- Author: Ben Faber
Some call it tip burn which is often what you see on an avocado as it goes into flowering. The areas where avocado are grown typically have a lot of salts in the water, but also specific salts like sodium and chloride. Over the irrigation season (which is all year long there is little or no rain), the salts in the water/soil are taken up by the tree. In adequate rainfall years, there is enough water to leach those accumulated salts from the root system. When we go for several years with low rainfall and we keep irrigating with the poor quality irrigation water, the trees develop die back at the tips and is conditions worsen more and more of the leaf is called. This can get to the point where you can not call it die back any longer. It's called leaf drop. I've recently seen a number of orchards that are completely defoliated. No leaves. We have had a number of homeowner calls asking what the problem is and what they can do about it. The damage is done and those leaves are not coming back. It's possible to reduce the damage if one acts early on by applying more water than is usually applied to aid the leaching process, but if it is poor quality water, there will still be damage, but possibly not defoliation. With high priced water or where water is being rationed, many growers and homeowners do not have themake the option of putting on the excess water. There is no chemical or equipment that is going to make the situation better. When you trees defoliating, you want to cut out those that are diseased or you know have been poor producers and put what water you have on the remaining trees in better condition.
This advice is good for other evergreen tree crops like citrus, although they are not as sensitive as avocado. Avocado is an indication of how bad it really is.
- Author: Ben Faber
- Author: Robert Vieth
The white sapote is a relative of citrus. However, it is too distant botanically for the fruit to resemble, be graft compatible, or hybridize with citrus. The white sapote should not be confused with other fruit termed sapote (aka zapote) which only signifies a soft, sweet fruit in the Nahuatl Indian language. The white sapote is a native of central Mexico and appears to be well adapted to any area in California in which oranges can be grown. The fruit is slightly larger than a baseball. The thin, smooth skin is green, yellow, or orange in color. The smooth textured pulp, contained around* 5 to 7 moderate sized seeds, is pleasantly flavored (banana + peach). For some tastes the fruit of many of the cultivars lacks sufficient acidity to offset the sweetness, nevertheless a market for fresh fruit would likely exist if it were not for its poor handling characteristics. No market has been established for preserved products such as jelly, juice or wine. The enormous productivity in combination with a potentially mature height of 30 to 50 feet and an extensive lateral root system make the white sapote a problematical choice for the home garden.
Botany
The citrus fruit family, Rutaceae, includes about 900 tropical and temperate species of which citrus are the most commercially important. Other less well known Casimiroa species having edible fruit are the woolly-leafed sapote (C. tetrameria) and matasano (C. sapote).
The seedling white sapote tree grows to 50 feet under ideal conditions; however, many grafted cultivars tend to grow more slowly and can be held between 15 and 20 feet.
The leaves are mostly evergreen, palmately compound with 5 to 6 inch leaflets, and sometimes hairy on the underside. The odorless greenish yellow flowers are 4 or 5 parted and born in axillary panicles The flowers are hermaphrodites; however, the stigmas may prematurely abort. Cross pollination sometimes improves fruit set. The 2 to 6 inch ovoid fruits are borne 6 to 9 months after pollination, generally in October and November. The fruit is soft when ripened and has a smooth consistency with a delicate banana flavor with hints of peach. In poorer varieties and overripe fruit, the bitter overtone predominates along with an unpleasant resinous flavor. Although tree ripened fruit has the best flavor, the fruit is readily bruised and damaged when ripe. Some cultivars can be picked early and ripened to good flavor while others become overly bitter.
Climatic requirements
The white sapote is hardy northward to Chico except for the desert areas. Frost damage occurs at about 22oF; however, young trees can be damaged at 30oF.
Soil Requirements
The white sapote prefers well draining soils but will tolerate almost any soil. For healthy trees, the pH should be between 5.5 and 7.5. Salty soil conditions should be avoided.
Cultural Requirements
Spacing and training
The terminal bud should be removed from young trees in order to encourage branching.
Watering
The white sapote prefers regular, deep watering. Shallow watering will encourage surface roots which can be a nuisance for the home gardener.
Fertilization
White sapotes prefer regular applications of nitrogen fertilizer. Minor nutrient deficiencies (not a major problem) can be treated as with citrus.
Pruning
The main purpose of pruning is to control size and secondarily shape.
Pests and Diseases
In California the tree is generally pest free. Black scale, mealy bugs and aphids are occasional problems which are best checked by controlling ants. Snails will damage the fruit. Phytophthora and armillaria are not problems.
Propagation
Seedlings are considered too variable to be reliable producers of good fruit. Clonal reproduction is normally done by grating and budding as with citrus. Grafted trees bear in 3 to 4 years.
Harvesting and Storage
The poor handling characteristics of the fruit have limited its commercial potential. The very thin skin provides little protection against bruising which is aggravated by the fact that if picked when underripe the fruit will not ripen to full flavor and pick up an unpalatable bitterness. Overripe fruit also becomes bitter. Careful selection of cultivars can mitigate these drawbacks.
Fiscal
Orchard costs should be approximately the same as oranges or less.
Market
White sapotes are seldom available in markets. Development of better handling cultivars would appear to be essential if a market for fresh fruit is to be established. Just as important is the establishment of other uses, for example, those which would allow use of bruised fruits. One challenge is that the delicate flavor of white sapote is easily lost if mixed with other fruits such as lemon to provide a better acid, sweetness balance.
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- Author: Ben Faber
- Author: Robert Vieth
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 tropical species, the purple granadilla (P. edulis), is prone to soil diseases. However, there is a yellow form which, though not as sweet, is not subject to these diseases. More importantly, the yellow form can be hybridized with the purple or used as a root stock. Marketwise, the United States can not compete in the production of passion fruit juice, and a demand for the fresh fruit has not been established except for a very limited gourmet business.
Botany
The family Passifloraceae contains about 550 species of which 400 are in the genus Passiflora. Of these all but about 40 are indigenous to tropical and subtropical America. They are commonly found as understory plants in rain forests. The passifloras are herbaceous and shallow rooted. Leaves are usually alternate. The leaf margin can be toothed or entire.
The unusual flowers are the outstanding characteristic of passifloras and many are grown only for their flowers. The flowers are bisexual, colorful, possessing a complex corolla, and a superior ovary on a gynophore. The flowers were named by missionaries who associated them with the Passion or suffering of Christ (the five petals and five sepals with the ten apostles, the corona with the crown of thorns, the five stamens with the five wounds, etc.).
P. edulis bears 2 to 3 inch spherical to ellipsoidal fruits. The fruits have a tough rind with a white pith adhering to the inside surface, about .3 inches in total thickness, and wrinkled when ripe. Inside is the edible portion consisting of many small black seeds on which adheres a juicy orange colored pulp. The flavor is highly fragrant, sub-acid to acid.
The P. edulis has a subspecies, yellow (P. edulis var. flavicarpa). The yellow form is more acid, less frost tolerant, and less prone to disease. In warmer climates the yellow will out-yield the purple, but this does not seem true with most areas in California.
Yellow and purple passion fruit flowers are perfect but self sterile and require insects to achieve fruit set. Flowers of the purple are self-compatible. They blossom in the spring and early summer. Pollen of the yellow will pollinate the purple, but not vice versa. The fruit of both ripen in 7 to 8 weeks.
Although there are many passiflora species that bear excellent fruit, the edulis is the only species that is sufficiently cold hardy to be grown outside of the banana belts in the milder areas of California. More cold hardy species do exist, but the fruit is not generally preferred to the edulis. Included here is a summary of the characteristics of the more important species:
- P. actinia (sea anemone)
Yellow, 1 inch ellipsoid, fragrant pulp
Can withstand 24oF
Potential rootstock for P. alta and P. quadrangularis
Fruit is at best equal to edulis
- P. alata (fragrant granadilla)
Yellow, 4 inch sphere, white pulp
Frost tender (35oF)
- P. coccinea (red granadilla)
Yellow-orange, 2 inch ellipsoid, white pulp
Amazon basin, frost tender
Often hand pollinated
- P. incarnata (maypop)
Makes good jams
Southeast US
Hardy to 10oF
- P. quadrangularis (giant granadilla)
Green-yellow to deep yellow, 5x10 inch ellipsoid
Yellow to pink pulp
Low elevations in tropics (1,500 to 5,000 feet)
Frost tender (30o - 31oF)
Often hand pollinated
Considered one of the better species
- P. ligularis (sweet granadilla)
Orange yellow, hard shell, 2x3 inch ellipsoid, yellow pulp
High tropics 3,000 to 8,000 feet
Considered one of the better species
Frost tender (30o - 31oF)
- P. laurifolia (water lemon, yellow granadilla, golden apple)
Orange yellow, 2x3 inch ellipsoid, white pulp
Low tropics
Very frost tender
Requires cross-pollination
- P. maliformis (sweet calabash)
Yellow-green, 1.5 inches spheroid, white pulp
Grows in high tropics
Frost tender 30oF
- P. mollissima (Tacsonia mollissima) (banana passion fruit)
Yellow, 2.5 inch banana shaped, good quality. white pulp
Andean valleys
Can survive 28oF
Planted in more frost prone areas of California
Climatic requirements
The purple edulis is native to southern Brazil, Paraguay, northern Argentina. This area has a humid, near-tropical climate. The yellow edulis subspecies is native to the Amazon basin and perhaps a hybrid of the purple and P. ligularis.
The optimal growing temperatures are 68 to 82 degrees. Passion fruit likes full sun along the coast, but inland full sun should be avoided since it does like hot, dry heat.
Soil Requirements
Passion fruit grow best in fast draining soils (sandy loam) with a pH 6.5 to 7. Drainage is particularly important for the purple subspecies since it is susceptible to soil diseases. Since the roots of plants are shallow, planting in raised beds can help provide the necessary drainage. The plants benefit from mulching.
Cultural Requirements
Spacing and training
Passion fruit are usually planted on 8 to 12 foot centers and trained on strong supports in a fashion similar to grapes. They are also cordoned on walls or flat trellises.
Watering
Passion fruit require a lot of water, particularly inland. However, careful attention must be paid to watering since overwatering can help further detrimental diseases and underwatering can leave the shallow roots too dry.
Fertilization
Passion fruit require frequent application of balanced fertilizer during growing season. In winter plants may be chlorotic (yellow between the veins of leaves) due to cold soil temperatures.
Pruning
Since the passion vines are vigorous growers, pruning is necessary to keep the plants to a desirable size, to remove tangles, and to remove deadwood. The plants are vigorous and can be pruned anytime; however, pruning just before spring flush is preferred.
Pests and Diseases
The purple passion fruit is subject to fusarium wilt, nematode attack, and crown rot and, therefore, may require replanting every 3 to 4 years. Planting on mounds or ridges is recommended for better drainage. Fungicide sometimes is used on the crown in wet season. The yellow form is resistant to wilt and nematodes and, therefore, is occasionally used as a rootstock for the purple; however, both are subject to Phytophthora cinnamoni. Other possible rootstocks worthy of trial for California are P. caerulea and P. coccinea. Snails will strip leaves if not controlled, and thrips can be a problem on seedlings.
Propagation
Plants can be propagated by seed; however, the progeny are variable. Fresh seeds are far easier to propagate than seeds that are older than a month or two. Seeds should not be exposed to light until they have germinated. Older seeds can be soaked in tea or coffee for at least one day to improve germination. Fresh seeds will germinate in 1 to 3 weeks; older seed may take months. Plants will bear in 2 or 3 years.
An easy method of propagation and one that will preserve characteristics of the parent is by rooted cuttings. Misting or enclosing in a humid atmosphere (a plastic bag enclosing a pot will do for an occasional rooting) improves the success rate. Grafting is also used to propagate purple passion fruit on disease resistant rootstock (P. flavicarpa).
Harvesting and Storage
Fruit can be harvested when it has turned from green to purple or yellow or allowed to drop if gathered from the ground daily. Unrefrigerated fruit will last 2 to 4 weeks, paraffin coated and refrigerated at 40o to 44oF it may be kept for more than a month.
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- Author: Robert Vieth
The star fruit, or carambola, is a member of the oxalis family. Only one other species is commonly cultivated for its fruit, the less esteemed, more frost sensitive Averrhoa bilimbi. The star fruit is native to Sri Lanka and popular throughout southeast Asia, India, southern China, New Zealand, and Australia. The tree is well adapted to a variety of tropical and subtropical climates and is now cultivated in Mexico, the Caribbean, Central and South America and to a lesser extent, Israel. The main restricting factor in California is frost, the tree being about as cold hardy as limes. The golden-yellow fruit is 3 to 8 inches long and 2 to 4 inches in width with an star shaped cross section. The thin skin, appears waxy but is edible. The sweet to acid flesh is juicy, crisp and mild flavored and usually eaten fresh. It makes an extremely attractive fresh or cooked garnish when cut to reveal its 5 or 6 pointed star cross section. It is also made into relishes and chutneys. The sourer varieties contain more oxalic acid and can be used for polishing brass and removing rust stains. The wood is used for furniture and construction. The fruit is used medicinally as a folk remedy for a large number of maladies including hangover.
Botany
The oxalis family, Oxalidaceae, includes about 1,000 species which are mainly subtropical and tropical and usually herbs and shrubs. The carambola is a slow growing tree eventually reaches 20 to 30 feet under ideal conditions. The tree is deciduous. The 6 to 10 inch leaves are spirally arranged and divided into 5 to 11 opposite 1 to 3.5 inch leaflets. The lilac pink .3 inch flowers are borne from the axils of the leaves. Cross pollination sometimes improves fruit set. The longitudinally ribbed, ellipsoidal fruits are borne 6 to 9 months after pollination, generally in late fall and winter. Fruits very greatly in acidity, from very acid to sweet. The cross section of the fruit ranges from a distinct star to a more roundish shape. The fruit can be seedless or contain up to a dozen .25 to .5 inch, flat, brown seeds.
Climatic requirements
Young trees can be killed if temperatures go below 32oF. Mature trees can withstand short periods of 27oF.
Soil Requirements
The carambola prefers well draining slightly acid soils. Salty soil conditions should be avoided.
Cultural Requirements
Spacing and training
Trees should be planted on 15 to 20 foot centers in a sunny location. No special training is recommended.
Watering
The star fruit needs moist conditions and must receive regular watering in the summer and even during dry periods in the winter.
Fertilization
Regular applications of nitrogen rich fertilizer should be applied every 60 to 90 days. Deficiencies of minors can be a problem and can be treated as with citrus.
Pruning
The main purpose of pruning is to control size and secondarily shape.
Pests and Diseases
In California the tree is generally pest free.
Propagation
Seedlings are considered too variable to be reliable producers of large, sweet fruit. Clonal reproduction is normally done by cleft or veneer grating. Grafted trees bear in 2 to 4 years. Air layering is difficult because of poor root formation.
Harvesting and Storage
The handling characteristics of the fruit are not well established. Bruising could be be a problem; however, fruits are shipped successfully from the United States to Europe. The fruits are sensitive to storage temperatures, 50o F being the optimal.
Fiscal Orchard costs should be approximately the same as oranges.
Market
A market for star fruits is well established in the Asian community. Elsewhere, star fruits are not well known and are only available in stores with gourmet produce counters. Competition from importation into California would appear to be limited due to the severe fruit fly problems associated with star fruit and the inability to retain the desired crispness characteristic of star fruit through sterilization processing. Development of more frost resistant varieties would decrease the financial risks associated with this crop.
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- Author: Ben Faber
- Author: Robert Vieth
The cherimoya is regarded by many as being among the best of tropical fruits. The cherimoya has a texture of a soft, non-gritty pear and a delicate, highly appealing fruit flavor with little acidity. Cherimoyas usually are eaten fresh; however they are excellent in ice cream and sherbets. The seeds, leaves, and limbs contain poisonous alkaloids that have been used to kill lice. Taken internally, these alkaloids act as an emetic and cathartic and should be regarded as poisonous. The biggest drawbacks in production in California are that the flowers usually require hand pollination to ensure a good set of fruit, and ripen over an extended period; however, from a marketing standpoint these shortcomings can be turned into advantages. A recent appearance or introduction into the Santa Barbara area, of the trash beetle or Rove beetle (Staphylinidae), may provide sufficient pollination to eliminate the need for hand pollination. The species is not readily grown outside of its native (high elevation tropics) habitat. In the United States, only the southern California coastal climates are conducive to cherimoya production. Southeast Asians and Hispanics prize the fruit and a national market has been established in gourmet groceries. The fruit commands a premium price in these limited market places.
Botany
The Annonaceae family consists of 50 genera of which Annona (about 100 species) and Rollinia (about 50 species) are the most important commercially. The most esteemed of the fruits of this family is theAnnona cherimola. The family is tropical and semi-deciduous in habit. The cherimoya drops its leaves in late spring (or early summer) after which it blooms. Its leaves are alternate, ovate to elliptical (1.5 to 3.5 inches wide by 3 to 6 inches long) with a slightly hairy upper surface.
The family exhibits a protogynous dichogamous flowering habit, that is, complete flowers in which the stigma is receptive before the pollen is ready to shed from the anthers. This condition is very important in cherimoya since the configuration of its flowers is not conducive to pollination by natural means. Therefore, pollination is done by hand: pollen is usually collected in the late afternoon or evening, stored in a cool place, and applied to the mature stigmas which are usually receptive in the morning. Cherimoya flowers, borne solitary or in groups of 2 or 3, are pendulous having three fleshy petals, a green to brown exterior, white interior, and are 1 to 2 inches in length.
As is typical of the family, the cherimoya fruit is formed by the fusion or partial fusion of the carpels resulting in a more or less bumpy fruit with many seeds. Cherimoyas ripen in 5 to 8 months after pollination changing in color from a darker to a light green or greenish tan, 3 to 8 inch ovoid weighing 1/2 to 6 lbs. In California fruit ripens from November to June.
Other members of the family that are grown for their fruit are:
- Sugar apple or custard apple (Annona squamosa)
- Atemoya (A. squamosa & A. cherimola)
- Soursop (Annona muricata)
- Ilama (Annona diversifolia)
- Bullock's heart (Annona reticulata)
- Biriba (Rollinia deliciosa)
- Pawpaw (Asimina triloba)
Annona squamosa resembles the cherimoya in texture and flavor and, since it is the more widely adaptable to humid conditions, it is the most widely planted in the more tropical parts of the world.
Climatic requirements
All of the species grown for fruit require a tropical or semitropical climate except for the pawpaw which is native to temperate North America. Moreover, all but the cherimoya are better adapted to wet tropical conditions. The cherimoya's home is the highland tropics which are often characterized as areas of eternal spring with temperatures seldom straying from the 60'so (F). There are wet and dry seasons with typical annual rainfalls being about 50 inches.
The cherimoya is adaptable to Mediterranean climates. In addition to San Diego and Santa Barbara and Ventura counties in the United States, significant commercial plantings have been made in Chile, Spain, Peru, Israel, New Zealand, Australia and Italy.
The cherimoya requires a relatively frost-free environment similar to lemons (short periods of 26oF for mature trees of hardy varieties). Some chilling seems beneficial (50 to 100 hours between 32oF and 45oF). However, a sunny location is needed since sufficient heat is required to develop a good flavor (inland, protection from extremely hot temperatures and dry winds is more important). In California most varieties do well extending 3 to 15 miles inland from the ocean. Further inland, care must be exercised in selecting a variety that will do well. The cherimoya will not tolerate prolonged high humidity, such as is encountered in Florida.
Soil Requirements
The most critical soil requirement is that of good drainage. Sandy loam or decomposed granite is preferred, but cherimoyas will succeed on many soil types with pH 5 to 8.
Cultural Requirements
Spacing
Trees are normally planted on 20 to 25 foot centers in California. Tighter centers are used where intensive pruning is employed.
Fertilization
Cherimoyas respond to fertilizer applications generally provided every 3 months with a balanced fertilizer such as 8-8-8. Yellow leaves may not indicate a need for fertilizer but may be a response to cold temperatures or to the soil being too dry or wet.
Pruning
Train to 2 scaffold branches. Severe pruning (2/3 of new growth) is popular in order to aid in picking. Only shoots that are approximately 60 degrees from trunk are normally saved.
Pests and Diseases
Cherimoyas are generally disease free. They are susceptible to Armillaria (oak root fungus) and Verticillium wilt. Good drainage and watering practices will minimize these problems. Similarly crown rot can occur if care is not taken in keeping the crown of the tree relatively dry. Ants are a problem since they promote mealy bugs on the fruit. Ants are most easily controlled by limiting access from the ground by placing a mechanical or acceptable chemical barrier on the trunk of the tree.
Propagation
Although seedlings have a good probability of producing acceptable fruit, trees are normally grafted or budded on seedling rootstock to ensure reliable results. Grafting is done in the spring at or before leaf drop. Scion wood should be collected just before leaf drop. Plants also can be rooted from cuttings, although it is somewhat difficult. Seed has good viability for 2 to 3 years if stored properly.
Harvesting and Storage
Harvesting is done by hand while the fruit is still firm on the tree (February to April depending on location). The crop is normally hand pollinated to ensure a long harvest season. Ripeness of fruit must be determined by the color of fruit. Depending on the variety, the fruit turns from a deep green to a light green or greenish tan.
The fruit is packed in single layer containers to prevent bruising. If stored, temperatures should not go below 50° F.
Fiscal
The fiscal aspects of orchard investment are similar to that of lemons.
Market
Market has exceeded demand and supported a significantly higher market price which offsets the need for hand pollination and picking.
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