Brown Spot and Stalk Rot Diseases of Maize (Zea Mays) and Susceptibility of Two Varieties to Physoderma Maydis in Far North Cameroon

Abstract

Corn (Zea mays L.) is one of the most widely grown cereals in the world. However, in Cameroon, particularly in the Far North Region, yields remain low because of diseases increasing due to farming practices and climate change. This work aimed to characterize Brown Spot and Stalk Rot of corn and evaluate the susceptibility of two maize varieties to Physoderma maydis in field conditions. Two maize varieties, CMS9015, and CMS8704 were evaluated in a randomized block design. Disease symptoms were observed and described using identification keys. Microscopic characteristics of pathogens were performed using a microscope. Incidence, severity, and areas under disease curve progress (AUIPC and AUSiPC) were calculated.  Brown spot occurred 3 or 4 weeks after sowing (WAS) at the growing stage in CMS8704 variety first, and stalk rot 7 WAS. Brown spot appeared in leaves and is characterized by oval yellowish spots in the leaf blade and brownish spots in the midrid. Stalk rot infects stem nodes and is characterized by brownish spots, leading to the broken stem. The incidence of brown spot increased with time and environmental conditions (rainfall). The highest incidence of Physoderma Brown Spot was recorded with CMS8704 variety 53.06 % against 51.72 % with CMS9015. Severity was respectively 54.40 % and 47.12 % with CMS8704 and CMS9015. The incidence and severity of stalk rot were almost identical in both varieties. AUIPC of PBS and PSR was higher in CMS9015 than in CMS 8704, 63 DAS. PBS and PSR infect maize production, and both varieties are susceptible to P. maydis.