Florida citrus industry has been influenced by citrus greening disease or huanglongbing (HLB) severely. Citrus greening is a bacterial disease that is transmitted by a tiny insect called Asian citrus psyllid (ACP). Unfortunately, there is no cure for greening yet and any controlling methods that growers are using are aiming to mitigate the negative effect of greening on trees.
Because there is no cure for the citrus greening disease, all chemical control methods focus on reducing the Asian citrus psyllid (ACP) population. Intensive use of insecticide is harmful to beneficial insects and the environment and most of the time this method is ineffective especially in new plantings. The important question is do we have any control method that is effective and at the same time is environment friendly?
Integrated pest management (IPM) is an effective and environmentally friendly approach to pest management that relies on a combination of common-sense practices. The aim of IPM is to control pests by the most economical means, and with the least possible hazard to people, property, and the environment (Environmental protection agency, 2022).
Monitoring and scouting
Monitoring is the key element in the successful control of ACP. One way to monitor the ACP population is using yellow sticky notes to capture adult insects. The monitoring method using sticky traps shows how bad the new flushes are infested by psyllids. The whole tree should be monitored visually or using DNA analysis as well.
Repellent and Attractants
The previous studies show interplanting guava and garlic chives in citrus groves reduced citrus greening infection as these plants play as a repellent for psyllids. Other materials that have been tested as a repellent and showed promising results include essential oils such as coriander, lavender, and thyme. Spraying kaolin clay also reduced the population of nymphs, eggs, and adults of psyllids on new flushes.
Psyllid Biological Control
Various parasites have been introduced to be released as a predator of psyllids. One of the effective parasitic insects is Tamaraxia radiata that act by attaching eggs to the underside of psyllid’s nymphs. The nymphs will be killed later. Other parasitoids insects include spiders, ladybugs, syrphid fly larvae, and lacewing. Biological control of greening bacteria has not been studied yet. In a simple way, if we want to explain, the tree is inoculated with an antagonist or a microbe such as Bacillus subtilis to provide cross-resistance to greening.
Natural pesticides such as Chromobacterium sp. Can reduce the spreading of adults and nymphs by interfering with reproduction. Horticultural oils such as Neem oil will damage nymphs, eggs, and adults.
Although the goal of IPM is to control greening with the least possible hazard to the environment, a combination of biological methods with chemical pesticides will boost the effectiveness of IPM. A systemic pesticide that has been used to control the psyllids population includes the neonicotinoids imidacloprid, thiamethoxam, and clothianidin. The problem of using systemic pesticides is increasing resistance to the pesticide and hazard to the native bees and beneficial insects. Likewise, using systemic pesticides has not reduced the psyllid population in Florida.
Although we always say that there is no cure for greening yet, I am positive that our researchers and growers will work together to bring more missing pieces of this puzzle together, and in near future, we will see Florida will shine in the citrus industry not only in the nation but also in the world.