Passiflora edulis or commonly known as passion fruit is a tropical plant that produces fruits with an acid and sweet flavor, while being rich in carbohydrates and water. It is very nutritious and can be equally enjoyed on its own or in juices, smoothies or combined in a yogurt. Although its cultivation is not complicated, it is necessary to always be alert to the possible appearance of diseases. For this reason we will dedicate this post to describe the most common passion fruit diseases, we will also analyze the most effective treatments.
Whether you have a large crop of passion fruit plants, or just have a plant in your garden, disease control is essential. You will see that there are diseases that attack different parts, such as the leaves, stems or fruits, although some are more dangerous than others, all must be controlled in time. Otherwise you could lose the season’s fruit crop or even end up letting this beautiful fruit tree die.
1. Passion fruit diseases – Pictures and Symptoms
In passion fruit cultivation, diseases associated with bacteriosis, scab, anthracnose, virosis and brown spot predominate. All these diseases are generally favored by humid climates and high temperatures. Let’s get to know each of them better.
1.1 Angular spot: Xanthomonas campestris
The symptoms of this disease are characterized by presenting irregularly shaped olive-green watery lesions, in advanced stages there are bacterial secretions and later wilting.
This disease attacks all the aerial organs of the plant including branches, leaves, floral peduncles and fruits. Once inside the plant, it causes the obstruction of the passage of water and nutrients. Commercially it affects a lot since necrotic zones are formed in the fruit, which makes it very difficult to sell.
The spread of this disease is highly favored by rainy, windy conditions and the use of non-disinfected tools. For example, if you prune your passion fruit without disinfecting the pruning shears, you will be infecting one plant with another.
1.2 Anthracnose Colletotrichum gloesporioides
In this case it is a fungal disease, highly favored by high temperatures and humidity. Again, it is a disease that affects various parts of the passion fruit such as the leaves, stems and fruits.
The most notorious symptoms are the appearance of watery spots with a dark green halo that later produces necrosis. When they attack the fruits, they become brittle, affect the pulp and become mummified. The sunken areas with black dots are the fruitings of the fungus.
1.3 Gray mold: Botrytis cinerea
It occurs in conditions of high humidity, temperatures between 15 to 20°C and the presence of water. Unlike the other diseases, it predominantly attacks flowers and fruits. In the case of flowers, it causes their premature fall. While in the fruits it forms a cottony layer that goes from gray to black.
The dispersion of Botrytis cinerea occurs through the spores produced in the remains fallen on the ground. These spores are disseminated by raindrops and by the wind, creating a large focus of infection.
In summer time or dry seasons the risk of gray mold is significantly reduced. Among the factors that predispose its appearance are the following:
- Poor management of weeds: a large number of weeds generates increases in crop humidity.
- Excess use of nitrogenous fertilizers: Excess nitrogen produces an increase in the foliage, and therefore in the area to be infected as the tissues are more succulent.
1.4 Brown spot: Alternaria passiflorae
Again we have a fungal disease, in this case caused by the fungus Alternaria sp. It attacks both the leaves and the stems and fruits.
Reddish-brown spots appear on the leaves and watery margins are observed in very humid conditions. Over time, the lesions enlarge and form rings. The lesions on the fruits are variable, oily spots followed by brown lesions and cankers, which turn black when they increase.
In severe attacks it causes defoliation and sunken wounds are seen on fruits. In affected stems it induces the sprouting of axillary buds. Its presence in the crops coincides with the rainy seasons and poor aeration within the lot.
1.5 Scab: Cladosporium sp.
It is recognized as scab or scab, and its causative agent is the fungus Cladosporium sp. The disease affects young tissues of the leaves, branches, tendrils and fruits.
Small round spots appear on the leaves, initially translucent, and as they grow they become necrotic, taking on a greenish color with a gray center.
On ripe fruit, the rind lesions grow to become a prominent, brown, corky lesion. It only affects the outer part, without damaging the internal part, and consequently, it does not harm the quality of the pulp. In any case, it makes it very difficult to sell the fruit. The lesions on the fruit are brown in color with sunken suberized epidermis tissue.
1.6 Mosaic virus (CMV)
The symptoms caused by CMV in passion flowers are restricted to small portions of the branches, the infected leaves present bright yellow spots or ring spots, the intensity of the symptoms decreases towards the tip of the branch, some leaves as they grow may return to be asymptomatic. The reduction of symptoms is accompanied by the disappearance of CMV, and the mechanism by which this phenomenon occurs is still unknown.
1.7 Woodiness potyvirus (PWV)
The symptoms induced by the PWV virus cause mosaics, roughness and distortion in the leaves, reduced development of the plant, and hardening and deformation of the fruits.
It is a virus that needs certain aphids for its transmission. Aphids that transmit PWV include Myzus persicae and Aphis gossypii. It can also be transmitted with the use of contaminated tools, hence the importance of always disinfecting them before use.
3. How to treat passion fruit diseases
We have already mentioned 7 of the most common and harmful diseases for your passion fruit. In all cases we saw the symptoms, and in almost all I left you an illustrative image to help. Now let’s discuss the best ways to treat or prevent each of the above diseases.
2.1 Angular spot: Xanthomonas campestris
Since effective chemical control measures are not currently available, the best treatment is preventive. For this, it is best to start using seed from healthy plants for sowing. In addition, always clean all tools with disinfectant, especially scissors or other sharp elements used at the time of pruning.
To reduce the intensity of the disease, you can use copper oxychloride and its mixture with mancozeb at intervals of 7 to 15 days. In any case, the presence of regular rains will wash away any application, something that will favor the pathogen.
2.2 Anthracnose Colletotrichum gloesporioides
To treat Anthracnose, an adequate level of nutrition is necessary based on soil analysis. Also carry out phytosanitary pruning or combine with chemical practices based on fungicide products in rotation to avoid resistance due to excessive use.
2.3 Gray mold: Botrytis cinerea
To treat fungal disease you can follow these tips:
- Prune to thin foliage and improve air circulation between plants. Be sure to sanitize your pruning equipment after each cut.
- Add a good amount of organic compost or mulch under the plants. Mulches will prevent fungal spores from re-splashing onto flowers and leaves.
- You can use copper soap fungicides, which will increase the protection of the plants against the spores of this fungus. The application is made in spring at the beginning of flowering, and regular applications every 8 days during harvest.
- Other useful fungicides that I can recommend are SERENADE Garden (broad spectrum biofungicide), Mycostop and Green Cure fungicide.
2.4 Brown spot: Alternaria passiflorae
As a preventive measure, sanitary pruning of the affected structures is recommended in order to maintain the best possible aeration of the crop.
The fungicides that work best for treatment are cupric compounds, carbamates and strobilurins applied at intervals of 7-14 days. Applications should start as soon as the first symptoms are detected. When the climatic conditions are favorable to the disease (high levels of humidity) you can make the applications more frequently (every 5 days).
2.5 Scab: Cladosporium sp.
As you will notice the recommendations for all fungal diseases are similar. In this case, it is recommended to carry out maintenance pruning and phytosanitary pruning, removing the affected residues from the crop and destroying the affected parts. In addition, the application of fungicides with active ingredients that contain copper is recommended.
2.6 Mosaic virus (CMV) and potyvirus (PWV)
Although there are no control measures for these viruses, it is advisable to carry out some preventive tasks:
- Planting of virus-free plants.
- Appropriate land preparation (ploughing, raking, ridges).
- Carry out an irrigation plan that prevents stress due to water deficit.
- Avoid mechanical damage, especially during training pruning practices.
- Regular monitoring of pests and diseases.
Although the above care will not 100% prevent the appearance of these viruses, it will decrease the chances that your passion fruit will get sick.
4. Passion fruit diseases Australia
In Australia, passion fruit began to be cultivated in the early 1950s, and is currently one of the country’s main export fruits. The control of diseases is key, since otherwise there is a lot of money that is lost due to its export.
The four most common passion fruit diseases in Australia are:
- Angular or angular leaf spot: as we have already said, it is caused by the bacterium Xanthomonas campestris and is characterized by the appearance of dark brown angular spots on the leaves. The recommended treatment is the use of fungicides and the removal of infected leaves.
- Fusarium wilt or vascular wilt: it is caused by the fungus Fusarium oxysporum and is characterized by wilting and progressive yellowing of the leaves. This disease can be fatal to passion fruit plants and can be spread through soil or irrigation water. The recommended treatment is the elimination of affected plants and the use of healthy and disinfected soils.
- Passion fruit mosaic virus: It is caused by a virus transmitted by aphids and other insects. It is characterized by the appearance of light and dark spots on the leaves, which can affect plant growth and yield. Currently there is no specific treatment for this disease, so the use of insecticides is recommended to prevent the spread of vector insects.
- Anthracnose: it is caused by the fungus Colletotrichum gloeosporioides and is characterized by the appearance of moist, dark spots on the leaves, stems, and fruits. This disease can significantly reduce the yield of passion fruit crops. The recommended treatment is the use of fungicides and the removal of infected fruits.
In general, control of passion fruit diseases in Australia relies on the application of Integrated Pest and Disease Management (IPM) practices, which include the use of preventive techniques such as selection of resistant varieties, removal of infected plants , crop rotation and the use of appropriate cultural practices. Also, the use of chemical products such as fungicides and insecticides should be limited and done responsibly.
Source information:
- RECOGNITION OF PASSION FRUIT DISEASES – unillanos.edu.co
- DISEASE AND PEST MANAGEMENT IN PASSION FRUIT CULTIVATION – agrosavia.co
- DETECTION AND IDENTIFICATION OF PATHOGENIC VIRUSES -unal.edu.co