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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: Developing a Phloem Penetration/antimicrobial Treatment to Reduce/elimate Candidatus Liberibacter from Existing Citrus Trees

Location: Subtropical Insects and Horticulture Research

2012 Annual Report


1a.Objectives (from AD-416):
Identify and optimize formulation of phloem penetrants with natural antimicrobials/insect antifeedants.


1b.Approach (from AD-416):
Greenhouse and field trials of different formulations will be conducted on citrus plants. These formulations will include combinations of putative phloem penetrants and antimicrobial compounds. Uptake will be monitored throughout the plant using GC-MS protocols, and influence on citrus greening bacterium will be monitored through PCR detection of the citrus greening bacterium.


3.Progress Report:

This project is related to Objective 3b: Develop novel control methods based on disrupting key processes in pest biology.

Greenhouse experiments were conducted to show that the level of Citrus Greening associated bacterium within diseased citrus trees could be reduced by basal bark applications of a mixture of antibiotics and specific phloem penetrants. Residue analysis in leaves of bark treated plants showed that the antibiotics activity was lost eight days following application, thus requiring frequent repeated applications. This result led to ongoing experiments designed to identify a time-release strategy to prolong the exposure of citrus to the antibiotics and thereby reduce the application costs. Similar greenhouse experiments were conducted to determine if foliar uptake of antibiotics by citrus could be improved. In these experiments foliar uptake was greatly improved by the addition of glycerol to the spray mixture. Field experiments using healthy citrus trees were continued from previous year resulting in a two year study that identified basal bark application treatments that reduced the occurrence of citrus greening disease in treated plants.


Last Modified: 9/29/2014
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