High rate of elimination of diseased plants keeps HLB incidence stable

The incidence of HLB (greening), the main citrus disease, has remained stable over the last year, according to a survey carried out by Fundecitrus – Citrus Defense Fund in the orchards of the citrus park, which encompasses 349 municipalities in the states of São Paulo and Minas Gerais. . Samplings carried out in June indicate that the disease is present in 16,92% of orange trees (the study does not cover lemons, tangerines and abandoned orchards). The number is similar to last year's 17,89%, if you consider the survey's margin of error of one percentage point plus or minus.

This is the first year that the disease has been stable since the survey began in 2008. The reason is the high rate of elimination of diseased plants, both by citrus growers who are rigorously managing HLB and by the removal of orchards , which led to the shrinking of the citrus park in the last year.

According to Fundecitrus manager, Antonio Juliano Ayres, most citrus growers have already incorporated HLB management measures not only within their orchard, but outside the property as well. “Regional management has proven to be efficient in controlling the incidence of the disease in groups of producers who work together to combat the psyllid. Associated with the elimination of diseased plants, this action was decisive in reducing the growth of greening,” he says.

The work of producers to keep HLB under control in their orchards and in the neighborhood was contributed by the departure of many orchards, most of which had a high incidence of the disease. According to the Harvest Estimation Survey (PES), 21,3 thousand hectares of orange were eradicated between April 2015 and March 2016, of which 57% were from orchards over 10 years old. In return, 9,5 thousand hectares were planted with oranges during the period. “There was an elimination of old and sick orchards, which were no longer productive because of HLB, at the same time that healthy seedlings were planted, which meant that the disease remained at the same level”, says researcher Renato Beozzo Bassanezi.

The incidence of HLB corresponds to 32,5 million diseased trees in the field. Of these, 51% present more than a quarter of the crown with symptoms, which is already considered an advanced stage of the disease. “Although the incidence of HLB is stable, the severity has increased slightly. Last year, there were 15,4 million trees with severe symptoms and, currently, there are 16,6 million”, says Ayres.

The behavior of the disease was different depending on the region. It decreased in the South and North macro-regions, remained stable in the Northwest and increased in the Center and Southwest areas.

The South macro-region, where the regions of Limeira, Porto Ferreira and Casa Branca are located, continues to be the most affected, with 32,34% of infected plants, but it was the one that showed the biggest drop in incidence, with 10 percentage points less than in last year, when 42,5% of the plants in its orchards were identified as showing symptoms of the disease. The macro-region had 5.304 hectares of citrus trees uprooted last year and, in return, 4.429 hectares of new orchards were planted.

In the North macro-region (Triângulo Mineiro, Bebedouro and Altinópolis), the disease fell from 6,81% to 5,74% of plants. The Northwest macro-region (Votuporanga and São José do Rio Preto) has 2,29% of trees showing symptoms. Last year it was 2,23%.

The Southwest macro-region (Avaré and Itapetininga) showed the largest proportional increase in the disease, jumping from 4,72% to 6,38%. In the Centro macro-region (Matão, Brotas and Duartina), the incidence went from 23,57% of orange trees in 2015 to 26,97% in the 2016 survey.

More survey data can be accessed at the link: