Preventing young trees from psyllids and infection with CLas through use of protective netting

Preventing young trees from psyllids and infection with CLas through use of protective netting

Report Date: 09/12/2019
Project: 18-032C   Year: 2019
Category: ACP Vector
Author: Fernando Alferez
Sponsor: Citrus Research and Development Foundation

August 31, 2019 – In this quarter, we have continued to work on objectives outlined in our chronogram.

Objective 1. We have completed assessment of trees planted in our pilot study (planted 22 months ago) for CLas infection and HLB symptoms. All the non-covered trees are PCR-positive for CLas whereas all trees covered with IPC have tested negative. We are continuing with quantification of leaf drop and comparing leaf drop in both treatments; 6-month cumulative data show no significant differences in leaf drop in IPC-covered trees compared with non-covered trees. Interestingly, when counted seasonally, in spring leaf drop was significantly higher in non-covered trees as compared to IPC trees, whereas in summer, it was slightly higher inside IPCs. This fact points out a seasonal component that we will investigate as the project progresses.

In August, we have replaced the old 4-ft IPCs with new 8-ft covers, donated by The Tree Defender, Inc, because the trees had filled the volume of the cover completely. This also has opened the possibility of studying the dynamics of branch unfolding, which we are doing visually (photography documentation) and by measuring canopy growth and leaf area index. We have also assessed other pest and disease incidences inside the IPCs. We have found less incidences of canker inside IPCs and approximately equal incidences of greasy spot. However, greasy spot severity is higher inside the IPCs. We have found more incidence of other pests such as mites, armyworms, and leafrollers inside the IPCs, and a total absence of predators (beneficials). This suggests that relying only on IPC for insect control is not sufficient, and insect management must still be conducted. No psyillid have been found inside the IPCs.

Objective 2. To study the edge effect in different IPC layouts, we are now preparing to plant 700 trees of SugarBelle, Tango and Early Pride mandarins and using 3 different arrangements (targeted, alternated and patterned, as described in the proposal) of IPC. We have performed initial measurements of the tree parameters (trunk diameter, and leaf sampling, for CLas, cholorophyll and sugar analysis).

Objectives 3 and 4. We are continuing to measure fruit set and development inside the IPCs and comparing this with our CUPS planting. We are taking fruitlet and fruit samples regularly for biochemical analysis.

Outreach, Professional Presentations and Extension Activities for this quarter :

-Grower Presentation: “Growing Young Citrus Trees Under Individual Protective Covers (IPCs): What We Know After 18 Months” Citrus Expo 2019, August 15, Fort Myers, Fl.

-Industry Magazine Article: “Individual Protective Covers for Psyllid Exclusion and HLB Disease Prevention in Young Trees”. Article submitted to Citrus Industry Magazine in July to be published in October issue.

-Our Project was also noted in the September’s issue of Citrus Industry Mag’s UF/IFAS. The Citrus State Opinion Column by Jack Payne highlighted this work as an example of collaboration between growers, extension agents, and scientists in Florida. The column was entitled “Collaboration breeds solutions”.

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