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Katia Viana Xavier

Specialist

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Katia Viana Xavier

Orcid ID0000-0002-2856-1075

Specialist

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Publications

thumbnail for publication: Tar Spot of Maize in Florida

Tar Spot of Maize in Florida

Larissa Carvalho Ferreira, Vitor Augusto Silva de Moura, Marcio F. R. Resende, and Katia Viana Xavier

Tar spot, a fungal foliar disease, affects most maize types commonly grown in Florida, such as sweet corn, field corn, and criollo corn. This disease is characterized by brown-to-black, raised structures called stromata, which are embedded in leaf tissue. As a polycyclic disease, tar spot lesions can increase in number as the disease progresses throughout the growing season, leading to reduction of photosynthetic area on the leaves. Tar spot has recently emerged as a significant threat in Florida and in the United States, with reports of up to 100% incidence in maize fields in south Florida. Tar spot occurrence and development in Florida is influenced by several factors, such as environmental conditions, maize types, crop maintenance, and corn growth stages. The purpose of this publication is to promote awareness among Florida growers regarding this newly identified disease and its management practices.

thumbnail for publication: The Emergence of Fusarium oxysporum f. sp. apii Race 4 Causing Fusarium Wilt on Celery in South Florida

The Emergence of Fusarium oxysporum f. sp. apii Race 4 Causing Fusarium Wilt on Celery in South Florida

Larissa Carvalho Ferreira, Anna Mészáros, and Katia Viana Xavier

Celery (Apium graveolens L.) production in south Florida spans approximately 1,500 acres yearly. Fusarium wilt, caused by Fusarium oxysporum f. sp. apii (Foa) race 4, emerged as a significant threat to celery production in the Everglades Agricultural Area (EAA) in Florida in 2022. Since it was first reported in the United States in Michigan in 1914, Foa has evolved into four different pathogenic races. In 2013, race 4 was first reported in California, ?and since then, it has been causing substantial losses to celery growers. The first occurrence in south Florida is critically alarming because (1) race 4 is the most virulent among the four races, (2) there is a lack of effective chemical and varietal control options for EAA Florida growers, and (3) this pathogen can survive in the soil for many years. This publication provides novel information to growers, Extension agents, and crop consultants of the celery industry in Florida regarding disease identification and management. 

thumbnail for publication: Identification and Management of Foliar Diseases Associated with Sweet Corn in Florida

Identification and Management of Foliar Diseases Associated with Sweet Corn in Florida

Vitor Silva de Moura, Anna Mészáros, Nicholas S. Dufault, Marcio F. R. Resende, yKatia Viana Xavier

Sweet corn is a high-value crop for the fresh market. This publication is intended for Florida sweet corn growers, crop consultants, and Extension professionals to support accurate identification and effective management of foliar diseases caused by fungal pathogens. These diseases consistently threaten market quality, requiring an integrated management approach. Host resistance involves selecting hybrids that resist the diseases most likely to occur in a given season. Cultural practices reduce inoculum and make conditions less favorable for disease. Fungicide applications use multi-site protectants and site-specific products. Fungicides are most effective before disease is observed, when timed to coincide with crop growth stages, and during periods of high disease risk. Pathogen pressure, corn susceptibility, and weather conditions vary across Florida’s production regions, so regular scouting, accurate disease identification, and timely decisions are essential.