The occurrence of a new disease in corn crops in Paraná is confirmed

The Agronomic Institute of Paraná (Iapar) confirmed the occurrence of bacterial streak in corn in crops in the North, Center-West and West regions of the State. Until now unknown in Brazil, the disease is caused by the bacteria Xanthomonas vasicola pv. vasculorum, and has the potential to reduce grain yield in highly susceptible corn hybrids by half, according to researcher Adriano de Paiva Custódio, from Iapar.

The occurrence was first detected in experimental areas of the Agricultural Research Center of the Consolata Agricultural Cooperative (Copacol), in the municipality of Cafelândia. “In 2016, we noticed plants with different lesions than we were used to, but it was not an obvious problem and we thought it was a secondary disease”, says agronomist Tiago Madalosso.

This harvest the problem presented itself with greater intensity. “We verified areas with high disease pressure, although without registering a significant compromise in productivity”, adds Madalosso.

After analyzing diseased plants sent to Iapar, the presence of the new disease in Paraná territory was confirmed and notified to the Ministry of Agriculture, Livestock and Supply (Mapa).

“In the laboratory, we carried out physiological, biochemical and molecular analyses, including gene sequencing, to avoid doubts about the identity of the pathogen”, explains researcher Rui Pereira Leite Jr., from Iapar, adding that the mere existence of symptoms in plants is not sufficient to characterize a given pathogen.

Bacterial streak in corn has already been recorded in the West region (municipalities of Cafelândia, Corbélia, Nova Aurora, Palotina, Santa Tereza do Oeste, Toledo and Ubiratã), Central-West (Campo Mourão and Floresta) and North (Londrina, Rolândia, Sertanópolis and Mandaguari).

RECORDS 

The first record of bacterial streak in corn crops occurred in 1949, in South Africa. After decades confined to the African continent, it was detected in the United States in 2016, where it is currently widespread in at least eight states. “In regions of Colorado, Kansas and Nebraska, the incidence level exceeded 90%, with severity reaching 50% of the leaf area”, points out Leite.

It was finally reported in Argentina in 2017, from where it arrived in Brazil, probably due to its proximity. Preliminary assessments found the disease in more than 30 hybrids cultivated in this second harvest, including transgenic ones. Popcorn corn is also susceptible.

DISSEMINATION AND CONTROL

Leite clarifies that the bacteria can spread in crops through rain, wind, irrigation water and equipment such as tractors, implements, harvesters and trucks. It can also survive from one crop to another in straw and crop residues, or even in other host, invasive or cultivated plants – species such as rice and oats are also susceptible to the disease. “The potential for dissemination through seeds is not yet fully understood,” he points out.

The use of suitable seeds and less susceptible cultivars, the disinfection of equipment, the adoption of crop rotation and the destruction of crop residues are the main control practices. Regarding chemical control, Leite points out that there are still no products tested to control the bacteria.

As an emergency action, the researchers defend investment in tests on the main corn cultivars currently available on the market, together with the evaluation of chemical products registered for the crop that may have bactericidal and bacteriostatic effects.

TECHNICAL MEETING 

Iapar, Mapa, Paraná Agricultural Defense Agency (Adapar) and Copacol invite leaders, researchers and technicians linked to the corn production chain to a technical meeting this Thursday (12), in Londrina. The objective of the meeting is to level information, discuss implications of the new disease for the production chain and outline strategies for prevention and control.

Participation is free, but you must confirm your presence by emailing vivos@iapar.br by Wednesday (11).

Service
Technical meeting – “Corn bacterial streak: a new disease in crops in Paraná”
Date: Thursday, July 12th
Time: 13 hours
Location: Iapar headquarters, in Londrina (Rodovia Celso Garcia Cid, km 375 – exit to Curitiba)
Program:
13 pm - Opening
14pm – Bacterial streak in corn crops in Western Paraná (Tiago Madalosso, Copacol
14:30 pm - Symptoms, epidemiology and potential for economic damage (Adriano de Paiva Custódio, Iapar)
15pm - The disease and characterization of the pathogen Xanthomonas vasicola pv. vasculorum (Rui Pereira Leite Jr., Iapar)
15:50 pm - Geographic distribution and measures for prevention and containment (Viviane Barbosa, Mapa; Juliano Galhardo, Adapar)
16:20 pm - Debate/Closing