- Author: Ben Faber
Walking a passionfruit vineyard in Carpinteria recently, we saw wilted leaves and total plant collapse.
Passion fruit (Passiflora edulis) belongs to the genus Passiflora, a large genus in the family Passifloraceae consisting of approximately 530 species, many of which are cultivated for edible fruit, pharmaceutical properties, and ornamental characteristics. Passiflora vines can be propagated sexually through seeds or asexually by cutting, air-layering, and grafting. Popular cultivars include purple passion fruit (Passiflora edulis) and yellow passion fruit (Passiflora edulis f. flavicarpa, lilikoi in Hawaii), with the purple passion fruit (‘Fredrick') being the more common type commercially in California.
The fruit can be consumed fresh or processed for juice, flavoring, or value-added products like jams and jellies. The fruit is round or egg-shaped and 2½ to 3 inches long (6.3 to 7.6 cm). The yellow passion fruit is very similar to the purple type except for its skin color, being slightly larger and more acid. The yellow is considered more cold sensitive, although it has been grown successfully in San Francisco Bay Area gardens.
One of the most harmful diseases of passion fruit is fusarium wilt, caused by the fungus Fusarium oxysporum. On young plants, the symptoms include pale-green leaves, mild dieback, leaf drop on lower leaves, and general plant wilting. Yellowing of young leaves appears in adult plants, followed by wilting and death. The disease affects the xylem, causing impermeability of vascular walls and preventing the movement of water to other plant parts. Thus, the vascular tissues become brown at the root, collar, stem, and twig areas. The pathogen can spread by soil movement (machines, implements, shoes, etc.) and by water runoff or irrigation. Injury, such as weed whip and gopher damage are often associated with the disease. Disease severity is greater in high relative humidity and temperature. The plant can die suddenly with a heat wave or strong winds which put a high water demand on the vine. A sunken, dried trunk collar is often seen in diseased plants. Most commercial vineyards can collapse from this disease after five years in the ground.
Shrunken stems characteristic of wilt
Root and crown rot fungal diseases caused by Phytophthora cinnamomi and P. nicotianae are also found in passionfruit. The typical symptoms include chlorosis, wilting, defoliation, and death. Other common symptoms include scorched leaves and aborted flowers. Soil with low drainage, long periods of rainfall, and high temperature increase the incidence of the disease. To prevent the disease, use disease-free plant material. Plant collapse is not common, as in wilt, and lack of roots are characteristic. Phosphorous acid materials should be effective in the treatment.
The yellow varieties are considered more tolerant of wilt
- Author: Ben Faber
To Passionfruit Growers, packers, shippers:
Several state researchers with passionfruit are collaborating with Dr. Eric Stafne, Professor, Fruit Crops from Mississippi State University on a project to prioritize research and extension programs for the U.S. passionfruit industry. As a part of that effort we need your help in completing a brief survey (SEE LINK BELOW). If you have questions about the survey please call (Eric Stafne (tel: 601-403-8939) or Jeff Wasielewski (tel: 305-248-3311 x.227 or 305-282-7526). Please fill-in or return the survey by May 31, 2022 (sooner is better). Thanks. The survey is being done in preparation for a Passionfruit Meeting at the University of Florida
Survey link: https://msudafvm.co1.qualtrics.com/jfe/form/SV_5oFY0ThcIoepwXQ
This survey will help all the researcher-extension faculty involved in this nationwide effort plan and apply for grants that could subsequently assist you with pest issues (insects, diseases), disorders, postharvest issues, and cultural practices.
To register for the meeting (to be held at U of F's Tropical Reserach and Extension Center, Homestead, FL) please follow the link below. It will be held both in person and by zoom. more information us forthcoming on the agenda
Registration: https://www.eventbrite.com/e/growing-the-us-passion-fruit-industry-strategic-conference-registration-301652409477
Passionfruit interplanted with cherimoya
- Author: Ben Faber
To Passionfruit Growers, packers, shippers:
Several researchers in states with passionfruit are collaborating with Dr. Eric Stafne, Professor, Fruit Crops from Mississippi State University on a project to prioritize research and extension programs for the U.S. passionfruit industry. As a part of that effort, we need your help in completing a brief survey (SEE LINK BELOW). If you have questions about the survey please call (Eric Stafne (tel: 601-403-8939) or Jeff Wasielewski (tel: 305-248-3311 x.227 or 305-282-7526). Please fill-in or return the survey by May 31, 2022 (sooner is better). Thanks. The survey is being done in preparation for a Passionfruit Meeting at the University of Florida
Survey link: https://msudafvm.co1.qualtrics.com/jfe/form/SV_5oFY0ThcIoepwXQ
This survey will help all the researcher-extension faculty involved in this nationwide effort plan and apply for grants that could subsequently assist you with pest issues (insects, diseases), disorders, postharvest issues, and cultural practices.
To register for the meeting (to be held at U of F's Tropical Research and Extension Center, Homestead, FL) please follow the link below. It will be held both in person and by zoom. More information will be forthcoming on the agenda
Registration: https://www.eventbrite.com/e/growing-the-us-passion-fruit-industry-strategic-conference-registration-301652409477
Passionfruit interplanted with cherimoya
- Author: Ben Faber
Passion fruit is widely grown and valued throughout the tropics and subtropics. Most Passifloras are vines which can climb to 20 or 30 feet. The fruit varies in color from purple to yellow-orange and in shape from an egg to a tennis ball. Inside its quarter-inch protective rind are numerous small seeds covered by a juicy aromatic, sweet-acidic pulp. The sweeter species are esteemed as a fresh fruit. The seeds are consumed with the pulp. The fruit is more commonly made into juice and often blended with other juices such as orange. The fruit also is used to make excellent ice creams, sherbets, jellies, and pies. The downside of the passion fruit is that most esteemed species are very frost tender. The best adapted to California of the subtropical species, the purple granadilla (P. edulis), is prone to a fusarium soil disease. However, there is a yellow form which, though not as sweet, is not subject to this disease. More importantly, the yellow form can be hybridized with the purple or used as a rootstock. The crop grows mainly along the coast where it enjoys the mild weather.
The purple ‘Frederick' variety is probably the most widely grown commercial variety in California. It's great tasting, and I've been known to suck the delicious innards of 15 fruit at a sitting. Aside from fusarium wilt, it has few pests or diseases. That was until this fall when fruit spotting started showing up on fruit and leaves. The cause is a fungus – Septoria spp. – which thrives in cool, moist conditions. These were exactly what we had this year. All summer long, there was fog along the coast, and this is what the fungus enjoys. It colonizes leaves, defoliating the plant and spreading to the fruit, causing Septoria Blotch (Spot). Once infected there's not much that can be done, other than preventing further spread to the rest of the vineyard.
Photo: Fruit Blotch
Fungal structures (pycnidia) growing on leaf, causing scarring spots
Disease symptoms:
- Leaves are the most affected organs, showing light brown slightly round necrotic spots normally encircled by a chlorotic halo. A single lesion per leaf is sufficient to cause abscission, and even leaves without visible symptoms may fall prematurely.
- When the disease reaches 15-20% of leaves in the same plant, partial or even complete leaf abscission is observed. In young twigs, lesions may promote girdling leading to wilt and twig tips death.
- Lesions on flowers are similar to those on leaves. The primary infection in the calyx may reach the stalk, causing the early drop of flowers. The infection may occur at any stage of the development of the fruits, affecting maturation or development.
- Leaf and fruit abscission, twig wilt and plant death may occur under disease favoring conditions.
Treatment: Under ideal conditions and forehand knowledge!!!!
1) Rake up infected leaves on the ground and bury or compost more than 50 ft away from the vines.
2) Pick off spotted fruit and leaves and remove from field as soon as possible as spores are being produced in the lesions and can infect surrounding leaves and fruit when moisture is present.
3) During periods with dew, rain or ocean mist, spray Abound (azoxystrobin) or generic version of this fungicide on the vines. It distributes well over the foliage and fruit, is fairly rainfast, and gives about 2 weeks' protection.
4) To minimize the risk of the fungus developing resistance to Abound, apply a copper fungicide between Abound sprays, for instance Cueva (copper octanoate) is a good product and approved for organic production. Copper is a protectant and needs good coverage to be effective. It provides about 7 days of protection, possibly longer without rain.
So this year has been weird. Most years are. Lots of rain, no freezes, but it was a cold winter. Then all this fog in the summer that normally clears up going into summer. it seems like there's always something new. Had that funny scale on citrus again this year - wax scale - And the effects of fire can always bring a round of new pests. And there is always a new winter waiting for us.
Photo: Leaf and fruit spotting (blotch) from Septoria.