One of the best methods is to prune off as much of the affected area of your plant and then dispose of the material in your green waste bin. Often, Psyllid attacks plants when the conditions are favourable. they love certain plant species such as Syzygium and Citrus. They are also excellent hitch-hikers, as they often are blown into the garden by the wind or hide on clothing, tools or other plants until they find one that is favourable to lay their eggs on. Alternative solutions are to use organic sprays such as Neem oil to treat heavier infestations or the introduction of beneficial insects such as lacewings, Ladybugs and parasitic wasps, which are natural predators of psyllids. You can buy these beneficial insects at garden stores or online, and they’ll help keep the psyllid population in check.