. The MSD severity was assessed using 1-5 visual scale. The study revealed that soils across the Volta Region were low in major nutrients, especially nitrogen and phosphorus, but adequate in potassium. Mean MSD incidence as high as 84.5% was recorded in the region and varied among the agro-ecological zones. No relationship was detected among soil N, P and K contents and MSD prevalence in the region. Fertilizer application effectively reduced the MSD impact on growth and yield. Incidence and severity of MSD under no-tillage system was significantly lower than under conventional tillage. Plants on the plots with no added nutrients exhibited severe MSD symptoms, including stunted growth and reduced grain yield. However, MSD incidence and severity did not correlate significantly with the content of grain crude protein. The severity of MSD positively correlated with maize leaf N content, while increasing leaf K content resulted in reduced MSD severity. It can therefore be concluded that tillage and fertilizer application affect the severity of MSD in low nutrients soils.