Fundecitrus study indicates adequate protection for each stage of sprouting to combat greening

Fundecitrus carried out work to identify the ideal application interval on vegetative orange tree shoots, which are attractive to the psyllid, aiming to avoid new greening infections. To do this, the sprouts received fluorescent dye, which simulates the presence of insecticides, and were photographed weekly in a growth chamber for 14 days, in spring and summer conditions.

Among the six stages of bud development, the first four (V1 to V4) are the most attractive to the psyllid and favorable for its feeding and reproduction, and, therefore, should be the most protected.

It was observed that stages V1 to V4 develop quickly and that the expansion of the leaves leaves all new tissue unprotected, making it vulnerable to the arrival of the psyllid and providing "windows for infection". Therefore, at this stage, spraying at intervals of more than seven days will not be effective in preventing the transmission of greening bacteria. 

According to the postdoctoral fellow at Fundecitrus and responsible for the work, Juan Arenas, the recommendation is that, in these phases, applications should have a maximum interval of seven days. “This is because the insecticides applied to the leaves do not have systemic action, that is, they do not move within the plant and do not follow the growth of the shoots”, he explains.

Another proof of the work is that, from stage V5 onwards, as there is no expansion and only ripening of the leaves, the product coverage remains intact on them, and applications can be made every 14 days. In this case, the application interval will depend on the occurrence of rain (which removes the insecticides) or the degradation of the product (which reduces its residual period).

These actions optimize applications and help citrus growers to be more efficient in protecting buds and controlling greening.