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: 06/25/2021
Project: 18-032C   Year: 2021
Category: ACP Vector
Author: FERNANDO ALFEREZ
Sponsor: Citrus Research and Development Foundation

1. Please state project objectives and what work was done this quarter to address them:  Objective 1. Assessing tree growth and absence of psyllids and HLB disease symptoms (including CLas bacteria titer) under protective covering (i.e., IPC). The most striking finding in this objective during the last quarter has been the finding that fruit retention was significantly improved in trees that were covered by IPCs, resulting in larger yields and improved internal quality. As a reminder, we removed covers in August 2020. These trees bloomed and set fruit for the first time in February 2020; therefore, this represented the first crop. Fruit drop was non-existent in trees that had been protected by the IPCs, whereas non-covered trees showed 60% fruit drop. Fruit quality was also dramatically improved by use of IPCs: Brix was 10.9 in IPC trees whereas in non covered trees Brix was 7.5.   Objective 2. Assessment of alternative netting approaches involved in ‘targeted’, ‘alternated’ or ‘patterned’ setup of IPC in groves for more cost-effective protection. We have started analyzing samples to determine HLB incidence in the different layouts and if layout dictates different psyllid colonization.  Objective 3. Monitoring the transition from vegetative to reproductive stage in the covered trees as compared to the non-covered trees.In the new plots, after having a good bloom in all three varieties (SugarBelle, Early Pride and Tango) covered by IPCs, we assessed fruit set and did not find significant differences compared to non-covered trees. This is promising, since it shows that these varieties do not need to be exposed to pollinators to set fruit, and IPC protection could potentially be prolonged to get the trees well into the productive age, producing high quality fruit, as we have shown in Objective 1. By applying brassinosteroids we expect to  prolong further tree health and produce a commercial-size crop of good quality fruit.    Objective 4. Comparing IPC with CUPS-like systems. We have collected data on bloom and fruit set on deficit irrigation plots for the second year, and we were able to confirm more bloom and fruit set in protected trees. We installed an automated irrigation system that is helping us to perform these treatments consistently. We have also installed several moisture probes to fine tune the treatments.  Outreach for this quarter:-Alferez, F. Citrus Institute 2021. Virtual. April 6.Individual Protective Covers (IPCs) influence on tree performance, fruit production, pests, and diseases. -Alferez, F. Invited presentation at CRDF BOD meeting. April 26, Arcadia. -Alferez, F, Batuman, O, Gaire, S, Albrecht, U, Qureshi, J. Assesing spatial patterns of IPCs deployment in young citrus. Submitted to Citrus Industry -Batuman, Alferez, Qureshi: Assesing spatial patterns of IPCs deployment in young citrus. CRAFT TWG meetings and one-on-one grower meetings. 2. Please state what work is anticipated for next quarter:Objective 1. We will perform regular work on horticultural/pathology parameters in all plots.Objective 2. We will continue collecting data on psyllid populations and HLB incidence in the different netting layouts. Our idea here is to find any seasonal differences that can be affected by the different patterns.Objectives 3 and 4.We will continue collecting data on fruit set and fruit growth and maturation for this second season of deficit irrigation treatments. We will also monitor early fruit drop, if it occurs.  Outreach:-Gaire, S, Alferez, F, Albrecht, U. Horticultural attributes of SugarBelle, Tango and Early Pride mandarin trees grafted on two different rootstocks grown with and without individual protective covers (IPCs). ASHS Annual meeting. August 5-9, 2021, Denver CO   3. Please state budget status (underspend or overspend, and why):We are on track with activities  and spending. Budgeted amounts for salaries and student stipend and tuition are being spent as predicted. We expect to spent more this quarter, as we will be paying publication fees for our first paper accepted and registration for the ASHS annual meeting in Denver, CO.   


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