Paraná extends the phytosanitary emergency to combat greening for another 180 days

The Government of the State of Paraná extended, through Decree 6.356/2024, the phytosanitary emergency to combat greening for another 180 days. The measure aims for greater mobility and the possibility of acting quickly and effectively to control the disease, which is considered one of the main pests affecting citrus trees in the world. 

Since the most effective actions in the field of greening or HLB (huanglongbing) and its main vector, the psyllid insect diaphorina citri started around two years ago, almost 280 thousand citrus and ornamental plants, such as myrtle, were eradicated in the Northwest and North regions of the State.

The eradication of diseased plants, the planting of healthy seedlings from registered nurseries and the efficient control of the insect vector with biological and chemical products are some of the good practices recommended in the face of this disease.

The actions are carried out by the Government, through the State Secretariat for Agriculture and Supply (Seab), the Paraná Agricultural Defense Agency (Adapar) and the Paraná Rural Development Institute (IDR-Paraná), together with citrus producers, industrial sector, agricultural research companies, cooperatives and city halls in producing regions.

“The phytosanitary emergency decree is a strong instrument, but necessary and desired by the entire citrus growing chain with a view to enabling effective measures in an attempt to control the problem and ensuring that citrus growing continues to be an important activity both from an economic and economic point of view. social situation in the State of Paraná”, said the Secretary of State for Agriculture and Supply, Natalino Avance de Souza.

A review of the actions was presented last week during a meeting of the Citriculture Technical Chamber, in Paranavaí, which was attended by around 120 people, including mayors or their representatives. “What we seek is to reinforce the involvement of technicians from public and private companies and at the same time ensure that political action supports and strengthens the work that is being carried out”, said citrus grower and agronomist Marlene Calzavara.

According to her, a working group has been set up since 2007 to deal with greening, which had recently been detected in Brazil. With the resurgence of the disease from 2022 onwards, the discussion was accentuated and the group became the Technical Chamber of Citrus in 2023, with an increase in participants. “Before the contamination rate was 1%, which is acceptable, but suddenly it rose to 10% and in some cases even 20% of the property”, she highlighted.

Big citrus  

One of the main activities that gave shape to the actions developed so far was Operation BIG Citros, in August last year. It involved raising awareness, monitoring and reinforcing greening prevention and control measures, which continue to be carried out until now.

The operation had the support of 40 employees in 24 municipalities in the centers of Apucarana, Cornélio Procópio, Ivaiporã, Londrina, Maringá, Paranavaí and Umuarama. According to the head of Adapar's Fruit Health Division, Paulo Marques, since then, 409 inspections have been carried out on properties with commercial citrus production, 376 in non-commercial areas and two in clandestine nurseries.

More than 200 notifications were issued to eradicate symptomatic plants or present a management plan to control HLB and the vector. 20 infraction notices were also issued. “It is important to reinforce that the private sector has contributed integrally and continuously to the success of the public sector’s actions,” stated Marques.

He also highlighted the work being carried out to curb the irregular trade in citrus seedlings, one of the ways pests spread. “This trade encourages the establishment of orchards without adequate technical monitoring, which is a risk for the entire activity”, he considered.

Disease 

Greening is an important pest due to its severity, rapid spread and control difficulties. In Brazil, the bacterium Candidatus Liberibacter asiaticus (CLas) is the main causal agent. The disease affects plants of practically all citrus species, in addition to myrtle (Murraya paniculata), Fortunella spp. And poncirus spp., and is transmitted by the Asian citrus psyllid Diaphorina citri Kuwayama.

HLB seriously affects citrus plants, mainly due to premature fruit drop, which results in reduced production and can lead to early death. Furthermore, the fruits become smaller, deformed, and may have aborted seeds, reduced sugars and high acidity, which depreciates their flavor, reducing quality and commercial value, both for fresh consumption and for industrial processing.

According to the head of Adapar's Plant Health Department, Renato Rezende Young Blood, greening is a disease that comes from outside to inside the orchards, reaching more intensely in the first 50 meters. “Small properties are more affected because they have more borders proportional to their areas than large ones,” he said. “Hence the importance of having good control work on the borders, which is where Adapar acts most effectively”.

Biological control 

In addition to prohibiting seedlings from irregular nurseries, the use of windbreaks, planting density, fertilization, quality irrigation and vegetation cover are also good allies for the rapid development of the plant, reducing exposure to the insect, as transmission is more common in shoots than in adult leaves.

Psyllid control can also be done with tamarixia radiata, a parasitoid wasp created in laboratories, including that of IDR-Paraná, to be the insect's biological enemy. Since 2016, more than 10 million wasps have been released in Paraná in areas bordering commercial properties in approximately 60 municipalities.

In the field, they look for the nests of diaphorina citri to reproduce. They lay their eggs under the nymphs (young form), which will serve as food for the larvae. Each wasp can eliminate up to 500 psyllids, reducing the number of vectors and the incidence of the disease.