Corn stunt spiroplasma

Taxonomy and pathogen nature: Spiroplasma kunkelii is a specialized species of wall-less bacteria within the class Mollicutes and the family Spiroplasmataceae. These organisms are known for their helical morphology and motility, functioning as obligate pathogens in both plant phloem tissues and their insect vectors.

Diseases and host crops: This pathogen is the primary cause of corn stunt disease, a significant phytopathological threat. The disease specifically targets maize crops, causing severe physiological disturbances that hinder the plant's ability to develop normal vegetative structures and reproductive organs.

Biology and life cycle: The lifecycle of Spiroplasma kunkelii is inextricably linked to the leafhopper Dalbulus maidis. When the insect feeds on an infected plant, it ingests the bacteria, which then colonize the insect's gut and salivary glands. The bacteria are subsequently transmitted to healthy maize plants during the leafhopper's feeding process.

Environmental conditions and impact: The spread of this pathogen is favored by warm climates where the insect vector thrives. The impact on crop production is devastating; infected plants exhibit stunted internodes, reddening or yellowing leaves, and significant yield reduction due to ear malformation or total lack of grain, potentially leading to total crop failure.

Control and management measures: Effective management of corn stunt requires an integrated approach to minimize the interaction between the vector and the host plant:

• Deployment of resistant maize hybrids adapted to the specific region.
• Implementation of host-free periods to break the cycle of the vector and pathogen.
• Elimination of volunteer maize plants and alternative weed hosts.
• Application of systematic insecticides to manage Dalbulus maidis populations during the early stages of crop growth.