Passionfruit Diseases

The biggest challenge in passionfruit growing are diseases, which can wipe out entire plantations. Some pests also cause damage but they are mainly relevant in meeting export standards. Pests also play a role as disease vectors. Here is a list of dieseases and treatments, which are common in East Africa.

Dieback

The worst passionfruit disease is certainly dieback, as it causes the whole plant to die. Dieback is not caused by one single disease though, but is a collective term for a number of fungal diseases caused by several different Fusarium and Phytophtora strains, namely: Collar rot, caused by Fusarium solani, which also cuases damping off in cucurbits (cucumber, melon, zucchini, pumpkin,etc.) and root rot in beans. Fusarium wilt, caused by Fusarium oxyporum, which also causes wilt in tomatoes and bananas. Fusarium wilt is more severe on sandy soils. Phytophtora root and crown rot, caused by Phytophtora cinnamomi, which attacks a large number of plants, e.g. avocado trees.

Anthracnose

Anthracnose is caused by another fungus called Glomerella cingulata. Anthracnose starts as small spots that first enlarge and darken and later cause the infected area to rot. It appears on the vine, causing dieback of side shoots, on flowers and fruits, causing premature flower and fruit drop and on the leaves, slowly causing leave drop. Fusarium wilt is favoured by  

Leafspot

Leafspot, caused by Alternaria passioflorae and Brown Spot, caused by Septoria passioflorae are both also fungal diseases that cause spots on leaves and fruits and eventually premature fruit drop. Brown spot can lead to significant losses. It is more prevailant in old and neglected plantations.

Treatment for Fungal Diseases

All above mentioned fungal diseases are favoured by high temperatures and high humidity. Monitoring for an outbreak should therefore always be closest in hot and humid weather conditions. As most fungal diseases are soilborne, planting in previously affected areas must be avoided. Pathogens also spread with irrigation and run-off water and often enter the plants through small wounds in the roots, which are e.g. caused by nematodes. Nematode control is therefore important.

Some measures help to keep the plantation healthy:

1. If possible use healthy seedling, grafted on disease and
    nematode resistant rootstock.

2. Monitor the plantation regularly and practise hygiene, which
    means removing and distroying any diseased leaves, fruits and
    vines.

3. Prune regularly to allow sufficient air movement through the vine.

4. During hot and humid weather spray preventive fungicides.

Fungicides

The use of toxic fungicides should be avoided as it damages important beneficial microorgansims in the soil and also leaves toxic residues on the fruits. Weekly preventive applications of copper oxychloride are recommended once first signs of fungal disease appear.
A more environmentally friendly option is a homemade organic fungicides made from coriander seeds and onions.

Organic Coriander-Onion Fungicide

Crush 2kg of coriander seeds and boil them in 10 litres of water for 10 minutes.
Chop 40 onions and pour the hot coriander-water over the chopped onions. Leave them to soak for 24 hours.
Strain the liquid through a cloth to remove all bigger particles that might clogg the sprayer.
Dilute the liquid with 20 litres of water.
Spray on the passionfruit vines and leaves weekly as a preventive.

Woodiness Virus

Woodiness virus is an infection with a virus of the Potyvirus family. It is transmitted during pruning or grafting and also through sucking insects like aphids. It occurs more often during the cooler season. Symptoms are mottled and distorted foliage and malformed fruits with a thickened, hard rind. Fruits produce no pulp.

The only control measure is hygiene in the plantation. Inspect the plantation regularly, especially during the first 6 months. Immediately remove and distroy infected vines, disinfect tools and hands during pruning and grafting. Control aphids.