Greening grows for the fourth consecutive year and warns of the need to tighten control actions

The annual greening survey carried out by the Citrus Defense Fund - Fundecitrus shows that the disease is present in 22,37% of orange trees in the citrus belt of São Paulo and Triângulo/Southwest Mineiro, the main orange producing region in the world, which is equivalent to more than 43 million diseased trees out of a total of 194 million plants.

Compared to last year, the incidence increased by 7,2%, and this is already the fourth consecutive jump in the disease (2018: 18,15%; 2019: 19,02%; 2020: 20,87%), considered the most destructive effect on the world's citrus industry due to the serious damage caused to production and because there is no cure for the contaminated plants. 

Given this scenario, the general manager of Fundecitrus, Juliano Ayres, assesses that the need to act against the growth trend is urgent.

“We have reached a critical level, as the advance of greening has the potential to make not only isolated commercial orchards unviable, but even entire regions. And, considering that insufficient control on a farm affects all surrounding citrus properties, the situation requires sector awareness and the adoption of rigorous internal and external management actions”, he states. “The speed with which the disease increases or decreases is proportional to the adherence of citrus growers”, he highlights.

The survey also reveals a 50% increase in greening in young orchards (up to five years old), accumulating an incidence of 10,21%, which reflects greater control difficulties at this stage, when plants are more susceptible to the disease. Another relevant fact is the 10% growth of the disease in large properties, which represent 65% of the entire cultivated area, reaching 15,4% in orchards with more than 100 thousand plants.

The analysis by Fundecitrus researcher Renato Bassanezi allows us to observe how greening can compromise the competitiveness of the citrus industry in São Paulo and Minas Gerais.

“The advancement of the disease leads to great losses, such as an increase in the rate of fruit drop and a decrease in production, which leads to a shorter productive longevity of the orchards. Furthermore, it worsens the quality of the fruit and increases the difficulty of controlling new plantings, affecting the renewal and expansion of orchards, which will cause citrus farming to migrate to other regions and states”, he assesses.

Climate and lax management are the main causes

The year 2020 saw a record population of the insect that transmits greening, the psyllid, due to a combination of factors. There was a high intensity of sprouting in an atypical period (April to June), when it is usually low and psyllid control is less frequent, which favored the population increase of the insect, which prefers sprouts to feed and reproduce. The drought that came in the second half of the year was not enough to reverse the situation, since the hot climate in most of the citrus belt was quite conducive to its reproduction and dispersion.

“Whenever there is an increase in the psyllid population, there is an increase in the incidence of the disease six to ten months later”, explains Bassanezi.

Another reason for the increase in the psyllid population and, consequently, greening is linked to the failure to eliminate diseased plants, especially in adult orchards, and the less rigorous control of the psyllid in these orchards – as these infected plants are a source of contamination, it is It is necessary to prevent the insect from reaching them, acquiring the bacteria and transmitting it to healthy plants.

“Failures in controlling the psyllid within properties worsen the situation, which includes the adoption of very long application intervals, inadequate coverage of plants due to poorly adjusted equipment and lack of product rotation, points that do not combat the insect effectively. and allow it to proliferate in the orchards”, points out Bassanezi.

Success story: greening decreases in the Matão region

Considering the producing regions that make up the citrus belt, the highest incidences of greening are in Limeira (61,75%), Brotas (50,4%), Porto Ferreira (37,84%) and Avaré, which had a large increase in compared to 2020 (from 16,77% to 29,41%). In Duartina, the incidence remains high (26,15%), but remains stable.

The lowest incidences are in Votuporanga (0,05%), Triângulo Mineiro (0,14%), São José do Rio Preto (5,32%), Itapetininga (despite accumulating 4,25%, the rate in 2020 was only 1,63%), Bebedouro (9,98%) and Altinópolis (12,59%).

The good news is that the disease has decreased again in Matão (from 14,47%, in 2020, to 9,77%).

“The control of greening in this region is the result of collective action, that is, the adoption, by the majority of citrus growers, of high rigor in controlling the psyllid within the orchards and actions also outside the farms, reducing inoculum sources and the insect population in areas with uncontrolled host plants [citrus and myrtle], which adds to the implementation of new orchards and the eradication of heavily affected areas”, describes the Fundecitrus researcher. “Our studies show the positive impact of adopting external control actions, with the potential to reduce the incidence of greening in a region by 2 to 3 percentage points, which is extremely significant”, he comments.

Greening arrived in Brazil in 2004 and, since then, a lot of knowledge has been generated to control the disease. The current incidence is the highest ever recorded, however, a projection by Fundecitrus indicates that it could be much higher, 95%, if no control measures had been adopted.

“Brazilian citrus farming has enough knowledge to reduce the disease, as the research carried out by Fundecitrus and partners managed to understand it in its various aspects, which led to the creation of an integrated management package that is efficient, but needs to be followed with care. rigor by most citrus growers to achieve success”, says the institution’s general manager, Juliano Ayres. “The drop in greening in a region of São Paulo with climate conditions extremely favorable to the disease proves this”, he explains.