By Harold Browning
Column sponsored by the Citrus Research and Development Foundation
Use of bactericides to reduce disease levels in infected trees continues to be a topic of debate in Florida citrus. Now in the second season of grower use, many growers are continuing to use the three products containing oxytetracycline or streptomycin within their seasonal spray programs.
The Citrus Research and Development Foundation (CRDF), under the supervision of Bactericides Project Manager Stephanie Slinski, is assisting growers in assessing how their programs are performing in this second season. Data summarized from nearly 70 grower field trials in which some form of untreated control plots were included demonstrate that after one year of use, there were positive yield responses at some locations.
The data are noisy, since there is little replication and limited controls, but the presentation at Citrus Expo provided insights for growers to contemplate. Slinski reported that a majority of the grower trials are continuing this season, allowing an assessment at harvest of the cumulate effects of two seasons of use. News from these trials complement the more rigorous trials conducted in recent years in Florida, which also show wide-ranging results after one year.
In registering for attendance at the 2017 Citrus Expo, a number of Florida growers completed a survey to describe their use of bactericides in the 2016–2017 season as well as their activities and plans for the current (2017–2018) season. There were 57 respondents, about half of the number who completed the survey one year ago. The respondents represented over 131,000 acres. As was the case last year, the respondents were distributed across grove sizes, but a larger proportion who responded represented Ridge and Southwest regions. Summaries gathered from this survey include the following:
- Six respondents did not use bactericides in 2016, and eight reported not using them in 2017.
- Those who used bactericides reported an average of 3.4 applications in 2016–2017 and projected that they would average 3.6 applications in 2017–2018.
- Respondents indicated that they were covering 74 percent of their acreage in 2016–2017 and 71 percent in 2017–2018.
- The majority of those who completed the survey used both active ingredients. The ratio was approximately two oxytetracycline to one streptomycin application.
These results provide insight into what growers are planning this year, and will be helpful as CRDF and its partners begin the process to seek approval for continued use of the bactericides in 2018. Thanks to AgNet Media for its assistance with this survey.
Harold Browning is chief operations officer of CRDF. The foundation is charged with funding citrus research and getting the results of that research to use in the grove.
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