Dr. Tara Wade, Agricultural Resource Economist

Dr. Shourish Chakravarty, Food and Resource Economics

The project and the rationale for developing it:

The CLas bacterium colonizes the citrus tree phloem, and thus significant research has been undertaken to develop technologies that facilitate better delivery of bactericides including antibiotics to suppress CLas populations in citrus trees. Using trunk injections for bactericide application has been found to be superior to sprays since the former can exactly target tree phloem, does not cause run-offs and are thus environmentally safe. However, trunk injections could be costlier, and depending on the method used, could result in varying degrees of trunk damage. Our project will be the first of its kind to inform growers about the economic feasibility of using trunk injection methods, including automated technology, for bactericide delivery in citrus production.

Some trends in citrus production

Citrus has been grown in California for more than two centuries, with commercial citrus being grown for the last 150 years. Commercial citrus production employs more than 20,000 in the state and contributes to more than $6 billion in GDP. The composition of acreage and production of the primary types of citrus crops produced have undergone substantial change in the last decade. Between 2020 and 2010, Navel oranges have lost over 14% of the total acreage, while Valencia oranges have lost more than 35% of total planted acres. There has been a shift towards production of Mandarin oranges, with over 79% increase in total acreage between the two time periods. 

What economists are doing?

In this study we conduct a cost benefit analysis of trunk injection in citrus, specifically for the automated technology. We start our analysis by obtaining application rates, costs of materials, labor costs, equipment costs, and fuel costs for various trunk injection methods. For an automated delivery system, which has not yet been implemented in citrus, we will consider savings such as those from decreased labor costs, decreased costs of equipment such as plugs and drills, and add increased costs of machinery. Next, we conduct partial budget analysis for each method considering, in addition to costs and savings, benefits in terms of decreased fruit drop and increased quality and yield that result from using trunk injections for delivering bactericides. We will also interact with citrus growers and extension agents to develop a survey for growers to estimate their willingness to pay for adopting automated trunk injection technology in citrus production.

The deliverables

1. A cost-benefit analysis of adopting cover crops for citrus production that includes detailed estimates of break-even prices post trunk injection adoption and profitability analysis; 2. An Excel web tool in which growers will be able to input their own costs of adopting trunk injections to generate break-even prices and profitability estimates. 3. Estimates of growers’ willingness to pay for the automated trunk injection technology. 

What we have learned so far

We have learned that using trunk injections for delivery of bactericides is more effective than direct spraying. Moreover, some field experiments in Florida have found that fruit drops have decreased, and fruit quality has increased for trees. However, we are yet to find out whether adopting trunk injection, especially the automated technology, is cost effective and sustainable.