- Posted by Guilherme Bezzarro
Climate, leafhopper, diseases and cultural practices. All of this affected 1st crop corn in southern Brazil. According to estimates by the National Supply Company (CONAB), production in the region should drop by at least 8%. In the 2019/20 harvest, the three southern states harvested 10,249 million tons. This year, it should not exceed 9,408 million tons.
The surveys carried out in the most affected regions detected malformation of the ears, multi-ear, abnormal corn straw, necrosis at the base and along the ears, premature death of the ears and lower weight of grains. Many areas also experienced toppling and premature plant death.
Because of this scenario, producers in the region fear that they will not be able to honor contracts with trading companies and cooperatives simply because there is no corn available to be delivered. The international price of the commodity stimulated an increase in the planted area of the grain and a large part of the 2021 production was sold in advance due to the favorable exchange rate. Internally, the country is experiencing a shortage due to the huge volume exported last year.
Among the experts, there is a consensus that the problems stemmed from a combination of factors. In relation to the climate, drought in the winter, late frosts and excess of rain in the summer caused losses and favored the spread of pests and diseases, especially in the southwest of Paraná, west of Santa Catarina and, also, in much of Rio Grande do Sul .
The Influence of La Niña
“In 2020, Brazil was under the influence of the La Niña climate phenomenon, which cools the water of the Pacific Ocean and, among other consequences, interferes in the rain regime”, explains Desirée Brandt, meteorologist at Somar Meteorologia.
"This phenomenon usually causes drought in the South. Between August and November 2020, in the three states of the region, rainfall was 50% below the average for the period," says Desirée.
The drought delayed sowing and extended the planting window in some regions. The lack of rain also caused an increase in temperatures, favoring the multiplication of pests, such as spittlebug, a vector of three diseases that are harmful to corn crops: corn streak (virose rayado fine), pale stinking and red stinging. The last two are caused by microorganisms called molicutes.
The manifestation of the symptoms of the stunting complex occurred in different intensities. It was more severe in some areas of Santa Catarina (West, Midwest and Planalto Norte) and Paraná and milder in Rio Grande do Sul.
“As leafhoppers have a preference for young plants, as soon as maize germinates it is already attacked by the pest, which, if it carries the virus or molicutes, will transmit diseases”, says phytopathologist Ricardo Trezzi Casa, professor at the State University of Santa Catarina (UDESC).
In December, rain fell heavily in the south of the country, mainly in the central parts of Rio Grande do Sul and Santa Catarina. The hot and humid climate brought more problems for corn. The incidence of fungi and bacteria has increased, explains Casa. Fusariosis, anthracnose and diplodia spot were some of the diseases that emerged. As a consequence, there was also an increase in stalk, root and ear rot.
The researchers warn of the need to adopt good practices and monitoring, especially when production is intensified. Measures such as seed treatment, crop rotation and the choice of suitable materials facilitate the control of unwanted pests.
To avoid breakages in the next harvests, the following actions are
- Seed treatment;
- Crop rotation;
- Elimination and control of small and invasive plants that can harbor pests and diseases;
- Monitoring of pests and diseases, which allow control whenever necessary and at the right time;
- Use of pesticides registered for the crop, the pest and / or disease and in the doses indicated for each target, according to the guidelines contained in the package inserts;
- Choice of suitable cultivars for each region, considering the greater or lesser susceptibility to pests and diseases existing in that location;
- Use of adequate planting densities;
- Definition of the sowing window taking into account the Agricultural Zoning of Climate Risk;
- Balanced nutritional management.
- Creation of regional monitoring systems for pests and diseases;
“We need strategies to balance and produce with more sustainability”, says Ivan Cruz, a researcher at Embrapa Milho e Sorgo and a doctor in integrated pest management. “It is necessary to plan and think about the systems in an integrated way, considering all the crops planted throughout the year”, he completes.
* With information from CropLife Brasil
This text was automatcally translated from portuguese
By: Eliza Maliszewski | Agrolink