Preventing fruit borers in coffee

Coffee berry borers bore into the beans, causing the beans to fall, the beans to turn black and reduce quality after processing. Instructions for monitoring from old green fruit to harvest, cleaning fallen fruit, harvesting at the right time and post-harvest handling.

Summary: Coffee berry borers are dangerous because they destroy the beans directly. Weevil-infested fruit can fall prematurely, the kernel will be black, light and lose quality when sold. Weevils often increase strongly in orchards that are not harvested cleanly, with many dried fruits left on the trees or fallen fruits on the ground. This article guides management from the stage of green fruit to post-harvest in the direction of reducing the source of weevils in the entire orchard.

Applies to: Robusta coffee in the Central Highlands, especially orchards with long harvests, with many dried fruits remaining.

Duration: Monitor from when the fruit begins to mature until after harvest.

Difficulty level: Medium. Fallen fruits need to be cleaned and harvested cleanly.

Estimated additional costs: 2-5 million VND per hectare per crop for cleaning, collection and traps/support measures if needed.

Characteristics of fruit borers

Coffee berry borers are small insects that bore through the skin of the fruit into the kernel:

• The female beetle makes a small hole in the top or side of the fruit.
• Weevils go inside and lay eggs, and the larvae eat in the nucleus.
• Damaged fruit may fall or remain on the tree until autumn.
• Weevils continue to live in dry fruits, leftover fruits, and fallen fruits.

The biggest source of weevils is usually not from outside, but from dry and fallen fruit left in the orchard itself.

Identify fruit infected with termites

On old green fruit

• Small hole like a needle in the peel.
• There is fine powder or dark spots around the hole.
• Fruits grow slowly or change color unevenly.

On ripe fruit

• The hole is more obvious at the top of the fruit.
• When squeezing or opening the fruit, you will see that the kernel is cloudy, black, and has sugar in it.
• The fruit is lighter than usual.

On dry and fallen fruit

Dried fruit on trees and fallen fruit on the ground are quick places to check:

• Add 100 fallen or dried fruits.
• Count the number of fruits with weevils or perforated lines.
• If the rate is high, it is necessary to clean the orchard thoroughly before the next crop.

Count the level of harm

Choose 10 representative trees, each tree checks 50 fruits:

High-quality coffee orchards should keep the threshold lower because weevils directly affect the rate of kernel errors.

Seasonal Room

After harvest

• Collect all ripe and dry fruits from the tree.
• Pick up fallen fruit on the ground.
• Do not let dried fruit survive the rainy season.
• Handle piles of peels and fruits to prevent weevils from continuing to live.

This is the most important measure. If the orchard has many leftover fruits after harvest, all measures will be more difficult next season.

Green fruit stage

• Monitor traps or check fruit periodically.
• Clear the grass moderately to easily see fallen fruit.
• Prune the canopy for ventilation, reducing moisture shelter.

The stage of old to ripe fruit

• Check for termite holes every 2 weeks.
• Harvest at the right time, doesn't last too long.
• Do not leave ripe fruit to dry on the tree because it is a nest for termites.

Management measures

Clean and clean

• Pick all ripe and dry fruits at the end of the season.
• Pick up fallen fruit, especially around the base of heavy trees.
• Incubate or handle discarded fruit properly, do not dump it right next to the orchard.

Trap and track

Traps can be used to monitor adult beetle populations:

• Put traps in plots that were once heavily damaged.
• Check the number of weevils caught each week.
• When weevil numbers increase, increase fruit inspection and cleaning.

Trapping is no substitute for clean harvesting. It helps to know when termites are most active.

Biological measures and drugs

Some places use insect-parasitic fungi or appropriate drugs according to local instructions. When used:

• Select products approved for use in coffee.
• Use the correct dose and the correct isolation time.
• Prioritize treatment when termites are still outside or have just invaded; Weevils are located deep in the nucleus and are very difficult to attack.

Do not increase the dose arbitrarily because it easily increases residue and does not solve the source of weevils in dried fruit.

After harvesting and processing

The fruit borer also affects the quality of the kernel:

• Classify floating and light fruits before processing.
• Do not mix heavily damaged batches with good batches if making quality products.
• Dry the fruit enough and stir well to avoid weevils and mold from continuing to grow.
• Cleaning drying yards, warehouses, and containers.

Weevil management doesn't stop at the orchard. Dirty warehouses and drying yards also reduce quality.

Common mistakes

Leaving dried fruit on the tree: a big source of weevils for the next crop.

Only treat when the fruit is heavily opaque: weevils are already in the kernel, low efficiency.

Harvest takes too long: many batches of dry ripe fruit, weevils increase rapidly.

Do not pick up fallen fruit: fallen fruit under the tree feeds weevils.

Mixing a damaged batch with a good batch: reduces the quality of the entire batch.

Monitor and record

• [ ] Proportion of fruits with weevil holes per 500 fruits tested.
• [ ] The number of dried fruits left after harvest.
• [ ] Number of fallen fruits collected per batch.
• [ ] Trap results by week if used.
• [ ] Error rate due to termites after processing.

Recording in batches helps detect areas with the heaviest weevil infestation, often areas where harvesting is left over or the canopy is too dense.

Related articles

• Prevention of coffee twig borers
• Coffee stem borer prevention
• Prevention of dry branch and fruit diseases in coffee
• Track coffee prices