Populations of Asian citrus psyllids in the Brazilian states of São Paulo and Minas Gerais have hit historically high levels, Fundecitrus recently reported. Fundecitrus described the development as “alarming” because the psyllids spread citrus greening disease.
Reversing the situation requires immediate and joint action among citrus growers in the same micro-region, Fundecitrus stated. It reported that in the first half of 2023, the traps counted by Fundecitrus captured 1.01 psyllids per trap, compared to 0.8 insects per trap in the first half of 2022. That’s an increase of 26.2%. “The problem is that last year’s population was already a record,” the association added.
“These are worrisome and dangerous numbers, but they are reversible,” said Fundecitrus General Manager Juliano Ayres. “The psyllid population directly impacts the incidence of greening. When one grows, after six to eight months the other grows, too. It is a directly proportional relationship.”
Several factors are responsible for the increase in the psyllid population, but the main ones are the non-rotation of insecticide modes of action — the repetitive use of pyrethroids and neonicotinoids on selected resistant psyllid populations — and the low frequency of application, especially in adult orchards.
“The lack of rotation of insecticide modes of action is bringing serious problems to citrus growing, selecting populations of resistant psyllids (that do not die when coming into contact with these products). And the inadequate frequency has allowed the psyllid to reproduce in the orchards,” said Ivaldo Sala, agronomist engineer at Fundecitrus.
The rotation of the modes of action is a basic premise in the management of pests and diseases of any crop. Where they are showing low efficiency, pyrethroids and neonicotinoids should be temporarily suppressed until these resistant populations are controlled by other products, Fundecitrus stated.
Fundecitrus researcher Renato Bassanezi said citrus growers should:
- Rotate the modes of action of insecticides
- Apply insecticides thoroughly, covering the entire plant
- Be rigorous in the frequency, so as not to allow reproduction of the psyllid in the orchards, preventing the insect from leaving the adult orchard and taking the disease to new orchards
- Monitor the shoots, so that the applications are directly related to them.
“The fundamental thing is that citrus growers do this together, all together, as regional management. Otherwise, the psyllid will migrate from one property to other properties,” Bassanezi emphasized. “It’s no use for one citrus grower to do it and another not to.”
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