Mealybugs (Planococcus citri and P. kenya)

Mealybugs infest fruits and foliage. They can be serious pests in the warm season, if natural enemies, which usually control them, are destroyed by spraying with pesticides.

They are 3-5 mm long, soft, elongate oval and somewhat flattened

Aphids (Aphis gossypii and Myzus persicae)

Aphids damage plants by sucking plant sap causing curling, wrinkling or cupping of infested leaves, giving plants a deformed shape. They spread viruses and excrete honeydew, which coat the plants and leads to growth of sooty mould, which can diminish the photosynthetic capacity of plants. Aphids are usually controlled by natural enemies if they have not been disturbed for instance by the use of broad-spectrum pesticides.

Leafmining flies (Lyriomyza spp)

Feeding and egg laying by leafmining flies cause stippling of leaves. This can kill seedlings and in older plants allows entry of disease-causing microorganisms. Feeding by maggots causes mining (tunnelling) of leaves reducing the productive leaf area. Heavily attacked leaves may drop off, and may lead to yield losses.

Bugs

Several species of sucking bugs feed on passion fruit. The most important are:

The green stinkbug (Nezara viridula)
The brown stinkbug (Boerias maculata)
Coreid bugs such as the giant coreid bug or tip wilter (Anoplocnemis curvipes) and the leaf footed plant bug (Leptoglossus membranaceus).

Bugs suck sap from the growing tips or developing fruits. The bugs pierce the terminal buds, which eventually wilt and die back. Young plants may be killed if the attack is severe. The punctured young fruits develop localised hardened spots that remain on the fruit reducing their market value.

Fruit flies (Bactrocera cucurbitae and Ceratitis capitata)

Fruit flies that feed on passion fruit in Africa include the melon fly (Bactrocera cucurbitae) and the Mediterranean fruit fly (Ceratitis capitata).

Pierced young fruit shrivels and falls; later injuries cause damage that lowers the market value of the fruit. However, the incidence of fruit flies on passion fruit is low, and usually of not economic importance. So control may not be necessary.

Spider mites (Tetranychus spp.)

Their feeding causes tiny yellow or white speckles, eventually leaves become yellowish and may drop, and may led to complete defoliation. Heavily infested plants may become stunted. A heavy infestation might also cause vine dieback and shrivelling and dropping of immature fruit.

The broad mite or yellow tea mite (Polyphagotarsonemus latus)

It is the most important mite pest of passion fruit in Kenya. Broad mites are tiny (0.1-0.2 mm long) and cannot be seen with the naked eye, and are even difficult to detect with a hand lens. An attack by the broad mites can be detected by the symptoms of damage.

Their feeding produces discolouration, necrosis of tissues and deformation. Initial attack occurs on stems of terminal shoots and young terminal leaves. Attacked young leaves are stunted, deformed (slender, twisted or crumpled), fail to elongate and finally may wilt and dry. Stems of terminal shoots may become slightly swollen, roughened or russeted. As a result the growth of the plant is affected and flower production reduced causing considerably yield reduction. A bronzed dusty appearance may occur on affected plant parts. Attacked fruits become deformed and show white to tan or brown scars on the skin. This damage usually does not affect the internal quality of fruits but affect their market value. Severely attacked fruits may fall. Symptoms remain for a long period of time after control.

Nematodes

Amongst nematodes infesting passion fruit the root-knot nematodes (Meloidogyne incognita, M. javanica and M. arenaria), are the most serious pests. Characteristic symptoms of infestation by root-knot nematodes are formation of galls or knots on roots, yellowing of leaves, stunting and eventual wilting of the affected plants.

Brown spot (Alternaria passiflorae)

The most important disease worldwide is brown spot on leaves, vines and fruits. Symptoms are brown spots, up to 10 mm diameter, on the leaves, often extending along the veins and drying out in the centre. On the stems, spots are up to 30 mm long, and when they occur at the leaf axils may kill the vine, resulting in dieback. On the fruit, the spots are light brown, round and sunken; they often merge, covering large areas, and produce red-brown spore masses. Spores, produced on the leaf, stem and fruit, are dispersed by wind-blown rain. Warm, moist weather favours disease development. (EcoPort)

Septoria spot (Septoria passiflorae)

The disease attacks leaves, stems and fruits. Brown spots up to 2 mm with minute, black dots (fruiting bodies containing fungal spores) develop on leaf surface. Infected leaves fall readily leading to defoliation of vines. Similar spots may form on the stems albeit elongated. On fruits light-brown spots studded with minute black dots may be formed. The spots often join up to cover large areas of the fruit. Affected fruits ripen unevenly. Spores produced by black dots (fruiting bodies) are blown to adjacent vines during wet, windy weather thus further spreading the disease. The disease is spread by rain, dew and overhead irrigation. Warm moist weather favours disease development.

Fusarium wilt (Fusarium oxysporum f.sp. passiflorae)

Fusarium wilt (also called collar rot) symptoms consist of yellowing of leaves, the collar region of affected plant at soil level turns brownish and vertically cracks and vines wilt followed by a complete collapse of the plant. On dissection of infected stem, vascular tissues show brown discolouration.

Phytophthora blight (Phytophthora nicotianae var. parastica)

Affected leaves are water-soaked and light-brown in colour. They fall readily, leading to defoliation of the vines. Affected areas of the stem are first purple and later brown above the graft union. They may completely girdle the stem causing wilting and collapse of the vine. Fruit symptoms comprise of large, water-soaked areas. Diseased fruits fall readily and in wet weather become covered with white, fungal growth.

Another strain of the fungus (Phytophthora cinnamoni) causes root rot. Yellow and purple varieties have different patterns of susceptibility. The yellow vine is susceptible to P. cinnamoni, and the purple vine is more susceptible to P. nicotianae. Both fungus strains attack both passion fruits and can cause root rot, wilt, damping off and leaf blight. Fungal spores are initially produced in wet soil beneath the vines and are splashed up to lower leaf canopy.

The disease is favoured by wet, windy weather.

Passion fruit woodiness potyvirus (PWV)

A number of virus diseases have been reported, notably the passion fruit woodiness potyvirus. Affected leaves show light and dark green mosaic pattern often with light yellow speckle. Sometimes small, yellow ring spots may develop on upper leaf surface. Infected fruits are small and misshapen with very hard rind and small pulp cavity. When affected fruit is cut, the inside rind tissue may have brown spots. Some strains of the virus cause cracking of affected fruits.
They are spread by aphids (Aphis gossypii and Myzus persicae) grafting and pruning knives. The virus has a wide host range including bananas, cucurbits and many weeds.