When I first started farming Kona Coffee more than 30 years ago the Black Twig Borer (BTB) was already here. Back then damage was barely noticeable and I considered it a minor threat. In fact, I used to tell other farmers that they didn’t have to worry about the BTB at all. This lack of concern continued for many years. It wasn’t until the early 2000’s that I started to notice that damage was notably increasing though still at a level that was tolerable. However, year by year damage levels started to increase to where I could see that yield was being more and more negatively impacted.
I tried to generate some interest in doing research by the university and the extension service. Virginia Smith who was the extension agent at the time agreed that we needed to do something. But no progress was made.
The problem with the BTB is that it is a difficult insect to control as it lives a very sheltered life inside the coffee lateral. It also has a wide range of other hosts, so removing infected laterals was not a very effective control strategy. Around this time a Phd. candidate whose name was Elsie Burbano decided to write her thesis on the BTB, doing a lot of work examining its life cycle and potential control mechanisms. Unfortunately, none of her ideas worked satisfactorily and controlling the BTB remained elusive. Meanwhile damage slowly progressed year by year.
I was firmly convinced that what we needed was an entomologist based in Kona who would be able to study the BTB every day in an attempt to figure out where in its life cycle it was most vulnerable. The state hired an entomologist named Rob Curtiss. I worked closely with him doing an extensive study of monthly damage counts and analysis of life cycle stages on my farm. I did these monthly samples for two years and Rob analyzed the data. We were able to determine that the BTB life cycle had two peaks in early spring and late summer but we were not able to come to any conclusions on what could be done to effectively use the data to come up with a control strategy. One interesting finding was that the beauveria fungus used for controlling Coffee Berry Borer (CBB) also kills the BTB but only in 5 to 10% of the samples.
Just at this time the Coffee Berry Borer(CBB) showed up and it was perceived as a much bigger threat and all efforts were focused on controlling it. The coconut Rhinoceros Beetle showed up on Oahu and Rob was sent to Oahu to deal with it and he was lost to us. The Pacific Basin Research Center in Hilo was very involved in working on the CBB problem and through this I got to meet many of the researchers working there. I tried to convince anyone who would listen that the BTB was also a major threat and we needed to work on it too. I got one of the researchers (Robbie Holllingsworth) interested and he agreed that he would look into it. He sadly passed away before he could conduct any research.
This is where we find ourselves today.
So with this brief bit of history, I would like to get some ideas on what can be done to try and figure out what our options are.
It is pretty evident to me that if the increasing trend continues, we will lose more production to BTB than the CBB or even the newly discovered Coffee Leaf Rust (CLR). Currently I estimate that I am losing 20 to 30 percent of bearing laterals on my farm and I know other farms are similarly affected in South Kona. As I like to point out, CBB affects one berry but BTB affects the whole lateral which can account for many more berries. And we have figured out how to manage the CBB.I believe the BTB threat is dire and something needs to be done or we will reach a point where it will no longer be profitable to farm coffee. I am not trying to be an alarmist but maybe some alarm is warranted here.