Fundecitrus warns of the occurrence of defoliating mites on citrus in the autumn-winter period

At this time of year, between March and September, citrus production is affected by climate change and phytosanitary problems, such as pests and diseases. The arrival of the dry period is a warning sign for the appearance of high infestations of tetranychid mites, also known as defoliating mites.

Every year, these mites cause great damage to citrus growers. Therefore, it is important to identify them quickly and manage them correctly in order to avoid a possible drop in productivity.

Main species

Mites are tiny arthropods that feed on various plants and, in some cases, transmit diseases to orchards.

The main defoliating mites that affect citrus are the purple mite (Panonychus citri), the Texas mite (Eutetranychus banksi) and the Mexican mite (Tetranychus mexicanus). The three species mainly attack plant leaves, causing chlorotic spots known as mottling, which result in defoliation and drying of plant tips.

In some situations, the damage caused by defoliating mites resembles the attack of leaf-cutter ants, due to the intense fall of leaves from the pointer. Furthermore, high infestations of defoliating mites can cause fruit abortion, especially in non-irrigated areas.   

Mite control

The control of defoliating mites has been hampered, mainly, by the lack of efficient acaricides on the market and the lack of rain in some years.

Furthermore, the management of other pests and diseases can also interfere with the control of defoliators. For example, the excessive and/or continuous use of pyrethroid, organophosphate and neonicotinoid insecticides, associated with the dry period, can cause a sudden increase in mite infestations, due to the elimination of their natural enemies. And certain products, especially insecticides, can also increase the reproduction rate of mites, a phenomenon known as the hormesis effect.

Driving

Management of defoliating mites begins with monitoring to detect the first infestations. According to the acarologist professor at UNESP/FCAV, Daniel Júnior de Andrade, control carried out at the beginning of infestations tends to be more efficient and longer.

“When the need for intervention is verified, the ideal is to choose the most efficient acaricides available on the market and authorized for the crop. Whenever possible, it is recommended to use biological products, such as entomopathogenic fungi, which help to suppress pests and better preserve natural enemies. The quality of the application is also fundamental in management”, he comments.

The state of conservation, regulation and calibration of application equipment are essential for successful control. The rotation of acaricides, with different modes of action, is also essential in management, in order to avoid the emergence of resistant mite populations. Therefore, with these precautions, the losses and costs caused by defoliating mites will be lower during the harvest.