Limited Persistence of Maize Bushy Stunt Phytoplasma and Survival of its Leafhopper Vector in Forage Grasses

Abstract

Maize bushy stunt, caused by phytoplasmas and transmitted by the corn leafhopper (Dalbulus maidis), is a major concern for maize production in Brazil, where it has led to significant yield losses. Although this pathosystem has been the focus of considerable research, important epidemiological gaps remain, particularly regarding inoculum and vector survival between crop seasons and the range of alternative hosts. In this study, we evaluated the survival of the maize bushy stunt phytoplasma and its vector in five widely cultivated forage grass cultivars. None of the tested grasses supported survival of D. maidis adults beyond three days. Phytoplasma was detected in all inoculated grasses 28 days after exposure, but persisted only until the second cutting, after which it was no longer detected. Furthermore, infected grasses did not serve as inoculum sources, as no phytoplasma transmission to maize occurred via D. maidis feeding. These results suggest that the forage grasses examined act as transient or dead-end hosts for maize bushy stunt phytoplasma under natural conditions, limiting their role in the disease epidemiology.