Ocorrência de epidemia do mal das folhas em regiões de "escape" do Brasil

Abstract

In January and February 2013 occurred a SouthAmerican leaf blight epidemic in regions considered as escape zones, causing concern to rubber tree growers and throughout the rubber industry. A possible adaptation of the fungus to escape zones was raised and the consistency of disease control by the use of the binomial: plants with uniform renewal of leaves + dry season, typical of the escape zones, was questioned. The aim of this work was to bring relevant information to the rubber growers about the interaction climate-pathogen-host and to compare normal climate (historical average) and climatic data of the occurrence period of epidemic (January and February 2013). We conclude that was not the pathogen that has adapted to rubber tree in drier conditions, typical in escape regions, but a more humid climate occurred in these drier regions during this period.KEYWOrDs: rubber tree; climate; Microcyclus ulei. rEsumO:Entre janeiro e fevereiro de 2013 ocorreu uma epidemia de mal das folhas em regiões consideradas como de "escape" à doença, causando preocupações e indagações nos produtores de borracha e ao setor heveícola como um todo. Uma possível adaptação do fungo a essas zonas foi levantada e a consistência do controle da doença pela utilização do binômio plantas com troca uniforme das folhas + período seco, típicos de regiões de "escape", foi questionada. O objetivo deste trabalho foi trazer informações importantes aos heveicultores sobre a interação clima-patógeno-hospedeiro e comparar variáveis de normais climatológicas (média histórica) e dados climáticos deste período de ocorrência da epidemia (janeiro e fevereiro de 2013). Concluiu-se que não foi o patógeno que se adaptou às plantas de seringueira em clima mais seco, nas regiões de "escape", mas que o clima mais úmido ocorreu nessas regiões mais secas, nesse período.

Global Assessment of Climate-Driven Susceptibility to South American Leaf Blight of Rubber Using Emerging Hot Spot Analysis and Gridded Historical Daily Data

“…Therefore, temperature turns to a superfluous criterion. There are precedents for the temporary loss of immunity to SALB in some established Brazilian 'escape zones' due to unusually humid weather conditions [21], but cases relating to temperature anomalies have not been reported.…”

“…In the 1970s and 1980s, a series of programs encouraging natural rubber production (Programa de Incentivo à Produção de Borracha Vegetal-PROBOR) was conducted by the Brazilian government to increase national self-sufficiency, and although not successful, revealed that rubber trees could be grown in some areas of Brazil (mainly in some parts of São Paulo State) without being affected by SALB [21]. These "escape zones" are colder and experience an annual dry period that coincides with the refoliation period of the rubber trees [22].…”

Epidemiology and Management of South American Leaf Blight on Rubber in Brazil

“…Climatologically, SACZ system is responsible for the considerable amount of summer rainfall among the Central-West, Southeast, and part of North and Northeast regions, causing humidity accumulation during the summer, which must have favored such leaf blight epidemics at the beginning of the year in São Paulo, Mato Grosso do Sul, Mato Grosso, and Goiás States. On the other hand, the absence of this system causes drastic reduction in rainfall in these regions, consequently leading to losses in agricultural production and risk of water and energy rationing [13].…”

“…As SACZ phenomenon is common in Brazil, new leaf blight epidemics are expected when a highly humid period coincides with the presence of new leaves in the rubber tree, since the pathogen is common, at low intensity, even in "scape" zones. The use of productive clones resistant to leaf blight is welcome, even for "scape" zones [13].…”

Performance of Hevea brasiliensis under drought conditions on osmoregulation and antioxidant activity through evaluation of vacuolar invertase and reducing sugars

“…Rubber trees are cultivated in the southeastern and centralwestern regions of Brazil to attend to high commercial demands for natural rubber, but also to escape from the fungal disease known as South American leaf blight caused by Microcyclus ulei (Henn.) Arx, which attacks plants in the Amazon region (6). One of the problems linked to the cultivation of H. brasiliensis (7,8) in these new areas (known as escape zones from the leaf fungus), however, is the presence of regions with warm frontand/or irregular rainfall regimes that impose water stress conditions (5).…”