Guava diseases are among the most important factors in guava production or farming, which cause a major loss in guava fruit yield and vigor.
The most common diseases of guava causal organisms are species of fungi and bacteria.
Bacteria and fungi are the major diseases causal organisms affecting guava leaves and fruits development.
Another common causal organism affecting guava is algae, which is responsible for causing algal leaf spot in guava.
keep reading to learn more about guava diseases and their management.
Let us start with guava disease number one:
Number 1#: Anthracnose (colletotrichum gloeosproides)
Anthracnose is a common fungal disease that is affecting most plants including guava.
Distribution
Anthracnose can be distributed through the following ways:
- Proximity of plants with sick foliage or infected leaves
- Moving water
- Injury which provides place for fungal spores
- Rain splashing
Symptoms
- Initial dieback of young shoots
- Appearance of small dotted black spots on fruits and leaves, which immediately turn into a dark brown
- Appearance of lesions, which eventually combine to form large necrotic patches on the surface of fruits
- Unripe fruits of the affected shoots remain stunted and stony
- Buds and flowers that are yet to open might become shedded
Survival Conditions
- Excessive water around guava plant
- Excessive rainfall , which encourage funus spores formation
- Lack of proper and timely application of preventive measures
- Contant available temperature range that favor the fungus growth
Management
- Use of resistant varieties
- Use of fungicide before flowering and during fruit development
Number 2#: Algal Leaf Spot (Ceplaleuros virescens)
Algal leaf spot is a disease of guava plant, which is caused by parasitic algae.
Distribution
- Algal leaf spot is spread or distributed through the following ways:
- Can be spread by wind
- Can be spread by rain splash
- Planting of guava on a prone or infected areas
Symptoms
- Appearance of lesions that are tiny and shallow brown on leaf tips and margins around the midvein
- The lesions can enlarge up to 2-3mm in diameter
- A thin grey-white or dark-colored necrotic spot may be seen on the leaves, if the tufts are removed
- Cracking of barks twigs and branches
- The young shoots and fruits of guava plant might be attacked by the disease
- Lesions on immature fruits are almost black, which are sunken and cracked as fruits enlarge
Survival Conditions
- This type of algae survives well on wet areas
- Promoted by humid conditions
- Heavy rainfall
Management
- Reduce moisture and water around the guava plant
- Apply adequet fertilizer
- Prune timely to allow proper airflow
- Disease can be controlled by applying copper based fungicide
Number 3#: Fungal Leaf Spot (Pseudocercospora psidii)
This is also another fungaal disease that affect guava plant.
Distribution
The disease is distributed through:
- Humid environment
- Rain splashing
- Spores can be transferred by wind
- Water splashing
- Infected fruits and leaves may spread the disease through transportation
Symptoms
- Appearance of minute irregular or rough round dark brown lesions
- The lesions affect the upper surface of leaves
- Lesions can be found on stems and fruits
- If the conditions are favorable, the fungus may produce a spores and some grey tufts of mycelium can be seen on the center of the lesions
- The lesions can combine to form a large patches of necrotic tissues
Survival Conditions
- The fungus survives well during wet and humid conditions
- Heavy rainfall and watering may also help with growth of the disease
Management
- Plant resistant varieties
- Avoid excessive watering
- Prune timely to avoid dense canopy and moisture
- Copper based fungicides are also helpful in the management
Number 4#: Fruit Canker (Restalotia psidii Pat.)
This is also a fungal disease that affects the fruit and growth quality of guava.
Distribution
The pathogen can be distributed by:
- Wind
- Water splash
- Proximal plant with infected leaves
- Transportation of infected leaves and fruits from a place that is dominated by the pathogen
- Injury
Symptoms
- Common symptoms of fruit canker of guava include:
- Symptoms first appear on a fresh green fruits
- The pathogen normally does not affect leaves
- Appearance of small, brown or rusty, circular, and unbroken necrotic tisssues on the fruits
- As the infection progresses, the epidermis may tear up in acircular way
- Appearance of noticeable elavated and depressed leaf margins
- The depressed and elavated margins are more pronouced on fruits than on leaves
- As the canker become more noticeable, a large deposit of white mycelium that contains many spores are seen
- In severe case of the infection, the fruits can break open and expose the seeds that perforated the fruit pulp
- Affected fruits are stunted and stony, which later detach from the parent plant to the ground
- Appearance of rust cloured brown angular spots are sometimes seen on the leaves
Survival Conditions
- Humid environment
- Heavy rainfall
- Dense canopy
- Insufficient airflow
Management
- Use of fungicides
- Use of proper preventive measures
- Planting of resistant guava varieties
Number 5#: Guava Wilt
This is one of the devastating diseases of guava that is very hard to manage. Guava wilt usually manifests the infestation of the pathogen during the rainy season.
Distribution
- Water splash
- Rain splash
- Leaves movement of infected plant
- Root injury
Symptoms
- Apprearance of a light yrllow leaves during mansoon season
- The leaves aslo loose tugidity and epinasty
- Early defoliation and shedding
- Sagging of leaves
- Early or premature shedding of fruits
- Fruits usually become stunted and stony
- Rotting of basal roots
- The bark becomes easily detachable from the plant cortex
- The plant then dried up and died
- The pathogen can attack both young growing and old guava plants
Survival Conditions
- Heavy rainfall, which lead to water stagnation aroung the guava plant
- Planting guava tree on humid area
- Dense canopy
- Lack of sufficient airflow
- Lack nutrients supplementation
Management
- Proper and timely application of preventive messures
- Planting of guava plant on a less humid area
- Supplementing or application of nitrogen-reached fertilizer
Number 6#: Stem Canker (Physalopara psidii Stevens)
This is another fungal disease, which mainly attack the stem of guava plant.
Distribution
The pathogen of stem canker can be distributed from plant to plant through:
- Wind
- Water splash
- Rain splash
Symptoms
- Stem lesions and cracking
- Wilting of branches and stems
- Appearance of minute blackish-brown spots and outgrowth on the stem
- Calyx end may develop brown spots
- The fruits turn brownish-black and later up after five days of infesstation
Survval Conditions
- Heavy rainfall
- Heavy watering
- Planting on humid area
Management
- Use of fungicides
- Use of proper preventive messures
- Proper and timely pruning
Number 7#: Styler end rot (Phomopsis psidii de Camara)
This is another pathogenic disease of guava that is caused by a fungus.
Distribution
- Application of manure that contains infected debris
- Proximal plant with infected leaves
- Infected Fruits and leaves transportation from prone area with the pathogen
- Water splash
- Rain splash
- Wind
Symptoms
- Appearance of dark brown spots below and around the calyx
- The infected fruits may become rotten and soft
- The mesocarp also become discolored like that of the calyx
- Fruits shedding
Survival Conditions
- Humid conditions that favor spores formation
- Dense canopy
- Lack of sufficient air flow
Management
- Reduce dense canopy
- Timely pruning
- Use of fungicides
- Picking away of infected fallen debris
- Increasing airflow by thining
Number 8#: Guava Rust (Piccinia psidii)
This is a fungal pathogen that affect guava plant leaves, fruits, and shoots.
Distribution
This disease of guava can be transmitted through:
- Infected debris
- Water splash
- Rain splash
Symptoms
- Leaves initially become orange and later turn to red
- Young shoots, flowers, and fruits also become redish-brown
- Appearance of round lesions on leaves
- Plant becomes stunted and underdeveloped
- Lesions turn yellow
- Premature falling of leavves
- Leaves become distorted
Survival Conditions
- Planting of guava plant on humid or moist area
- Dense canopy
- Lack of airflow
- Warm temperature
Management
- Timely pruning
- Thining of reducing of dense canopy
- Picking of infected debris
- Use of fungicide
- Use of proper preventive messures