Limited efficacy of guava interplanting on citrus greening disease: Effectiveness of protection against disease invasion breaks down after one year

No sustainable management practices have been established yet for citrus greening disease (CG). Here we show the efficacy of interplanting guava on CG and its limitation. In 2004, four farmers in southern Vietnam found fewer occurrences of CG in their orchards with guava interplanting than in other orchards without it. The efficacy of guava interplanting was evaluated from field assessment in 93 citrus orchards in southern Vietnam. The CG infection was lowest in orchards where either chemical control with both non-neonicotinoid insecticides and neonicotinoids or the interplanting with guava was performed. Three field experiments were then carried out investigating guava interplanting. In these experiments, no citrus trees in orchards interplanted with guavas were infected by CG for over one year and a few months, while about 20% of trees were infected during the same period in orchards without guavas. There were significantly fewer psyllids in guava interplanted orchards in the first year, but the insect increased thereafter. Almost all trees were infected by CG after two and a half years irrespective of the presence of guavas, indicating that guava interplanting was effective for one year at most. Guava interplanting reduced invasion by the vector but failed to regulate its subsequent generation succession. (C) 2011 Elsevier Ltd. All rights reserved.