Replacing Citrus

Presentation by Bob G Cannon II

Thanks for the invitation to speak tonight. I’ve been here before and always found this to be a fun group. I have some cards to hand out that have contact information should anyone want them. You will find both telephone and internet information.

Why do we need to replace our citrus? The State’s canker eradication program is one example. This program is an ineffective reaction to canker and the Citrus lobby’s desire to protect commercial groves. Perhaps if the program had been implemented and administered properly, it would not have failed to stop the disease’s spread. Unfortunately, I have seen cases, where no lawsuit was involved, where diseased trees were not removed for 4 months or more. Healthy trees are removed, eventually, along with the diseased with no compensation to the owners, and only the barest concern for civil rights.

If the current eradication program was going to work, then canker would have been eradicated already. The program has failed, canker continues to spread, and the powers that be continue to destroy healthy trees with the diseased.

As if canker (Xanthomonas citri ex Hasse) was not bad enough, there is a virus,Citrus Tristeza (CTV),that kills sour orange. Guess what most of our citrus is grafted onto? At least with this disease there are rootstocks that are resistant and, as yet, no one has called for the wholesale removal of all sour orange.

What seems to be left is a vague hope that those with the money and research capabilities will begin to focus on something other than wholesale destruction of citrus. Perhaps resistant trees can be found, or existing varieties can be made resistant through genetic manipulation. A number of trees on sour orange are being replaced by those on other rootstocks.

A home owner can replace their trees if they die but may face their loss again to canker or a government mandated chain saw. What IS the average homeowner to do?

Rarefruiters will want to replace their citrus not only with an attractive tree but with one that provides fruit as well. I’ll tell you, right up front, that if you are craving a pummelo or pon gan orange (what ever your favorite citrus) there is nothing that can replace it. Not for flavor, texture and aroma.

Still, faced with holes in our landscape and diet there are some plants that used as citrus replacements will give us good fruit and be an addition to out landscapes. What follows are some of my selections and why I would choose them. Without a doubt, some of you will have other suggestions to add, while others may sigh “Oh, not THAT!"

Some citrus relatives (Rutaceae family)

Not known to be canker or Tristeza virus susceptible but with research this may change.

White sapote, matasano, Casimiroa edulis (and C. tetrameria), these are from Central America and Mexico. C. tetrameria is known as the wooly leafed white sapote. Here in Florida we don’t see this fruit very often, but when you travel to California you find that it is quite popular (even out of the typical rare fruit circles) and that a number of varieties exist. Californians commonly refer to them as sapote. A well fertilized tree is quite pretty and adds to the landscape.

The compound leaves are not very citrus like and I would liken the texture of the fruit to a soft pear or peach. Flavor varies widely from one variety to the next as does flesh color. Most have white flesh but I have seen some with a golden color.

They are easy to propagate from seeds and grafts, and give a fairly rapid growth. They respond well to any good fruit tree fertilizer and benefit from nutritional sprays.

Wampi, Calusena lansium, is from China. Long cultivated in China and SE Asia, there are many varieties. Here in Florida I think I have heard of three, maybe four. The tree is rather pretty and the fruits look a great deal like small longans. You even eat them like a longan or litchi, splitting them out of their brown papery skins.

The taste is described by some as too resinous, but they are not too bad. Some of the varieties have little of this characteristic. I’ve never had any but I am told that they make good jellies and jams. I do eat the fruit out of hand when I can get it.

Non Citrus Relatives

Black Sapote, Chocolate Pudding fruit, Axle Grease Fruit, (Diospyros digyna) Ebenaceae. These are from Central America and related to our North American persimmon, D. virginiana. The common names vary widely for this fruit; Black Sapote, Chocolate Pudding Fruit, or Axle Grease Fruit, and while the last one may describe the ripe fruit’s texture the best, using the “Australian Chocolate Pudding fruit” may do the most to get folks to actually grow and use it.

A healthy, dark green Black Sapote is one of the prettiest trees you will see in any landscape. The leaves shine in the sun and the tree can be grown as a mound or be trimmed up enough to mow or plant under. Healthy, they look good enough to be used as a specimen plant. They also take wind fairly well.

There are a number of named varieties and the fruits come in all sizes. My own seedling tree has been slow to bear, but this year I stressed it and it produced flowers. I am sure that the fact I let it get frozen to the ground a couple of years back has not helped.

Fruit size and shape varies some between varieties, but, I have never had one that was not edible. Since I have a typically North American palate, I find these too soft to really enjoy out of hand but have made tasty smoothies, ice cream and bread from them.

Named varieties include Bernecker, from Homestead, and Maher which comes from a member of the Palm Beach RFCI. From the seedlings I’ve tasted fruit from, it seems that you have a fair chance of producing a good fruit from seed, especially if the seed is from a good variety. Like most of our fruits, they benefit from a fruit tree fertilizer and occasional nutritional spray. Mulching around the base of this (like most of the trees we grow) helps stabilize soil moisture and temperatures, and cuts down on competition from weeds.

Other Diospyros which I am not covering here, such as our native virginiana and the Japanese persimmon D. kaki might also be considered for our landscapes. Both for fruit and appearances.

Having mentioned both white and black sapote I must note that there are some true Sapotaceae that, climate permitting, can substitute for citrus.

Pouteria sapota, Sapotaceae family, from Central America, form an interesting large leafed tree with big, sandpaper-skinned fruits. A number of varieties exist and I have never had one that was not good to eat right from the tree. They also make good ice cream, drinks, and can be baked into breads and such.

Some fruits have a learning curve; that is, most people have to eat them several times before they really like them. Not this Sapote. From time to time I host travelers from far flung areas. If they are from areas where these do not grow I love to introduce them to this sapote. So far, whether from Africa, Bangladesh or Germany, every one has liked this fruit on the first try.

Other Sapotaceae that might be used are:
Canistel, P. campechiana which is a smaller tree with yellow to yellow orange fruits whose flesh is similar in texture to a sweet potato. Several varieties are found in Florida. The one called ‘Ross’, which may be a hybrid, or other species is very appealing.

The Abiu, P. caimito with flesh texture somewhere between the Sapote and Canistel has yellow fruit and a good growth habit. The variety Gray’s 1 from Australia has a good flavor. So do Z1 and Z2.

Sapodilla, Manilkara zapota also called chico sapote and naseberry from the tropical Americas is very pretty, most especially so when young. Several varieties are available and most, even seedlings have a good taste. They do contain schalrids, starch cells like in pears that make some varieties gritty to eat. An RFCI member in Tahiti likes these so much he named his son Manilkara. Under the best of conditions these grow bigger and spread more than Citrus.

Most of the species I mentioned propagate from seed and grafting fairly well.

How about Passiflora to replace citrus? I suspect that everyone here has tasted either a key lime or lemon meringue pie. That tangy tartness can be had with some of the passiflora - flavor is different, but quite agreeable if you like fruit pies. Some of the best syrup I have ever tasted came from a lady in California and was made from Passiflora edulis.

True, you need to grow these on a fence or trellis but the fragrant flowers and edible fruits are worthwhile.

I want to mention a mangosteen and relative here.Mangosteen (Garcinia mangostana) Guttiferae (Clusiaceae) would be a great citrus replacement except for the fact that 95% of Florida is too cold for them. Ed Krajalis made a start on finding one with cold tolerance and getting us to try them. With time and some luck, we just might get one that withstands our climate.

Many of us like to grow small citrus in containers and this is where the Button Mangosteen, G. prainiana comes in. Also called Cherapu this plant comes in male and female. Both have a beautiful pink flower and when pollinated the female produces orange fruits the size of small tangerines. I love them, finding their flavour a bit better than true mangosteen. They grow and will fruit in medium sized pots, and one could graft male and female on the same plant. You would need to take them in or protect them from frost, as they are sensitive. They grow from seeds.

I also like a Rheedia sp. that Bill Whitman grows. This is an evergreen tree that bears bright yellow lime sized fruits. Propagation is difficult. The seeds need to literally go from mouth to seed pot and as far as I know I am the only one to successfully airlayer one. Sadly I suspect it’s too cold in most of Florida for this.

Macadamia integrifolia and M. tetraphylla, Protaceae, from Australia may produce one of the most beautiful fruits we grow. Their tight form and spiny leaves reminds many of northern varieties of holly. Hybrids between the two exist but the variations between the two are minor.

These produce a medium sized tree that withstands some cold. Wind can be a problem especially with young trees. Squirrels will fight you for the nuts. My mom lost her second crop when the squirrels went inside her patio to get the nuts she had picked to hide from them. There are a couple of varieties. I have heard that the so-called ‘thin shell’ develops more fungus than the others. This may be true, as the shell is not really thin, but has a defect that allows for easier cracking. Even if the squirrels get all the nuts the tree is really beautiful. They propagate fairly easily and are precocious, I have seen them in bloom when less than 3’ tall.

As to eating quality I would place these in a tie (with Cashew) for the second best nut in the world. Who knows what the best nut is? Taste is subjective but I have never found any nut that equals a good fresh pecan.

Loquat, Eriobotrya japonica, a member of the Rosaceae like apple and pears is not tropical but can be worth growing. Like many of the other fruits mentioned there are several varieties available. More if you (or your nurseryman) is willing to import bud wood from California. I have always liked these fresh but have also had a jelly that was good.

The tree, once established, will withstand almost any of our cold spells. The course leaves are a lighter green on the underside and very showy. Commonly the trees you see used in landscaping are seedlings, not selected for fruit, and it would benefit you (and the rare fruit movement) to find the varieties selected for large fruit.

Carib fly is the main pest with these, as with many of our smaller fruit the larvae will infest and ruin the fruit. Fortunately in our area Carib fly is an intermittent problem and a couple of frosts seems to knock the populations down so that not all fruit is affected. Good grove practices such as mulching and removing surplus fruit also helps to a degree. One other positive note is that the flowers, while small, are fragrant and fairly prolific.

Once I got started on this I realized that there were many more plants that come to mind as citrus replacements. A number of plants in the Myrtaceae such as guavas, various ‘cherries’ and the jaboticaba. Whose yard would not be improved with a beautiful jaboticaba whose trunk was covered in snowy white flowers (or ripe purple/black fruits)? Myrciaria cauliflora (Plinia cauliflora). Small mangos also have a place. Some might even be used in containers. Many of you are growing Carambola, and Annonas are quick and small to replace lost fruit. Red sugar apple, atemoya.

I wanted to end the presentation with a couple of members of the Sapindaceae. I like the Alupag (Might be Litchi chinensis, or not, depending on the experts) but they are hard to propagate and seem quite cold sensitive.Rambutan, Nephelium lappaceum, also finds it too cold here. I tried several varieties in Hawaii and found the taste somewhat disappointing.

Lychee, Litchi chinensis, despite the fact that most are irregular fruiting, should do well for most of you. The tree has a good form, is evergreen and takes well to pruning to size and shape. Once established they show a good degree of cold tolerance. There are a growing number of varieties available and since they propagate through layering and grafting the selections available to buy are not bad.

I like the old Bengal and Sweet Cliff and Kwai Mai Pink. Kwai Mai Pink does not have as bright a colour of fruit as some of the others but the taste is good and the one tree I have had a chance to watch for several years seems to bear fairly well. Of course this tree gets a lot of stress as many people layer starts off it, myself included. A number of people in Australia claim that the lychee can be made to fruit regularly if stressed.

My favorite variety is Emperor, with large juicy fruits and a small compact size.

Longan, Dimocarpus longan, is the last to consider tonight. Longan is quite similar to lychee in size and shape as a tree. Most that I have seen in Florida grow larger than lychee if left alone. Fruiting seems more consistent and it seems easier to meet the tree’s nutritional needs. While there is currently much discussion on the profitability of growing longan I find the fruit not quite as good as lychee.

This tree also propagates easily from seed, layer and graft. The growth rate is fairly quick and layered plants are precocious, producing some fruit while still fairly small. The fruit is not as pretty as lychee being covered in a brown sand-papery skin. As with lychee a couple of new varieties seem to show up every year but Kohala still seems to be the standard to measure against.

There is a continuing discussion as to which is hardier, lychee or longan. The experts I spoke with seem to be about evenly divided on the issue. I suspect that depending on the microclimate and soil we will see some confusion for some time on this. For now it may be best to think of them as about the same once established.

Again, I would like to thank you for your invitation to speak tonight and your hospitality. The Caloosa Rare Fruit Exchange has always been fun and I enjoy promoting you and your events through my internet and other activities. If there are any questions....?

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First presentation January 2003, with some updates over time.

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