Coffee anthracnose is one of the biggest enemies of coffee crops.
Anthracnose is a disease that affects coffee cultures almost as badly as coffee rust.
The fungus Colletotrichum coffeanum is the cause of anthracnose, as the German botanist Fritz Noack established in 1903 based on samples collected in Costa Rica and Brazil.
Anthracnose attacks coffee leaves, twigs, flowers and fruits at various stages of development.
It is often confused with coffee berry disease (CBD) as both are caused by fungi in the same family, but anthracnose exhibits different symptoms. Anthracnose affects the entire plant, while CBD only affects the green bean, although it can cause losses of up to 80%.
When anthracnose is very advanced, it can be easily recognized as spots on the leaves called necrosis.
Climate zones with a humidity of more than 90% or with a rainy and windy interval favor the spread of the anthracnose. Plants with wounds caused by either bruises, insect infestations, bites, or other influences are also more likely to be affected by the disease.
Anthracnose can cause damage to both green and ripe fruits. In ripe fruit, damage is limited to the flesh without damaging the pit, but hinders pulping and affects the quality of the pit, while in green fruit, damage begins at the stalk, causing the pits to fall off and turn black.
Spread of anthracnose
Anthracnose is a silent disease because it is not initially noticeable. However, it is very difficult to combat once the symptoms appear.
The fungus that causes anthracnose produces conidia, its reproductive organs, which survive from one cycle to the next and can also infect new plantings.
The conidia produce a series of lesions on leaves, branches and fruits. When the weather is favorable, the conidia migrate from plant to plant, multiplying and creating multiple disease cycles.
The disease is thus primarily spread by infected plants from plant to plant and from farm to farm, but it can also be transmitted through the hands and wet clothing of coffee pickers and birds.
Symptoms and damage of coffee anthracnose
Below are the most common anthracnose symptoms and damage so you can spot them on your coffee trees.
- Premature fruit and flower drop
- Dark, round spots on the leaves
- Decay of leaves and stems
- Lesions show brown dead tissue
- Dark, round spots on the fruit
- The plant may not fully mature. If this is the case, the fruit will have an astringent taste.
- The diseased tree can be further weakened by Anthracnose.
- The leaves of the tree fall off prematurely, affecting the photosynthetic process that the plant uses to create its food.
- The branches of the tree can die and, in the case of very aggressive infestations, even the tree itself.
- The coffee plantation may suffer yield losses.
How to treat coffee anthracnose?
Below are some measures that can be taken to control anthracnose disease.
Make sure the soil the plants are placed on has good drainage. Because if the soil is not well drained, there can be a build-up of water in which the fungi can multiply more easily.
Disinfection of the floor
Before planting, disinfect the soil with organic fungicides to reduce the risk of developing anthracnose and other fungi. If the fungus does appear, it is best to remove all infected parts of the plant and apply a larger amount of fungicide.
It is important to make an initial assessment as the fungus causing anthracnose can develop resistance to various fungicides.
Keep humidity low
Try not to get the leaves, stems and flowers wet as they are very susceptible to fungus if given plenty of moisture on a regular basis. To avoid this, use a direct soil irrigation system.
Good plant spacing
Leave enough space between plants to make it more difficult for the fungus to spread if one of the plants becomes infected.
Note that coffee plants placed in full sun coffee plantations can wear out faster because the plants have higher physiological activity under these conditions. This leads to higher fruit production, so the plants need a lot more nutrients in these conditions. This can create additional stress in the plant and make it more susceptible to anthracnose disease.
On the other hand, plants that are in the shade maintain a high level of humidity, which can favor the appearance of anthracnose.
For this reason, you should ensure adequate shading in your coffee plantations so that there is never a lack of air circulation and light and the development and further spread of anthracnose can be avoided.
Keep in mind that the appropriate shading for a coffee plantation depends on elevation and climate. However, there is a general measure of shading, which is between 40% and 60%.
Plantations located at an altitude of more than 800 m above sea level should get 40% shade, while plantations at lower elevations should get by with 60% shade to make disease more difficult to emerge.
Avoid monocultures, because a variety of plants strengthens the beneficial microorganisms in the soil that prevent the emergence of various fungi that can affect the plants.
Remove damaged plants
Try to remove damaged plants as they can be a major factor in the spread of the disease. In fact, the mycelia of these plants can be active for up to two years, or even longer in some cases. Therefore, you should collect infected plants, remove them and burn them outside the property.
Feed the plant
Establish a feeding program that meets the needs of the plant. Keep in mind that weak or poorly nourished plants are more likely to be attacked by anthracnose, while well-nourished plants are better able to resist the disease.
In order to run a good nutritional program, you need to know what nutrient deficiencies the soil has, so you should first conduct a soil analysis.
Try to correct any potassium and phosphorus deficiencies and avoid excess nitrogen.
Ideal are micronutrients such as zinc and boron applied to the foliage to increase the plants resistance to anthracnose.
Natural sources of nutrients are also good for strengthening the plant and soil. Bio-fertilizers and bio-ferments applied to the foliage increase the plant’s tolerance to anthracnose.
Disinfection of tools
Before and after cutting, disinfect the cutting tools with alcohol or a drop of dishwashing liquid. Every time you cut off a branch, you should disinfect the tool and remember that the cuts should be made 4 inches below the edge of the diseased area.
Monitor the plant
Constantly monitor the plantings to know how the disease is behaving so that you can take appropriate measures to combat it.
Weeds or unwanted plants growing in coffee plantations should be controlled as they favor the development of anthracnose in two ways.
For one, they compete with the plants for water and nutrients, which puts stress on the coffee plants and makes them more susceptible to the disease.
On the other hand, weeds play a major role in keeping the moisture content of the plot high.
For these reasons, weeds must be strictly controlled. However, it is important to recognize which are the most aggressive weeds in order to properly control them.
The most aggressive weeds are those that, due to their root system and cycle, represent greater competition for the crops. An example of this type of weed is perennial broadleaf weeds and grasses, which typically grow in coffee plantations that lack shade and are fully exposed to the sun.
Interesting facts about anthracnose
- Anthracnose is one of the main diseases affecting Arabica coffee cultivation in Africa.
- Coffee anthracnose can cause crop losses of 20-60%.
- The disease was first discovered in Kenya in 1922 in the western Rift Valley.
- Warmth favors the appearance of the anthracnose, making it easier to spot in summer and spring.
- Anthracnose is also known as cancer or cancer.
- In 1964, anthracnose-related losses in Kenya amounted to £6 million.
- Anthracnose disease control can account for around 30% of total production costs on an average farm.
- The disease was recorded in Angola in 1930, Zaire in 1937, Cameroon in 1955, Rwanda in 1957, Uganda in 1959, Tanzania in 1964 and Ethiopia in 1971.
- The disease can remain on the plant without causing major problems until the conditions for its development arise, i.e. climate changes, attack by other diseases that weaken the plants, and poor management.
- In the case of anthracnose, the plants are attacked by fungi of the genera Colletotrichum, Gloeosporium and Coniothyrium fuckelii.
- Anthracnose is also very common on pumpkin, avocado, mango, papaya and tomato crops.
- Coffee anthracnose is known as a polycyclic disease due to multiple disease cycles repeating themselves in a single growing season.
- Symptoms can appear as early as 24 days if the plant is in good condition and the weather is not favorable for the development of the disease.
- Anthracnose is considered a phytosanitary problem of economic importance.
- When anthracnose is combined with rust, the catheti are severely damaged as their photosynthetic capacity is reduced.
Is Anthracnose a Big Problem for Coffee Growers?
Anthracnose can affect any farm, large or small. But coffee farmers cultivating small and medium-sized farms are having much more trouble fighting the disease due to lack of resources.
It must be considered that every coffee grower has to spend a significant amount of money to take measures to prevent or control the disease if it has already infected the crops.
Anthracnose is a very serious disease that needs to be controlled through a plan of action to reduce the likelihood of the disease occurring.
The best way to prevent anthracnose is to consider the different options available and use them together rather than individually to properly combat the disease.