Coffee growers and pickers are working hard to continue producing good quality coffee in the Big Island, which allows us to drink one of the best coffees in the world every morning. However, a lot of work goes behind a cup of coffee. Growers in Kona, Ka’u and other districts have a new pest with deal with as they approach the harvest season. The coffee berry borer (CBB), a tiny beetle native to Africa and the most serious coffee pest worldwide, is feasting on our coffee. The Kohala Centre is training coffee growers to deal with this new threat.
Now, coffee growers are planning to harvest coffee berries that result from several months of hard work. During the growing season (January – August) activities such as pruning, cutting weeds, removing suckers, applying fertilizer, spraying a biological pesticide (Beauveria bassiana) to control CBB, have been completed, in preparation of harvest. A coffee berry requires seven to nine months to develop from the flower. In Kona, coffee farms at a low elevation, under 1,000 feet, start harvest in early August and finish in December. Coffee farms at high elevation start harvest in September and don’t finish until February. In Ka’u, the harvest season is as late as March, which makes controlling the CBB even more challenging.
CBB that have survived efforts to thwart them are reproducing inside the coffee endosperm (berry seeds). Infested berries are a primary source the CBB, especially in inside over-ripe berries. If those infested berries are not collected in time and removed from the trees or if they fall to the ground, hundreds and thousands of CBB female beetles emerge, disperse, and attack new berries.
In my research, I have observed the activity of CBB increases as the harvest season progresses. Collected cherries go to the wet mill and are processed. Luckily, many of the infested berries become “floaters,” which can be destroyed. However, those cherries missed by pickers remain a problem. I personally have named them factories of CBB.
Four aspects should be addressed by coffee growers and pickers during harvesting season, in order to reduce CBB populations and prevent unacceptable damage to coffee yield:
1. Frequent harvesting. Collecting berries every two to three weeks is one of the best ways to minimize CBB, since this pests’ lifecycle is cut when infested berries are collected.
2. Efficient harvesting. Similarly, pickers can be trained to effective collect all overripe berries in order to eliminate the factories. Preventing those berries from falling to the ground by collecting them first is a proactive strategy. Coffee pickers can place all collected berries inside black plastic bags and tie them when full to prevent escape of CBB.
3. Post-harvest. Growers can take steps to prevent CBB escaping from the wet and dry mill. Transparent plastic covers smeared with grease traps CBB from the hopper, flotation, and fermentation tanks. Cover the similarly, containers of coffee residuals (skin, pulp and mucilage) can be smeared with grease to trap CBB. The dry mill may be enclosed with screen or plastic to prevent the escape of CBB from parchment (processed coffee).
4- Traps: Alcohol-based traps help to capture CBB in the plantations and also emerging from the wet and dry mill. This helps growers learn which areas the CBB are mostly found.
Growing coffee the right way can help pickers harvest more effectively. Such practices include standardizing the number of verticals per tree, removing suckers, controlling weeds, and applying fertilizers. In this way, coffee trees are healthier, more productive, and cherries easier to see by pickers. A final problem is there are not enough coffee pickers in Hawaii. Many of them are Latino, Philippines, and Marshallese. These pickers need to be trained in new techniques to harvest coffee in order to eliminate CBB populations, while receiving fair compensation for doing a good job.
The goal is to leave no more than five infested raisin berries per tree in order to be successful. Our research in commercial coffee farms from Ka’u District shows that on average 15.5 berries/tree are left after a harvesting round. This means there is a still work to do is we are to beat this pest!
Luis F. Aristizábal is an independent consultant for management of CBB