My Citrus Inheritance

I've never written about my own citrus trees. I find the topic of citrus a depressing one--- such a marvelous fruit ruined, not by villains but by the invisible hand's relentless preference for unsustainable practices that no one could manage to get stopped. But citrus trees have been receiving a lot of attention lately at my north Sarasota County fruit tree haven, so here goes.

We've owned this land for five years now. All of the rare fruit trees on it are my doing, but it came with a couple of dozen citrus trees. Neighbors date them back to the owner before the owner before us, Errol “Old Man” Campbell. I never met him, but one can see that he knew something about fruit trees. They were grafted, and the low-lying areas had been worked to put the trees on long mounds with shallow swales between.

I've never figured out all the varieties. Some were obvious: the Temple orange, the two Minneolas, the red navels, and a couple of Valencias. One is some kind of tangelo. The previous owner, who knew more about construction and drinking vodka than about fruit trees, said he had all the names written on a piece of paper, but couldn't find it.

Some say Campbell grafted the trees himself. Whether or not that's true, I'm sure he would not have been pleased by their condition when I first saw them. At least half were not even worth trying to save. The best one was a big Valencia orange, but try as I might, there was no place to locate our house construction that didn't require its removal. That hurt, but at least it was possible to leave the big lemon tree that is still very productive today.

The first couple of years, after major pruning, installation of irrigation, fertilizing, and some can't-hurt meditation to Ma'am Gaia, most of the dozen or so trees that survived triage produced some fine fruit. In my book there's nothing quite like a perfect Minneola, except maybe a perfect Temple. The unknown varieties also produced some tasty fruit, as did one of the three red navels--- the one that's not in too much shade.

But all of them were already battling citrus maladies. The Minneolas were the first to show a serious downward trend. I even stripped all their fruit in 2014, hoping to give them a chance, but by early 2015, they were hopeless. Along with the remaining Valencia, that never got healthy enough to produce any fruit, they were replaced by a Sweetheart lychee, a tasty black mulberry I got from Pete Ray, and an Alano sapodilla.

To try to keep the dwindling collection going, I've followed the standard recommendation of foliar fertilization and strong slow-release ground fertilizer, as well as various might-help organic products on leaves and soil. The two lemon trees seem to be holding their own, especially the big one just west of the house. It has supplied our kitchen six months of every year, plus the equally demanding annual lemon cleanse of friend Francisco, with plenty left over for the in-laws, pal Kevin, and the fellow who mows my lawn. But the grapefruit tree and the remaining seven orange trees have continued their slide.

With help from my right-hand man, MRFC Secretary Josh Starry, we've been doing the annual citrus evaluation and pruning. The tangelo's main trunks were splitting and filled with ants, and when one of them fractured with just a one-arm pull, we marked the tree for removal. And one of the unknown orange varieties didn't produce fruit last year or even any healthy leaves in its spring flush, so it will be put out of its misery.

The remaining trees have earned another year of effort, but it's obvious that they don't have enough energy coming from the roots to support their foliage. So this year we decided to be more aggressive, removing not just dead wood and bad branches, but thinning out all but the strongest-looking portions. Most of the trees are being reduced by 30 to 50%. Here are some “after” shots.

 I hope for at least a couple more years of oranges, and dream of keeping the lemon trees going for a long time. And to look for a silver lining, when the oranges do stop coming, I'll have some nice spots opening up for whatever the latest can't-live-without rare fruit trees may be.

Big Jim And The French Woman

A couple of weeks back, as I lounged with a book, Dear Wife returned home after a visit to her boyfriend, a 94-year-old gent who lives in a nearby nursing home. He's still mentally sharp, despite a body that's letting him down. They play geography word games, and hold hands on imaginary Ferris wheel rides. A joy for both of them.

My wife dislikes perfumes and the like, and I'm not fond of them myself, so when she walked in, I gave her fair warning: “If I smell like perfume, it's because I've been hugging a French woman.”



How so? A couple driving by my house saw my Big Jim loquat tree, a muscular-looking 7-foot specimen. It was showing lots of colorful fruit, even though I had thinned them out a few weeks back. Big Jim is in the very corner of the northwest grove, next to the main road, and the man and his wife, who hails from France, had seen it week-after-week on the way to the nearby farm stand.

The wife loves loquats, though she knows them by a different name, and she finally persuaded her husband to stop by. He came my door and offered to buy some. I told him I had plenty, and would be happy to give them some, and off we went to harvest some Big Jim and Bradenton loquats.






In footwear quite unsuitable for trekking through my Bahia, wedelia, fire ants, and heavy mulch, the pretty lady had remained at the car. When I returned with a big bag of ripe fruit, she was overjoyed, and rewarded me with a warm and very aromatic hug.

Fruit tree growers meet the most interesting people.

Too Young To Be a Mama

One of the points I emphasized in my recent classes for new fruit tree growers is the need to remove fruit from young trees. Most every grower learns this early on, but it's actually something that doesn't occur intuitively to most people.

And why not? My theory (based on no evidence, but that's never stopped me from theorizing) is that it's natural to assume that a tree “knows what to do”, so if it's making fruit, it must be right. And indeed, plants generally do know exactly what to do.

The catch, though, is that a grafted tree (or one propagated by cutting, or airlayering) doesn't follow a normal course of maturation. Almost the first topic we discussed in the classes was the nature of grafted trees, and the reasons it's so important to use grafted trees for most of the major fruit species. I explained that the scion “thinks it's still on top of a big, strong tree” that will be providing it with lots of energy and nutrients. So it tries to do what would then be appropriate--- make more trees--- even when there's no hope of having the wherewithal to bring the fruit to full size and ripeness. A seedling, on the other hand, must prepare to compete with other plants for sunlight, so it puts its resources into growing big and tall as fast as it can. Its best strategy is to establish itself before risking resources on reproduction.

A three-gallon Kesar mango made a good prop. It was pushing flowers in all directions. How, I asked, can this little thing come up with enough energy to make mangos and still have enough left to grow, or even keep itself healthy? And with such limited capacity, the fruit is unlikely to be of high quality anyway. Once one understands this, it really shouldn't take any will power to remove the fruit. All of this made total sense to the classes.

Of course it's far easier to give advice than to follow it, and last year I made the very mistake I warn against. A young Tropic Beauty peach tree was covered with fruit. I took scores of them off, but figured I could get away with leaving half a dozen on. They ripened fine and made a tasty spring treat, but the tree then languished well into the growing season, ending up only little larger than it started.

Suitably chastened, I'm being rigorous this year. No peaches on young trees, and just a few small plums remain on the Scarlet Beauty. Among the mangos, only those with some muscle will get to try. When it comes to avocados, Steve Cucura warns that they can kill themselves with early fruiting, so only the Brogdon and Oro Negro that sport two-inch trunks will get the green light.

But what might put me to the test is all those flowers on my young lychee trees. If they turn into little fruits...

More On Mango Fungicides

A couple of weeks ago we examined some of the options for fighting mango fungi, especially the big two, anthracnose and powdery mildew. It's an important topic for us mango growers, and this is the critical time of year for forming and holding fruit, so let's give it another look.

The Washington State University investigated a number of organic fungicides registered for home use and compiled an informative table about their effectiveness and side effects. Most are available from makers of garden products such as Bayer Natria, Earth Tone, Garden Safe, and Worryfree. Bearing in mind that the focus was not on mango production but rather on home gardening, here are some notable items:

---Bacillus subtilis (sold as Serenade) - Low to moderate efficiency of up to 50% disease reduction. Best results are when used to treat powdery mildew at the first signs of disease.

---Canola oil - Very high (near 100%) effectiveness. Acts directly and locally. May cause damage in high concentrations.

---Neem oil - Moderate to high efficiency, from 60-90%. Not long lasting, not known to damage plant tissues. One of its components is an insecticide that should be used with caution if bees are present. (Maybe we'll find out more from our next MRFC speaker.)

---Potassium bicarbonate (sold as Bi-Carb Old Fashioned Fungicide) - Moderate to high efficiency, highest on smooth surfaces. Only effective on contact, and may damage plant tissues.

A recent thread at the Tropical Fruit Forum discussed copper-based fungicides. A veteran grower in Broward County, self-described as “bio-sensible”, makes the case for copper. On a half acre of 30 mostly large mango trees, he uses a mix of copper octanoate and elemental sulfur, which he says contains about a quarter as much copper as regular liquid copper fungicide. He says that he can spray all of his trees using just two gallons of mix, making the total amount of copper “miniscule”.

In more detail, Broward calculates that the ½ cup of copper octanoate used for one spraying contains only about 1/15 of an ounce of copper, compared to a quarter-ounce in a bag of palm fertilizer. Alternatively, one gallon of concentrate--- enough for an entire year in his grove--- contains about 0.15 pounds of copper, below the recommended application rate as a soil nutrient. He also notes that according to the label, copper soap is allowed on organic vegetables up to the day of harvest.

To accomplish this efficiency in his spraying, he uses a thousand-dollar mister (pump included). I suspect that my $15 hand pump sprayer would need a lot more concentrate to do the job.

A very, um, outspoken mango professional (TFF readers will know of whom I speak), who rarely leaves Broward's comments uncontradicted, says

“Many years ago people used copper to treat powdery mildew. Like humans and taking penicillin, copper ceased to be effective for the treatment of powdery mildew. Sulfur is now the `drug of choice' for treating powdery mildew.”

And what does the Washington State Extension say?

---Copper octanoate - Potentially high efficiency of 74% in greenhouse trials. “Material may persist in soil, but potential effects are not documented.”

---Sulfur - Low efficiency by itself, but seems to boost the effectiveness of other fungicides. Some may be absorbed as a plant nutrient, strengthening the plant's natural resistance.

And now that I've made everything perfectly clear, it's your call!

Spring Training

Baseball spring training is well underway, and there's also been some spring training for mango season here in north Sarasota. All thanks to Rosie, my Rosigold mango, not to be confused with the well-traveled Rosie who now lives with Mr. and Mrs. Colorado.

Rosie was bought at the MRFC's 2012 tree sale, and stands a little over six feet tall. In the crazy warm weather last fall, she bloomed and managed to hang on to several mangos. They were going along fine, but seemed to stop growing after the near-freeze on January 24 ushered in a stretch of cooler weather. I picked one on the 31st, just in hope that I could say I grew a January mango, but it never ripened.

So I wasn't very optimistic about the one I picked early in March. It sat on the shelf for a long time. Lemons and loquats joined it briefly, before moving on to their culinary destinies. Finally, a patch of anthracnose on its skin started to spread, and maybe it didn't feel quite so firm, so on March 23 I decided to give it a try.

RBI for Rosie, it was a pretty good mango! Firm, but sweet and very flavorful. Best I've had since, oh, last fall.
 

Regular season baseball starts in a week, but regular season mangos are farther off. At least there's a little more to come for now. Here is another of Rosie's, that will be ripening on the shelf by the time you read this.

And Rosie's all caught up in the frenzy of mango-making going on around here, so she's making more fruit too.

As long as I'm showing off mango photos, I can't resist closing with this shot of three on the east side. From the left: Glenn, Coconut Cream, and Mallika. With oak trees to the east and west, they have to get by on a few hours of midday sun. But they have grown well--- well enough to earn the green light to produce a few fruit this year if they can manage it.

Hold The Copper

Mango trees are blooming like crazy right now. They are mighty easy trees to grow, at least for those within a few miles of the coast, but they do have one Achilles' heel--- their vulnerability to fungi. Anthracnose and powdery mildew are the big two, but there are also scab, leaf spot, and Verticillium wilt. An extensive collection of photos of these uglies, taken by Scot Nelson of the University of Hawaii at Manoa, can be found at growables.org.

The big two can attack newly emerging panicles, flowers, and young fruit, leading to the disappointing fruit drop that often follows a promising start. What's a dooryard grower to do?

Prevention is always the best place to begin, and good basic practices include selecting anthracnose-resistant varieties and growing in sunny locations where the trees can dry off faster. Also, prune to keep the interior open to airflow, again to minimize fungus-friendly moisture. This carries the added benefit of letting more light reach the lower branches, helping the grower to keep the tree shorter and bushier.

When fungal problems do appear, sulfur and copper are the standard fungicidal options. One application when the panicles are half-size and a second about 10 to 21 days later is a typical recommendation. Elemental sulfur is non-toxic, while copper definitely falls in the toxic category, and can persist and accumulate. Sources are inconsistent concerning the relative effectiveness of these against each of the big two fungi, but the general impression I get is that sulfur is effective against powdery mildew but perhaps not so much against anthracnose. The "safe" recommendation seems to be copper or a combination of the two fungicides.

I reckon there is sulfur in my future. As for copper, never say never, but I'll have to be dragged there kicking and screaming.

For now, I'll make use of the twin luxuries that dooryard growers have and commercial growers don't. First, our fruit can be ugly, as long as it tastes fine. And second, we can fail without going out of business. So this season I'm trying a biological approach using a well-known fungus-fighting microbe, Bacillus amyloliquefaciens. It comes in different strains, and strain D747 is approved for use against papaya anthracnose in Hawaii. At least one strain, DGA14, has worked against mango anthracnose on fruit surfaces in the laboratory.

Last year I obtained some D747 from a large supplier of ag products for the southern region, and I've been spraying it on my mango trees during this flowering season. Of course the great and sometimes insurmountable challenge of horticultural science is to ferret out which of the dozens of variables involved are actually having an effect, so I don't expect anything definitive from my limited sample. But if my larger trees all hold some fruit this year, B. amyloliquefaciens will get a longer look. If not, then there's Bacillus subtilis...

The Latest Commercial Banana Disaster

I hope everyone enjoyed Betty Kearns' article and photos in the March MRFC newsletter as much as I did. In January Betty and Pete toured a banana plantation in Costa Rica, including its ultra-efficient processing facilities preparing the fruit for export. If you missed Betty's article, do catch it in the MRFC archive here.

Bananas were again a topic, this time for the second hour of the March 10 Diane Rehm show on NPR, available on iTunes or for direct download here. The title was “The Uncertain Future of the Banana”, and featured scientists Robert Bertram of the USAID and Randy Ploetz of TREC, as well as Dan Koeppel, author of Banana: The Fate of the Fruit That Changed the World.

The program's headline story is the latest version of Panama disease, the soil-borne fungus Tropical Race 4. TR4 refers to the fungal strains of Fusaium oxysporum f. sp. cubense that cause Fusarium wilt in Cavendish cultivars grown in tropical conditions. In addition to the normally fungus-resistant Cavendish, TR4 affects a number of varieties of dessert and finger bananas, and is devastating commercial operations wherever it appears. It's been detected traveling halfway around the world on muddy boots, and its spread to all major banana-growing areas is considered inevitable.

There is no cure for TR4, and drastic techniques such as sterilizing the soil with methyl bromide (not a favored Druidic practice) provide only a couple of years of production before the soil is recolonized worse than before. Leaving land fallow is useless, as TR4 can survive below ground for decades. Conventional selective breeding for resistance looks hopelessly difficult for the seedless domesticated banana. Dr. Ploetz holds some hope for genetic engineering methods, but only time will tell whether they bring more rapid progress for bananas than for our beloved citrus.

The program has some interesting discussion of bananas and their commercial industry. Around 400 million people rely on bananas as a primary source of calories, and about the same number derive a significant part of their livelihood from its cultivation. In contract to the large-scale production methods of the Americas, around 95% of bananas in Africa are produced by small farmers.

The panelists agreed that Cavendish is not a great-tasting banana. Indeed in India, which has 600 varieties of bananas, it's called the “hotel banana” since only tourists want to eat it. It's inferior to the Gros Michel, which was the dominant commercial variety until the 1950's when an earlier edition of Panama disease destroyed its commercial value. Tasty or not, the Cavendish is the most productive commercial variety, accounting for half the world's banana production, and now it's on its way out.

The panelists had differing speculation about the future of the banana industry. Dr. Ploetz doubts that American consumers will accept higher prices for unfamiliar and less beautiful bananas, but Dan Koeppel was more optimistic. I am more in the latter camp, agreeing with Koeppel that just as apples are now accepted in several commercial varieties, bananas can diversify and still keep a space--- perhaps a lesser one--- on grocery store shelves. The major banana companies are well aware of the educational challenge before them: teaching Americans that many varieties need to be well-browned before reaching their optimal flavor. Enormous amounts of Cavendish are discarded from stores simply because they have a few brown spots.

Is TR4 a worry for us dooryard growers? Not much, as there are still plenty of good-tasting TR4-resistant varieties to choose from. Only in the kilos-per-hectare commercial world does “productivity” matter so much. The question is whether bananas will become one of the “rare” fruits we've named our club for.